261 results on '"Johns DG"'
Search Results
2. Mechanism of ‘bystander effect’ killing in the herpes simplex thymidine kinase gene therapy model of cancer treatment
- Author
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Ishii-Morita, H, Agbaria, R, Mullen, CA, Hirano, H, Koeplin, DA, Ram, Z, Oldfield, EH, Johns, DG, and Blaese, RM
- Published
- 1997
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3. From days to decades: short- and long-term variation in environmental conditions affect offspring diet composition of a marine top predator
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Howells, RJ, primary, Burthe, SJ, additional, Green, JA, additional, Harris, MP, additional, Newell, MA, additional, Butler, A, additional, Johns, DG, additional, Carnell, EJ, additional, Wanless, S, additional, and Daunt, F, additional
- Published
- 2017
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4. Quantitative argument for long-term ecological monitoring
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Giron-Nava, A, primary, James, CC, additional, Johnson, AF, additional, Dannecker, D, additional, Kolody, B, additional, Lee, A, additional, Nagarkar, M, additional, Pao, GM, additional, Ye, H, additional, Johns, DG, additional, and Sugihara, G, additional
- Published
- 2017
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5. Seroprevalence of Cytomegalovirus,Toxoplasma gondii, Syphilis, and Hepatitis B and C Virus Infections in a Regional Population Seropositive for HIV Infection
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Michael Gill and Johns Dg
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Microbiology (medical) ,Hepatitis B virus ,education.field_of_study ,business.industry ,viruses ,Hepatitis C virus ,Population ,Congenital cytomegalovirus infection ,virus diseases ,Hepatitis B ,medicine.disease ,medicine.disease_cause ,Virology ,digestive system diseases ,Virus ,lcsh:Infectious and parasitic diseases ,parasitic diseases ,Immunology ,Medicine ,Seroprevalence ,Original Article ,lcsh:RC109-216 ,Syphilis ,business ,education - Abstract
OBJECTIVE: To determine the prevalence of exposure to cytomegalovirus (CMV),Toxoplasma gondii, syphilis, hepatitis B virus (HBV) and hepatitis C virus (HCV) in a large, well characterized, regional population presenting for human immunodeficency virus (HIV) care.DESIGN: Demographic and serological data compiled prospectively in a relational database used for routine patient care. Results were analyzed for statistically significant trends within demographic subpopulations known to be at risk of such infections.PATIENTS AND SETTING: A total of 1274 persons with documented HIV infection in southern Alberta have sought medical care since 1985. Serological status to CMV,T gondii, syphilis, HBV and HCV infections were routinely requested as part of the initial assessment. All patients with serological results available were included in the analysis.RESULTS: CMV infection was found in 84.1% of patients. A lower prevalence of CMV infection in those under 30 yeasr old (PT gondiiseropositivity was found in 10.6% of patients, with an increased risk of seropositivity in those born outside of Canada (PCONCLUSION: Seroprevalence to common pathogens in HIV disease varies significantly among subpopulations, necessitating individual testing.
- Published
- 1998
6. Increased blooms of a dinoflagellate in the NW Atlantic
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Johns, DG, primary, Edwards, M, additional, Richardson, A, additional, and Spicer, JI, additional
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- 2003
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7. 2′-Fluoro-2′,3′-Dideoxyarabinosyladenine (F-ddA): Activity against Drug-Resistant Human Immunodeficiency Virus Strains and Clades A-E
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Driscoll, JS, primary, Mayers, DL, additional, Bader, JP, additional, Weislow, OS, additional, Johns, DG, additional, and Buckheit, RW, additional
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- 1997
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8. Effects of bone marrow stimulatory cytokines on human immunodeficiency virus replication and the antiviral activity of dideoxynucleosides in cultures of monocyte/macrophages
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Perno, CF, primary, Cooney, DA, additional, Gao, WY, additional, Hao, Z, additional, Johns, DG, additional, Foli, A, additional, Hartman, NR, additional, Calio, R, additional, Broder, S, additional, and Yarchoan, R, additional
- Published
- 1992
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9. The Antiretroviral and Cytostatic Activity, and Metabolism of 3′-Azido-2′, 3′-Dideoxythymidine, 3′-Fluoro-2′, 3′-Dideoxythymidine and 2′, 3′-Dideoxycytidine are Highly Cell Type-Dependent
- Author
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Meeus P, De Clercq E, Johns Dg, Jan Balzarini, and Matthes E
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Cell type ,Zidovudine ,Zalcitabine ,Cell division ,Viral replication ,Dideoxynucleosides ,Chemistry ,Cell culture ,2'3' dideoxycytidine ,medicine ,Virology ,medicine.drug - Published
- 1989
10. Perfusion Damage to Renal Allografts
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Chassin Mm, Johns Dg, Chirigos Ma, and Adamson Rh
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Adenosine deaminase ,biology ,business.industry ,medicine.medical_treatment ,biology.protein ,medicine ,AMP deaminase ,Immunosuppression ,General Medicine ,Pharmacology ,business - Published
- 1977
11. Long-term changes in spatiotemporal distribution of Noctiluca scintillans in the southern North Sea.
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Kordubel K, Martínez-Rincón RO, Baschek B, Boersma M, Hieronymi M, Johns DG, Kirstein IV, Voynova YG, and Möller KO
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- North Sea, Germany, Spatio-Temporal Analysis, Dinoflagellida physiology, Harmful Algal Bloom
- Abstract
To assess the spatiotemporal evolution of the heterotrophic dinoflagellate Noctiluca scintillans in the North Sea, the Helgoland Roads time series and Continuous Plankton Recorder survey were analysed using generalized additive models. Over the last decades, blooms of N. scintillans have occurred more frequently and intensively in many regions. This harmful algal bloom forming species can alter food webs, reduce ecosystem productivity, and lead to economic losses while causing lower aquacultural yields. After the 1990s, N. scintillans abundances have significantly increased by 1.65-fold and a significant prolongation of the bloom window was found (from 27.5 to 98 days in recent decades) off the island of Helgoland, Germany. Significant correlations were found between bloom initiation and nutrients, as well as light availability since these factors lead to increased prey availability. Highest abundances of N. scintillans were associated with water temperatures around 17 °C and wind speed below 6 ms
-1 causing dense surface accumulations. Solar radiation of more than 200 Wm-2 was identified as a main driver for post-bloom conditions as it can deteriorate the cells and lead to the decline of N. scintillans abundances. In the southern North Sea, N. scintillans occurrences have intensified and spread since the 1980s with hotspots identified as the coastal waters adjacent to the estuaries of the Elbe and Rhine rivers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)- Published
- 2024
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12. Orally Bioavailable Macrocyclic Peptide That Inhibits Binding of PCSK9 to the Low Density Lipoprotein Receptor.
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Johns DG, Campeau LC, Banka P, Bautmans A, Bueters T, Bianchi E, Branca D, Bulger PG, Crevecoeur I, Ding FX, Garbaccio RM, Guetschow ED, Guo Y, Ha SN, Johnston JM, Josien H, Kauh EA, Koeplinger KA, Kuethe JT, Lai E, Lanning CL, Lee AYH, Li L, Nair AG, O'Neill EA, Stoch SA, Thaisrivongs DA, Tucker TJ, Vachal P, van Dyck K, Vanhoutte FP, Volckaert B, Wolford DG, Xu A, Zhao T, Zhou D, Zhou S, Zhu X, Zokian HJ, Walji AM, and Wood HB
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- Adult, Humans, Cholesterol, Cholesterol, LDL, Peptides therapeutic use, Proprotein Convertase 9 genetics, Proprotein Convertase 9 metabolism, Receptors, LDL genetics, Receptors, LDL metabolism, Anticholesteremic Agents adverse effects, Hydroxymethylglutaryl-CoA Reductase Inhibitors therapeutic use, Hypercholesterolemia
- Abstract
Background: Inhibition of PCSK9 (proprotein convertase subtilisin/kexin type 9)-low density lipoprotein receptor interaction with injectable monoclonal antibodies or small interfering RNA lowers plasma low density lipoprotein-cholesterol, but despite nearly 2 decades of effort, an oral inhibitor of PCSK9 is not available. Macrocyclic peptides represent a novel approach to target proteins traditionally considered intractable to small-molecule drug design., Methods: Novel mRNA display screening technology was used to identify lead chemical matter, which was then optimized by applying structure-based drug design enabled by novel synthetic chemistry to identify macrocyclic peptide (MK-0616) with exquisite potency and selectivity for PCSK9. Following completion of nonclinical safety studies, MK-0616 was administered to healthy adult participants in a single rising-dose Phase 1 clinical trial designed to evaluate its safety, pharmacokinetics, and pharmacodynamics. In a multiple-dose trial in participants taking statins, MK-0616 was administered once daily for 14 days to characterize the safety, pharmacokinetics, and pharmacodynamics (change in low density lipoprotein cholesterol)., Results: MK-0616 displayed high affinity ( K
i = 5pM) for PCSK9 in vitro and sufficient safety and oral bioavailability preclinically to enable advancement into the clinic. In Phase 1 clinical studies in healthy adults, single oral doses of MK-0616 were associated with >93% geometric mean reduction (95% CI, 84-103) of free, unbound plasma PCSK9; in participants on statin therapy, multiple-oral-dose regimens provided a maximum 61% geometric mean reduction (95% CI, 43-85) in low density lipoprotein cholesterol from baseline after 14 days of once-daily dosing of 20 mg MK-0616., Conclusions: This work validates the use of mRNA display technology for identification of novel oral therapeutic agents, exemplified by the identification of an oral PCSK9 inhibitor, which has the potential to be a highly effective cholesterol lowering therapy for patients in need., Competing Interests: Disclosures D.G.J., L.-C.C., P.B., A.B., T.B., P.G.B., I.C., F.-X.D., R.M.G., E.D.G., Y.G., S.N.H., J.M.J., H.J., E.A.K., K.A.K., J.T.K., E.L., C.L.L., A.Y.H.L., L.L., A.G.N., E.A.O., S.A.S., D.A.T., T.J.T., P.V., K.v.D., D.G.W., A.X., T.Z., D.Z., S.Z., X.Z., H.J.Z., A.M.W., and H.B.W. are current or former employees of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ and may own stock/stock options in Merck & Co., Inc., Rahway, NJ. The other authors have no conflicts of interest.- Published
- 2023
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13. The FORCIS database: A global census of planktonic Foraminifera from ocean waters.
