41 results on '"Wang, Liangsu"'
Search Results
2. Racing to define pharmaceutical R&D external innovation models
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Wang, Liangsu, Plump, Andrew, and Ringel, Michael
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- 2015
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3. The Transcriptomic Signature Of Disease Development And Progression Of Nonalcoholic Fatty Liver Disease
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Cazanave, Sophie, Podtelezhnikov, Alexei, Jensen, Kristian, Seneshaw, Mulugeta, Kumar, Divya P., Min, Hae-Ki, Santhekadur, Prasanna K., Banini, Bubu, Mauro, Adolfo Gabriele, M. Oseini, Abdul, Vincent, Robert, Tanis, Keith Q., Webber, Andrea L., Wang, Liangsu, Bedossa, Pierre, Mirshahi, Faridoddin, and Sanyal, Arun J.
- Published
- 2017
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4. Small molecule activation of lecithin cholesterol acyltransferase modulates lipoprotein metabolism in mice and hamsters
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Chen, Zhu, Wang, Sheng-ping, Krsmanovic, Mihajlo L., Castro-Perez, Jose, Gagen, Karen, Mendoza, Vivienne, Rosa, Ray, Shah, Vinit, He, Timothy, Stout, Steve J., Geoghagen, Neil S., Lee, Sang H., McLaren, David G., Wang, Liangsu, Roddy, Thomas P., Plump, Andrew S., Hubbard, Brian K., Sinz, Christopher J., and Johns, Douglas G.
- Published
- 2012
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5. Increased Bile Acid Synthesis and Impaired Bile Acid Transport in Human Obesity
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Haeusler, Rebecca A., Camastra, Stefania, Nannipieri, Monica, Astiarraga, Brenno, Castro-Perez, Jose, Xie, Dan, Wang, Liangsu, Chakravarthy, Manu, and Ferrannini, Ele
- Published
- 2016
6. Increased Bile Acid Synthesis and Deconjugation After Biliopancreatic Diversion
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Ferrannini, Ele, Camastra, Stefania, Astiarraga, Brenno, Nannipieri, Monica, Castro-Perez, Jose, Xie, Dan, Wang, Liangsu, Chakravarthy, Manu, and Haeusler, Rebecca A.
- Published
- 2015
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7. Identification of a metabolic, transcriptomic and molecular signature of PNPLA3-mediated acceleration of steatohepatitis
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Banini, Bubu A, Kumar, Divya. P., Cazanave, Sophie, Seneshaw, Mulugeta, Mirshahi, Faridoddin, Santhekadur, Prasanna K., Wang, Liangsu, Guan, Hong Ping, Oseini, Abdul, Alonso, Cristina, Bedossa, Pierre, Koduru, Srinivas V., Min, Hae-Ki, and Sanyal, Arun J.
- Subjects
Liver Cirrhosis ,Male ,Polymorphism, Genetic ,Gene Expression ,Membrane Proteins ,Hep G2 Cells ,Lipase ,Diet, High-Fat ,Article ,Mice, Inbred C57BL ,Disease Models, Animal ,Mice ,Diet, Western ,Non-alcoholic Fatty Liver Disease ,Mutation ,Disease Progression ,Hepatic Stellate Cells ,Hepatocytes ,Animals ,Humans ,Transcriptome - Abstract
BACKGROUND & AIMS: The mechanisms by which the I148M mutant variant of the patatin-like phospholipase domain-containing 3 (PNPLA3(I148M)) drives development of nonalcoholic steatohepatitis (NASH) is not known. The aim of this study was to obtain insights on mechanisms underlying PNPLA3(I148M) induced acceleration of NASH. APPROACH & RESULTS: Hepatocyte-specific overexpression of empty vector (Luc), human wild-type PNPLA3 (PNPLA3(WT)), or PNPLA3(I148M) was achieved using adeno-associated virus (AAV)-8 in DIAMOND mice followed by chow diet or high fat Western diet with ad lib administration of sugar in drinking water (WDSW) for 8 weeks. Under WDSW, PNPLA3(I148M) overexpression accelerated steatohepatitis with increased steatosis, inflammation ballooning and fibrosis (p< 0.001 vs other groups for all). Silencing PNPLA3(I148M) after its initial overexpression abrogated these findings. PNPLA3(I148M) caused 22:6n3 docosahexanoic acid depletion and increased ceramides under WDSW in addition to increasing triglycerides and diglycerides especially enriched with unsaturated fatty acids. It also increased oxidative stress and ER-stress. Increased total ceramides was associated with STAT3 activation with downstream activation of multiple immune-inflammatory pathways at a transcriptomic level by network analyses. Silencing PNPLA3(I148M) reversed STAT3 activation. Conditioned media from HepG2 cells overexpressing PNPLA3(I148M) increased procollagen mRNA expression in LX2 cells; this was abrogated by hepatocyte STAT3 inhibition. CONCLUSIONS: Under WDSW, PNPLA3(I148M) overexpression promotes steatosis and NASH by metabolic reprogramming characterized by increased triglycerides and diglycerides, n3 PUFA depletion and increased ceramides with resultant STAT3 phosphorylation and downstream inflammatory pathway activation driving increased stellate cell fibrogenic activity.
- Published
- 2020
8. Development of an integrated semi-automated system for in vitro pharmacodynamic modelling
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Wang, Liangsu, Wismer, Michael K., Racine, Fred, Conway, Donald, Giacobbe, Robert A., Berejnaia, Olga, and Kath, Gary S.
- Published
- 2008
9. Genome-wide operon prediction in Staphylococcus aureus
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Wang, Liangsu, Trawick, John D., Yamamoto, Robert, and Zamudio, Carlos
- Published
- 2004
10. A genome-wide strategy for the identification of essential genes in Staphylococcus aureus
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Forsyth, R. Allyn, Haselbeck, Robert J, Ohlsen, Kari L, Yamamoto, Robert T, Xu, Howard, Trawick, John D, Wall, Daniel, Wang, Liangsu, Brown-Driver, Vickie, Froelich, Jamie M, C, Kedar G, King, Paula, McCarthy, Melissa, Malone, Cheryl, Misiner, Brian, Robbins, David, Tan, Zehui, Zhu, Zhan-yang, Carr, Grant, Mosca, Deborah A, Zamudio, Carlos, Foulkes, J. Gordon, and Zyskind, Judith W
- Published
- 2002
11. Identification of a Metabolic, Transcriptomic, and Molecular Signature of Patatin‐Like Phospholipase Domain Containing 3–Mediated Acceleration of Steatohepatitis.
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Banini, Bubu A., Kumar, Divya P., Cazanave, Sophie, Seneshaw, Mulugeta, Mirshahi, Faridoddin, Santhekadur, Prasanna K., Wang, Liangsu, Guan, Hong Ping, Oseini, Abdul M., Alonso, Cristina, Bedossa, Pierre, Koduru, Srinivas V., Min, Hae‐Ki, and Sanyal, Arun J.
