Publications by authors named "Robert P Davis"

19 Publications

  • Page 1 of 1

Subnormothermic ex vivo lung perfusion attenuates graft inflammation in a rat transplant model.

J Thorac Cardiovasc Surg 2021 Jan 30. Epub 2021 Jan 30.

Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University, Durham, NC; Department of Immunology, Duke University School of Medicine, Durham, NC.

Objective: Ex vivo lung perfusion has emerged as a novel technique to safely preserve lungs before transplantation. Recent studies have demonstrated an accumulation of inflammatory molecules in the perfusate during ex vivo lung perfusion. These proinflammatory molecules, including damage-associated molecular patterns and inflammatory cytokines, may contribute to acute and chronic allograft dysfunction. At present, ex vivo lung perfusion is performed clinically at normothermic temperature (37°C). The effect of lowering temperature to the subnormothermic range during ex vivo lung perfusion has not been reported. In this study, we hypothesized that lower ex vivo lung perfusion temperature will lead to a reduction in allograft inflammation and result in improved post-transplant graft function.

Methods: Lewis rat heart-lung blocs underwent 4 hours of ex vivo lung perfusion in 3 temperature groups: 37°C (MP37), 30°C (MP30), and 25°C (MP25). In the control group, lung grafts were preserved by static cold storage before transplantation. After ex vivo lung perfusion or static cold storage, the left lung was transplanted for 2 hours before the animal was killed. Sera and tissue were collected and analyzed.

Results: There were no differences in partial pressure of arterial oxygenation to fraction of inspired oxygen ratios during 4 hours of ex vivo lung perfusion between temperature groups. Tumor necrosis factor α significantly increased in the MP37 group during ex vivo lung perfusion, whereas this was not seen at lower temperatures. Extracellular DNA and high-mobility group box 1 perfusate concentrations increased significantly during ex vivo lung perfusion in all groups, but the rate of increase was diminished at lower temperature. Two hours post-transplant, there were no significant differences in partial pressure of arterial oxygenation to fraction of inspired oxygen ratios of the lung graft or serum damage-associated molecular pattern levels among groups. On histologic grading after transplantation, greater injury was observed in the MP30 and MP37 groups, but not MP25, when compared with static cold storage.

Conclusions: Subnormothermic ex vivo lung perfusion at 25°C reduces the production of inflammatory mediators during ex vivo lung perfusion and is associated with reduced histologic graft injury after transplantation.
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http://dx.doi.org/10.1016/j.jtcvs.2021.01.066DOI Listing
January 2021

Donor Leukocyte Trafficking and Damage-associated Molecular Pattern Expression During Ex Vivo Lung Perfusion.

Transplant Direct 2020 Mar 10;6(3):e532. Epub 2020 Feb 10.

Department of Surgery, Duke University Medical Center, Durham, NC.

Background: While ex vivo lung perfusion (EVLP) has become established in lung transplantation, the cellular processes occurring during this period are not yet fully understood. Prior studies demonstrated that donor leukocytes (DLs) migrate from the graft into the perfusate during EVLP, but the distribution of DLs in graft and perfusate compartments has not been characterized. Moreover, cell death of DLs has been implicated in mediating graft injury during EVLP, but the underlying mechanisms have not been elucidated. We hypothesized the following: (1) there is a nonspecific migration of DLs from the graft into perfusate and (2) cell death of DLs releases damage-associated molecular patterns (DAMPs) that contribute to the inflammatory milieu during EVLP.

Methods: EVLP was performed on rat lungs for 3 hours (N = 6). At the end of EVLP, flow cytometry was used to quantify the distribution of different DL cell types in both the graft and perfusate compartments. During EVLP, the perfusate was also sampled hourly to measure levels of DAMPs and downstream inflammatory cytokines generated during EVLP.

Results: At the conclusion of EVLP, there was a significantly higher proportion of T and B cells present in the perfusate compartment compared with the graft compartment. There was a time-dependent increase in extracellular DNA and tumor necrosis factor α in the perfusate during EVLP.