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Chaabane S, de Garidel-Thoron T, Giraud X, Schiebel R, Beaugrand G, Brummer GJ, Casajus N, Greco M, Grigoratou M, Howa H, Jonkers L, Kucera M, Kuroyanagi A, Meilland J, Monteiro F, Mortyn G, Almogi-Labin A, Asahi H, Avnaim-Katav S, Bassinot F, Davis CV, Field DB, Hernández-Almeida I, Herut B, Hosie G, Howard W, Jentzen A, Johns DG, Keigwin L, Kitchener J, Kohfeld KE, Lessa DVO, Manno C, Marchant M, Ofstad S, Ortiz JD, Post A, Rigual-Hernandez A, Rillo MC, Robinson K, Sagawa T, Sierro F, Takahashi KT, Torfstein A, Venancio I, Yamasaki M, and Ziveri P
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- Censuses, Climate Change, Oceans and Seas, Plankton, Foraminifera
- Abstract
Planktonic Foraminifera are unique paleo-environmental indicators through their excellent fossil record in ocean sediments. Their distribution and diversity are affected by different environmental factors including anthropogenically forced ocean and climate change. Until now, historical changes in their distribution have not been fully assessed at the global scale. Here we present the FORCIS (Foraminifera Response to Climatic Stress) database on foraminiferal species diversity and distribution in the global ocean from 1910 until 2018 including published and unpublished data. The FORCIS database includes data collected using plankton tows, continuous plankton recorder, sediment traps and plankton pump, and contains ~22,000, ~157,000, ~9,000, ~400 subsamples, respectively (one single plankton aliquot collected within a depth range, time interval, size fraction range, at a single location) from each category. Our database provides a perspective of the distribution patterns of planktonic Foraminifera in the global ocean on large spatial (regional to basin scale, and at the vertical scale), and temporal (seasonal to interdecadal) scales over the past century., (© 2023. The Author(s).)
- Published
- 2023
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14. Evidence of a range expansion in sunfish from 47 years of coastal sightings.
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Lyashevska O, Brophy D, Wing S, Johns DG, Haberlin D, and Doyle TK
- Abstract
Almost nothing is known about the historical abundance of the ocean sunfish. Yet as an ecologically and functionally important taxa, understanding changes in abundance may be a useful indicator of how our seas are responding to anthropogenic changes including overfishing and climate change. Within this context, sightings from a coastal bird observatory (51.26 ∘ N, 9.30 ∘ W) over a 47 year period (from April to October 1971-2017) provided the first long-term index of sunfish abundance. Using a general linear mixed effect model with a hurdle to deal with imperfect detectability and to model trends, a higher probability of detecting sunfish was found in the 1990s and 2000s. Continuous Plankton Recorder (CPR) phytoplankton color indices and the annual mean position of the 13 ∘ C sea surface isotherm were significantly correlated with the probability of detecting sunfish. An increase in siphonophore abundance (as measured by the CPR) was also documented. However, this increase occurred 10-15 years after the sunfish increase and was not significantly correlated with sunfish abundance. Our results suggest that the observed increase in sunfish sightings is evidence of a range expansion because it was significantly correlated with the mean position of the 13 ∘ C isotherm which moved northwards by over 200 km. Furthermore, the observed increase in sunfish occured 10 years before sunfish sightings are documented in Icelandic and Norwegian waters, and was concurrent with well-known range expansions for other fish species during the 1990s. This study demonstrates how sustained citizen science projects can provide unique insights on the historical abundance of this enigmatic species., Supplementary Information: The online version contains supplementary material available at 10.1007/s00227-021-04005-8., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest., (© The Author(s) 2022.)
- Published
- 2022
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15. A Series of Novel, Highly Potent, and Orally Bioavailable Next-Generation Tricyclic Peptide PCSK9 Inhibitors.
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Tucker TJ, Embrey MW, Alleyne C, Amin RP, Bass A, Bhatt B, Bianchi E, Branca D, Bueters T, Buist N, Ha SN, Hafey M, He H, Higgins J, Johns DG, Kerekes AD, Koeplinger KA, Kuethe JT, Li N, Murphy B, Orth P, Salowe S, Shahripour A, Tracy R, Wang W, Wu C, Xiong Y, Zokian HJ, Wood HB, and Walji A
- Subjects
- Administration, Oral, Animals, Biological Availability, Crystallography, X-Ray, Macaca fascicularis, Molecular Structure, PCSK9 Inhibitors chemistry, PCSK9 Inhibitors pharmacokinetics, Peptides, Cyclic chemistry, Peptides, Cyclic pharmacokinetics, Rats, Structure-Activity Relationship, PCSK9 Inhibitors pharmacology, Peptides, Cyclic pharmacology
- Abstract
Proprotein convertase subtilisin-like/kexin type 9 (PCSK9) is a key regulator of plasma LDL-cholesterol (LDL-C) and a clinically validated target for the treatment of hypercholesterolemia and coronary artery disease. Starting from second-generation lead structures such as 2 , we were able to refine these structures to obtain extremely potent bi- and tricyclic PCSK9 inhibitor peptides. Optimized molecules such as 44 demonstrated sufficient oral bioavailability to maintain therapeutic levels in rats and cynomolgus monkeys after dosing with an enabled formulation. We demonstrated target engagement and LDL lowering in cynomolgus monkeys essentially identical to those observed with the clinically approved, parenterally dosed antibodies. These molecules represent the first report of highly potent and orally bioavailable macrocyclic peptide PCSK9 inhibitors with overall profiles favorable for potential development as once-daily oral lipid-lowering agents. In this manuscript, we detail the design criteria and multiparameter optimization of this novel series of PCSK9 inhibitors.
- Published
- 2021
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16. Invention of MK-8262, a Cholesteryl Ester Transfer Protein (CETP) Inhibitor Backup to Anacetrapib with Best-in-Class Properties.
- Author
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Vachal P, Duffy JL, Campeau LC, Amin RP, Mitra K, Murphy BA, Shao PP, Sinclair PJ, Ye F, Katipally R, Lu Z, Ondeyka D, Chen YH, Zhao K, Sun W, Tyagarajan S, Bao J, Wang SP, Cote J, Lipardi C, Metzger D, Leung D, Hartmann G, Wollenberg GK, Liu J, Tan L, Xu Y, Chen Q, Liu G, Blaustein RO, and Johns DG
- Subjects
- Animals, Anticholesteremic Agents chemical synthesis, Anticholesteremic Agents pharmacokinetics, Anticholesteremic Agents toxicity, Dogs, Humans, Macaca mulatta, Mice, Inbred C57BL, Molecular Structure, Oxazolidinones chemical synthesis, Oxazolidinones pharmacokinetics, Oxazolidinones toxicity, Rats, Wistar, Structure-Activity Relationship, Mice, Rats, Anticholesteremic Agents therapeutic use, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Coronary Disease drug therapy, Oxazolidinones therapeutic use
- Abstract
Cholesteryl ester transfer protein (CETP) represents one of the key regulators of the homeostasis of lipid particles, including high-density lipoprotein (HDL) and low-density lipoprotein (LDL) particles. Epidemiological evidence correlates increased HDL and decreased LDL to coronary heart disease (CHD) risk reduction. This relationship is consistent with a clinical outcomes trial of a CETP inhibitor (anacetrapib) combined with standard of care (statin), which led to a 9% additional risk reduction compared to standard of care alone. We discuss here the discovery of MK-8262, a CETP inhibitor with the potential for being the best-in-class molecule. Novel in vitro and in vivo paradigms were integrated to drug discovery to guide optimization informed by a critical understanding of key clinical adverse effect profiles. We present preclinical and clinical evidence of MK-8262 safety and efficacy by means of HDL increase and LDL reduction as biomarkers for reduced CHD risk.
- Published
- 2021
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17. Anthropogenic climate change impacts on copepod trait biogeography.
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McGinty N, Barton AD, Record NR, Finkel ZV, Johns DG, Stock CA, and Irwin AJ
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- Animals, Ecosystem, Greenland, Temperature, Zooplankton, Climate Change, Copepoda
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Copepods are among the most abundant marine metazoans and form a key link between marine primary producers, higher trophic levels, and carbon sequestration pathways. Climate change is projected to change surface ocean temperature by up to 4°C in the North Atlantic with many associated changes including slowing of the overturning circulation, areas of regional freshening, and increased salinity and reductions in nutrients available in the euphotic zone over the next century. These changes will lead to a restructuring of phytoplankton and zooplankton communities with cascading effects throughout the food web. Here we employ observations of copepods, projected changes in ocean climate, and species distribution models to show how climate change may affect the distribution of copepod species in the North Atlantic. On average species move northeast at a rate of 14.1 km decade
-1 . Species turnover in copepod communities will range from 5% to 75% with the highest turnover rates concentrated in regions of pronounced temperature increase and decrease. The changes in species range vary according to copepod traits with the largest effects found to occur in the cooling, freshening area in the subpolar North Atlantic south of Greenland and in an area of significant warming along the Scotian shelf. Large diapausing copepods (>2.5 mm) which are higher in lipids and a crucial food source for whales, may have an advantage in the cooling waters due to their life-history strategy that facilitates their survival in the arctic environment. Carnivorous copepods show a basin wide increase in species richness and show significant habitat area increases when their distribution moves poleward while herbivores see significant habitat area losses. The trait-specific effects highlight the complex consequences of climate change for the marine food web., (© 2020 John Wiley & Sons Ltd.)- Published
- 2021
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18. Cholesteryl ester transfer protein (CETP) inhibitors based on cyclic urea, bicyclic urea and bicyclic sulfamide cores.
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Liu J, Shao PP, Guiadeen D, Krikorian A, Sun W, Deng Q, Cumiskey AM, Duffy RA, Murphy BA, Mitra K, Johns DG, Duffy JL, and Vachal P
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- Animals, Anticholesteremic Agents metabolism, Anticholesteremic Agents therapeutic use, Cholesterol Ester Transfer Proteins metabolism, Cholesterol, HDL blood, Cyclization, Dyslipidemias drug therapy, Dyslipidemias pathology, Humans, Mice, Mice, Transgenic, Structure-Activity Relationship, Sulfonamides metabolism, Sulfonamides therapeutic use, Urea metabolism, Urea therapeutic use, Anticholesteremic Agents chemical synthesis, Bridged Bicyclo Compounds chemistry, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Sulfonamides chemistry, Urea analogs & derivatives
- Abstract
Cholesteryl ester transfer protein (CETP) inhibitors reduce the transfer of cholesteryl esters from the high-density lipoprotein (HDL-C) to apolipoprotein such as VLDL/LDL, with exchange of triglycerides. Thus, this inhibition increases the HDL-C levels, which is believed to lower the risk for heart disease and stroke. We report here a series of CETP inhibitors based on the cyclic, bicyclic urea and sulfamide cores. These CETP inhibitors exemplified by 15, 31, and 45 demonstrated in vitro potency in inhibiting the CETP transfer activity, and 15, 31 showing in vivo efficacy to increase HDL-C levels in cynomolgus-CETP transgenic mice. The synthesis and biological evaluations of these CETP inhibitors are described., (Copyright © 2020. Published by Elsevier Ltd.)