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- 2021
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12. Tu1283 PRECLINICAL CHARACTERIZATION OF AN ORAL SMALL MOLECULE INHIBITOR TARGETING THE INTEGRIN α4β7 FOR THE TREATMENT OF INFLAMMATORY BOWEL DISEASES (IBD)
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Wong, Jamie, Bursavich, Matthew, Blanco, Natalia, Camblin, Adam, Cappellucci, Laura, Cohen, Rhianna, Cui, Dan, Hahn, Kris, Krumpoch, Megan, Lee, Dooyoung, Lin, Fu-Yang, Lippa, Blaise, Lugovskoy, Alex, McShea, Molly, Mangada, Maloy, Mostafavi, Siavash, Moy, Terence, Ray, Adrian S., Redhu, Naresh Singh, Sang, Allison, Sullivan, Andrew, Traber, Peter G., Troast, Dawn, Zhong, Cheng, Wang, Liangsu, and Rogers, Bruce N.
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- 2020
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13. GPR119 Agonism Increases Glucagon Secretion During Insulin-Induced Hypoglycemia.
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Xiaoyan Li, Nina, Brown, Stacey, Kowalski, Tim, Wu, Margaret, Liming Yang, Dai, Ge, Petrov, Aleksandr, Yuyan Ding, Dlugos, Tamara, Wood, Harold B., Liangsu Wang, Erion, Mark, Sherwin, Robert, Kelley, David E., Li, Nina Xiaoyan, Yang, Liming, Ding, Yuyan, and Wang, Liangsu
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GLUCAGON ,HYPOGLYCEMIA ,LABORATORY rats ,PANCREATIC secretions ,INSULIN - Abstract
Insulin-induced hypoglycemia in diabetes is associated with impaired glucagon secretion. In this study, we tested whether stimulation of GPR119, a G-protein-coupled receptor expressed in pancreatic islet as well as enteroendocrine cells and previously shown to stimulate insulin and incretin secretion, might enhance glucagon secretion during hypoglycemia. In the study, GPR119 agonists were applied to isolated islets or perfused pancreata to assess insulin and glucagon secretion during hypoglycemic or hyperglycemic conditions. Insulin infusion hypoglycemic clamps were performed with or without GPR119 agonist pretreatment to assess glucagon counterregulation in healthy and streptozotocin (STZ)-induced diabetic rats, including those exposed to recurrent bouts of insulin-induced hypoglycemia that leads to suppression of hypoglycemia-induced glucagon release. Hypoglycemic clamp studies were also conducted in GPR119 knockout (KO) mice to evaluate whether the pharmacological stimulatory actions of GPR119 agonists on glucagon secretion during hypoglycemia were an on-target effect. The results revealed that GPR119 agonist-treated pancreata or cultured islets had increased glucagon secretion during low glucose perfusion. In vivo, GPR119 agonists also significantly increased glucagon secretion during hypoglycemia in healthy and STZ-diabetic rats, a response that was absent in GPR119 KO mice. In addition, impaired glucagon counterregulatory responses were restored by a GPR119 agonist in STZ-diabetic rats that were exposed to antecedent bouts of hypoglycemia. Thus, GPR119 agonists have the ability to pharmacologically augment glucagon secretion, specifically in response to hypoglycemia in diabetic rodents. Whether this effect might serve to diminish the occurrence and severity of iatrogenic hypoglycemia during intensive insulin therapy in patients with diabetes remains to be established. [ABSTRACT FROM AUTHOR]
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- 2018
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14. Glucagon like receptor 1/ glucagon dual agonist acutely enhanced hepatic lipid clearance and suppressed de novo lipogenesis in mice.
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More, Vijay R., Lao, Julie, McLaren, David G., Cumiskey, Anne-Marie, Murphy, Beth Ann, Chen, Ying, Previs, Stephen, Stout, Steven, Patel, Rajesh, Satapati, Santhosh, Li, Wenyu, Kowalik, Edward, Szeto, Daphne, Nawrocki, Andrea, Pocai, Alessandro, Wang, Liangsu, and Carrington, Paul
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GLUCAGON-like peptide-1 receptor ,LIPID synthesis ,CHOLESTEROL ,DEUTERIUM ,ESTERIFICATION - Abstract
Lipid lowering properties of glucagon have been reported. Blocking glucagon signaling leads to rise in plasma LDL levels. Here, we demonstrate the lipid lowering effects of acute dosing with Glp1r/Gcgr dual agonist (DualAG). All the experiments were performed in 25 week-old male diet-induced (60% kCal fat) obese mice. After 2 hrs of fasting, mice were injected subcutaneously with vehicle, liraglutide (25nmol/kg) and DualAG (25nmol/kg). De novo cholesterol and palmitate synthesis was measured by deuterium incorporation method using D
2 O.13 C18 -oleate infusion was used for measuring fatty acid esterification. Simultaneous activation of Glp1r and Gcgr resulted in decrease in plasma triglyceride and cholesterol levels. DualAG enhanced hepatic LDLr protein levels, along with causing decrease in content of plasma ApoB48 and ApoB100. VLDL secretion, de novo palmitate synthesis and fatty acid esterification decreased with acute DualAG treatment. On the other hand, ketone levels were elevated with DualAG treatment, indicating increased fatty acid oxidation. Lipid relevant changes were absent in liraglutide treated group. In an acute treatment, DualAG demonstrated significant impact on lipid homeostasis, specifically on hepatic uptake, VLDL secretion and de novo synthesis. These effects collectively reveal that lipid lowering abilities of DualAG are primarily through glucagon signaling and are liver centric. [ABSTRACT FROM AUTHOR]- Published
- 2017
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15. The Fatty Acid Synthase Inhibitor Platensimycin Improves Insulin Resistance without Inducing Liver Steatosis in Mice and Monkeys.
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Singh, Sheo B., Kang, Ling, Nawrocki, Andrea R., Zhou, Dan, Wu, Margaret, Previs, Stephen, Miller, Corey, Liu, Haiying, Hines, Catherine D. G., Madeira, Maria, Cao, Jin, Herath, Kithsiri, Wang, Liangsu, Kelley, David E., Li, Cai, and Guan, Hong-Ping
- Subjects
FATTY liver ,FATTY acid synthetase ,PLATENSIMYCIN ,INSULIN resistance ,LABORATORY mice - Abstract
Objectives: Platensimycin (PTM) is a natural antibiotic produced by Streptomyces platensis that selectively inhibits bacterial and mammalian fatty acid synthase (FAS) without affecting synthesis of other lipids. Recently, we reported that oral administration of PTM in mouse models (db/db and db/+) with high de novo lipogenesis (DNL) tone inhibited DNL and enhanced glucose oxidation, which in turn led to net reduction of liver triglycerides (TG), reduced ambient glucose, and improved insulin sensitivity. The present study was conducted to explore translatability and the therapeutic potential of FAS inhibition for the treatment of diabetes in humans. Methods: We tested PTM in animal models with different DNL tones, i.e. intrinsic synthesis rates, which vary among species and are regulated by nutritional and disease states, and confirmed glucose-lowering efficacy of PTM in lean NHPs with quantitation of liver lipid by MRS imaging. To understand the direct effect of PTM on liver metabolism, we performed ex vivo liver perfusion study to compare FAS inhibitor and carnitine palmitoyltransferase 1 (CPT1) inhibitor. Results: The efficacy of PTM is generally reproduced in preclinical models with DNL tones comparable to humans, including lean and established diet-induced obese (eDIO) mice as well as non-human primates (NHPs). Similar effects of PTM on DNL reduction were observed in lean and type 2 diabetic rhesus and lean cynomolgus monkeys after acute and chronic treatment of PTM. Mechanistically, PTM lowers plasma glucose in part by enhancing hepatic glucose uptake and glycolysis. Teglicar, a CPT1 inhibitor, has similar effects on glucose uptake and glycolysis. In sharp contrast, Teglicar but not PTM significantly increased hepatic TG production, thus caused liver steatosis in eDIO mice. Conclusions: These findings demonstrate unique properties of PTM and provide proof-of-concept of FAS inhibition having potential utility for the treatment of diabetes and related metabolic disorders. [ABSTRACT FROM AUTHOR]
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- 2016
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16. Duodenal-jejunal bypass surgery induces hepatic lipidomic alterations associated with ameliorated hepatic steatosis in mice.