Conclusions: T cells and B cells are enriched in the perfusate compartment during EVLP. Cell death of DLs contributes to an accumulation of DAMPs during EVLP.
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http://dx.doi.org/10.1097/TXD.0000000000000968DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7056278PMC
March 2020

Kidney Donor Profile Index Is a Reliable Alternative to Liver Donor Risk Index in Quantifying Graft Quality in Liver Transplantation.

Transplant Direct 2019 Dec 25;5(12):e511. Epub 2019 Nov 25.

Department of Surgery, Duke University Medical Center, Durham, NC.

Background: The most established metric for estimating graft survival from donor characteristics in liver transplantation is the liver donor risk index (LDRI). The LDRI is calculated from donor and transplant-related variables, including cold ischemic time. Because cold ischemic time is unknown at the time of organ offer, LDRI is not available for organ acceptance decisions. In contrast, the kidney donor profile index (KDPI) is derived purely from donor variables known at the time of offer and thus calculated for every deceased donor in the United States. The similarity in donor factors included in LDRI and KDPI led us to hypothesize that KDPI would reliably approximate LDRI in estimating graft survival in liver transplantation.

Methods: The United Network of Organ Sharing registry was queried for adults who underwent deceased donor liver transplantation from 2002 to 2016. The cohort was divided into quintiles of KDPI and LDRI, and graft survival was calculated according to Kaplan Meier. Hazard ratios for LDRI and KDPI were estimated from Cox proportional hazards models, and Uno's concordance statistic was compared.

Results: In our analysis of 63 906 cases, KDPI closely approximated LDRI in estimating liver graft survival, with an equivalent concordance statistic of 0.56.

Conclusions: We conclude that KDPI can serve as a reasonable alternative to LDRI in liver acceptance decisions.
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http://dx.doi.org/10.1097/TXD.0000000000000955DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7004589PMC
December 2019

Discovery of a Bromodomain and Extraterminal Inhibitor with a Low Predicted Human Dose through Synergistic Use of Encoded Library Technology and Fragment Screening.

J Med Chem 2020 01 6;63(2):714-746. Epub 2020 Jan 6.

GSK , Gunnels Wood Road , Stevenage , Hertfordshire SG1 2NY , U.K.

The bromodomain and extraterminal (BET) family of bromodomain-containing proteins are important regulators of the epigenome through their ability to recognize -acetyl lysine (KAc) post-translational modifications on histone tails. These interactions have been implicated in various disease states and, consequently, disruption of BET-KAc binding has emerged as an attractive therapeutic strategy with a number of small molecule inhibitors now under investigation in the clinic. However, until the utility of these advanced candidates is fully assessed by these trials, there remains scope for the discovery of inhibitors from new chemotypes with alternative physicochemical, pharmacokinetic, and pharmacodynamic profiles. Herein, we describe the discovery of a candidate-quality dimethylpyridone benzimidazole compound which originated from the hybridization of a dimethylphenol benzimidazole series, identified using encoded library technology, with an -methyl pyridone series identified through fragment screening. Optimization via structure- and property-based design led to I-BET469, which possesses favorable oral pharmacokinetic properties, displays activity in vivo, and is projected to have a low human efficacious dose.
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http://dx.doi.org/10.1021/acs.jmedchem.9b01670DOI Listing
January 2020

Secondary lymphoid tissue and costimulation-blockade resistant rejection: A nonhuman primate renal transplant study.

Am J Transplant 2019 08 12;19(8):2350-2357. Epub 2019 Apr 12.

Department of Surgery, Duke University Medical Center, Durham, North Carolina.

Naïve T cell activation requires antigen presentation combined with costimulation through CD28, both of which optimally occur in secondary lymphoid tissues such as lymph nodes and the spleen. Belatacept impairs CD28 costimulation by binding its ligands, CD80 and CD86, and in doing so, impairs de novo alloimmune responses. However, in most patients belatacept is ineffective in preventing allograft rejection when used as a monotherapy, and adjuvant therapy is required for control of costimulation-blockade resistant rejection (CoBRR). In rodent models, impaired access to secondary lymphoid tissues has been demonstrated to reduce alloimmune responses to vascularized allografts. Here we show that surgical maneuvers, lymphatic ligation, and splenectomy, designed to anatomically limit access to secondary lymphoid tissues, control CoBRR and facilitate belatacept monotherapy in a nonhuman primate model of kidney transplantation without adjuvant immunotherapy. We further demonstrate that animals sustained on belatacept monotherapy progressively develop an increasingly naïve T and B cell repertoire, an effect that is accelerated by splenectomy and lost at the time of belatacept withdrawal and rejection. These pilot data inform the role of secondary lymphoid tissues on the development of CoBRR and the use of costimulation molecule-focused therapies.
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http://dx.doi.org/10.1111/ajt.15365DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6658331PMC
August 2019