- Published
- 2021
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19. Series of Novel and Highly Potent Cyclic Peptide PCSK9 Inhibitors Derived from an mRNA Display Screen and Optimized via Structure-Based Design.
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Alleyne C, Amin RP, Bhatt B, Bianchi E, Blain JC, Boyer N, Branca D, Embrey MW, Ha SN, Jette K, Johns DG, Kerekes AD, Koeplinger KA, LaPlaca D, Li N, Murphy B, Orth P, Ricardo A, Salowe S, Seyb K, Shahripour A, Stringer JR, Sun Y, Tracy R, Wu C, Xiong Y, Youm H, Zokian HJ, and Tucker TJ
- Subjects
- Animals, Cells, Cultured, Crystallography, X-Ray methods, Enzyme Inhibitors chemistry, Female, Humans, Macaca fascicularis, Male, Mice, Mice, Inbred C57BL, Proprotein Convertase 9 chemistry, Protein Structure, Secondary, Protein Structure, Tertiary, RNA, Messenger chemistry, Rats, Rats, Wistar, Structure-Activity Relationship, Drug Design, Enzyme Inhibitors metabolism, PCSK9 Inhibitors, Proprotein Convertase 9 metabolism, RNA, Messenger metabolism
- Abstract
Proprotein convertase subtilisin-like/kexin type 9 (PCSK9) is a key regulator of plasma LDL-cholesterol (LDL-C) and a clinically validated target for the treatment of hypercholesterolemia and coronary artery disease. In this paper, we describe a series of novel cyclic peptides derived from an mRNA display screen which inhibit the protein-protein interaction between PCSK9 and LDLR. Using a structure-based drug design approach, we were able to modify our original screening lead 2 to optimize the potency and metabolic stability and minimize the molecular weight to provide novel bicyclic next-generation PCSK9 inhibitor peptides such as 78 . These next-generation peptides serve as a critical foundation for continued exploration of potential oral, once-a-day PCSK9 therapeutics for the treatment of cardiovascular disease.
- Published
- 2020
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20. Increasing picocyanobacteria success in shelf waters contributes to long-term food web degradation.
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Schmidt K, Birchill AJ, Atkinson A, Brewin RJW, Clark JR, Hickman AE, Johns DG, Lohan MC, Milne A, Pardo S, Polimene L, Smyth TJ, Tarran GA, Widdicombe CE, Woodward EMS, and Ussher SJ
- Subjects
- Animals, Arctic Regions, Biomass, Zooplankton, Diatoms, Food Chain
- Abstract
Continental margins are disproportionally important for global primary production, fisheries and CO
2 uptake. However, across the Northeast Atlantic shelves, there has been an ongoing summertime decline of key biota-large diatoms, dinoflagellates and copepods-that traditionally fuel higher tropic levels such as fish, sea birds and marine mammals. Here, we combine multiple time series with in situ process studies to link these declines to summer nutrient stress and increasing proportions of picophytoplankton that can comprise up to 90% of the combined pico- and nanophytoplankton biomass in coastal areas. Among the pico-fraction, it is the cyanobacterium Synechococcus that flourishes when iron and nitrogen resupply to surface waters are diminished. Our field data show how traits beyond small size give Synechococcus a competitive edge over pico- and nanoeukaryotes. Key is their ability to grow at low irradiances near the nutricline, which is aided by their superior light-harvesting system and high affinity to iron. However, minute size and lack of essential biomolecules (e.g. omega-3 polyunsaturated fatty acids and sterols) render Synechococcus poor primary producers to sustain shelf sea food webs efficiently. The combination of earlier spring blooms and lower summer food quantity and quality creates an increasing period of suboptimal feeding conditions for zooplankton at a time of year when their metabolic demand is highest. We suggest that this nutrition-related mismatch has contributed to the widespread, ~50% decline in summer copepod abundance we observe over the last 60 years. With Synechococcus clades being prominent from the tropics to the Arctic and their abundances increasing worldwide, our study informs projections of future food web dynamics in coastal and shelf areas where droughts and stratification lead to increasing nutrient starvation of surface waters., (© 2020 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)- Published
- 2020
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21. Cyp1 Inhibition Prevents Doxorubicin-Induced Cardiomyopathy in a Zebrafish Heart-Failure Model.
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Lam PY, Kutchukian P, Anand R, Imbriglio J, Andrews C, Padilla H, Vohra A, Lane S, Parker DL Jr, Cornella Taracido I, Johns DG, Beerens M, MacRae CA, Caldwell JP, Sorota S, Asnani A, and Peterson RT
- Subjects
- Animals, Animals, Genetically Modified, Cardiomyopathies chemically induced, Cardiomyopathies pathology, Cytochrome P450 Family 1 antagonists & inhibitors, Cytochrome P450 Family 1 genetics, Disease Models, Animal, Doxorubicin toxicity, Heart Failure, Mutagenesis, Phenotype, Small Molecule Libraries chemistry, Small Molecule Libraries metabolism, Small Molecule Libraries therapeutic use, Structure-Activity Relationship, Zebrafish, Zebrafish Proteins antagonists & inhibitors, Zebrafish Proteins genetics, Cardiomyopathies prevention & control, Cytochrome P450 Family 1 metabolism, Zebrafish Proteins metabolism
- Abstract
Doxorubicin is a highly effective chemotherapy agent used to treat many common malignancies. However, its use is limited by cardiotoxicity, and cumulative doses exponentially increase the risk of heart failure. To identify novel heart failure treatment targets, a zebrafish model of doxorubicin-induced cardiomyopathy was previously established for small-molecule screening. Using this model, several small molecules that prevent doxorubicin-induced cardiotoxicity both in zebrafish and in mouse models have previously been identified. In this study, exploration of doxorubicin cardiotoxicity is expanded by screening 2271 small molecules from a proprietary, target-annotated tool compound collection. It is found that 120 small molecules can prevent doxorubicin-induced cardiotoxicity, including 7 highly effective compounds. Of these, all seven exhibited inhibitory activity towards cytochrome P450 family 1 (CYP1). These results are consistent with previous findings, in which visnagin, a CYP1 inhibitor, also prevents doxorubicin-induced cardiotoxicity. Importantly, genetic mutation of cyp1a protected zebrafish against doxorubicin-induced cardiotoxicity phenotypes. Together, these results provide strong evidence that CYP1 is an important contributor to doxorubicin-induced cardiotoxicity and highlight the CYP1 pathway as a candidate therapeutic target for clinical cardioprotection., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2020
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22. Lifeform indicators reveal large-scale shifts in plankton across the North-West European shelf.
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Bedford J, Ostle C, Johns DG, Atkinson A, Best M, Bresnan E, Machairopoulou M, Graves CA, Devlin M, Milligan A, Pitois S, Mellor A, Tett P, and McQuatters-Gollop A
- Subjects
- Animals, Biodiversity, Climate, North Sea, Ecosystem, Plankton
- Abstract
Increasing direct human pressures on the marine environment, coupled with climate-driven changes, is a concern to marine ecosystems globally. This requires the development and monitoring of ecosystem indicators for effective management and adaptation planning. Plankton lifeforms (broad functional groups) are sensitive indicators of marine environmental change and can provide a simplified view of plankton biodiversity, building an understanding of change in lower trophic levels. Here, we visualize regional-scale multi-decadal trends in six key plankton lifeforms as well as their correlative relationships with sea surface temperature (SST). For the first time, we collate trends across multiple disparate surveys, comparing the spatially and temporally extensive Continuous Plankton Recorder (CPR) survey (offshore) with multiple long-term fixed station-based time-series (inshore) from around the UK coastline. These analyses of plankton lifeforms showed profound long-term changes, which were coherent across large spatial scales. For example, 'diatom' and 'meroplankton' lifeforms showed strong alignment between surveys and coherent regional-scale trends, with the 1998-2017 decadal average abundance of meroplankton being 2.3 times that of 1958-1967 for CPR samples in the North Sea. This major, shelf-wide increase in meroplankton correlated with increasing SSTs, and contrasted with a general decrease in holoplankton (dominated by small copepods), indicating a changing balance of benthic and pelagic fauna. Likewise, inshore-offshore gradients in dinoflagellate trends, with contemporary increases inshore contrasting with multi-decadal decreases offshore (approx. 75% lower decadal mean abundance), urgently require the identification of causal mechanisms. Our lifeform approach allows the collation of many different data types and time-series across the NW European shelf, providing a crucial evidence base for informing ecosystem-based management, and the development of regional adaptation plans., (© 2020 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)
- Published
- 2020
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23. Impact of drug distribution into adipose on tissue function: The cholesteryl ester transfer protein (CETP) inhibitor anacetrapib as a test case.
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Johns DG, Wang SP, Rosa R, Hubert J, Xu S, Chen Y, Bateman T, and Blaustein RO
- Subjects
- Adipose Tissue, White metabolism, Animals, Biomarkers blood, Biomarkers metabolism, Caloric Restriction, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Cholesterol, HDL blood, Cholesterol, HDL metabolism, Cholesterol, LDL blood, Cholesterol, LDL metabolism, Diet, High-Fat adverse effects, Disease Models, Animal, Humans, Hypolipidemic Agents administration & dosage, Lipid Metabolism drug effects, Male, Mice, Obesity blood, Obesity drug therapy, Obesity etiology, Oxazolidinones administration & dosage, Tissue Distribution, Weight Loss, Adipose Tissue, White drug effects, Hypolipidemic Agents pharmacokinetics, Obesity metabolism, Oxazolidinones pharmacokinetics
- Abstract
Anacetrapib is an inhibitor of cholesteryl ester transfer protein (CETP) previously under development as a lipid-modifying agent that reduces LDL-cholesterol and increases HDL-cholesterol in hypercholesterolemic patients. Anacetrapib demonstrates a long terminal half-life and accumulates in adipose tissue, which contributes to a long residence time of anacetrapib. Given our previous report that anacetrapib distributes into the lipid droplet of adipose tissue, we sought to understand whether anacetrapib affected adipose function, using a diet-induced obese (DIO) mouse model. Following 20 weeks of treatment with anacetrapib (100 mg/kg/day), levels of the drug increased to approximately 0.6 mmol/L in white adipose tissue. This level of anacetrapib was not associated with any impairment in adipose functionality as evidenced by a lack of any reduction in biomarkers of adipose functionality (plasma adiponectin, leptin, insulin; adipose adiponectin, leptin mRNA). In DIO wild-type (WT) mice treated with anacetrapib for 2 weeks and then subjected to 30% food restriction during washout to induce weight loss (18%) and fat mass loss (7%), levels of anacetrapib in adipose and plasma were not different between food restricted and ad lib-fed mice. These data indicate that despite deposition and long-term residence of ~0.6 mmol/L levels of anacetrapib in adipose tissue, adipose tissue function appears to be unaffected in mice. In addition, these data also indicate that even with severe caloric restriction and acute loss of fat mass, anacetrapib does not appear to be mobilized from the fat depot, thereby solidifying the role of adipose as a long-term storage site of anacetrapib., Competing Interests: At the time of completion of the manuscript, all authors were employees of Merck, Sharpe & Dohme, Corp., a subsidiary of Merck & Co., Inc, Kenilworth, NJ, USA and potentially own stock and/or hold stock options in Merck & Co., Inc, Kenilworth, NJ USA., (© 2019 The Authors. Pharmacology Research & Perspectives published by John Wiley & Sons Ltd, British Pharmacological Society and American Society for Pharmacology and Experimental Therapeutics.)