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Shang, Jin, Castro‐Perez, Jose M., Shen, Xiaolan, Zhu, Yonghua, Liu, Haiying, Qian, Ying, Previs, Stephen, Howard, Andrew D., Erion, Mark, Kelley, David E., and Wang, Liangsu
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DUODENAL diseases ,JEJUNOILEAL bypass ,OBESITY ,GENE expression ,TRIGLYCERIDES ,LYSOPHOSPHOLIPIDS ,DUODENUM surgery ,JEJUNUM surgery ,ANIMAL experimentation ,BLOOD sugar ,FATTY liver ,INSULIN resistance ,MICE ,BARIATRIC surgery ,GASTRIC bypass - Abstract
Objective: Bariatric surgery induces weight loss and improvement of insulin resistance; one aspect of both is an amelioration of hepatic steatosis. This study was undertaken to assess the changes in the hepatic lipidome after duodenal-jejunal bypass (DJB) surgery.Methods: A DJB surgical model was developed and characterized in diet-induced obese mice. In comparison with sham-operated mice, an unbiased lipidomic profiling of hepatic lipids was performed together with measurements of gene expression within key pathways of hepatic lipid metabolism.Results: In the liver of DJB mice, a dramatic reduction (by 77%) in hepatic triacylglycerols was observed. Global lipidomic profiling identified marked decreases of triacylglycerols comprised of medium length fatty acids and with low double bond content. Specific diacylglycerol species were also among the most dramatic decreases in hepatic lipids, whereas lysophosphatidic acids and phosphatidic acids were increased. Expression of fatty acid transporter and lipogenic genes was down-regulated.Conclusions: From in-depth analysis of hepatic lipid composition, specific lipid intermediates were identified that are preferentially changed following DJB surgery. These changes were most likely due to DJB-induced weight loss, and only further studies will be able to distinguish weight loss-dependent from weight loss-independent changes. [ABSTRACT FROM AUTHOR]- Published
- 2016
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17. Gene expression in WAT from healthy humans and monkeys correlates with FGF21-induced browning of WAT in mice.
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Schlessinger, Karni, Li, Wenyu, Tan, Yejun, Liu, Franklin, Souza, Sandra C., Tozzo, Effie, Liu, Kevin, Thompson, John R., Wang, Liangsu, and Muise, Eric S.
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GENE expression ,MOLECULAR genetics ,WHITE adipose tissue ,ADIPOSE tissues ,HUMAN beings - Abstract
Objective Identify a gene expression signature in white adipose tissue (WAT) that reports on WAT browning and is associated with a healthy phenotype. Methods RNA from several different adipose depots across three species were analyzed by whole transcriptome profiling, including 1) mouse subcutaneous white fat, brown fat, and white fat after in vivo treatment with FGF21; 2) human subcutaneous and omental fat from insulin-sensitive and insulin-resistant patients; and 3) rhesus monkey subcutaneous fat from healthy and dysmetabolic individuals. Results A 'browning' signature in mice was identified by cross-referencing the FGF21-induced signature in WAT with the brown adipose tissue (BAT) vs. WAT comparison. In addition, gene expression levels in WAT from insulin-sensitive/healthy vs. insulin-resistant/dysmetabolic humans and rhesus monkeys, respectively, correlated with the gene expression levels in mouse BAT vs. WAT. A subset of 49 genes were identified that were consistently regulated or differentially expressed in the mouse and human data sets that could be used to monitor browning of WAT across species. Conclusions Gene expression profiles of WATs from healthy insulin-sensitive individuals correlate with those of BAT and FGF21-induced browning of WAT. [ABSTRACT FROM AUTHOR]
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- 2015
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18. Potentiation of Insulin-Mediated Glucose Lowering without Elevated Hypoglycemia Risk by a Small Molecule Insulin Receptor Modulator.
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Wu, Margaret, Dai, Ge, Yao, Jun, Hoyt, Scott, Wang, Liangsu, and Mu, James
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TYPE 2 diabetes ,HYPOGLYCEMIA ,DRUG synergism ,SMALL molecules ,INSULIN receptors ,INSULIN resistance ,DISEASE risk factors - Abstract
Insulin resistance is the key feature of type 2 diabetes and is manifested as attenuated insulin receptor (IR) signaling in response to same levels of insulin binding. Several small molecule IR activators have been identified and reported to exhibit insulin sensitization properties. One of these molecules, TLK19781 (Cmpd1), was investigated to examine its IR sensitizing action in vivo. Our data demonstrate that Cmpd1, at doses that produced minimal efficacy in the absence of insulin, potentiated insulin action during an OGTT in non-diabetic mice and enhanced insulin-mediated glucose lowering in diabetic mice. Interestingly, different from insulin alone, Cmpd1 combined with insulin showed enhanced efficacy and duration of action without increased hypoglycemia. To explore the mechanism underlying the apparent glucose dependent efficacy, tissue insulin signaling was compared in healthy and diabetic mice. Cmpd1 enhanced insulin’s effects on IR phosphorylation in both healthy and diabetic mice. In contrast, the compound potentiated insulin’s effects on Akt phosphorylation in diabetic but not in non-diabetic mice. These differential effects on signaling corresponding to glucose levels could be part of the mechanism for reduced hypoglycemia risk. The in vivo efficacy of Cmpd1 is specific and dependent on IR expression. Results from these studies support the idea of targeting IR for insulin sensitization, which carries low hypoglycemia risk by standalone treatment and could improve the effectiveness of insulin therapies. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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19. Control and Prevention of MRSA Infections.
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Wang, Liangsu and Barrett, John F.
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- 2007
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20. Demonstration of diet-induced decoupling of fatty acid and cholesterol synthesis by combining gene expression array and 2H2O quantification.
- Author
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Jensen, Kristian K., Previs, Stephen F., Lei Zhu, Herath, Kithsiri, Wang, Sheng-Ping, Bhat, Gowri, Hu, Guanghui, Miller, Paul L., McLaren, David G., Shin, Myung K., Vogt, Thomas F., Wang, Liangsu, Wong, Kenny K., Roddy, Thomas P., Johns, Douglas G., and Hubbard, Brian K.
