ABSTRACT
We find strong path dependence in the evolution of the Plio-Pleistocene glaciations using CLIMBER-2 Earth System Model simulations from the mid-Pliocene to modern preindustrial (3 My-0 My BP) driven by a gradual decrease in volcanic carbon dioxide outgassing and regolith removal from basal ice interaction. Path dependence and hysteresis are investigated by alternatively driving the model forward and backward in time. Initiating the model with preindustrial conditions and driving the model backward using time-reversed forcings, the increase in volcanic outgassing back-in-time (BIT) does not generate the high CO2 levels and relatively ice-free conditions of the late Pliocene seen in forward-in-time (FIT) simulations of the same model. This behavior appears to originate from nonlinearities and initial state dependence in the carbon cycle. A transition from low-amplitude sinusoidal obliquity (~41 ky) and precession (~23 ky) driven glacial/interglacial cycles to high-amplitude ~100 ky likely eccentricity-related sawtooth cycles seen between -1.25 My and -0.75 My BP (the Mid-Pleistocene transition or "MPT") in FIT simulations disappears in BIT integrations depending on the details of how the regolith removal process is treated. A transition toward depleted regolith and lowered atmospheric CO2 levels are both required to reproduce the MPT.
ABSTRACT
PURPOSE OF REVIEW: Our understanding of the fundamental cellular and molecular factors leading to atrial fibrillation (AF) remains stagnant despite significant advancement in ablation and device technologies. Diagnosis and prevention strategies fall behind that of treatment, but expanding knowledge in AF genetics holds the potential to drive progress. We aim to review how an understanding of the genetic contributions to AF can guide an approach to individualized risk stratification and novel avenues in drug discovery. RECENT FINDINGS: Rare familial forms of AF identified monogenic contributions to the development of AF. Genome-wide association studies (GWAS) further identified single-nucleotide polymorphisms (SNPs) suggesting polygenic and multiplex nature of this common disease. Polygenic risk scores accounting for the multitude of associated SNPs that each confer mildly elevated risk have been developed to translate genetic information into clinical practice, though shortcomings remain. Additionally, novel laboratory methods have been empowered by recent genetic findings to enhance drug discovery efforts. AF is increasingly recognized as a disease with a significant genetic component. With expanding sequencing technologies and accessibility, polygenic risk scores can help identify high risk individuals. Advancement in digital health tools, artificial intelligence and machine learning based on standard electrocardiograms, and genomic driven drug discovery may be integrated to deliver a sophisticated level of precision medicine in this modern era of emphasis on prevention. Randomized, prospective studies to demonstrate clinical benefits of these available tools are needed to validate this approach.
Subject(s)
Atrial Fibrillation , Artificial Intelligence , Atrial Fibrillation/genetics , Genetic Predisposition to Disease , Genome-Wide Association Study , Genomics , Humans , Prospective StudiesABSTRACT
BACKGROUND: Africa's economic transformation relies on a radical transformation of its higher education institutions. The establishment of regional higher education Centres of Excellence (CoE) across Africa through a World Bank support aims to stimulate the needed transformation in education and research. However, excellence is a vague, and often indiscriminately used concept in academic circles. More importantly, the manner in which aspiring institutions can achieve academic excellence is described inadequately. The main objective of this paper is to describe the core processes of excellence as a prerequisite to establishing academic CoE in Africa. METHODS: The paper relies on our collaborative discussions and real-world insight into the pursuit of academic excellence, a narrative review using Pubmed search for a contextual understanding of CoEs in Africa supplemented by a Google search for definitions of CoEs in academic contexts. RESULTS: We identified three key, synergistic processes of excellence central to institutionalizing academic CoEs: participatory leadership, knowledge management, and inter-disciplinary collaboration. (1) Participatory leadership encourages innovations to originate from the different parts of the organization, and facilitates ownership as well as a culture of excellence. (2) Centers of Excellence are future-oriented in that they are constantly seeking to achieve best practices, informed by the most up-to-date and cutting-edge research and information available. As such, the process by which centres facilitate the flow of knowledge within and outside the organization, or knowledge management, is critical to their success. (3) Such centres also rely on expertise from different disciplines and 'engaged' scholarship. This multidisciplinarity leads to improved research productivity and enhances the production of problem-solving innovations. CONCLUSION: Participatory leadership, knowledge management, and inter-disciplinary collaborations are prerequisites to establishing academic CoEs in Africa. Future studies need to extend our findings to understand the processes key to productivity, competitiveness, institutionalization, and sustainability of academic CoEs in Africa.