Damage-Associated Molecular Patterns Induce Inflammatory Injury During Machine Preservation of the Liver: Potential Targets to Enhance a Promising Technology.

Liver Transpl 2019 04 15;25(4):610-626. Epub 2019 Mar 15.

Department of Surgery, Duke University Medical Center, Durham, NC.

Machine preservation (MP) has emerged as a promising technology in liver transplantation, but the cellular processes occurring during MP have not been characterized. Recent studies have noted the presence of inflammatory molecules generated during MP. We hypothesized that there is a metabolism-dependent accumulation of damage-associated molecular patterns (DAMPs) and inflammatory cytokines during MP and that these molecules provoke inflammation in the graft. To stratify groups by metabolic rate, MP was performed on rat livers from standard donors at 3 different temperatures: room temperature (RT), subnormothermic (30°C), and normothermic (37°C). Static cold storage at 4°C was included as a reference group. Following a 4-hour preservation period, graft reperfusion was performed ex vivo at 37°C (n = 6 for all groups). Levels of DAMPs and inflammatory cytokines were measured, and their biological activity was assessed by determining toll-like receptor (TLR) stimulation, inflammatory gene expression, and activation of cell death pathways. There was a time-dependent increase in levels of DAMPs during MP with high-mobility group box 1 and extracellular DNA levels increasing for all groups (P < 0.05, 30 versus 240 minutes). Tumor necrosis factor α levels in the perfusate also increased during MP for all groups (P < 0.05, 30 minutes versus 240 minutes). Levels of inflammatory molecules correlated with increased activation of TLRs (TLR3, P = 0.02, normothermic machine preservation [MP37] versus machine preservation at room temperature [MPRT]; TLR9, P = 0.02, MP37 versus MPRT). Priming of the NLRP3 inflammasome and activation of cell death pathways were reduced in grafts preserved by MP at room temperature. In conclusion, inflammatory molecules produced during MP have a biological impact on the graft. Therapies to attenuate DAMP-mediated inflammation during MP may further enhance this promising technology.
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http://dx.doi.org/10.1002/lt.25429DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6593678PMC
April 2019

Elevated Donor Hemoglobin A1C Impairs Kidney Graft Survival From Deceased Donors With Diabetes Mellitus: A National Analysis.

Exp Clin Transplant 2019 10 21;17(5):613-618. Epub 2019 Jan 21.

From the Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA.

Objectives: Kidney transplant is the optimal therapy for patients with end-stage renal disease. The presence of donor diabetes mellitus is a recognized risk factor for impaired kidney graft survival and is incorporated into the Kidney Donor Profile Index. At present, however, there are limited assessments of the severity of this risk factor. Hemoglobin A1c reflects glycemic control over the preceding 3 months, and we hypothesized that donor hemoglobin A1c levels could confer additional discriminatory power in assessments of deceased donors with diabetes mellitus.

Materials And Methods: The United Network for Organ Sharing/Organ Procurement and Organ Transplantation Network Standard Transplant Analysis Research file was queried for adult deceased-donor kidney transplants performed using allografts from donors with diabetes mellitus who had measurements of hemoglobin A1c before donation.

Results: The study cohort consisted of 1518 kidney transplants performed using allografts from deceased donors with diabetes mellitus. Kaplan-Meier survival analysis and log-rank test were performed to compare survival of grafts from donors with diabetes mellitus with elevated (≥ 6.5%) versus lower (< 6.5%) hemoglobin A1c levels. Graft survival at 5 years was significantly lower for recipients of donors with hemoglobin A1c ≥ 6.5% (58.9% vs 68.3%; P < .001). On multivariate analysis, hemoglobin A1c ≥ 6.5% was an independent predictor of diminished graft survival.