- Abstract
The liver is a crossroad for metabolism of lipid and carbohydrates, with acetyl-CoA serving as an important metabolic intermediate and a precursor for fatty acid and cholesterol biosynthesis pathways. A better understanding of the regulation of these pathways requires an experimental approach that provides both quantitative metabolic flux measurements and mechanistic insight. Under conditions of high carbohydrate availability, excess carbon is converted into free fatty acids and triglyceride for storage, but it is not clear how excessive carbohydrate availability affects cholesterol biosynthesis. To address this, C57BL/6J mice were fed either a low-fat, high-carbohydrate diet or a high-fat, carbohydrate- free diet. At the end of the dietary intervention, the two groups received
2 H2 O to trace de novo fatty acid and cholesterol synthesis, and livers were collected for gene expression analysis. Expression of lipid and glucose metabolism genes was determined using a customdesigned pathway focused PCR-based gene expression array. The expression analysis showed downregulation of cholesterol biosynthesis genes and upregulation of fatty acid synthesis genes in mice receiving the high-carbohydrate diet compared with the carbohydratefree diet. In support of these findings,2 H2 O tracer data showed that fatty acid synthesis was increased 10-fold and cholesterol synthesis was reduced by 1.6-fold in mice fed the respective diets. In conclusion, by applying gene expression analysis and tracer methodology, we show that fatty acid and cholesterol synthesis are differentially regulated when the carbohydrate intake in mice is altered. [ABSTRACT FROM AUTHOR]- Published
- 2012
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21. A Comparison of Inhibitors for Thrombin, FXa, FXIa, and FXIIa in Whole Blood Coagulation and Fibrinolysis Using Thromboelastography
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Chen, Zhu, Wu, Weizhen, Xu, Yiming, Ogletree, Martin L, Plump, Andrew S, Graziano, Michael, and Wang, Liangsu
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- 2011
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22. Expression of IGF ligand and receptor genes during preimplantation mammalian development.
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Schultz, Gilbert A., Hahnel, Ann, Arcellana-Panlilio, Mayi, Wang, Liangsu, Goubau, Sabine, Watson, Andrew, and Harvey, Mark
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- 1993
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23. Correction: The Fatty Acid Synthase Inhibitor Platensimycin Improves Insulin Resistance without Inducing Liver Steatosis in Mice and Monkeys.
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Singh, Sheo B., Kang, Ling, Nawrocki, Andrea R., Zhou, Dan, Wu, Margaret, Previs, Stephen, Miller, Corey, Liu, Haiying, Hines, Catherine D. G., Madeira, Maria, Cao, Jin, Herath, Kithsiri, Spears, Larry D., Semenkovich, Clay F., Wang, Liangsu, Kelley, David E., Li, Cai, and Guan, Hong-Ping
- Subjects
FATTY degeneration ,FATTY acid synthases ,INSULIN resistance - Published
- 2017
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24. Identification of genes affecting apolipoprotein B secretion following siRNA-mediated gene knockdown in primary human hepatocytes
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Shen, Xun, Wang, Wei, Wang, Liangsu, Houde, Caroline, Wu, Weizhen, Tudor, Matt, Thompson, John R., Sisk, Christine McCrary, Hubbard, Brian, and Li, Jing
- Subjects
- *
APOLIPOPROTEIN B , *GENOMES , *SMALL interfering RNA , *LIVER cells , *ATHEROSCLEROSIS , *PROPROTEIN convertases , *FUCOSYLTRANSFERASES , *HAPTOGLOBINS - Abstract
Abstract: Objective: Genome-wide association studies (GWAS) are useful in studying the complex pathways underlying diseases such as atherosclerosis; however, additional testing is often necessary to identify the disease causal genes linked to GWAS loci. We used siRNA-mediated gene knockdown in primary human hepatocytes (PHuH) to identify potential GWAS causal genes affecting the hepatic secretion of apolipoprotein B (ApoB), ApoA1, and proprotein convertase subtilisin/kexin type 9. Materials and methods: Candidate causal genes within GWAS loci affecting human plasma levels of total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides were identified from the literature; 191 genes were selected from 74 loci. A functional siRNA screen was performed using PHuH. Results: Four genes: poly (ADP-ribose) polymerases member 10, haptoglobin, fucosyltransferase 1, and lysophosphatidic acid receptor 2 were identified and confirmed. Knocking down these genes reduced cell-associated and secreted ApoB levels. Conclusion: Modification of these four genes may affect plasma lipids through modulation of ApoB secretion. [Copyright &y& Elsevier]
- Published
- 2012
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25. FRI243 - Fibrosis phenotypic analysis of collagen stained liver histology sections discern anti-fibrotic agents in DDC-induced cholangitis mouse model.
- Author
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Chen, Li, Chen, Richard, Wang, Liangsu, and Petitjean, Mathieu
- Subjects
- *
LIVER histology , *FIBROSIS , *COLLAGEN , *MICE - Published
- 2020
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26. A Staphylococcus aureus Fitness Test Platform for Mechanism-Based Profiling of Antibacterial Compounds
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Donald, Robert G.K., Skwish, Stephen, Forsyth, R. Allyn, Anderson, Jennifer W., Zhong, Tanya, Burns, Colleen, Lee, Suzy, Meng, Xin, LoCastro, Lynn, Jarantow, Lisa Wang, Martin, Jesus, Lee, Sang Ho, Taylor, Ian, Robbins, David, Malone, Cheryl, Wang, Liangsu, Zamudio, Carlos S., Youngman, Philip J., and Phillips, John W.
- Subjects
- *
ANTIBACTERIAL agents , *STAPHYLOCOCCUS aureus , *DRUG resistance in microorganisms , *ANTISENSE RNA , *GENE targeting , *GENE expression , *BACTERIAL cell walls - Abstract
Summary: The emergence of drug-resistant bacteria coupled with the limited discovery of novel chemical scaffolds and druggable targets inspires new approaches to antibiotic development. Here we describe a chemical genomics strategy based on 245 Staphylococcus aureus antisense RNA strains, each engineered for reduced expression of target genes essential for S. aureus growth. Attenuation of gene expression can sensitize cells to compounds that inhibit the activity of a gene product or associated process. Pools of strains grown competitively in the presence of bioactive compounds generate characteristic profiles of strain sensitivities reflecting compound mechanism of action. Here, we validate this approach with a structurally and mechanistically diverse set of reference antibiotics and, in the accompanying paper in this issue of Chemistry & Biology (), demonstrate its use in the discovery of new cell wall inhibitors. [Copyright &y& Elsevier]
- Published
- 2009
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27. FRI247 - Integrin alphaVbeta1 inhibition ameliorates liver fibrosis in mice.
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Chen, Richard, Saxena, Parmita, Senices, Mayra, Yadav, Vinod, Harrison, Bryce, Dowling, James E., Nowakowski, Patrycja, Cappellucci, Laura, Finley, Faith, Sullivan, Andrew, Kennedy-Curran, Angela, Moy, Terence, Lin, Albert, Cui, Dan, Ray, Adrian, Lippa, Blaise, Lugovskoy, Alex, Rogers, Bruce, Wang, Liangsu, and Lu, Min
- Subjects
- *
INTEGRINS , *LIVER , *FIBROSIS , *HEPATOLOGY , *MICE - Published
- 2020
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28. Targeting a ceramide double bond improves insulin resistance and hepatic steatosis.
