ABSTRACT
First responders encounter many hazards in the execution of their duties, and exposure to hazardous materials such as opioids is a primary safety concern. The ongoing opioid crisis in the United States continues to be a major public health issue, with overdose deaths from opioids reaching epidemic levels. Although responders frequently encounter opioids, available data on safety and risk are not always well-communicated, and we identified a need for refresher and just-in-time training products on this topic. In response, we created a training video series that is informative, concise, and visually appealing. The video series, available on YouTube, was tested with a small initial population, with findings suggesting key questions for a larger study focused on integration of the refresher training with existing programs to optimize retention and adoption of safety practices.
Subject(s)
Drug Overdose , Emergency Responders , Analgesics, Opioid/therapeutic use , Drug Overdose/drug therapy , Drug Overdose/prevention & control , Humans , United StatesABSTRACT
Physical activity promotes metabolic and cardiovascular health benefits that derive in part from the transcriptional responses to exercise that occur within skeletal muscle and other organs. There is interest in discovering a pharmacologic exercise mimetic that could imbue wellness and alleviate disease burden. However, the molecular physiology by which exercise signals the transcriptional response is highly complex, making it challenging to identify a single target for pharmacological mimicry. The current studies evaluated the transcriptome responses in skeletal muscle, heart, liver, and white and brown adipose to novel small molecule activators of AMPK (pan-activators for all AMPK isoforms) compared to that of exercise. A striking level of congruence between exercise and pharmacological AMPK activation was observed across the induced transcriptome of these five tissues. However, differences in acute metabolic response between exercise and pharmacologic AMPK activation were observed, notably for acute glycogen balances and related to the energy expenditure induced by exercise but not pharmacologic AMPK activation. Nevertheless, intervention with repeated daily administration of short-acting activation of AMPK was found to mitigate hyperglycemia and hyperinsulinemia in four rodent models of metabolic disease and without the cardiac glycogen accretion noted with sustained pharmacologic AMPK activation. These findings affirm that activation of AMPK is a key node governing exercise mediated transcription and is an attractive target as an exercise mimetic.
Subject(s)
AMP-Activated Protein Kinases/metabolism , Adipose Tissue/metabolism , Liver/metabolism , Muscle, Skeletal/metabolism , Myocardium/metabolism , Animals , Energy Metabolism , Enzyme Activation/drug effects , Fatty Acids/metabolism , Gene Expression Regulation/drug effects , Glucose/metabolism , Homeostasis , Mice, Inbred C57BL , Oxidation-Reduction , Physical Conditioning, AnimalABSTRACT
5'-Adenosine monophosphate-activated protein kinase (AMPK) is a key regulator of mammalian energy homeostasis and has been implicated in mediating many of the beneficial effects of exercise and weight loss including lipid and glucose trafficking. As such, the enzyme has long been of interest as a target for the treatment of Type 2 Diabetes Mellitus. We describe the optimization of ß1-selective, liver-targeted AMPK activators and their evolution into systemic pan-activators capable of acutely lowering glucose in mouse models. Identifying surrogates for the key acid moiety in early generation compounds proved essential in improving ß2-activation and in balancing improvements in plasma unbound fraction while avoiding liver sequestration.
ABSTRACT
5'-Adenosine monophosphate-activated protein kinase (AMPK) is a master regulator of energy homeostasis in eukaryotes. Despite three decades of investigation, the biological roles of AMPK and its potential as a drug target remain incompletely understood, largely because of a lack of optimized pharmacological tools. We developed MK-8722, a potent, direct, allosteric activator of all 12 mammalian AMPK complexes. In rodents and rhesus monkeys, MK-8722-mediated AMPK activation in skeletal muscle induced robust, durable, insulin-independent glucose uptake and glycogen synthesis, with resultant improvements in glycemia and no evidence of hypoglycemia. These effects translated across species, including diabetic rhesus monkeys, but manifested with concomitant cardiac hypertrophy and increased cardiac glycogen without apparent functional sequelae.