Subject(s)
Fellowships and Scholarships , Leadership , Africa , Humans , Surveys and Questionnaires , UniversitiesABSTRACT
Target-engagement pharmacodynamic (PD) biomarkers are valuable tools in the prioritization of drug candidates, especially for novel, first-in-class mechanisms whose robustness to alter disease outcome is unknown. Methionine aminopeptidase 2 (MetAP2) is a cytosolic metalloenzyme that cleaves the N-terminal methionine from nascent proteins. Inhibition of MetAP2 leads to weight loss in obese rodents, dogs and humans. However, there is a need to develop efficacious compounds that specifically inhibit MetAP2 with an improved safety profile. The objective of this study was to identify a PD biomarker for selecting potent, efficacious compounds and for predicting clinical efficacy that would result from inhibition of MetAP2. Here we report the use of NMet14-3-3γ for this purpose. Treatment of primary human cells with MetAP2 inhibitors resulted in an approx. 10-fold increase in NMet14-3-3γ levels. Furthermore, treatment of diet-induced obese mice with these compounds reduced body weight (approx. 20%) and increased NMet14-3-3γ (approx. 15-fold) in adipose tissues. The effects on target engagement and body weight increased over time and were dependent on dose and administration frequency of compound. The relationship between compound concentration in plasma, NMet14-3-3γ in tissue, and reduction of body weight in obese mice was used to generate a pharmacokinetic-pharmacodynamic-efficacy model for predicting efficacy of MetAP2 inhibitors in mice. We also developed a model for predicting weight loss in humans using a target engagement PD assay that measures inhibitor-bound MetAP2 in blood. In summary, MetAP2 target engagement biomarkers can be used to select efficacious compounds and predict weight loss in humans. SIGNIFICANCE STATEMENT: The application of target engagement pharmacodynamic biomarkers during drug development provides a means to determine the dose required to fully engage the intended target and an approach to connect the drug target to physiological effects. This work exemplifies the process of using target engagement biomarkers during preclinical research to select new drug candidates and predict clinical efficacy. We determine concentration of MetAP2 antiobesity compounds needed to produce pharmacological activity in primary human cells and in target tissues from an appropriate animal model and establish key relationships between pharmacokinetics, pharmacodynamics, and efficacy, including the duration of effects after drug administration. The biomarkers described here can aid decision-making in early clinical trials of MetAP2 inhibitors for the treatment of obesity.
Subject(s)
Chlorobenzenes/pharmacology , Cinnamates/pharmacology , Cyclohexanes/pharmacology , Epoxy Compounds/pharmacology , Human Umbilical Vein Endothelial Cells/drug effects , Human Umbilical Vein Endothelial Cells/metabolism , Methionyl Aminopeptidases/antagonists & inhibitors , Methionyl Aminopeptidases/metabolism , Sesquiterpenes/pharmacology , Angiogenesis Inhibitors/chemistry , Angiogenesis Inhibitors/pharmacology , Animals , Biomarkers/metabolism , Chlorobenzenes/chemistry , Cinnamates/chemistry , Cyclohexanes/chemistry , Dose-Response Relationship, Drug , Epoxy Compounds/chemistry , HeLa Cells , Humans , Male , Mice , Mice, Inbred C57BL , Predictive Value of Tests , Sesquiterpenes/chemistry , Treatment OutcomeABSTRACT
NOTCH plays a pivotal role during normal development and in congenital disorders and cancer. γ-secretase inhibitors are commonly used to probe NOTCH function, but also block processing of numerous other proteins. We discovered a new class of small molecule inhibitor that disrupts the interaction between NOTCH and RBPJ, which is the main transcriptional effector of NOTCH signaling. RBPJ Inhibitor-1 (RIN1) also blocked the functional interaction of RBPJ with SHARP, a scaffold protein that forms a transcriptional repressor complex with RBPJ in the absence of NOTCH signaling. RIN1 induced changes in gene expression that resembled siRNA silencing of RBPJ rather than inhibition at the level of NOTCH itself. Consistent with disruption of NOTCH signaling, RIN1 inhibited the proliferation of hematologic cancer cell lines and promoted skeletal muscle differentiation from C2C12 myoblasts. Thus, RIN1 inhibits RBPJ in its repressing and activating contexts, and can be exploited for chemical biology and therapeutic applications.