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Chaurasia B, Tippetts TS, Mayoral Monibas R, Liu J, Li Y, Wang L, Wilkerson JL, Sweeney CR, Pereira RF, Sumida DH, Maschek JA, Cox JE, Kaddai V, Lancaster GI, Siddique MM, Poss A, Pearson M, Satapati S, Zhou H, McLaren DG, Previs SF, Chen Y, Qian Y, Petrov A, Wu M, Shen X, Yao J, Nunes CN, Howard AD, Wang L, Erion MD, Rutter J, Holland WL, Kelley DE, and Summers SA
- Subjects
- Animals, Ceramides chemistry, Ceramides genetics, Diet, High-Fat adverse effects, Gene Deletion, Leptin deficiency, Mice, Mice, Mutant Strains, Sphingolipids chemistry, Sphingolipids metabolism, Ceramides metabolism, Fatty Liver genetics, Fatty Liver metabolism, Insulin Resistance genetics, Membrane Proteins genetics, Oxidoreductases genetics
- Abstract
Ceramides contribute to the lipotoxicity that underlies diabetes, hepatic steatosis, and heart disease. By genetically engineering mice, we deleted the enzyme dihydroceramide desaturase 1 (DES1), which normally inserts a conserved double bond into the backbone of ceramides and other predominant sphingolipids. Ablation of DES1 from whole animals or tissue-specific deletion in the liver and/or adipose tissue resolved hepatic steatosis and insulin resistance in mice caused by leptin deficiency or obesogenic diets. Mechanistic studies revealed ceramide actions that promoted lipid uptake and storage and impaired glucose utilization, none of which could be recapitulated by (dihydro)ceramides that lacked the critical double bond. These studies suggest that inhibition of DES1 may provide a means of treating hepatic steatosis and metabolic disorders., (Copyright © 2019, American Association for the Advancement of Science.)
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- 2019
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29. GPR119 Agonism Increases Glucagon Secretion During Insulin-Induced Hypoglycemia.
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Li NX, Brown S, Kowalski T, Wu M, Yang L, Dai G, Petrov A, Ding Y, Dlugos T, Wood HB, Wang L, Erion M, Sherwin R, and Kelley DE
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- Adult, Animals, Cells, Cultured, Diabetes Mellitus, Experimental drug therapy, Diabetes Mellitus, Experimental metabolism, Glucose Tolerance Test, Humans, Hypoglycemic Agents adverse effects, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Middle Aged, Rats, Rats, Wistar, Receptors, G-Protein-Coupled genetics, Streptozocin, Young Adult, Glucagon metabolism, Hypoglycemia chemically induced, Hypoglycemia metabolism, Insulin adverse effects, Receptors, G-Protein-Coupled agonists
- Abstract
Insulin-induced hypoglycemia in diabetes is associated with impaired glucagon secretion. In this study, we tested whether stimulation of GPR119, a G-protein-coupled receptor expressed in pancreatic islet as well as enteroendocrine cells and previously shown to stimulate insulin and incretin secretion, might enhance glucagon secretion during hypoglycemia. In the study, GPR119 agonists were applied to isolated islets or perfused pancreata to assess insulin and glucagon secretion during hypoglycemic or hyperglycemic conditions. Insulin infusion hypoglycemic clamps were performed with or without GPR119 agonist pretreatment to assess glucagon counterregulation in healthy and streptozotocin (STZ)-induced diabetic rats, including those exposed to recurrent bouts of insulin-induced hypoglycemia that leads to suppression of hypoglycemia-induced glucagon release. Hypoglycemic clamp studies were also conducted in GPR119 knockout (KO) mice to evaluate whether the pharmacological stimulatory actions of GPR119 agonists on glucagon secretion during hypoglycemia were an on-target effect. The results revealed that GPR119 agonist-treated pancreata or cultured islets had increased glucagon secretion during low glucose perfusion. In vivo, GPR119 agonists also significantly increased glucagon secretion during hypoglycemia in healthy and STZ-diabetic rats, a response that was absent in GPR119 KO mice. In addition, impaired glucagon counterregulatory responses were restored by a GPR119 agonist in STZ-diabetic rats that were exposed to antecedent bouts of hypoglycemia. Thus, GPR119 agonists have the ability to pharmacologically augment glucagon secretion, specifically in response to hypoglycemia in diabetic rodents. Whether this effect might serve to diminish the occurrence and severity of iatrogenic hypoglycemia during intensive insulin therapy in patients with diabetes remains to be established., (© 2018 by the American Diabetes Association.)
- Published
- 2018
- Full Text
- View/download PDF
30. GPR120 suppresses adipose tissue lipolysis and synergizes with GPR40 in antidiabetic efficacy.
- Author
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Satapati S, Qian Y, Wu MS, Petrov A, Dai G, Wang SP, Zhu Y, Shen X, Muise ES, Chen Y, Zycband E, Weinglass A, Di Salvo J, Debenham JS, Cox JM, Lan P, Shah V, Previs SF, Erion M, Kelley DE, Wang L, Howard AD, and Shang J
- Subjects
- Adipose Tissue drug effects, Animals, CHO Cells, Cricetinae, Cricetulus, Diabetes Mellitus, Experimental pathology, Gene Expression Regulation drug effects, Insulin Resistance, Islets of Langerhans drug effects, Islets of Langerhans physiopathology, Male, Mice, Rats, Receptors, G-Protein-Coupled agonists, Adipose Tissue metabolism, Diabetes Mellitus, Experimental metabolism, Lipolysis drug effects, Receptors, G-Protein-Coupled metabolism
- Abstract
GPR40 and GPR120 are fatty acid sensors that play important roles in glucose and energy homeostasis. GPR40 potentiates glucose-dependent insulin secretion and demonstrated in clinical studies robust glucose lowering in type 2 diabetes. GPR120 improves insulin sensitivity in rodents, albeit its mechanism of action is not fully understood. Here, we postulated that the antidiabetic efficacy of GPR40 could be enhanced by coactivating GPR120. A combination of GPR40 and GPR120 agonists in db / db mice, as well as a single molecule with dual agonist activities, achieved superior glycemic control compared with either monotherapy. Compared with a GPR40 selective agonist, the dual agonist improved insulin sensitivity in ob/ob mice measured by hyperinsulinemic-euglycemic clamp, preserved islet morphology, and increased expression of several key lipolytic genes in adipose tissue of Zucker diabetic fatty rats. Novel insights into the mechanism of action for GPR120 were obtained. Selective GPR120 activation suppressed lipolysis in primary white adipocytes, although this effect was attenuated in adipocytes from obese rats and obese rhesus, and sensitized the antilipolytic effect of insulin in rat and rhesus primary adipocytes. In conclusion, GPR120 agonism enhances insulin action in adipose tissue and yields a synergistic efficacy when combined with GPR40 agonism., (Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2017