- Published
- 2019
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24. The rise in ocean plastics evidenced from a 60-year time series.
- Author
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Ostle C, Thompson RC, Broughton D, Gregory L, Wootton M, and Johns DG
- Abstract
Plastic production has increased exponentially since its use became widespread in the 1950s. This has led to increased concern as plastics have become prevalent in the oceanic environment, and evidence of their impacts on marine organisms and human health has been highlighted. Despite their prevalence, very few long-term (>40 years) records of the distribution and temporal trends of plastics in the world's oceans exist. Here we present a new time series, from 1957 to 2016 and covering over 6.5 million nautical miles, based on records of when plastics have become entangled on a towed marine sampler. This consistent time series provides some of the earliest records of plastic entanglement, and is the first to confirm a significant increase in open ocean plastics in recent decades.
- Published
- 2019
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25. Characterization of Anacetrapib Distribution into the Lipid Droplet of Adipose Tissue in Mice and Human Cultured Adipocytes.
- Author
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Johns DG, LeVoci L, Krsmanovic M, Lu M, Hartmann G, Xu S, Wang SP, Chen Y, Bateman T, and Blaustein RO
- Subjects
- Adipocytes cytology, Adipose Tissue cytology, Animals, Cell Line, Cholesterol, HDL blood, Cholesterol, HDL metabolism, Cholesterol, LDL blood, Cholesterol, LDL metabolism, Half-Life, Humans, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Hypercholesterolemia blood, Hypercholesterolemia drug therapy, Lipase antagonists & inhibitors, Lipase metabolism, Lipolysis drug effects, Male, Mice, Mice, Inbred C57BL, Oxazolidinones administration & dosage, Oxazolidinones therapeutic use, Poloxamer pharmacology, Tissue Distribution drug effects, Adipocytes metabolism, Adipose Tissue metabolism, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Lipid Droplets metabolism, Oxazolidinones pharmacology
- Abstract
Anacetrapib is an inhibitor of cholesteryl ester transfer protein (CETP), associated with reduction in LDL cholesterol and increase in HDL cholesterol in hypercholesterolemic patients. Anacetrapib was not taken forward into filing/registration as a new drug for coronary artery diease, despite the observation of a ∼9% reduction in cardiovascular risk in a large phase III cardiovascular outcomes trial (REVEAL). Anacetrapib displayed no adverse effects throughout extensive preclinical safety evaluation, and no major safety signals were observed in clinical trials studying anacetrapib, including REVEAL. However, anacetrapib demonstrated a long terminal half-life in all species, thought to be due, in part, to distribution into adipose tissue. We sought to understand the dependence of anacetrapib's long half-life on adipose tissue and to explore potential mechanisms that might contribute to the phenomenon. In mice, anacetrapib localized primarily to the lipid droplet of adipocytes in white adipose tissue; in vitro, anacetrapib entry into cultured human adipocytes depended on the presence of a mature adipocyte and lipid droplet but did not require active transport. In vivo, the entry of anacetrapib into adipose tissue did not require lipase activity, as the distribution of anacetrapib into adipose was-not affected by systemic lipase inhibition using poloaxamer-407, a systemic lipase inhibitor. The data from these studies support the notion that the entry of anacetrapib into adipose tissue/lipid droplets does not require active transport, nor does it require mobilization or entry of fat into adipose via lipolysis., (Copyright © 2019 by The American Society for Pharmacology and Experimental Therapeutics.)
- Published
- 2019
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26. Highly potent visnagin derivatives inhibit Cyp1 and prevent doxorubicin cardiotoxicity.
- Author
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Asnani A, Zheng B, Liu Y, Wang Y, Chen HH, Vohra A, Chi A, Cornella-Taracido I, Wang H, Johns DG, Sosnovik DE, and Peterson RT
- Subjects
- Animals, Apoptosis, Cardiotoxicity pathology, Cell Line, Doxorubicin toxicity, Khellin administration & dosage, Khellin chemistry, Male, Mice, Mice, Inbred C57BL, Models, Animal, Myocytes, Cardiac drug effects, Structure-Activity Relationship, Xenobiotics, Zebrafish, Cardiotoxicity prevention & control, Cytochrome P450 Family 1 antagonists & inhibitors, Doxorubicin antagonists & inhibitors, Heart drug effects, Khellin pharmacology
- Abstract
Anthracyclines such as doxorubicin are highly effective chemotherapy agents used to treat many common malignancies. However, their use is limited by cardiotoxicity. We previously identified visnagin as protecting against doxorubicin toxicity in cardiac but not tumor cells. In this study, we sought to develop more potent visnagin analogs in order to use these analogs as tools to clarify the mechanisms of visnagin-mediated cardioprotection. Structure-activity relationship studies were performed in a zebrafish model of doxorubicin cardiomyopathy. Movement of the 5-carbonyl to the 7 position and addition of short ester side chains led to development of visnagin analogs with 1,000-fold increased potency in zebrafish and 250-fold increased potency in mice. Using proteomics, we discovered that doxorubicin caused robust induction of Cytochrome P450 family 1 (CYP1) that was mitigated by visnagin and its potent analog 23. Treatment with structurally divergent CYP1 inhibitors, as well as knockdown of CYP1A, prevented doxorubicin cardiomyopathy in zebrafish. The identification of potent cardioprotective agents may facilitate the development of new therapeutic strategies for patients receiving cardiotoxic chemotherapy. Moreover, these studies support the idea that CYP1 is an important contributor to doxorubicin cardiotoxicity and suggest that modulation of this pathway could be beneficial in the clinical setting.
- Published
- 2018
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27. Assessing the mechanisms of cholesteryl ester transfer protein inhibitors.
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Zhang M, Lei D, Peng B, Yang M, Zhang L, Charles MA, Rye KA, Krauss RM, Johns DG, and Ren G
- Subjects
- Amides, Esters, Humans, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Cholesterol Ester Transfer Proteins chemistry, Lipoproteins, HDL chemistry, Lipoproteins, LDL chemistry, Multiprotein Complexes chemistry, Multiprotein Complexes ultrastructure, Oxazolidinones chemistry, Quinolines chemistry, Sulfhydryl Compounds chemistry
- Abstract
Cholesteryl ester transfer protein (CETP) inhibitors are a new class of therapeutics for dyslipidemia that simultaneously improve two major cardiovascular disease (CVD) risk factors: elevated low-density lipoprotein (LDL) cholesterol and decreased high-density lipoprotein (HDL) cholesterol. However, the detailed molecular mechanisms underlying their efficacy are poorly understood, as are any potential mechanistic differences among the drugs in this class. Herein, we used electron microscopy (EM) to investigate the effects of three of these agents (Torcetrapib, Dalcetrapib and Anacetrapib) on CETP structure, CETP-lipoprotein complex formation and CETP-mediated cholesteryl ester (CE) transfer. We found that although none of these inhibitors altered the structure of CETP or the conformation of CETP-lipoprotein binary complexes, all inhibitors, especially Torcetrapib and Anacetrapib, increased the binding ratios of the binary complexes (e.g., HDL-CETP and LDL-CETP) and decreased the binding ratios of the HDL-CETP-LDL ternary complexes. The findings of more binary complexes and fewer ternary complexes reflect a new mechanism of inhibition: one distal end of CETP bound to the first lipoprotein would trigger a conformational change at the other distal end, thus resulting in a decreased binding ratio to the second lipoprotein and a degraded CE transfer rate among lipoproteins. Thus, we suggest a new inhibitor design that should decrease the formation of both binary and ternary complexes. Decreased concentrations of the binary complex may prevent the inhibitor was induced into cell by the tight binding of binary complexes during lipoprotein metabolism in the treatment of CVD., (Published by Elsevier B.V.)
- Published
- 2017
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28. Enhancing Studies of Pharmacodynamic Mechanisms via Measurements of Metabolic Flux: Fundamental Concepts and Guiding Principles for Using Stable Isotope Tracers.
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Daurio NA, Wang SP, Chen Y, Zhou H, McLaren DG, Roddy TP, Johns DG, Milot D, Kasumov T, Erion MD, Kelley DE, and Previs SF
- Subjects
- Animals, Humans, Isotope Labeling, Isotopes chemistry, Water chemistry, Water metabolism, Drug Discovery methods, Metabolic Flux Analysis methods
- Abstract
Drug discovery and development efforts are largely based around a common expectation, namely, that direct or indirect action on a cellular process (e.g., statin-mediated enzyme inhibition or insulin-stimulated receptor activation) will have a beneficial impact on physiologic homeostasis. To expand on this, one could argue that virtually all pharmacologic interventions attempt to influence the flow of "traffic" in a biochemical network, irrespective of disease or modality. Since stable isotope tracer kinetic methods provide a measure of traffic flow (i.e., metabolic flux), their inclusion in study designs can yield novel information regarding pathway biology; the application of such methods requires the integration of knowledge in physiology, analytical chemistry, and mathematical modeling. Herein, we review the fundamental concepts that surround the use of tracer kinetics, define basic terms, and outline guiding principles via theoretical and experimental problems. Specifically, one needs to 1) recognize the types of biochemical events that change isotopic enrichments, 2) appreciate the distinction between fractional turnover and flux rate, and 3) be aware of the subtle differences between tracer kinetics and pharmacokinetics. We hope investigators can use the framework presented here to develop applications that address their specific questions surrounding biochemical flux, and thereby gain insight into the pathophysiology of disease states, and examine pharmacodynamic mechanisms., (Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.)
- Published
- 2017
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29. Use of Microcomputed Tomography to Measure the Relaxin-induced Expansion of Intrapubic Ligaments in Mice.