Subject(s)
Immunoglobulin J Recombination Signal Sequence-Binding Protein/antagonists & inhibitors , Receptors, Notch/metabolism , Signal Transduction/drug effects , Cell Differentiation/drug effects , Cell Line , Gene Expression Regulation/drug effects , Humans , Myoblasts/drug effects , Myoblasts/metabolismABSTRACT
Inhibitors of methionine aminopeptidase 2 (MetAP2) have been shown to reduce body weight in obese mice and humans. The target tissue and cellular mechanism of MetAP2 inhibitors, however, have not been extensively examined. Using compounds with diverse chemical scaffolds, we showed that MetAP2 inhibition decreases body weight and fat mass and increases lean mass in the obese mice but not in the lean mice. Obesity is associated with catecholamine resistance and blunted ß-adrenergic receptor signaling activities, which could dampen lipolysis and energy expenditure resulting in weight gain. In the current study, we examined effect of MetAP2 inhibition on brown adipose tissue and brown adipocytes. Norepinephrine increases energy expenditure in brown adipose tissue by providing fatty acid substrate through lipolysis and by increasing expression of uncoupled protein-1 (UCP1). Metabolomic analysis shows that in response to MetAP2 inhibitor treatment, fatty acid metabolites in brown adipose tissue increase transiently and subsequently decrease to basal or below basal levels, suggesting an effect on fatty acid metabolism in this tissue. Treatment of brown adipocytes with MetAP2 inhibitors enhances norepinephrine-induced lipolysis and energy expenditure, and prolongs the activity of norepinephrine to increase ucp1 gene expression and energy expenditure in norepinephrine-desensitized brown adipocytes. In summary, we showed that the anti-obesity activity of MetAP2 inhibitors can be mediated, at least in part, through direct action on brown adipocytes by enhancing ß-adrenergic-signaling-stimulated activities.
Subject(s)
Adipocytes, Brown/physiology , Aminopeptidases/antagonists & inhibitors , Body Weight/drug effects , Chlorobenzenes/pharmacology , Energy Metabolism/drug effects , Metalloendopeptidases/antagonists & inhibitors , Obesity/prevention & control , Adipocytes, Brown/cytology , Adipocytes, Brown/drug effects , Animals , Humans , Lipolysis , Male , Mice , Mice, Inbred C57BL , Mice, Obese , Rats , Signal Transduction , ThermogenesisABSTRACT
Human brown adipose tissue (BAT) is experimentally modeled to better understand the biology of this important metabolic tissue, and also to enable the potential discovery and development of novel therapeutics for obesity and sequelae resulting from the persistent positive energy balance. This chapter focuses on translation into humans of findings and hypotheses generated in nonhuman models of BAT pharmacology. Given the demonstrated challenges of sustainably reducing caloric intake in modern humans, potential solutions to obesity likely lie in increasing energy expenditure. The energy-transforming activities of a single cell in any given tissue can be conceptualized as a flow of chemical energy from energy-rich substrate molecules into energy-expending, endergonic biological work processes through oxidative degradation of organic molecules ingested as nutrients. Despite the relatively tight coupling between metabolic reactions and products, some expended energy is incidentally lost as heat, and in this manner a significant fraction of the energy originally captured from the environment nonproductively transforms into heat rather than into biological work. In human and other mammalian cells, some processes are even completely uncoupled, and therefore purely energy consuming. These molecular and cellular actions sum up at the physiological level to adaptive thermogenesis, the endogenous physiology in which energy is nonproductively released as heat through uncoupling of mitochondria in brown fat and potentially skeletal muscle. Adaptive thermogenesis in mammals occurs in three forms, mostly in skeletal muscle and brown fat: shivering thermogenesis in skeletal muscle, non-shivering thermogenesis in brown fat, and diet-induced thermogenesis in brown fat. At the cellular level, the greatest energy transformations in humans and other eukaryotes occur in the mitochondria, where creating energetic inefficiency by uncoupling the conversion of energy-rich substrate molecules into ATP usable by all three major forms of biological work occurs by two primary means. Basal uncoupling occurs as a passive, general, nonspecific leak down the proton concentration gradient across the membrane in all mitochondria in the human body, a gradient driving a key step in ATP synthesis. Inducible uncoupling, which is the active conduction of protons across gradients through processes catalyzed by proteins, occurs only in select cell types including BAT. Experiments in rodents revealed UCP1 as the primary mammalian molecule accounting for the