- Full Text
- View/download PDF
31. Cyp8b1 ablation prevents Western diet-induced weight gain and hepatic steatosis because of impaired fat absorption.
- Author
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Bertaggia E, Jensen KK, Castro-Perez J, Xu Y, Di Paolo G, Chan RB, Wang L, and Haeusler RA
- Subjects
- Animals, Bile Acids and Salts metabolism, Diet, High-Fat, Fatty Liver metabolism, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Diet, Western adverse effects, Dietary Fats metabolism, Fatty Liver genetics, Intestinal Absorption genetics, Lipid Metabolism genetics, Steroid 12-alpha-Hydroxylase genetics, Weight Gain genetics
- Abstract
Bile acids (BAs) are cholesterol derivatives that regulate lipid metabolism, through their dual abilities to promote lipid absorption and activate BA receptors. However, different BA species have varying abilities to perform these functions. Eliminating 12α-hydroxy BAs in mice via Cyp8b1 knockout causes low body weight and improved glucose tolerance. The goal of this study was to determine mechanisms of low body weight in Cyp8b1
-/- mice. We challenged Cyp8b1-/- mice with a Western-type diet and assessed body weight and composition. We measured energy expenditure, fecal calories, and lipid absorption and performed lipidomic studies on feces and intestine. We investigated the requirement for dietary fat in the phenotype using a fat-free diet. Cyp8b1-/- mice were resistant to Western diet-induced body weight gain, hepatic steatosis, and insulin resistance. These changes were associated with increased fecal calories, due to malabsorption of hydrolyzed dietary triglycerides. This was reversed by treating the mice with taurocholic acid, the major 12α-hydroxylated BA species. The improvements in body weight and steatosis were normalized by feeding mice a fat-free diet. The effects of BA composition on intestinal lipid handling are important for whole body energy homeostasis. Thus modulating BA composition is a potential tool for obesity or diabetes therapy., (Copyright © 2017 the American Physiological Society.)- Published
- 2017
- Full Text
- View/download PDF
32. Phenotyping of adipose, liver, and skeletal muscle insulin resistance and response to pioglitazone in spontaneously obese rhesus monkeys.
- Author
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Shang J, Previs SF, Conarello S, Chng K, Zhu Y, Souza SC, Staup M, Chen Y, Xie D, Zycband E, Schlessinger K, Johnson VP, Arreaza G, Liu F, Levitan D, Wang L, van Heek M, Erion M, Wang Y, and Kelley DE
- Subjects
- Adipose Tissue drug effects, Animals, Blood Glucose metabolism, Diabetes Mellitus, Type 2 drug therapy, Diabetes Mellitus, Type 2 metabolism, Glucose Clamp Technique, Hypoglycemic Agents therapeutic use, Lipolysis physiology, Liver drug effects, Macaca mulatta, Muscle, Skeletal drug effects, Obesity drug therapy, Pioglitazone, Thiazolidinediones therapeutic use, Adipose Tissue metabolism, Hypoglycemic Agents pharmacology, Insulin Resistance physiology, Liver metabolism, Muscle, Skeletal metabolism, Obesity metabolism, Thiazolidinediones pharmacology
- Abstract
Insulin resistance and diabetes can develop spontaneously with obesity and aging in rhesus monkeys, highly similar to the natural history of obesity, insulin resistance, and progression to type 2 diabetes in humans. The current studies in obese rhesus were undertaken to assess hepatic and adipose contributions to systemic insulin resistance-currently, a gap in our knowledge-and to benchmark the responses to pioglitazone (PIO). A two-step hyperinsulinemic-euglycemic clamp, with tracer-based glucose flux estimates, was used to measure insulin resistance, and in an intervention study was repeated following 6 wk of PIO treatment (3 mg/kg). Compared with lean healthy rhesus, obese rhesus has a 60% reduction of glucose utilization during a high insulin infusion and markedly impaired suppression of lipolysis, which was evident at both low and high insulin infusion. However, obese dysmetabolic rhesus manifests only mild hepatic insulin resistance. Six-week PIO treatment significantly improved skeletal muscle and adipose insulin resistance (by ~50%). These studies strengthen the concept that insulin resistance in obese rhesus closely resembles human insulin resistance and indicate the value of obese rhesus for appraising new insulin-sensitizing therapeutics., (Copyright © 2017 the American Physiological Society.)
- Published
- 2017
- Full Text
- View/download PDF
33. Glucagon receptor antagonism induces increased cholesterol absorption.
- Author
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Guan HP, Yang X, Lu K, Wang SP, Castro-Perez JM, Previs S, Wright M, Shah V, Herath K, Xie D, Szeto D, Forrest G, Xiao JC, Palyha O, Sun LP, Andryuk PJ, Engel SS, Xiong Y, Lin S, Kelley DE, Erion MD, Davis HR, and Wang L
- Subjects
- Animals, Diabetes Mellitus, Type 2 blood, Diabetes Mellitus, Type 2 drug therapy, Drug Evaluation, Preclinical, Humans, Hypercholesterolemia chemically induced, Inhibitory Concentration 50, Intestinal Absorption, Male, Mice, Inbred C57BL, Mice, Transgenic, Pyrazoles adverse effects, beta-Alanine adverse effects, beta-Alanine pharmacology, Cholesterol blood, Pyrazoles pharmacology, Receptors, Glucagon antagonists & inhibitors, beta-Alanine analogs & derivatives
- Abstract
Glucagon and insulin have opposing action in governing glucose homeostasis. In type 2 diabetes mellitus (T2DM), plasma glucagon is characteristically elevated, contributing to increased gluconeogenesis and hyperglycemia. Therefore, glucagon receptor (GCGR) antagonism has been proposed as a pharmacologic approach to treat T2DM. In support of this concept, a potent small-molecule GCGR antagonist (GRA), MK-0893, demonstrated dose-dependent efficacy to reduce hyperglycemia, with an HbA1c reduction of 1.5% at the 80 mg dose for 12 weeks in T2DM. However, GRA treatment was associated with dose-dependent elevation of plasma LDL-cholesterol (LDL-c). The current studies investigated the cause for increased LDL-c. We report findings that link MK-0893 with increased glucagon-like peptide 2 and cholesterol absorption. There was not, however, a GRA-related modulation of cholesterol synthesis. These findings were replicated using structurally diverse GRAs. To examine potential pharmacologic mitigation, coadministration of ezetimibe (a potent inhibitor of cholesterol absorption) in mice abrogated the GRA-associated increase of LDL-c. Although the molecular mechanism is unknown, our results provide a novel finding by which glucagon and, hence, GCGR antagonism govern cholesterol metabolism., (Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2015
- Full Text
- View/download PDF
34. Improved Stability of Proline-Derived Direct Thrombin Inhibitors through Hydroxyl to Heterocycle Replacement.
- Author
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Chobanian HR, Pio B, Guo Y, Shen H, Huffman MA, Madeira M, Salituro G, Terebetski JL, Ormes J, Jochnowitz N, Hoos L, Zhou Y, Lewis D, Hawes B, Mitnaul L, O'Neill K, Ellsworth K, Wang L, Biftu T, and Duffy JL
- Abstract
Modification of the previously disclosed (S)-N-(2-(aminomethyl)-5-chlorobenzyl)-1-((R)-2-hydroxy-3,3-dimethylbutanoyl)pyrrolidine-2-carboxamide 2 by optimization of the P3 group afforded novel, low molecular weight thrombin inhibitors. Heterocycle replacement of the hydroxyl functional group helped maintain thrombin in vitro potency while improving the chemical stability and pharmacokinetic profile. These modifications led to the identification of compound 10, which showed excellent selectivity over related serine proteases as well as in vivo efficacy in the rat arteriovenous shunt. Compound 10 exhibited significantly improved chemical stability and pharmacokinetic properties over 2 and may be utilized as a structurally differentiated preclinical tool comparator to dabigatran etexilate (Pro-1) to interrogate the on- and off-target effects of oral direct thrombin inhibitors.