- Author
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Zimmerman HA, Kennan RP, Zhang C, Shah K, Johns DG, Lynch JJ, and Dajee M
- Subjects
- Administration, Intravenous, Animals, Estradiol administration & dosage, Female, Infusion Pumps, Implantable, Infusions, Subcutaneous, Injections, Subcutaneous, Mice, Predictive Value of Tests, Time Factors, Biological Assay methods, Ligaments diagnostic imaging, Ligaments drug effects, Relaxin administration & dosage, X-Ray Microtomography
- Abstract
Relaxin is a 6-kDa peptide in the insulin superfamily of hormones. In addition to its effects on reproductive and musculoskeletal ligaments, relaxin has demonstrated beneficial effects on cardiac, renal, and vascular systems in preclinical models. The mouse intrapubic ligament ex vivo bioassay is the current standard for measuring in vivo relaxin bioactivity. However, this bioassay necessitates euthanasia and dissection of large cohorts to measure the intrapubic ligament at specified time points. We hypothesized that μCT imaging could be used to reduce the number of animals necessary for the intrapubic ligament bioassay by enabling a single animal to be followed longitudinally throughout the study rather than euthanizing different cohorts at established time points. Female CD1 mice were used to compare μCT imaging with the current standard. Both protocols revealed significant differences in intrapubic ligament length, with the μCT data having greater power when corrected for baseline imaging. From these data, we concluded that using μCT to measure the intrapubic ligament in mice primed with estrogen and dosed with relaxin is a viable refinement and will allow the use of fewer animals in longitudinal studies and provide more robust data, because animals can serve as their own controls.
- Published
- 2017
30. Relaxin and Matrix Metalloproteinase-9 in Angiotensin II-Induced Abdominal Aortic Aneurysms.
- Author
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Howatt DA, Dajee M, Xie X, Moorleghen J, Rateri DL, Balakrishnan A, Da Cunha V, Johns DG, Gutstein DE, Daugherty A, and Lu H
- Subjects
- Angiotensin II pharmacology, Animals, Aortic Aneurysm, Abdominal chemically induced, Aortic Aneurysm, Abdominal genetics, Aortic Aneurysm, Abdominal pathology, Apolipoproteins E deficiency, Matrix Metalloproteinase 9 genetics, Mice, Mice, Knockout, Relaxin genetics, Angiotensin II adverse effects, Aortic Aneurysm, Abdominal metabolism, Matrix Metalloproteinase 9 metabolism, Relaxin biosynthesis
- Abstract
Background: This study determined whether relaxin or matrix metalloproteinase (MMP)-9 influences angiotensin II (AngII)-induced abdominal aortic aneurysms (AAA).Methods and Results:Male C57BL/6 or apolipoprotein E
-/- mice were infused with AngII with or without relaxin. Relaxin did not influence AngII-induced AAA in either mouse strain. Infusion of AngII reduced, but relaxin increased, MMP-9 mRNA in macrophages. We then determined the effects of MMP-9 deficiency on AAA in apolipoprotein E-/- mice. MMP-9 deficiency led to AAA formation in the absence of AngII, and augmented AngII-induced aortic rupture and AAA incidence., Conclusions: MMP-9 deficiency augmented AngII-induced AAA.- Published
- 2017
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31. Phenological sensitivity to climate across taxa and trophic levels.
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Thackeray SJ, Henrys PA, Hemming D, Bell JR, Botham MS, Burthe S, Helaouet P, Johns DG, Jones ID, Leech DI, Mackay EB, Massimino D, Atkinson S, Bacon PJ, Brereton TM, Carvalho L, Clutton-Brock TH, Duck C, Edwards M, Elliott JM, Hall SJ, Harrington R, Pearce-Higgins JW, Høye TT, Kruuk LE, Pemberton JM, Sparks TH, Thompson PM, White I, Winfield IJ, and Wanless S
- Subjects
- Animals, Aquatic Organisms, Climate, Datasets as Topic, Forecasting, Rain, Seasons, Species Specificity, Temperature, Time Factors, United Kingdom, Climate Change statistics & numerical data, Ecosystem
- Abstract
Differences in phenological responses to climate change among species can desynchronise ecological interactions and thereby threaten ecosystem function. To assess these threats, we must quantify the relative impact of climate change on species at different trophic levels. Here, we apply a Climate Sensitivity Profile approach to 10,003 terrestrial and aquatic phenological data sets, spatially matched to temperature and precipitation data, to quantify variation in climate sensitivity. The direction, magnitude and timing of climate sensitivity varied markedly among organisms within taxonomic and trophic groups. Despite this variability, we detected systematic variation in the direction and magnitude of phenological climate sensitivity. Secondary consumers showed consistently lower climate sensitivity than other groups. We used mid-century climate change projections to estimate that the timing of phenological events could change more for primary consumers than for species in other trophic levels (6.2 versus 2.5-2.9 days earlier on average), with substantial taxonomic variation (1.1-14.8 days earlier on average).
- Published
- 2016
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32. Evaluation of CETP activity in vivo under non-steady-state conditions: influence of anacetrapib on HDL-TG flux.
- Author
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McLaren DG, Previs SF, Phair RD, Stout SJ, Xie D, Chen Y, Salituro GM, Xu SS, Castro-Perez JM, Opiteck GJ, Akinsanya KO, Cleary MA, Dansky HM, Johns DG, and Roddy TP
- Subjects
- Animals, Lipoproteins, HDL blood, Macaca mulatta, Male, Models, Biological, Triglycerides blood, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Cholesterol Ester Transfer Proteins metabolism, Lipoproteins, HDL metabolism, Oxazolidinones pharmacology, Triglycerides metabolism
- Abstract
Studies in lipoprotein kinetics almost exclusively rely on steady-state approaches to modeling. Herein, we have used a non-steady-state experimental design to examine the role of cholesteryl ester transfer protein (CETP) in mediating HDL-TG flux in vivo in rhesus macaques, and therefore, we developed an alternative strategy to model the data. Two isotopomers ([(2)H11] and [(13)C18]) of oleic acid were administered (orally and intravenously, respectively) to serve as precursors for labeling TGs in apoB-containing lipoproteins. The flux of a specific TG (52:2) from these donor lipoproteins to HDL was used as the measure of CETP activity; calculations are also presented to estimate total HDL-TG flux. Based on our data, we estimate that the peak total postprandial TG flux to HDL via CETP is ∼ 13 mg · h(-1) · kg(-1) and show that this transfer was inhibited by 97% following anacetrapib treatment. Collectively, these data demonstrate that HDL TG flux can be used as a measure of CETP activity in vivo. The fact that the donor lipoproteins can be labeled in situ using well-established stable isotope tracer techniques suggests ways to measure this activity for native lipoproteins in free-living subjects under any physiological conditions., (Copyright © 2016 by the American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2016
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33. Discovery of Novel Indoline Cholesterol Ester Transfer Protein Inhibitors (CETP) through a Structure-Guided Approach.
- Author
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Wilson JE, Kurukulasuriya R, Reibarkh M, Reiter M, Zwicker A, Zhao K, Zhang F, Anand R, Colandrea VJ, Cumiskey AM, Crespo A, Duffy RA, Murphy BA, Mitra K, Johns DG, Duffy JL, and Vachal P
- Abstract
Using the collective body of known (CETP) inhibitors as inspiration for design, a structurally novel series of tetrahydroquinoxaline CETP inhibitors were discovered. An exemplar from this series, compound 5, displayed potent in vitro CETP inhibition and was efficacious in a transgenic cynomologus-CETP mouse HDL PD (pharmacodynamic) assay. However, an undesirable metabolic profile and chemical instability hampered further development of the series. A three-dimensional structure of tetrahydroquinoxaline inhibitor 6 was proposed from (1)H NMR structural studies, and this model was then used in silico for the design of a new class of compounds based upon an indoline scaffold. This work resulted in the discovery of compound 7, which displayed potent in vitro CETP inhibition, a favorable PK-PD profile relative to tetrahydroquinoxaline 5, and dose-dependent efficacy in the transgenic cynomologus-CETP mouse HDL PD assay.
- Published
- 2016
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34. Quantitative profiling of oxylipins in plasma and atherosclerotic plaques of hypercholesterolemic rabbits.
- Author
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Bojic LA, McLaren DG, Harms AC, Hankemeier T, Dane A, Wang SP, Rosa R, Previs SF, Johns DG, and Castro-Perez JM
- Subjects
- Animals, Chromatography, High Pressure Liquid, Fatty Acids, Unsaturated metabolism, Humans, Hypercholesterolemia metabolism, Male, Mass Spectrometry, Oxylipins metabolism, Plaque, Atherosclerotic metabolism, Rabbits, Hypercholesterolemia blood, Oxylipins blood, Plaque, Atherosclerotic blood
- Abstract
Oxylipins are oxidation products of polyunsaturated fatty acids (PUFAs) that affect a broad range of physiological processes, including cell proliferation, inflammation, inflammation resolution, and vascular function. Moreover, oxylipins are readily detectable in plasma, and certain subsets of oxylipins have been detected in human atherosclerotic lesions. Taken together, we set out to produce a detailed quantitative assessment of plasma and plaque oxylipins in a widely used model of atherosclerosis, to identify potential biomarkers of disease progression. We administered regular chow or regular chow supplemented with 0.5% cholesterol (HC) to male New Zealand white rabbits for 12 weeks to induce hypercholesterolemia and atherosclerosis. Our targeted lipidomic analyses of oxylipins on plaques isolated from rabbits fed the HC diet detected 34 oxylipins, 28 of which were in compliance with our previously established quality control acceptance criteria. The arachidonic acid (AA) metabolite derived from the COX pathway, 6-keto-PGF1α was the most abundant plaque oxylipin, followed by the linoleic acid (LA) metabolites 9-HODE, 13-HODE and 9,12,13-TriHOME and the arachidonic acid (AA)-derivatives 11-HETE and 12-HETE. We additionally found that the most abundant oxylipins in plasma were three of the five most abundant oxylipins in plaque, namely 11-HETE, 13-HODE, and 9-HODE. The studies reported here make the first step towards a comprehensive characterization of oxylipins as potentially translatable biomarkers of atherosclerosis.
- Published
- 2016
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35. Inhibition of cholesteryl ester transfer protein increases cholesteryl ester content of large HDL independently of HDL-to-HDL homotypic transfer: in vitro vs in vivo comparison using anacetrapib and dalcetrapib.
- Author
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Johns DG, Chen Y, Wang SP, Castro-Perez J, Previs SF, and Roddy TP
- Subjects
- Amides, Animals, Cholesterol, VLDL metabolism, Esters, Humans, Male, Mice, Mice, Inbred C57BL, Anticholesteremic Agents pharmacology, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Cholesterol Esters metabolism, Cholesterol, HDL chemistry, Cholesterol, HDL metabolism, Oxazolidinones pharmacology, Sulfhydryl Compounds pharmacology
- Abstract
The increase in high density lipoprotein (HDL)-cholesterol observed with cholesteryl ester transfer protein (CETP) inhibition is commonly attributed to blockade of cholesteryl ester (CE) transfer from HDL to low density lipoprotein particles. In vitro, it has been observed that CETP can mediate transfer of CE between HDL particles ("homotypic transfer"), and it is postulated that this contributes to HDL remodeling and generation of anti-atherogenic pre-beta HDL. Inhibition of CETP could limit this beneficial remodeling and reduce pre-beta HDL levels. We observed that anacetrapib does not reduce pre-beta HDL in vivo, but the role of HDL homotypic transfer was not examined. This study evaluated the effects of anacetrapib on homotypic transfer from HDL3 to HDL2 in vivo using deuterium-labeled HDL3, and compared this to in vitro settings, where homotypic transfer was previously described. In vitro, both anacetrapib and dalcetrapib inhibited transfer of CE from HDL3 to HDL2 particles. In CETP transgenic mice, anacetrapib did not inhibit the appearance of labeled CE derived from HDL3 in HDL2 particles, but rather promoted the appearance of labeled CE in HDL2. We concluded that inhibition of CETP by anacetrapib promoted HDL particle remodeling, and does not impair the flux of cholesterol ester into larger HDL particles when studied in vivo, which is not consistent with in vitro observations. We further conclude, therefore, that the in vitro conditions used to examine HDL-to-HDL homotypic transfer may not recapitulate the in vivo condition, where multiple mechanisms contribute to cholesteryl ester flux into and out of the HDL pool., (Copyright © 2015 Elsevier B.V. All rights reserved.)