regulated, inducible uncoupling of BAT, and responsive to both cold and pharmacological stimulation. Cold stimulation of BAT has convincingly translated into humans, and older clinical observations with nonselective 2,4-DNP validate that human BAT's participation in pharmacologically mediated, though nonselective, mitochondrial membrane decoupling can provide increased energy expenditure and corresponding body weight loss. In recent times, however, neither beta-adrenergic antagonism nor unselective sympathomimetic agonism by ephedrine and sibutramine provide convincing evidence that more BAT-selective mechanisms can impact energy balance and subsequently body weight. Although BAT activity correlates with leanness, hypothesis-driven selective ß3-adrenergic agonism to activate BAT in humans has only provided robust proof of pharmacologic activation of ß-adrenergic receptor signaling, limited proof of the mechanism of increased adaptive thermogenesis, and no convincing evidence that body weight loss through negative energy balance upon BAT activation can be accomplished outside of rodents. None of the five demonstrably ß3 selective molecules with sufficient clinical experience to merit review provided significant weight loss in clinical trials (BRL 26830A, TAK 677, L-796568, CL 316,243, and BRL 35135). Broader conclusions regarding the human BAT therapeutic hypothesis are limited by the absence of data from most studies demonstrating specific activation of BAT thermogenesis in most studies. Additionally, more limited data sets with older or less selective ß3 agonists also did not provide strong evidence of body weight effects. Encouragingly, ß3-adrenergic agonists, catechins, capsinoids, and nutritional extracts, even without robust negative energy balance outcomes, all demonstrated increased total energy expenditure that in some cases could be associated with concomitant activation of BAT, though the absence of body weight loss indicates that in no cases did the magnitude of negative energy balance reach sufficient levels. Glucocorticoid receptor agonists, PPARg agonists, and thyroid hormone receptor agonists all possess defined molecular and cellular pharmacology that preclinical models predicted to be efficacious for negative energy balance and body weight loss, yet their effects on human BAT thermogenesis upon translation were inconsistent with predictions and disappointing. A few new mechanisms are nearing the stage of clinical trials and may yet provide a more quantitatively robust translation from preclinical to human experience with BAT. In conclusion, translation into humans has been demonstrated with BAT molecular pharmacology and cell biology, as well as with physiological response to cold. However, despite pharmacologically mediated, statistically significant elevation in total energy expenditure, translation into biologically meaningful negative energy balance was not achieved, as indicated by the absence of measurable loss of body weight over the duration of a clinical study.
Subject(s)
Adipose Tissue, Brown , Thermogenesis , Adipose Tissue, Brown/metabolism , Adipose Tissue, Brown/physiology , Animals , Body Weight , Energy Metabolism , Humans , Obesity , Thermogenesis/physiologyABSTRACT
OBJECTIVE: Atherosclerosis is a major cause of cardiovascular disease. Monocyte-endothelial cell interactions are partly mediated by expression of monocyte CX3CR1 and endothelial cell fractalkine (CX3CL1). Interrupting the interaction between this ligand-receptor pair should reduce monocyte binding to the endothelial wall and reduce atherosclerosis. We sought to reduce atherosclerosis by preventing monocyte-endothelial cell interactions through use of a long-acting CX3CR1 agonist. METHODS: In this study, the chemokine domain of CX3CL1 was fused to the mouse Fc region to generate a long-acting soluble form of CX3CL1 suitable for chronic studies. CX3CL1-Fc or saline was injected twice a week (30 mg/kg) for 4 months into Ldlr knockout (KO) mice on an atherogenic western diet. RESULTS: CX3CL1-Fc-treated Ldlr KO mice showed decreased en face aortic lesion surface area and reduced aortic root lesion size with decreased necrotic core area. Flow cytometry analyses of CX3CL1-Fc-treated aortic wall cell digests revealed a decrease in M1-like polarized macrophages and T cells. Moreover, CX3CL1-Fc administration reduced diet-induced atherosclerosis after switching from an atherogenic to a normal chow diet. In vitro monocyte adhesion studies revealed that CX3CL1-Fc treatment caused fewer monocytes to adhere to a human umbilical vein endothelial cell monolayer. Furthermore, a dorsal window chamber model demonstrated that CX3CL1-Fc treatment decreased in vivo leukocyte adhesion and rolling in live capillaries after short-term ischemia-reperfusion. CONCLUSION: These results indicate that CX3CL1-Fc can inhibit monocyte/endothelial cell adhesion as well as reduce atherosclerosis.