Conclusions: Hemoglobin A1c has potential as an additional discriminatory test for estimating outcomes of grafts from donors with diabetes mellitus and should be routinely measured in this population.
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http://dx.doi.org/10.6002/ect.2017.0322DOI Listing
October 2019

Improvement in Liver Transplant Outcomes From Older Donors: A US National Analysis.

Ann Surg 2019 08;270(2):333-339

Department of Surgery, Duke University Medical Center, Durham, NC.

Objective: To investigate trends in long-term graft and patient outcomes following liver transplantation using grafts from donors ≥60 years old.

Summary Background Data: The scarcity of donor livers has led to increased utilization of organs from donors ≥60 years old. However, few studies have examined how long-term transplant outcomes from older donors have evolved over time.

Methods: The OPTN/UNOS database was queried for all first-time isolated adult liver transplants. We identified 14,796 adult liver transplant using donors ≧60-year-old suitable for analysis from 1990 to 2014. Cohorts were then developed based on 5-year intervals of transplant date. Kaplan-Meier analysis was used to compare graft and patient survival for recipients from older donor across each 5-year era.

Results: Utilization of donor grafts ≥60 years old increased steadily for the first 15 years of the study, but has leveled off over the last 10 years. Comparison of the earliest and latest eras in the study was notable for an increase in median recipient age (51 vs. 59, P < 0.001) and reduction in median cold ischemic time (10 vs. 6 h, P = 0.001). Unadjusted 5-year graft and patient survival has improved significantly over time (P < 0.0001). More importantly, the discrepancy in survival between older and younger grafts has narrowed substantially over time (P < 0.0001).

Conclusions: This study demonstrates significant improvement in transplant outcomes with donor grafts ≥60-years old and supports increased but judicious use of extended criteria donors liver grafts. Improved patient selection and reduction in cold ischemia time appear to be contributing factors.
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http://dx.doi.org/10.1097/SLA.0000000000002876DOI Listing
August 2019

Reductions in fish-community contamination following lowhead dam removal linked more to shifts in food-web structure than sediment pollution.

Environ Pollut 2017 Dec 29;231(Pt 1):671-680. Epub 2017 Aug 29.

School of Environment and Natural Resources, The Ohio State University, 2021 Coffey Road, Columbus, OH 43210, United States.

Recent increases in dam removals have prompted research on ecological and geomorphic river responses, yet contaminant dynamics following dam removals are poorly understood. We investigated changes in sediment concentrations and fish-community body burdens of mercury (Hg), selenium (Se), polychlorinated biphenyls (PCB), and chlorinated pesticides before and after two lowhead dam removals in the Scioto and Olentangy Rivers (Columbus, Ohio). These changes were then related to documented shifts in fish food-web structure. Seven study reaches were surveyed from 2011 to 2015, including controls, upstream and downstream of the previous dams, and upstream restored vs. unrestored. For most contaminants, fish-community body burdens declined following dam removal and converged across study reaches by the last year of the study in both rivers. Aldrin and dieldrin body burdens in the Olentangy River declined more rapidly in the upstream-restored vs. the upstream-unrestored reach, but were indistinguishable by year three post dam removal. No upstream-downstream differences were observed in body burdens in the Olentangy River, but aldrin and dieldrin body burdens were 138 and 148% higher, respectively, in downstream reaches than in upstream reaches of the Scioto River following dam removal. The strongest relationships between trophic position and body burdens were observed with PCBs and Se in the Scioto River, and with dieldrin in the Olentangy River. Food-chain length - a key measure of trophic structure - was only weakly related to aldrin body burdens, and unrelated to other contaminants. Overall, we demonstrate that lowhead dam removal may effectively reduce ecosystem contamination, largely via shifts in fish food-web dynamics versus sediment contaminant concentrations. This study presents some of the first findings documenting ecosystem contamination following dam removal and will be useful in informing future dam removals.
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http://dx.doi.org/10.1016/j.envpol.2017.07.096DOI Listing
December 2017

Elevated HbA1c in donor organs from patients without a diagnosis of diabetes portends worse liver allograft survival.