- Published
- 2015
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36. Discovery of GSK2795039, a Novel Small Molecule NADPH Oxidase 2 Inhibitor.
- Author
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Hirano K, Chen WS, Chueng AL, Dunne AA, Seredenina T, Filippova A, Ramachandran S, Bridges A, Chaudry L, Pettman G, Allan C, Duncan S, Lee KC, Lim J, Ma MT, Ong AB, Ye NY, Nasir S, Mulyanidewi S, Aw CC, Oon PP, Liao S, Li D, Johns DG, Miller ND, Davies CH, Browne ER, Matsuoka Y, Chen DW, Jaquet V, and Rutter AR
- Subjects
- Aminopyridines chemistry, Animals, Cells, Cultured, Enzyme Inhibitors therapeutic use, Male, Membrane Glycoproteins antagonists & inhibitors, Mice, Inbred C57BL, NADPH Oxidase 2, NADPH Oxidases antagonists & inhibitors, Pancreatitis drug therapy, Rats, Sprague-Dawley, Reactive Oxygen Species metabolism, Sulfonamides chemistry, Aminopyridines pharmacology, Drug Discovery, Enzyme Inhibitors pharmacology, Membrane Glycoproteins metabolism, NADPH Oxidases metabolism, Sulfonamides pharmacology
- Abstract
Aims: The NADPH oxidase (NOX) family of enzymes catalyzes the formation of reactive oxygen species (ROS). NOX enzymes not only have a key role in a variety of physiological processes but also contribute to oxidative stress in certain disease states. To date, while numerous small molecule inhibitors have been reported (in particular for NOX2), none have demonstrated inhibitory activity in vivo. As such, there is a need for the identification of improved NOX inhibitors to enable further evaluation of the biological functions of NOX enzymes in vivo as well as the therapeutic potential of NOX inhibition. In this study, both the in vitro and in vivo pharmacological profiles of GSK2795039, a novel NOX2 inhibitor, were characterized in comparison with other published NOX inhibitors., Results: GSK2795039 inhibited both the formation of ROS and the utilization of the enzyme substrates, NADPH and oxygen, in a variety of semirecombinant cell-free and cell-based NOX2 assays. It inhibited NOX2 in an NADPH competitive manner and was selective over other NOX isoforms, xanthine oxidase, and endothelial nitric oxide synthase enzymes. Following systemic administration in mice, GSK2795039 abolished the production of ROS by activated NOX2 enzyme in a paw inflammation model. Furthermore, GSK2795039 showed activity in a murine model of acute pancreatitis, reducing the levels of serum amylase triggered by systemic injection of cerulein., Innovation and Conclusions: GSK2795039 is a novel NOX2 inhibitor that is the first small molecule to demonstrate inhibition of the NOX2 enzyme in vivo.
- Published
- 2015
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37. HDL surface lipids mediate CETP binding as revealed by electron microscopy and molecular dynamics simulation.
- Author
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Zhang M, Charles R, Tong H, Zhang L, Patel M, Wang F, Rames MJ, Ren A, Rye KA, Qiu X, Johns DG, Charles MA, and Ren G
- Subjects
- Cholesterol Ester Transfer Proteins genetics, Cholesterol Ester Transfer Proteins ultrastructure, Cryoelectron Microscopy, Electron Microscope Tomography, Humans, Hydrophobic and Hydrophilic Interactions, Imaging, Three-Dimensional, Lipoproteins, HDL blood, Lipoproteins, HDL ultrastructure, Liposomes chemistry, Liposomes metabolism, Liposomes ultrastructure, Membrane Lipids chemistry, Microscopy, Electron, Transmission, Protein Binding, Recombinant Proteins chemistry, Recombinant Proteins metabolism, Recombinant Proteins ultrastructure, Cholesterol Ester Transfer Proteins metabolism, Lipoproteins, HDL metabolism, Membrane Lipids metabolism, Molecular Dynamics Simulation
- Abstract
Cholesteryl ester transfer protein (CETP) mediates the transfer of cholesterol esters (CE) from atheroprotective high-density lipoproteins (HDL) to atherogenic low-density lipoproteins (LDL). CETP inhibition has been regarded as a promising strategy for increasing HDL levels and subsequently reducing the risk of cardiovascular diseases (CVD). Although the crystal structure of CETP is known, little is known regarding how CETP binds to HDL. Here, we investigated how various HDL-like particles interact with CETP by electron microscopy and molecular dynamics simulations. Results showed that CETP binds to HDL via hydrophobic interactions rather than protein-protein interactions. The HDL surface lipid curvature generates a hydrophobic environment, leading to CETP hydrophobic distal end interaction. This interaction is independent of other HDL components, such as apolipoproteins, cholesteryl esters and triglycerides. Thus, disrupting these hydrophobic interactions could be a new therapeutic strategy for attenuating the interaction of CETP with HDL.
- Published
- 2015
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38. Development of lipoprotein(a) siRNAs for mechanism of action studies in non-human primate models of atherosclerosis.
- Author
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Tadin-Strapps M, Robinson M, Le Voci L, Andrews L, Yendluri S, Williams S, Bartz S, and Johns DG
- Subjects
- Animals, Atherosclerosis blood, Atherosclerosis genetics, Atherosclerosis pathology, Cell Line, Disease Models, Animal, Female, Gene Transfer Techniques, Humans, Lipids chemistry, Lipoprotein(a) blood, Liver metabolism, Macaca mulatta, Male, Nanomedicine, Nanoparticles, RNA, Small Interfering chemistry, RNA, Small Interfering metabolism, Time Factors, Transfection, Atherosclerosis therapy, Lipoprotein(a) genetics, RNA, Small Interfering genetics, RNAi Therapeutics
- Abstract
Lipoprotein(a) [Lp(a)] has recently been recognized as an independent risk factor for coronary heart disease. While plasma Lp(a) levels are correlated with cardiovascular risk, the mechanism by which this particle contributes to atherosclerosis is largely unknown. Although humanized transgenic mouse model has recently been described to study Lp(a) biology, non-human primates (NHP) are the only preclinical model available that allow study of the role of Lp(a) in atherosclerosis in an innate setting. We describe targeting of LPA using lipid nanoparticle formulated short interfering RNAs (siRNAs) in lean rhesus macaque monkeys. We show >90 % LPA mRNA lowering in the liver and >95 % Lp(a) plasma reduction for over 3 weeks after a single siRNA dose. Given the potency of LPA siRNAs, siRNA approach may enable chronic reduction of Lp(a) in atherosclerotic NHP and help to unmask the role for Lp(a) in the genesis and progression of atherosclerosis in man.
- Published
- 2015
- Full Text
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39. Effect of Error Propagation in Stable Isotope Tracer Studies: An Approach for Estimating Impact on Apparent Biochemical Flux.
- Author
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Previs SF, Herath K, Castro-Perez J, Mahsut A, Zhou H, McLaren DG, Shah V, Rohm RJ, Stout SJ, Zhong W, Wang SP, Johns DG, Hubbard BK, Cleary MA, and Roddy TP
- Subjects
- Animals, Carbon Isotopes, Chromatography, Gas methods, Chromatography, Liquid methods, Deuterium Oxide, Humans, Signal-To-Noise Ratio, Isotope Labeling methods, Mass Spectrometry methods, Metabolism
- Abstract
Stable isotope tracers are widely used to quantify metabolic rates, and yet a limited number of studies have considered the impact of analytical error on estimates of flux. For example, when estimating the contribution of de novo lipogenesis, one typically measures a minimum of four isotope ratios, i.e., the precursor and product labeling pre- and posttracer administration. This seemingly simple problem has 1 correct solution and 80 erroneous outcomes. In this report, we outline a methodology for evaluating the effect of error propagation on apparent physiological endpoints. We demonstrate examples of how to evaluate the influence of analytical error in case studies concerning lipid and protein synthesis; we have focused on (2)H2O as a tracer and contrast different mass spectrometry platforms including GC-quadrupole-MS, GC-pyrolysis-IRMS, LC-quadrupole-MS, and high-resolution FT-ICR-MS. The method outlined herein can be used to determine how to minimize variations in the apparent biology by altering the dose and/or the type of tracer. Likewise, one can facilitate biological studies by estimating the reduction in the noise of an outcome that is expected for a given increase in the number of replicate injections., (© 2015 Elsevier Inc. All rights reserved.)
- Published
- 2015
- Full Text
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40. Lipidome of atherosclerotic plaques from hypercholesterolemic rabbits.
- Author
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Bojic LA, McLaren DG, Shah V, Previs SF, Johns DG, and Castro-Perez JM
- Subjects
- Animals, Ceramides blood, Cholesterol Esters blood, Fatty Acids blood, Glycerophospholipids blood, Hypercholesterolemia complications, Male, Plaque, Atherosclerotic etiology, Rabbits, Sphingomyelins blood, Triglycerides blood, Hypercholesterolemia metabolism, Lipid Metabolism, Plaque, Atherosclerotic metabolism
- Abstract
The cellular, macromolecular and neutral lipid composition of the atherosclerotic plaque has been extensively characterized. However, a comprehensive lipidomic analysis of the major lipid classes within atherosclerotic lesions has not been reported. The objective of this study was to produce a detailed framework of the lipids that comprise the atherosclerotic lesion of a widely used pre-clinical model of plaque progression. Male New Zealand White rabbits were administered regular chow supplemented with 0.5% cholesterol (HC) for 12 weeks to induce hypercholesterolemia and atherosclerosis. Our lipidomic analyses of plaques isolated from rabbits fed the HC diet, using ultra-performance liquid chromatography (UPLC) and high-resolution mass spectrometry, detected most of the major lipid classes including: Cholesteryl esters, triacylglycerols, phosphatidylcholines, sphingomyelins, diacylglycerols, fatty acids, phosphatidylserines, lysophosphatidylcholines, ceramides, phosphatidylglycerols, phosphatidylinositols and phosphatidylethanolamines. Given that cholesteryl esters, triacylglycerols and phosphatidylcholines comprise greater than 75% of total plasma lipids, we directed particular attention towards the qualitative and quantitative assessment of the fatty acid composition of these lipids. We additionally found that sphingomyelins were relatively abundant lipid class within lesions, and compared the abundance of sphingomyelins to their precursor phosphatidylcholines. The studies presented here are the first approach to a comprehensive characterization of the atherosclerotic plaque lipidome.