Subject(s)
Atherosclerosis/drug therapy , Chemokine CX3CL1/therapeutic use , Plaque, Atherosclerotic/drug therapy , Animals , Aorta/pathology , Atherosclerosis/genetics , Atherosclerosis/prevention & control , Cells, Cultured , Chemokine CX3CL1/genetics , Immunoglobulin Fc Fragments/genetics , Male , Mice , Mice, Inbred C57BL , Plaque, Atherosclerotic/prevention & control , Receptors, LDL/genetics , Recombinant Proteins/genetics , Recombinant Proteins/therapeutic useABSTRACT
We have previously reported that the fractalkine (FKN)/CX3CR1 system represents a novel regulatory mechanism for insulin secretion and ß cell function. Here, we demonstrate that chronic administration of a long-acting form of FKN, FKN-Fc, can exert durable effects to improve glucose tolerance with increased glucose-stimulated insulin secretion and decreased ß cell apoptosis in obese rodent models. Unexpectedly, chronic FKN-Fc administration also led to decreased α cell glucagon secretion. In islet cells, FKN inhibited ATP-sensitive potassium channel conductance by an ERK-dependent mechanism, which triggered ß cell action potential (AP) firing and decreased α cell AP amplitude. This results in increased glucose-stimulated insulin secretion and decreased glucagon secretion. Beyond its islet effects, FKN-Fc also exerted peripheral effects to enhance hepatic insulin sensitivity due to inhibition of glucagon action. In hepatocytes, FKN treatment reduced glucagon-stimulated cAMP production and CREB phosphorylation in a pertussis toxin-sensitive manner. Together, these results raise the possibility of use of FKN-based therapy to improve type 2 diabetes by increasing both insulin secretion and insulin sensitivity.
Subject(s)
Blood Glucose/metabolism , Chemokine CX3CL1/pharmacology , Immunoglobulin Fc Fragments/pharmacology , Insulin Secretion/drug effects , Insulin-Secreting Cells/metabolism , Recombinant Fusion Proteins/pharmacology , Animals , Blood Glucose/genetics , CREB-Binding Protein/genetics , CREB-Binding Protein/metabolism , Chemokine CX3CL1/genetics , Diabetes Mellitus, Experimental/drug therapy , Diabetes Mellitus, Experimental/genetics , Diabetes Mellitus, Experimental/metabolism , Diabetes Mellitus, Experimental/pathology , Diabetes Mellitus, Type 2/drug therapy , Diabetes Mellitus, Type 2/genetics , Diabetes Mellitus, Type 2/metabolism , Diabetes Mellitus, Type 2/pathology , Hepatocytes/metabolism , Hepatocytes/pathology , Immunoglobulin Fc Fragments/genetics , Insulin Secretion/genetics , Insulin-Secreting Cells/pathology , Mice , Mice, Transgenic , Recombinant Fusion Proteins/geneticsABSTRACT
Prolyl hydroxylases (PHDs) down-regulate the level of hypoxia-inducible factors (HIFs) by hydroxylating key proline residues that trigger the degradation of the protein and affect the cell and its ability to respond to hypoxic stress. Several small molecule PHD inhibitors are now in various preclinical and clinical stages for the treatment of anemia. The present study provides a detail kinetic analysis for some of these inhibitors. The data generated in the present study suggest that these compounds are reversible and compete directly with the co-substrate, 2-oxoglutarate (2-OG) for binding at the enzyme active site. Most of these compounds are pan PHD inhibitors and exhibit a time-dependent inhibition (TDI) mechanism due to an extremely slow dissociation rate constant, koff, and a long residence time.