Clin Transplant 2017 Sep 21;31(9). Epub 2017 Jul 21.

Department of Surgery, Duke University Medical Center, Durham, NC, USA.

Recipients of liver allografts from diabetic donors have decreased graft survival. However, limited data exist on the effects of donor HbA1c. We hypothesized that allografts from nondiabetic donors with elevated HbA1c would be associated with decreased survival. Liver transplant recipients from the UNOS database from nondiabetic donors were stratified into two groups: euglycemic (HbA1c<6.5) and hyperglycemic (HbA1c≥6.5). Propensity score matching (10:1) was used to adjust for donor and recipient characteristics. Kaplan-Meier analysis was used to assess survival. Donors of hyperglycemic allografts were older (49 vs 36, P<.001), were more likely to be non-white, had a higher BMI (29.8 vs 26.2, P<.001), were more likely to engage in heavy cigarette use (1.5% vs 1.3%, P=.004), had higher serum creatinine levels (1.3 vs 1.0, P=.002), and were more likely to be an expanded-criteria donor (35.8% vs 14.4%, P<.001). After propensity matching to account for these differences, allograft survival was significantly decreased in the recipients of hyperglycemic allografts (P=.049), and patient survival showed a trend toward reduction (P=.082). These findings suggest that HbA1c may be a simple and inexpensive test with potential utility for better organ risk stratification.
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http://dx.doi.org/10.1111/ctr.13047DOI Listing
September 2017

5-Hydroxytryptamine does not reduce sympathetic nerve activity or neuroeffector function in the splanchnic circulation.

Eur J Pharmacol 2015 May 28;754:140-7. Epub 2015 Feb 28.

Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan USA. Electronic address:

Infusion of 5-hydroxytryptamine (5-HT) in conscious rats results in a sustained (up to 30 days) fall in blood pressure. This is accompanied by an increase in splanchnic blood flow. Because the splanchnic circulation is regulated by the sympathetic nervous system, we hypothesized that 5-HT would: 1) directly reduce sympathetic nerve activity in the splanchnic region; and/or 2) inhibit sympathetic neuroeffector function in splanchnic blood vessels. Moreover, removal of the sympathetic innervation of the splanchnic circulation (celiac ganglionectomy) would reduce 5-HT-induced hypotension. In anaesthetized Sprague-Dawley rats, mean blood pressure was reduced from 101±4 to 63±3mm Hg during slow infusion of 5-HT (25μg/kg/min, i.v.). Pre- and postganglionic splanchnic sympathetic nerve activity were unaffected during 5-HT infusion. In superior mesenteric arterial rings prepared for electrical field stimulation, neither 5-HT (3, 10, 30nM), the 5-HT1B receptor agonist CP 93129 nor 5-HT1/7 receptor agonist 5-carboxamidotryptamine inhibited neurogenic contraction compared to vehicle. 5-HT did not inhibit neurogenic contraction in superior mesenteric venous rings. Finally, celiac ganglionectomy did not modify the magnitude of fall or time course of 5-HT-induced hypotension when compared to animals receiving sham ganglionectomy. We conclude it is unlikely 5-HT interacts with the sympathetic nervous system at the level of the splanchnic preganglionic or postganglionic nerve, as well as at the neuroeffector junction, to reduce blood pressure. These important studies allow us to rule out a direct interaction of 5-HT with the splanchnic sympathetic nervous system as a cause of the 5-HT-induced fall in blood pressure.
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http://dx.doi.org/10.1016/j.ejphar.2015.02.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4385506PMC
May 2015

Identification of clinical candidates from the benzazepine class of histamine H3 receptor antagonists.

Bioorg Med Chem Lett 2013 Dec 5;23(24):6890-6. Epub 2013 Oct 5.