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- 2014
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41. In vivo isotopically labeled atherosclerotic aorta plaques in ApoE KO mice and molecular profiling by matrix-assisted laser desorption/ionization mass spectrometric imaging.
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Castro-Perez J, Hatcher N, Kofi Karikari N, Wang SP, Mendoza V, Shion H, Millar A, Shockcor J, Towers M, McLaren D, Shah V, Previs S, Akinsanya K, Cleary M, Roddy TP, and Johns DG
- Abstract
Rationale: The ability to quantify rates of formation, regression and/or remodeling of atherosclerotic plaque should facilitate a better understanding of the pathogenesis and management of cardiovascular disease. In the current study, we coupled a stable isotope labeled tracer protocol with matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to examine spatial and temporal lipid dynamics in atherosclerotic plaque., Methods: To promote plaque formation in the aorta region, ApoE KO mice were fed a high cholesterol diet (0.15% cholesterol) and orally dosed with (2,2,3,4,4,6-d(6))-cholesterol over several weeks. Tissue sections of ~10 µm thickness were analyzed by MALDI-MSI using matrix deposition by either chemical sublimation or acoustic droplet ejection., Results: MALDI-MSI yielded distinct spatial distribution information for a variety of lipid classes including specific lysophosphatidylcholines typically associated with atherosclerosis-related tissue damage such as phospholipase 2 (Lp-PLA(2)) that mediate chemotactic responses to inflammation (e.g. LPC 16:0, LPC 18:0 and LPC 18:1) as well as free cholesterol and cholesteryl esters that contribute to atheroma formation. MALDI mass spectra acquired from aorta tissue sections clearly distinguished non-esterified and esterified versions of (2,2,3,4,4,6-d(6))-cholesterol within aortic plaque regions and showed distinct spatial accumulation of the cholesterol tracer., Conclusions: The ability to couple stable isotope based protocols with MALDI-MSI enables a novel strategy to characterize the effects of therapeutic treatments on atherosclerotic plaque formation, regression and potential remodeling of the complex lipid components with high chemical specificity and spatiotemporal information., (Copyright © 2014 John Wiley & Sons, Ltd.)
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- 2014
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42. Anacetrapib and dalcetrapib differentially alters HDL metabolism and macrophage-to-feces reverse cholesterol transport at similar levels of CETP inhibition in hamsters.
- Author
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Briand F, Thieblemont Q, Muzotte E, Burr N, Urbain I, Sulpice T, and Johns DG
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- Amides, Animals, Biological Transport, Cholesterol blood, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Cholesterol Ester Transfer Proteins blood, Cricetinae, Dyslipidemias blood, Dyslipidemias metabolism, Esters, Male, Triglycerides blood, Anticholesteremic Agents pharmacology, Cholesterol metabolism, Feces chemistry, Macrophages metabolism, Oxazolidinones pharmacology, Sulfhydryl Compounds pharmacology
- Abstract
Cholesteryl ester transfer protein (CETP) inhibitors dalcetrapib and anacetrapib differentially alter LDL- and HDL-cholesterol levels, which might be related to the potency of each drug to inhibit CETP activity. We evaluated the effects of both drugs at similar levels of CETP inhibition on macrophage-to-feces reverse cholesterol transport (RCT) in hamsters. In normolipidemic hamsters, both anacetrapib 30 mg/kg QD and dalcetrapib 200 mg/kg BID inhibited CETP activity by ~60%. After injection of 3H-cholesteryl oleate labeled HDL, anacetrapib and dalcetrapib reduced HDL-cholesteryl esters fractional catabolic rate (FCR) by 30% and 26% (both P<0.001 vs. vehicle) respectively, but only dalcetrapib increased HDL-derived 3H-tracer fecal excretion by 30% (P<0.05 vs. vehicle). After 3H-cholesterol labeled macrophage intraperitoneal injection, anacetrapib stimulated 3H-tracer appearance in HDL, but both drugs did not promote macrophage-derived 3H-tracer fecal excretion. In dyslipidemic hamsters, both anacetrapib 1 mg/kg QD and dalcetrapib 200 mg/kg BID inhibited CETP activity by ~65% and reduced HDL-cholesteryl ester FCR by 36% (both P<0.001 vs. vehicle), but only anacetrapib increased HDL-derived 3H-tracer fecal excretion significantly by 39%. After 3H-cholesterol labeled macrophage injection, only anacetrapib 1 mg/kg QD stimulated macrophage-derived 3H-tracer appearance in HDL. These effects remained weaker than those observed with anacetrapib 60 mg/kg QD, which induced a maximal inhibition of CETP and stimulation of macrophage-derived 3H-tracer fecal excretion. In contrast, dalcetrapib 200 mg/kg BID reduced macrophage-derived 3H-tracer fecal excretion by 23% (P<0.05 vs. vehicle). In conclusion, anacetrapib and dalcetrapib differentially alter HDL metabolism and RCT in hamsters. A stronger inhibition of CETP may be required to promote macrophage-to-feces reverse cholesterol transport in dyslipidemic hamsters., (Copyright © 2014 Elsevier B.V. All rights reserved.)
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- 2014
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43. Effects of anacetrapib on plasma lipids, apolipoproteins and PCSK9 in healthy, lean rhesus macaques.
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Roddy TP, McLaren DG, Chen Y, Xie D, Dunn K, Kulick A, Szeto D, Forrest G, Albanese K, Donnelly M, Gai C, Gewain A, Lederman H, Jensen KK, Ai X, Vachal P, Akinsanya KO, Cleary MA, Previs SF, Dansky HM, and Johns DG
- Subjects
- Animals, Apolipoproteins blood, Cholesterol Ester Transfer Proteins blood, Cholesterol, HDL blood, Cholesterol, LDL blood, Macaca mulatta, Male, Proprotein Convertases blood, Serine Endopeptidases blood, Triglycerides blood, Anticholesteremic Agents pharmacology, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Oxazolidinones pharmacology
- Abstract
Inhibition of cholesteryl ester transfer protein (CETP) has been vigorously pursued as a potential therapy to treat patients who are at an elevated risk for coronary artery disease. Anacetrapib, a novel CETP inhibitor, has been shown clinically to raise HDL cholesterol and reduce LDL cholesterol when provided as monotherapy or when co-administered with a statin. Preclinically, the effects of anacetrapib on the functionality and composition of HDL have been extensively studied. In contrast, the effects of anacetrapib on other parameters related to lipoprotein metabolism and cardiovascular risk have been difficult to explore. The aim of the present investigation was to evaluate the effects of anacetrapib in rhesus macaques and to compare these to effects reported in dyslipidemic humans. Our results from two separate studies show that administration of anacetrapib (150 mg/kg q.d. for 10 days) to rhesus macaques results in alterations in CETP activity (reduced by more than 70%) and HDL cholesterol (increased by more than 110%) which are similar to those reported in dyslipidemic humans. Levels of LDL cholesterol were reduced by more than 60%, an effect slightly greater than what has been observed clinically. Treatment with anacetrapib in this model was also found to lead to statistically significant reductions in plasma PCSK9 and to reduce cholesterol excursion in the combined chylomicron and remnant lipoprotein fraction isolated from plasma by fast protein liquid chromatography. Collectively, these data suggest that rhesus macaques may be a useful translational model to study the mechanistic effects of CETP inhibition., (Copyright © 2014 Elsevier B.V. All rights reserved.)
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- 2014
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44. New methodologies for studying lipid synthesis and turnover: looking backwards to enable moving forwards.
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Previs SF, McLaren DG, Wang SP, Stout SJ, Zhou H, Herath K, Shah V, Miller PL, Wilsie L, Castro-Perez J, Johns DG, Cleary MA, and Roddy TP
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- Body Fat Distribution, Cholesterol biosynthesis, Cholesterol metabolism, Energy Metabolism, Humans, Kinetics, Triglycerides chemistry, Adipose Tissue metabolism, Lipid Metabolism, Lipids biosynthesis, Triglycerides metabolism
- Abstract
Our ability to understand the pathogenesis of problems surrounding lipid accretion requires attention towards quantifying lipid kinetics. In addition, studies of metabolic flux should also help unravel mechanisms that lead to imbalances in inter-organ lipid trafficking which contribute to dyslipidemia and/or peripheral lipid accumulation (e.g. hepatic fat deposits). This review aims to outline the development and use of novel methods for studying lipid kinetics in vivo. Although our focus is directed towards some of the approaches that are currently reported in the literature, we include a discussion of the older literature in order to put "new" methods in better perspective and inform readers of valuable historical research. Presumably, future advances in understanding lipid dynamics will benefit from a careful consideration of the past efforts, where possible we have tried to identify seminal papers or those that provide clear data to emphasize essential points. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease., (Copyright © 2013 Elsevier B.V. All rights reserved.)
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- 2014
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45. Understanding the distribution of marine megafauna in the English channel region: identifying key habitats for conservation within the busiest seaway on earth.
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McClellan CM, Brereton T, Dell'Amico F, Johns DG, Cucknell AC, Patrick SC, Penrose R, Ridoux V, Solandt JL, Stephan E, Votier SC, Williams R, and Godley BJ
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- Animals, Biodiversity, Birds, Conservation of Natural Resources, Ecosystem, Fishes, Mammals, Models, Theoretical, Turtles, Marine Biology methods
- Abstract
The temperate waters of the North-Eastern Atlantic have a long history of maritime resource richness and, as a result, the European Union is endeavouring to maintain regional productivity and biodiversity. At the intersection of these aims lies potential conflict, signalling the need for integrated, cross-border management approaches. This paper focuses on the marine megafauna of the region. This guild of consumers was formerly abundant, but is now depleted and protected under various national and international legislative structures. We present a meta-analysis of available megafauna datasets using presence-only distribution models to characterise suitable habitat and identify spatially-important regions within the English Channel and southern bight of the North Sea. The integration of studies from dedicated and opportunistic observer programmes in the United Kingdom and France provide a valuable perspective on the spatial and seasonal distribution of various taxonomic groups, including large pelagic fishes and sharks, marine mammals, seabirds and marine turtles. The Western English Channel emerged as a hotspot of biodiversity for megafauna, while species richness was low in the Eastern English Channel. Spatial conservation planning is complicated by the highly mobile nature of marine megafauna, however they are important components of the marine environment and understanding their distribution is a first crucial step toward their inclusion into marine ecosystem management.