Subject(s)
Enzyme Inhibitors/pharmacology , Hypoxia-Inducible Factor-Proline Dioxygenases/antagonists & inhibitors , Small Molecule Libraries/pharmacology , Catalytic Domain , Enzyme Inhibitors/chemistry , Humans , Hypoxia-Inducible Factor-Proline Dioxygenases/chemistry , Hypoxia-Inducible Factor-Proline Dioxygenases/metabolism , Ketoglutaric Acids/metabolism , Kinetics , Protein Binding , Small Molecule Libraries/chemistryABSTRACT
The increasing burden and the continued suboptimal outcomes for patients with heart failure underlines the importance of continued research to develop novel therapeutics for this disorder. This can only be accomplished with successful translation of basic science discoveries into direct human application through effective clinical trial design and execution that results in a substantially improved clinical course and outcomes. In this respect, phase II clinical trials play a pivotal role in determining which of the multitude of potential basic science discoveries should move to the large and expansive registration trials in humans. A critical examination of the phase II trials in heart failure reveals multiple shortcomings in their concept, design, execution, and interpretation. To further a dialogue on the challenges and potential for improvement and the role of phase II trials in patients with heart failure, the Food and Drug Administration facilitated a meeting on October 17, 2016, represented by clinicians, researchers, industry members, and regulators. This document summarizes the discussion from this meeting and provides key recommendations for future directions.
Subject(s)
Cardiovascular Agents/therapeutic use , Clinical Trials, Phase II as Topic/standards , Heart Failure/drug therapy , Research Design/standards , Cardiovascular Agents/adverse effects , Clinical Trials, Phase II as Topic/methods , Consensus , Heart Failure/diagnosis , Heart Failure/mortality , Heart Failure/physiopathology , Humans , Treatment Outcome , United States , United States Food and Drug AdministrationABSTRACT
Compared with heart failure (HF) care 20 to 30 years ago, there has been tremendous advancement in therapy for ambulatory HF with reduced ejection fraction with the use of agents that block maladaptive neurohormonal pathways. However, during the past decade, with few notable exceptions, the frequency of successful drug development programs has fallen as most novel therapies have failed to offer incremental benefit or raised safety concerns (ie, hypotension). Moreover, no therapy has been approved specifically for HF with preserved ejection fraction or for worsening chronic HF (including acutely decompensated HF). Across the spectrum of HF, preliminary results from many phase II trials have been promising but are frequently followed by unsuccessful phase III studies, highlighting a disconnect in the translational process between basic science discovery, early drug development, and definitive clinical testing in pivotal trials. A major unmet need in HF drug development is the ability to identify homogeneous subsets of patients whose underlying disease is driven by a specific mechanism that can be targeted using a new therapeutic agent. Drug development strategies should increasingly consider therapies that facilitate reverse remodeling by directly targeting the heart itself rather than strictly focusing on agents that unload the heart or target systemic neurohormones. Advancements in cardiac imaging may allow for more focused and direct assessment of drug effects on the heart early in the drug development process. To better understand and address the array of challenges facing current HF drug development, so that future efforts may have a better chance for success, the Food and Drug Administration facilitated a meeting on February 17, 2015, which was attended by clinicians, researchers, regulators, and industry representatives. The following discussion summarizes the key takeaway dialogue from this meeting.
Subject(s)
Cardiovascular Agents/therapeutic use , Drug Discovery/methods , Heart Failure/drug therapy , Heart/drug effects , Animals , Biomarkers/metabolism , Cardiovascular Agents/adverse effects , Diffusion of Innovation , Drug Discovery/trends , Forecasting , Heart/physiopathology , Heart Failure/diagnosis , Heart Failure/metabolism , Heart Failure/physiopathology , Humans , Signal Transduction/drug effectsABSTRACT
The second messenger cyclic guanosine monophosphate (cGMP) is a key mediator in physiological processes such as vascular tone, and its essential involvement in pathways regulating metabolism has been recognized in recent years. Here, we focus on the fundamental role of cGMP in brown adipose tissue (BAT) differentiation and function. In contrast to white adipose tissue (WAT), which stores energy in the form of lipids, BAT consumes energy stored in lipids to generate heat. This so-called non-shivering thermogenesis takes place in BAT mitochondria, which express the specific uncoupling protein 1 (UCP1). The energy combusting properties of BAT render it a promising target in antiobesity strategies in which BAT could burn the surplus energy that has accumulated in obese and overweight individuals. cGMP is generated by guanylyl cyclases upon activation by nitric oxide or natriuretic peptides. It affects several downstream molecules including cGMP-receptor proteins such as cGMP-dependent protein kinase and is degraded by phosphodiesterases. The cGMP pathway contains several signaling molecules that can increase cGMP signaling, resulting in activation and recruitment of brown adipocytes, and hence can enhance the energy combusting features of BAT. In this review we highlight recent results showing the physiological significance of cGMP signaling in BAT, as well as pharmacological options targeting cGMP signaling that bear a high potential to become BAT-centered therapies for the treatment of obesity.