GlaxoSmithKline R&D, Neurology Centre of Excellence for Drug Discovery, Harlow, Essex CM19 5AW, United Kingdom. Electronic address:

This Letter describes the discovery of GSK189254 and GSK239512 that were progressed as clinical candidates to explore the potential of H3 receptor antagonists as novel therapies for the treatment of Alzheimer's disease and other dementias. By carefully controlling the physicochemical properties of the benzazepine series and through the implementation of an aggressive and innovative screening strategy that employed high throughput in vivo assays to efficiently triage compounds, the medicinal chemistry effort was able to rapidly progress the benzazepine class of H3 antagonists through to the identification of clinical candidates with robust in vivo efficacy and excellent developability properties.
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http://dx.doi.org/10.1016/j.bmcl.2013.09.090DOI Listing
December 2013

The discovery of the benzazepine class of histamine H3 receptor antagonists.

Bioorg Med Chem Lett 2013 Dec 5;23(24):6897-901. Epub 2013 Oct 5.

GlaxoSmithKline R&D, Neurology CEDD, Harlow, Essex CM19 5AW, United Kingdom. Electronic address:

This Letter describes the discovery of a novel series of H3 receptor antagonists. The initial medicinal chemistry strategy focused on deconstructing and simplifying an early screening hit which rapidly led to the discovery of a novel series of H3 receptor antagonists based on the benzazepine core. Employing an H3 driven pharmacodynamic model, the series was then further optimised through to a lead compound that showed robust in vivo functional activity and possessed overall excellent developability properties.
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http://dx.doi.org/10.1016/j.bmcl.2013.09.089DOI Listing
December 2013

Dynamics of Aβ42 reduction in plasma, CSF and brain of rats treated with the γ-secretase modulator, GSM-10h.

Neurodegener Dis 2011 10;8(6):455-64. Epub 2011 Mar 10.

Neurosciences Centre of Excellence for Drug Discovery, GlaxoSmithKline Research and Development Ltd., New Frontiers Science Park, Harlow, UK.

Background: Allosteric modulation of γ-secretase is an attractive therapeutic approach for the treatment of Alzheimer's disease. We recently identified a novel γ-secretase modulator, GSM-10h, which effectively lowers Aβ42 production in cells and in amyloid precursor protein transgenic mice.

Objective: Here, we describe the in vivo characterization of GSM-10h in a model of endogenous Aβ production.

Methods: Rats were administered orally with GSM-10h, and the effect on Aβ levels in peripheral and central compartments was determined. In addition, the effect of GSM-10h on Notch processing was assessed.

Results: Acute administration of GSM-10h to rats causes a dose-dependent decrease in the level of Aβ42 in plasma, CSF and brain, with little effect on the level of Aβ40 in these compartments. The magnitude of Aβ42 lowering in the CSF and brain was further enhanced upon sub-chronic administration of GSM-10h. No deleterious effect on Notch processing was evident in either of these studies. To further explore the dynamics of Aβ42 reduction in peripheral and CNS compartments, a time course study was conducted. In all compartments, the decrease in Aβ42 was greatest at 6 h after administration of GSM-10h. This decrease in Aβ42 was maintained for 9-15 h, after which time Aβ42 levels returned to baseline levels. Encouragingly, no rebound in Aβ42 levels beyond baseline levels was observed.

Conclusions: These findings support the γ-secretase modulator profile of GSM-10h, and highlight the utility of the rat for assessing the pre-clinical efficacy of γ-secretase modulators.
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http://dx.doi.org/10.1159/000324511DOI Listing
December 2011

Allopurinol does not decrease blood pressure or prevent the development of hypertension in the deoxycorticosterone acetate-salt rat model.

J Cardiovasc Pharmacol 2010 Dec;56(6):627-34

Pharmacology and Toxicology Department, Michigan State University, East Lansing, MI 48824-1317, USA.

Reactive oxygen species play an important role in the pathogenesis of hypertension, disease in which reactive oxygen species levels and markers of oxidative stress are increased. Xanthine oxidase (XO) is a reactive oxygen species-producing enzyme the activity of which may increase during hypertension. Studies on XO inhibition effects on blood pressure have yielded controversial results. We hypothesized that XO inhibition would decrease blood pressure or attenuate the development of deoxycorticosterone acetate (DOCA)-salt hypertension. We administered the XO inhibitor, allopurinol (50 mg/kg per day, orally) or its vehicle to rats during the established or development stages of DOCA-salt hypertension. We validated XO inhibition by high-performance liquid chromatography measurements of XO metabolites in urine, serum, and tissues demonstrating a decrease in products, increase in substrates, and detection of the active metabolite of allopurinol, oxypurinol. We monitored blood pressure continuously through radiotelemetry and performed gross evaluations of target organs of hypertension. Allopurinol treatment did not impact the course of DOCA-salt hypertension regardless of the timing of administration. Aside from a significant decrease in pulse pressure in allopurinol-treated rats, no positive differences were observed between the allopurinol and the vehicle-treated rats. We conclude that XO does not play an important role in the development or maintenance of hypertension in the rat DOCA-salt hypertension model.
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http://dx.doi.org/10.1097/FJC.0b013e3181f80194DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3049193PMC
December 2010