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- 2014
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46. Determination of low levels of 2H-labeling using high-resolution mass spectrometry: application in studies of lipid flux and beyond.
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Herath KB, Zhong W, Yang J, Mahsut A, Rohm RJ, Shah V, Castro-Perez J, Zhou H, Attygalle AB, Kang L, Singh S, Johns DG, Cleary MA, Hubbard BK, Previs SF, and Roddy TP
- Subjects
- Animals, Chlorocebus aethiops, Deuterium chemistry, Deuterium metabolism, Deuterium Oxide administration & dosage, Fatty Acids metabolism, Female, Linear Models, Macaca mulatta, Male, Peptides chemistry, Peptides metabolism, Deuterium analysis, Fatty Acids chemistry, Isotope Labeling methods, Mass Spectrometry methods
- Abstract
Rationale: The ability to measure low levels of (2)H-labeling is important in studies of metabolic flux, e.g. one can estimate lipid synthesis by administering (2)H2O and then measuring the incorporation of (2)H into fatty acids. Unfortunately, the analyses are complicated by the presence of more abundant naturally occurring stable isotopes, e.g. (13)C. Conventional approaches rely on coupling gas chromatographic separation of lipids with either quadrupole-mass spectrometry (q-MS) and/or pyrolysis-isotope ratio mass spectrometry (IRMS). The former is limited by high background labeling (primarily from (13)C) whereas the latter is not suitable for routine high-throughput analyses., Methods: We have contrasted the use of continuous flow-pyrolysis-IRMS against high-resolution mass spectrometry (i.e. Qq-FT-ICR MS) for measuring the (2)H-enrichment of fatty acids and peptides., Results: In contrast to IRMS, which requires ~30 min per analysis, it is possible to measure the (2)H-enrichment of palmitate via direct infusion high-resolution mass spectrometry (HRMS) in ~3 min per sample. In addition, Qq-FT-ICR MS enabled measurements of the (2)H-enrichment of peptides (which is not possible using IRMS)., Conclusions: High-resolution mass spectrometry can be used to measure low levels of (2)H-labeling so we expect that this approach will enhance studies of metabolic flux that rely on (2)H-labeled tracers, e.g. (2)H2O. However, since the high-resolution analyses require greater amounts of a given analyte one potential limitation centers on the overall sensitivity. Presumably, future advances can overcome this barrier., (Copyright © 2013 John Wiley & Sons, Ltd.)
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- 2014
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47. Inverse relationship between LDL cholesterol and PCSK9 plasma levels in dyslipidemic cynomolgus monkeys: effects of LDL lowering by ezetimibe in the absence of statins.
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Hentze H, Jensen KK, Chia SM, Johns DG, Shaw RJ, Davis HR Jr, Shih SJ, and Wong KK
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- Animals, Cholesterol, Dietary administration & dosage, Diet, High-Fat, Ezetimibe, Macaca fascicularis, Azetidines therapeutic use, Cholesterol, LDL blood, Dyslipidemias drug therapy, Proprotein Convertases blood, Serine Endopeptidases blood
- Abstract
Objectives: To assess the lipid-lowering efficacy of ezetimibe in dyslipidemic cynomolgus monkeys comparing two dosing methods, and to evaluate PCSK9 plasma levels during dyslipidemia induction by feeding a high-fat/high-cholesterol diet (HFD), ezetimibe (Zetia(®), Ezetrol(®)) treatment, ezetimibe washout, and HFD washout., Methods and Results: Twenty dyslipidemic cynomolgus monkeys on HFD for seven months (LDL cholesterol 100-400 mg/dL) were randomized into two groups and treated with ezetimibe for two weeks, either by oral gavage or by using food treats. The lipid-lowering effects of ezetimibe were identical between the two groups. After treatment, mean LDL cholesterol was decreased by 58% (174-72 mg/dL), total cholesterol by 42% (241-138 mg/dL), and PCSK9 levels were increased by 137% (147-314 ng/mL). PCSK9 levels on regular diet before and after HFD were also inversely correlated to LDL cholesterol., Conclusions: In a cynomolgus dyslipidemia model, PCSK9 levels are inversely correlated with LDL cholesterol in the absence of statin treatment, regardless whether lipid changes are modulated by diet or ezetimibe treatment., (Copyright © 2013. Published by Elsevier Ireland Ltd.)
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- 2013
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48. In vivo effects of anacetrapib on preβ HDL: improvement in HDL remodeling without effects on cholesterol absorption.
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Wang SP, Daniels E, Chen Y, Castro-Perez J, Zhou H, Akinsanya KO, Previs SF, Roddy TP, and Johns DG
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- Amides, Animals, Anticholesteremic Agents therapeutic use, Area Under Curve, Azetidines pharmacology, Azetidines therapeutic use, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Cholesterol Ester Transfer Proteins metabolism, Cricetinae, Diet, High-Fat adverse effects, Drug Evaluation, Preclinical, Dyslipidemias blood, Dyslipidemias etiology, Esters, Ezetimibe, Humans, Male, Mesocricetus, Oxazolidinones therapeutic use, Sulfhydryl Compounds pharmacology, Sulfhydryl Compounds therapeutic use, Anticholesteremic Agents pharmacology, Cholesterol metabolism, Dyslipidemias drug therapy, High-Density Lipoproteins, Pre-beta blood, Intestinal Absorption drug effects, Oxazolidinones pharmacology
- Abstract
Cholesteryl ester transfer protein (CETP) transfers cholesteryl ester and triglyceride between HDL and apoB-containing lipoproteins. Anacetrapib (ANA), a reversible inhibitor of CETP, raises HDL cholesterol and lowers LDL cholesterol in dyslipidemic patients. We previously demonstrated that ANA increases macrophage-to-feces reverse cholesterol transport and fecal cholesterol excretion in hamsters, and increased preβ HDL-dependent cholesterol efflux via ABCA1 in vitro. However, the effects of ANA on in vivo preβ HDL have not been characterized. In vitro, ANA inhibited the formation of preβ, however in ANA-treated dyslipidemic hamsters, preβ HDL levels (measured by two-dimensional gel electrophoresis) were increased, in contrast to in vitro findings. Because changes in plasma preβ HDL have been proposed to potentially affect markers of cholesterol absorption with other CETP inhibitors, a dual stable isotope method was used to directly measure cholesterol absorption in hamsters. ANA treatment of hamsters (on either dyslipidemic or normal diet) had no effect on cholesterol absorption, while dalcetrapib-treated hamsters displayed an increase in cholesterol absorption. Taken together, these data support the notion that ANA promotes preβ HDL functionality in vivo, with no effects on cholesterol absorption.
- Published
- 2013
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49. Use of [13C18] oleic acid and mass isotopomer distribution analysis to study synthesis of plasma triglycerides in vivo: analytical and experimental considerations.
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McLaren DG, Cardasis HL, Stout SJ, Wang SP, Mendoza V, Castro-Perez JM, Miller PL, Murphy BA, Cumiskey AM, Cleary MA, Johns DG, Previs SF, and Roddy TP
- Subjects
- Animals, Carbon Isotopes, Mice, Mice, Inbred C57BL, Obesity blood, Obesity diagnosis, Oleic Acid administration & dosage, Mass Spectrometry methods, Oleic Acid analysis, Triglycerides biosynthesis, Triglycerides blood
- Abstract
We have previously reported on a liquid chromatography-mass spectrometry method to determine the disposition of [(13)C18]-oleic acid following intravenous and oral administration in vivo. This approach has enabled us to study a variety of aspects of lipid metabolism including a quantitative assessment of triglyceride synthesis. Here we present a more rigorous evaluation of the constraints imposed upon the analytical method in order to generate accurate data using this stable-isotope tracer approach along with more detail on relevant analytical figures of merit including limits of quantitation, precision, and accuracy. The use of mass isotopomer distribution analysis (MIDA) to quantify plasma triglyceride synthesis is specifically highlighted, and a re-evaluation of the underlying mathematics has enabled us to present a simplified series of equations. The derivation of this MIDA model and the significance of all underlying assumptions are explored in detail, and examples are given of how it can successfully be applied to detect differences in plasma triglyceride synthesis in lean and high-fat diet fed mouse models. More work is necessary to evaluate the applicability of this approach to triglyceride stores with slower rates of turnover such as in adipose or muscle tissue; however, the present report provides investigators with the tools necessary to conduct such studies.
- Published
- 2013
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50. Inhibition of cholesteryl ester transfer protein by anacetrapib does not impair the anti-inflammatory properties of high density lipoprotein.
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Han S, Levoci L, Fischer P, Wang SP, Gagen K, Chen Y, Xie D, Fisher T, Ehrhardt AG, Peier AM, and Johns DG
- Subjects
- Cells, Cultured, E-Selectin metabolism, Humans, Intercellular Adhesion Molecule-1 metabolism, Tumor Necrosis Factor-alpha pharmacology, Vascular Cell Adhesion Molecule-1 metabolism, Anti-Inflammatory Agents pharmacology, Cholesterol Ester Transfer Proteins antagonists & inhibitors, Endothelial Cells drug effects, Endothelial Cells metabolism, Lipoproteins, HDL pharmacology, Oxazolidinones pharmacology
- Abstract
Cholesteryl ester transfer protein (CETP) is a target of therapeutic intervention for coronary heart disease. Anacetrapib, a potent inhibitor of CETP, has been shown to reduce LDL-cholesterol by 40% and increase HDL-cholesterol by 140% in patients, and is currently being evaluated in a phase III cardiovascular outcomes trial. HDL is known to possess anti-inflammatory properties, however with such large increases in HDL-cholesterol, it is unclear whether CETP inhibition perturbs HDL functionality such as anti-inflammatory effects on endothelial cells. The purpose of the present study was to determine whether CETP inhibition by anacetrapib affects the anti-inflammatory properties of HDL. HDL was isolated from either hamsters treated with vehicle or anacetrapib for 2weeks, or from normal human subjects treated either placebo, 20mg, or 150mg anacetrapib daily for 2weeks. Anacetrapib treatment increased plasma HDL cholesterol levels by 65% and between 48 and 82% in hamsters and humans, respectively. Pre-incubation of human aortic endothelial cells with HDL isolated from both control and anacetrapib treated hamsters suppressed TNFα induced expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and E-selectin. Similar results were obtained with human HDL samples pre and post treatment with placebo or anacetrapib. Further, HDL inhibited TNFα-induced MCP-1 secretion, monocyte adhesion and NF-κB activation in endothelial cells, and the inhibition was similar between control and anacetrapib treated groups. These studies demonstrate that anacetrapib treatment does not impair the ability of HDL to suppress an inflammatory response in endothelial cells., (Copyright © 2013 Elsevier B.V. All rights reserved.)
- Published
- 2013
- Full Text
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