Subject(s)
Adipose Tissue, Brown/physiology , Cyclic GMP/physiology , Adipocytes/physiology , Adipose Tissue, Brown/drug effects , Animals , Diabetes Mellitus/drug therapy , Humans , Mitochondria/physiology , Obesity/drug therapy , Signal Transduction/drug effects , Signal Transduction/physiologyABSTRACT
Patients with peripheral artery disease have a marked reduction in exercise performance and daily ambulatory activity irrespective of their limb symptoms of classic or atypical claudication. This review will evaluate the multiple pathophysiologic mechanisms underlying the exercise impairment in peripheral artery disease based on an evaluation of the current literature and research performed by the authors. Peripheral artery disease results in atherosclerotic obstructions in the major conduit arteries supplying the lower extremities. This arterial disease process impairs the supply of oxygen and metabolic substrates needed to match the metabolic demand generated by active skeletal muscle during walking exercise. However, the hemodynamic impairment associated with the occlusive disease process does not fully account for the reduced exercise impairment, indicating that additional pathophysiologic mechanisms contribute to the limb manifestations. These mechanisms include a cascade of pathophysiological responses during exercise-induced ischemia and reperfusion at rest that are associated with endothelial dysfunction, oxidant stress, inflammation, and muscle metabolic abnormalities that provide opportunities for targeted therapeutic interventions to address the complex pathophysiology of the exercise impairment in peripheral artery disease.
Subject(s)
Exercise/physiology , Intermittent Claudication/physiopathology , Lower Extremity/physiopathology , Muscle, Skeletal/physiopathology , Peripheral Arterial Disease/physiopathology , Ankle Brachial Index , Hemodynamics/physiology , Humans , Intermittent Claudication/therapy , Lower Extremity/blood supply , Models, Cardiovascular , Muscle, Skeletal/blood supply , Peripheral Arterial Disease/therapyABSTRACT
Despite significant advances in diabetes care since the introductions of insulin and metformin, disease burden continues to grow. Large gaps in standard of care remain, and no robustly disease-modifying pharmacotherapy exists. Substantial research has been directed towards beta cell preservation and regeneration with no translational success, while little drug discovery or development is aimed at the other major cause of diabetes, namely, insulin resistance. Given the absence of convincing evidence that human beta cells can be regenerated, the diabetes community must broaden its focus to include new therapeutic strategies to limit, and reverse, insulin resistance.
ABSTRACT
Targeting glycosphingolipid synthesis has emerged as a novel approach for treating metabolic diseases. 32 (EXEL-0346) represents a new class of glucosylceramide synthase (GCS) inhibitors. This report details the elaboration of hit 8 with the goal of achieving and maintaining maximum GCS inhibition in vivo. 32 inhibited GCS with an IC(50) of 2 nM and achieved maximum hepatic GCS inhibition after four or five daily doses in rodents. Robust improvements in glucose tolerance in DIO mice and ZDF rats were observed after 2 weeks of q.d. dosing. Four weeks of dosing resulted in decreased plasma triglycerides and reduced hepatic fat deposition. Thus, 32 provides insight into the amount of metabolic regulation that can be restored following achievement of maximal target knockdown.
Subject(s)
Enzyme Inhibitors/chemical synthesis , Glucosyltransferases/antagonists & inhibitors , Phenylalanine/analogs & derivatives , Adipose Tissue, White/drug effects , Adipose Tissue, White/metabolism , Animals , Diabetes Mellitus, Type 2/drug therapy , Diabetes Mellitus, Type 2/enzymology , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Female , Gangliosides/metabolism , Glucose Tolerance Test , Glucosyltransferases/metabolism , Humans , Liver/drug effects , Liver/enzymology , Magnetic Resonance Spectroscopy , Mass Spectrometry , Mice , Mice, Inbred C57BL , Mice, Nude , Phenylalanine/pharmacology , Rats , Rats, Sprague-Dawley , Rats, Zucker , Structure-Activity Relationship , Triglycerides/bloodABSTRACT
BACKGROUND: The Bariatric Analysis and Reporting Outcome System (BAROS) uses a point scale (maximal score of 9) to evaluate weight loss, complications, improvement in medical conditions, and quality of life among postoperative bariatric patients. The BAROS was originally developed to address the need for a standardized method of reporting open gastric bypass outcomes and has been shown to be both valid and reliable. BAROS scores >7 are considered "excellent." Our objective was to assess the overall BAROS scores in patients undergoing laparoscopic Roux-en-Y gastric bypass at each postoperative follow-up interval and to examine the effect of age and gender on BAROS scores. METHODS: A total of 700 patients who had undergone LRYGB were asked to complete a BAROS questionnaire at their postoperative visits. The BAROS scores were recorded in a prospective database. The patients were stratified by their initial age and body mass index. The statistical analysis included analysis of variance. P <.05 was considered significant. RESULTS: The mean BAROS score peaked at 7.29 at the 18-month appointment. More than one half of the patients presenting for follow-up visits at 12, 18, 24, and 36 months had BAROS scores in the "excellent" range. Age stratification (20-29, 30-39, 40-49, and ≥ 50 years) resulted in significant differences at 3, 6, 9, 12, and 18 months postoperatively. When stratified by the initial body mass index, differences were seen at 3 weeks and 3, 6, 9, and 12 months postoperatively. CONCLUSION: Patients with a lower initial body mass index had greater BAROS scores at many of the follow-up intervals. Laparoscopic Roux-en-Y gastric bypass effectively improved the overall health and quality of life of patients.