The identification of potent, selective and CNS penetrant furan-based inhibitors of B-Raf kinase.

Bioorg Med Chem Lett 2008 Aug 24;18(15):4373-6. Epub 2008 Jun 24.

Department of Medicinal Chemistry, Neurology and GI Centre of Excellence for Drug Discovery, GlaxoSmithKline Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, UK.

Modification of the potent imidazole-based B-Raf inhibitor SB-590885 resulted in the identification of a series of furan-based derivatives with enhanced CNS penetration. One such compound, SB-699393 (17), was examined in vivo to challenge the hypothesis that selective B-Raf inhibitors may be of value in the treatment of stroke.
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http://dx.doi.org/10.1016/j.bmcl.2008.06.070DOI Listing
August 2008

GSK189254, a novel H3 receptor antagonist that binds to histamine H3 receptors in Alzheimer's disease brain and improves cognitive performance in preclinical models.

J Pharmacol Exp Ther 2007 Jun 27;321(3):1032-45. Epub 2007 Feb 27.

Neurology and GI Centre of Excellence for Drug Discovery, GlaxoSmithKline, Third Ave., Harlow, Essex, CM19 5AW, UK.

6-[(3-Cyclobutyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)oxy]-N-methyl-3-pyridinecarboxamide hydrochloride (GSK189254) is a novel histamine H(3) receptor antagonist with high affinity for human (pK(i) = 9.59 -9.90) and rat (pK(i) = 8.51-9.17) H(3) receptors. GSK189254 is >10,000-fold selective for human H(3) receptors versus other targets tested, and it exhibited potent functional antagonism (pA(2) = 9.06 versus agonist-induced changes in cAMP) and inverse agonism [pIC(50) = 8.20 versus basal guanosine 5'-O-(3-[(35)S]thio)triphosphate binding] at the human recombinant H(3) receptor. In vitro autoradiography demonstrated specific [(3)H]GSK189254 binding in rat and human brain areas, including cortex and hippocampus. In addition, dense H(3) binding was detected in medial temporal cortex samples from severe cases of Alzheimer's disease, suggesting for the first time that H(3) receptors are preserved in late-stage disease. After oral administration, GSK189254 inhibited cortical ex vivo R-(-)-alpha-methyl[imidazole-2,5(n)-(3)H]histamine dihydrochloride ([(3)H]R-alpha-methylhistamine) binding (ED(50) = 0.17 mg/kg) and increased c-Fos immunoreactivity in prefrontal and somatosensory cortex (3 mg/kg). Microdialysis studies demonstrated that GSK189254 (0.3-3 mg/kg p.o.) increased the release of acetylcholine, noradrenaline, and dopamine in the anterior cingulate cortex and acetylcholine in the dorsal hippocampus. Functional antagonism of central H(3) receptors was demonstrated by blockade of R-alpha-methylhistamine-induced dipsogenia in rats (ID(50) = 0.03 mg/kg p.o.). GSK189254 significantly improved performance of rats in diverse cognition paradigms, including passive avoidance (1 and 3 mg/kg p.o.), water maze (1 and 3 mg/kg p.o.), object recognition (0.3 and 1 mg/kg p.o.), and attentional set shift (1 mg/kg p.o.). These data suggest that GSK189254 may have therapeutic potential for the symptomatic treatment of dementia in Alzheimer's disease and other cognitive disorders.
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http://dx.doi.org/10.1124/jpet.107.120311DOI Listing
June 2007

Structurally novel histamine H3 receptor antagonists GSK207040 and GSK334429 improve scopolamine-induced memory impairment and capsaicin-induced secondary allodynia in rats.