- Published
- 2015
- Full Text
- View/download PDF
35. Identification of four novel genes contributing to familial elevated plasma HDL cholesterol in humans.
- Author
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Singaraja RR, Tietjen I, Hovingh GK, Franchini PL, Radomski C, Wong K, vanHeek M, Stylianou IM, Lin L, Wang L, Mitnaul L, Hubbard B, Winther M, Mattice M, Legendre A, Sherrington R, Kastelein JJ, Akinsanya K, Plump A, and Hayden MR
- Subjects
- ATP Binding Cassette Transporter 1 genetics, Adult, Aged, Apolipoprotein A-I genetics, Cholesterol Ester Transfer Proteins genetics, Cholesterol, HDL genetics, Female, Humans, Lipase genetics, Male, Middle Aged, N-Acetylgalactosaminyltransferases genetics, Phosphatidylcholine-Sterol O-Acyltransferase genetics, Polypeptide N-acetylgalactosaminyltransferase, Adaptor Proteins, Signal Transducing genetics, Axonemal Dyneins genetics, Cholesterol, HDL blood, Endoribonucleases genetics, Mutation, Receptors, Immunologic genetics
- Abstract
While genetic determinants strongly influence HDL cholesterol (HDLc) levels, most genetic causes underlying variation in HDLc remain unknown. We aimed to identify novel rare mutations with large effects in candidate genes contributing to extreme HDLc in humans, utilizing family-based Mendelian genetics. We performed next-generation sequencing of 456 candidate HDLc-regulating genes in 200 unrelated probands with extremely low (≤10th percentile) or high (≥90th percentile) HDLc. Probands were excluded if known mutations existed in the established HDLc-regulating genes ABCA1, APOA1, LCAT, cholesteryl ester transfer protein (CETP), endothelial lipase (LIPG), and UDP-N-acetyl-α-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 2 (GALNT2). We identified 93 novel coding or splice-site variants in 72 candidate genes. Each variant was genotyped in the proband's family. Family-based association analyses were performed for variants with sufficient power to detect significance at P < 0.05 with a total of 627 family members being assessed. Mutations in the genes glucokinase regulatory protein (GCKR), RNase L (RNASEL), leukocyte immunoglobulin-like receptor 3 (LILRA3), and dynein axonemal heavy chain 10 (DNAH10) segregated with elevated HDLc levels in families, while no mutations associated with low HDLc. Taken together, we have identified mutations in four novel genes that may play a role in regulating HDLc levels in humans., (Copyright © 2014 by the American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2014
- Full Text
- View/download PDF
36. Differential profiles of thrombin inhibitors (heparin, hirudin, bivalirudin, and dabigatran) in the thrombin generation assay and thromboelastography in vitro.
- Author
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Xu Y, Wu W, Wang L, Chintala M, Plump AS, Ogletree ML, and Chen Z
- Subjects
- Biological Assay standards, Blood Coagulation, Dabigatran, Humans, Recombinant Proteins chemistry, Thrombelastography standards, Tissue Plasminogen Activator chemistry, Whole Blood Coagulation Time, beta-Alanine chemistry, Antithrombins chemistry, Benzimidazoles chemistry, Heparin chemistry, Hirudins chemistry, Peptide Fragments chemistry, Thrombin chemistry, beta-Alanine analogs & derivatives
- Abstract
Thrombin is a central enzyme in hemostasis and thrombosis, and a proven target for anticoagulant therapies. We compared four marketed and representative thrombin inhibitors, heparin, hirudin, bivalirudin, and dabigatran, in in-vitro spike-in assays that covered their therapeutic ranges. The assays employed were low tissue factor (1 pmol/l)-triggered thrombin generation assay (TGA) with plasma and 1:8000 Recombiplastin-triggered thromboelastography (TEG) with whole blood, with or without tissue plasminogen activator (tPA)-induced fibrinolysis. The three direct thrombin inhibitors (DTIs) prolonged TGA lag time and TEG clotting time (R) with a potency stack-ranking of hirudin>dabigatran approximately equal to bivalirudin. Heparin had the most steep concentration-response curve for both parameters. In TGA, 1-2 μmol/l dabigatran or hirudin resulted in complete inhibition on peak, slope, and endogenous thrombin potential, whereas bivalirudin had no effect on these parameters up to 10 μmol/l. All three DTIs, but not heparin, displayed a paradoxical increase in peak and slope in the low concentration range. In TEG, whereas all four agents reduced clot strength (maximal amplitude) in synergy with tPA, hirudin was the only DTI that reduced maximal amplitude appreciably without tPA. Dabigatran had the strongest potentiating effect on tPA-induced fibrinolytic activity (Ly30). With regard to the effects on coagulation and clot strength (lag time, R, and maximal amplitude) in the respective therapeutic range, dabigatran elicited the most modest changes. In summary, our observations highlight the distinct features of each agent in thrombin generation, coagulation, and fibrinolysis. The contrasts between the agents are consistent with their known properties and are informative on efforts to define the optimal profiles of new anticoagulants.
- Published
- 2013
- Full Text
- View/download PDF
37. Demonstration of diet-induced decoupling of fatty acid and cholesterol synthesis by combining gene expression array and 2H2O quantification.
- Author
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Jensen KK, Previs SF, Zhu L, Herath K, Wang SP, Bhat G, Hu G, Miller PL, McLaren DG, Shin MK, Vogt TF, Wang L, Wong KK, Roddy TP, Johns DG, and Hubbard BK
- Subjects
- Animals, Cholesterol genetics, Dietary Carbohydrates metabolism, Dietary Fats metabolism, Fatty Acids genetics, Gene Expression, Gene Expression Profiling, Male, Mice, Cholesterol biosynthesis, Diet, Carbohydrate-Restricted, Diet, High-Fat, Fatty Acids biosynthesis, Liver metabolism
- Abstract
The liver is a crossroad for metabolism of lipid and carbohydrates, with acetyl-CoA serving as an important metabolic intermediate and a precursor for fatty acid and cholesterol biosynthesis pathways. A better understanding of the regulation of these pathways requires an experimental approach that provides both quantitative metabolic flux measurements and mechanistic insight. Under conditions of high carbohydrate availability, excess carbon is converted into free fatty acids and triglyceride for storage, but it is not clear how excessive carbohydrate availability affects cholesterol biosynthesis. To address this, C57BL/6J mice were fed either a low-fat, high-carbohydrate diet or a high-fat, carbohydrate-free diet. At the end of the dietary intervention, the two groups received (2)H(2)O to trace de novo fatty acid and cholesterol synthesis, and livers were collected for gene expression analysis. Expression of lipid and glucose metabolism genes was determined using a custom-designed pathway focused PCR-based gene expression array. The expression analysis showed downregulation of cholesterol biosynthesis genes and upregulation of fatty acid synthesis genes in mice receiving the high-carbohydrate diet compared with the carbohydrate-free diet. In support of these findings, (2)H(2)O tracer data showed that fatty acid synthesis was increased 10-fold and cholesterol synthesis was reduced by 1.6-fold in mice fed the respective diets. In conclusion, by applying gene expression analysis and tracer methodology, we show that fatty acid and cholesterol synthesis are differentially regulated when the carbohydrate intake in mice is altered.