Subject(s)
Activities of Daily Living , Body Mass Index , Gastric Bypass/methods , Laparoscopy , Obesity, Morbid/surgery , Quality of Life , Adult , Aged , Female , Humans , Length of Stay , Male , Middle Aged , Postoperative Period , Surveys and Questionnaires , Treatment Outcome , Weight Loss , Young AdultABSTRACT
We have optimized a novel series of potent p38 MAP kinase inhibitors based on an alpha-ketoamide scaffold through structure based design that due to their extended molecular architecture bind, in addition to the ATP site, to an allosteric pocket. In vitro ADME, in vivo PK and efficacy studies show these compounds to have drug-like characteristics and have resulted in the nomination of a development candidate which is currently in phase II clinical trials for the oral treatment of inflammatory conditions.
Subject(s)
Amides/chemistry , Anti-Inflammatory Agents, Non-Steroidal/chemistry , Protein Kinase Inhibitors/chemistry , p38 Mitogen-Activated Protein Kinases/antagonists & inhibitors , Administration, Oral , Allosteric Site , Amides/chemical synthesis , Amides/pharmacology , Animals , Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Anti-Inflammatory Agents, Non-Steroidal/pharmacokinetics , Binding Sites , Cell Line , Computer Simulation , Humans , Protein Binding , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Rats , Structure-Activity Relationship , p38 Mitogen-Activated Protein Kinases/metabolismABSTRACT
The tumor necrosis factor-alpha (TNF-alpha) cytokine, secreted by activated monocytes/macrophages and T lymphocytes, is implicated in several diseases, including rheumatoid arthritis, chronic obstructive pulmonary disease, inflammatory bowel disease, and osteoporosis. Monocyte/macrophage production of TNF-alpha is largely driven by p38alpha mitogen-activated protein kinase (MAP kinase), an intracellular soluble serine-threonine kinase. p38alpha MAP kinase is activated by growth factors, cellular stresses, and cytokines such as TNF-alpha and interleukin-l (IL-I). The primary contribution of p38alpha activation to excess TNF-alpha in settings of both chronic and acute inflammation has instigated efforts to find inhibitors of this enzyme as possible therapies for associated disease states. Analogue design, synthesis, and structure-activity studies led to the identification of 5-tert-butyl-N-cyclopropyl-2-methoxy-3-{2-[4-(2-morpholin-4-yl-ethoxy)-naphthalen-1-yl]-2-oxo-acetylamino}-benzamide (KR-003048) as a potent inhibitor of the p38 MAP kinase signaling pathway in vitro and in vivo. The inhibition in vitro of human p38alpha enzyme activity and lipopolysaccharide (LPS)-induced p38 activation and subsequent TNF-alpha release is described. KR-00348 was demonstrated to be a potent inhibitor of inflammatory cytokine production ex vivo in rat and human whole blood, and showed good oral bioavailability. Additionally, efficacy in mouse and rat models of acute and chronic inflammation was obtained. KR-003048 possessed therapeutic activity in acute models, demonstrating substantial inhibition of carrageenan-induced paw edema and in vivo LPS-induced TNF release at 30mg/kg p.o. Collagen-induced arthritis in mice was significantly inhibited by 10 and 30mg/kg doses of KR-003048. Evidence for disease-modifying activity in this model was indicated by histological evaluation of joints.