Biochem Pharmacol 2007 Apr 7;73(8):1182-94. Epub 2007 Jan 7.

Neurology and GI Centre of Excellence for Drug Discovery, GlaxoSmithKline, Third Avenue, Harlow, Essex CM19 5AW, UK.

GSK207040 (5-[(3-cyclobutyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)oxy]-N-methyl-2-pyrazinecarboxamide) and GSK334429 (1-(1-methylethyl)-4-({1-[6-(trifluoromethyl)-3-pyridinyl]-4-piperidinyl}carbonyl)hexahydro-1H-1,4-diazepine) are novel and selective non-imidazole histamine H(3) receptor antagonists from distinct chemical series with high affinity for human (pK(i)=9.67+/-0.06 and 9.49+/-0.09, respectively) and rat (pK(i)=9.08+/-0.16 and 9.12+/-0.14, respectively) H(3) receptors expressed in cerebral cortex. At the human recombinant H(3) receptor, GSK207040 and GSK334429 were potent functional antagonists (pA(2)=9.26+/-0.04 and 8.84+/-0.04, respectively versus H(3) agonist-induced changes in cAMP) and exhibited inverse agonist properties (pIC(50)=9.20+/-0.36 and 8.59+/-0.04 versus basal GTPgammaS binding). Following oral administration, GSK207040 and GSK334429 potently inhibited cortical ex vivo [(3)H]-R-alpha-methylhistamine binding (ED(50)=0.03 and 0.35 mg/kg, respectively). Functional antagonism of central H(3) receptors was demonstrated by blockade of R-alpha-methylhistamine-induced dipsogenia in rats (ID(50)=0.02 and 0.11 mg/kg p.o. for GSK207040 and GSK334429, respectively). In more pathophysiologically relevant pharmacodynamic models, GSK207040 (0.1, 0.3, 1 and 3mg/kg p.o.) and GSK334429 (0.3, 1 and 3mg/kg p.o.) significantly reversed amnesia induced by the cholinergic antagonist scopolamine in a passive avoidance paradigm. In addition, GSK207040 (0.1, 0.3 and 1mg/kg p.o.) and GSK334429 (3 and 10mg/kg p.o.) significantly reversed capsaicin-induced reductions in paw withdrawal threshold, suggesting for the first time that blockade of H(3) receptors may be able to reduce tactile allodynia. Novel H(3) receptor antagonists such as GSK207040 and GSK334429 may therefore have therapeutic potential not only in dementia but also in neuropathic pain.
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http://dx.doi.org/10.1016/j.bcp.2007.01.007DOI Listing
April 2007

Pharmacological and immunohistochemical characterization of the APJ receptor and its endogenous ligand apelin.

J Neurochem 2003 Mar;84(5):1162-72

Neurology Centre of Excellence for Drug Discovery, GlaxoSmithKline Pharmaceuticals, Third Avenue, Harlow, Essex CM19 5AW, UK.

Apelin peptides have recently been identified to be the endogenous ligands for the G protein-coupled receptor APJ. However, little is known about the physiological roles of this ligand-receptor pairing. In the present study we investigated the pharmacology of several apelin analogues at the human recombinant APJ receptor using radioligand binding and functional assays. This has led to the identification of key residues in the apelin peptide required for functional potency and binding affinity through structure-activity studies. In particular, we have identified that replacement of leucine in position 5, or arginine in position 2 and 4 of the C-terminal apelin peptide, apelin-13, resulted in significant changes in pharmacology. We also investigated the detailed localization of pre-proapelin and APJ receptor mRNA in a wide range of human, rat and mouse tissues using quantitative RT-PCR, and carried out a detailed immunohistochemical study of the distribution of the APJ receptor in rat brain and spinal cord. Interestingly, the APJ receptor was not only co-localized in white matter with GFAP in the spinal cord, but was also clearly localized on neurones in the brain, suggesting that this receptor and its peptide may be involved in a wide range of biological process yet to be determined.
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http://dx.doi.org/10.1046/j.1471-4159.2003.01587.xDOI Listing
March 2003