- Published
- 2012
- Full Text
- View/download PDF
38. Staphylococcus aureus TargetArray: comprehensive differential essential gene expression as a mechanistic tool to profile antibacterials.
- Author
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Xu HH, Trawick JD, Haselbeck RJ, Forsyth RA, Yamamoto RT, Archer R, Patterson J, Allen M, Froelich JM, Taylor I, Nakaji D, Maile R, Kedar GC, Pilcher M, Brown-Driver V, McCarthy M, Files A, Robbins D, King P, Sillaots S, Malone C, Zamudio CS, Roemer T, Wang L, Youngman PJ, and Wall D
- Subjects
- Gene Expression Regulation, Bacterial drug effects, RNA, Antisense genetics, Staphylococcus aureus drug effects, Anti-Bacterial Agents pharmacology, Gene Expression Regulation, Bacterial genetics, Genes, Essential genetics, Staphylococcus aureus genetics
- Abstract
The widespread emergence of antibiotic-resistant bacteria and a lack of new pharmaceutical development have catalyzed a need for new and innovative approaches for antibiotic drug discovery. One bottleneck in antibiotic discovery is the lack of a rapid and comprehensive method to identify compound mode of action (MOA). Since a hallmark of antibiotic action is as an inhibitor of essential cellular targets and processes, we identify a set of 308 essential genes in the clinically important pathogen Staphylococcus aureus. A total of 446 strains differentially expressing these genes were constructed in a comprehensive platform of sensitized and resistant strains. A subset of strains allows either target underexpression or target overexpression by heterologous promoter replacements with a suite of tetracycline-regulatable promoters. A further subset of 236 antisense RNA-expressing clones allows knockdown expression of cognate targets. Knockdown expression confers selective antibiotic hypersensitivity, while target overexpression confers resistance. The antisense strains were configured into a TargetArray in which pools of sensitized strains were challenged in fitness tests. A rapid detection method measures strain responses toward antibiotics. The TargetArray antibiotic fitness test results show mechanistically informative biological fingerprints that allow MOA elucidation.
- Published
- 2010
- Full Text
- View/download PDF
39. Development of an integrated semi-automated system for in vitro pharmacodynamic modelling.
- Author
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Wang L, Wismer MK, Racine F, Conway D, Giacobbe RA, Berejnaia O, and Kath GS
- Subjects
- Acetamides pharmacokinetics, Acetamides pharmacology, Colony Count, Microbial, Humans, In Vitro Techniques, Linezolid, Microbial Sensitivity Tests, Microbial Viability, Oxazolidinones pharmacokinetics, Oxazolidinones pharmacology, Time Factors, Anti-Bacterial Agents pharmacokinetics, Anti-Bacterial Agents pharmacology, Automation, Staphylococcus aureus drug effects
- Abstract
Objectives: The aim of this study was to develop an integrated system for in vitro pharmacodynamic modelling of antimicrobials with greater flexibility, easier control and better accuracy than existing in vitro models., Methods: Custom-made bottle caps, fittings, valve controllers and a modified bench-top shaking incubator were used. A temperature-controlled automated sample collector was built. Computer software was developed to manage experiments and to control the entire system including solenoid pinch valves, peristaltic pumps and the sample collector. The system was validated by pharmacokinetic simulations of linezolid 600 mg infusion. The antibacterial effect of linezolid against multiple Staphylococcus aureus strains was also studied in this system., Results: An integrated semi-automated bench-top system was built and validated. The temperature-controlled automated sample collector allowed unattended collection and temporary storage of samples. The system software reduced the labour necessary for many tasks and also improved the timing accuracy for performing simultaneous actions in multiple parallel experiments. The system was able to simulate human pharmacokinetics of linezolid 600 mg intravenous infusion accurately. A pharmacodynamic study of linezolid against multiple S. aureus strains with a range of MICs showed that the required 24 h free drug AUC/MIC ratio was approximately 30 in order to keep the organism counts at the same level as their initial inoculum and was about > or = 68 in order to achieve > 2 log(10) cfu/mL reduction in the in vitro model., Conclusions: The integrated semi-automated bench-top system provided the ability to overcome many of the drawbacks of existing in vitro models. It can be used for various simple or complicated pharmacokinetic/pharmacodynamic studies efficiently and conveniently.
- Published
- 2008
- Full Text
- View/download PDF
40. Techniques for the isolation and use of conditionally expressed antisense RNA to achieve essential gene knockdowns in Staphylococcus aureus.
- Author
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Forsyth A and Wang L
- Subjects
- Anti-Bacterial Agents pharmacology, Gene Expression Regulation, Bacterial drug effects, Staphylococcus aureus drug effects, Staphylococcus aureus growth & development, Gene Targeting, Genes, Essential, Genome, Bacterial, RNA, Antisense, Staphylococcus aureus genetics
- Abstract
This chapter provides methods and insights into the use of antisense RNA as a molecular genetic tool. Posttranscriptional inhibition of specific gene expression can be achieved by antisense RNA fragments under control of a conditional promoter. Effective titration of gene expression can cause an apparent null mutation or can be modulated to levels of interest in comparison with wild type. Validation of antisense RNA can be achieved by both RNA and protein quantitation techniques. Applications include phenotypic studies of genes in response to specific stimuli, environments, or the contribution of genes in regulatory networks. This chapter will focus on shotgun-cloned antisense for comprehensive gene identification and cell-based hypersensitivity assays for antibiotic screening. Antisense RNA strategies have high utility when the target gene is essential for survival and needs to be compared with wild type.
- Published
- 2008
- Full Text
- View/download PDF
41. Pharmacoeconomics of treatment with the newer anti-Gram-positive agents.
- Author
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Wang L and Barrett JF
- Subjects
- Animals, Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents therapeutic use, Drug Resistance, Bacterial drug effects, Drug Resistance, Bacterial physiology, Gram-Positive Bacteria drug effects, Gram-Positive Bacterial Infections microbiology, Humans, Anti-Bacterial Agents economics, Gram-Positive Bacterial Infections drug therapy, Gram-Positive Bacterial Infections economics
- Abstract
The unmet medical need of emerging resistance among Gram-positive pathogens, such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and penicillin-resistant Streptococcus pneumoniae, has driven industry towards the identification and development of novel anti-Gram-positive agents. Among the newer agents are improved quinolones, a lipopeptide, an oxazolidinone and novel glycopeptides. Scientific distinctions between these drugs, which impact on the placement, usage and, ultimately, the pharmacoeconomics of several of these new agents, may lead to further consideration despite poor initial observations of minimal improvement. Key differences in the characteristics of these drugs (i.e., spectrum, activity, resistance emergence, efficacy, target, safety) provide a basis for an emerging pharmacoeconomic-based distinction between these newer anti-Gram-positive agents.
- Published
- 2006
- Full Text
- View/download PDF
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