Subject(s)
AMP-Activated Protein Kinases/metabolism , Cardiomegaly/chemically induced , Glucose/metabolism , Homeostasis/drug effects , Imidazoles/pharmacology , Pyridines/pharmacology , Animals , Benzimidazoles , Blood Glucose/drug effects , Fasting , Glycogen/metabolism , Hypoglycemia/chemically induced , Imidazoles/adverse effects , Imidazoles/chemistry , Insulin/pharmacology , Macaca mulatta , Male , Mice , Mice, Inbred C57BL , Muscle, Skeletal/drug effects , Muscle, Skeletal/metabolism , Pyridines/adverse effects , Pyridines/chemistryABSTRACT
Dichloromethane (DCM) is a lung and liver carcinogen in mice at inhalation exposures≥2000ppm. The modes of action (MOA) of these responses have been attributed to formation of genotoxic, reactive metabolite(s). Here, we examined gene expression in lung and liver from female B6C3F1 mice exposed to 0, 100, 500, 2000, 3000 and 4000ppm DCM for 90days. We also simulated dose measures - rates of DCM oxidation to carbon monoxide (CO) in lung and liver and expected blood carboxyhemoglobin (HbCO) time courses with a PBPK model inclusive of both conjugation and oxidation pathways. Expression of large numbers of genes was altered at 100ppm with maximal changes in the numbers occurring by 500 or 2000ppm. Most changes in genes common to the two tissues were related to cellular metabolism and circadian clock. At the lower concentrations, the changes in metabolism-related genes were discordant - up in liver and down in lung. These processes included organelle biogenesis, TCA cycle, and respiratory electron transport. Changes in circadian cycle genes - primarily transcription factors - showed strong concentration-related response at higher concentrations (Arntl, Npas2, and Clock were down-regulated; Cry2, Wee1, Bhlhe40, Per3, Nr1d1, Nr1d2 and Dbp) were up-regulated with similar directionality in both tissues. Overall, persistently elevated HbCO from DCM oxidation appears to cause extended periods of hypoxia, leading to altered circadian coupling to cellular metabolism. The dose response for altered circadian processes correlates with the cancer outcome. We found no evidence of changes in genes indicative of responses to cytotoxic, DNA-reactive metabolites.
Subject(s)
Circadian Rhythm , Hypoxia/genetics , Liver/drug effects , Lung/drug effects , Methylene Chloride/toxicity , Transcriptome , Animals , Carboxyhemoglobin/genetics , Carboxyhemoglobin/metabolism , Circadian Rhythm/drug effects , Circadian Rhythm/genetics , Dose-Response Relationship, Drug , Female , Gene Expression Regulation , Hypoxia/chemically induced , Hypoxia/pathology , Inhalation Exposure/adverse effects , Liver/metabolism , Lung/metabolism , Mice , Mice, Inbred Strains , Pharmacokinetics , Transcription Factors/genetics , Transcription Factors/metabolismSubject(s)
C-Reactive Protein/metabolism , Disability Evaluation , Gait , Vitamin D Deficiency/epidemiology , Vitamin D/blood , Walking/physiology , Female , Humans , MaleABSTRACT
Phosphatidylinositol 4-kinase type IIIα (PI4KA) is a host factor essential for hepatitis C virus replication and hence is a target for drug development. PI4KA has also been linked to endoplasmic reticulum exit sites and generation of plasma membrane phosphoinositides. Here, we developed highly specific and potent inhibitors of PI4KA and conditional knock-out mice to study the importance of this enzyme in vitro and in vivo. Our studies showed that PI4KA is essential for the maintenance of plasma membrane phosphatidylinositol 4,5-bisphosphate pools but only during strong stimulation of receptors coupled to phospholipase C activation. Pharmacological blockade of PI4KA in adult animals leads to sudden death closely correlating with the drug's ability to induce phosphatidylinositol 4,5-bisphosphate depletion after agonist stimulation. Genetic inactivation of PI4KA also leads to death; however, the cause in this case is due to severe intestinal necrosis. These studies highlight the risks of targeting PI4KA as an anti-hepatitis C virus strategy and also point to important distinctions between genetic and pharmacological studies when selecting host factors as putative therapeutic targets.
Subject(s)
Cell Membrane/enzymology , Phosphatidylinositol 4,5-Diphosphate/metabolism , Phosphatidylinositol Phosphates/metabolism , Phosphotransferases (Alcohol Group Acceptor)/metabolism , Animals , COS Cells , Cell Membrane/genetics , Chlorocebus aethiops , Enzyme Activation/genetics , Gene Targeting , HEK293 Cells , Hepatitis C/enzymology , Hepatitis C/genetics , Hepatitis C/therapy , Humans , Mice , Mice, Transgenic , Minor Histocompatibility Antigens , Phosphatidylinositol 4,5-Diphosphate/genetics , Phosphatidylinositol Phosphates/genetics , Phosphotransferases (Alcohol Group Acceptor)/antagonists & inhibitors , Phosphotransferases (Alcohol Group Acceptor)/genetics , Type C Phospholipases/genetics , Type C Phospholipases/metabolismABSTRACT
Recent studies, including one from our own lab, report that different subpopulations of obese individuals display a variable inflammatory signature in their visceral adipose tissue that may contribute significantly to their risk for developing insulin resistance, type 2 diabetes, and other metabolic diseases. Understanding the molecular mechanisms and signaling pathways that lead to these differences in susceptibility to insulin resistance will equip us with important targets to help stem the tide of such debilitating diseases. Here we discuss an emerging theory that chronic, low-grade endotoxemia may represent a causal factor in obesity-related inflammatory states, and that diet-induced changes in the gut microbiome may be a key regulator of metabolic health. The implications to both disease prevention and to therapeutic intervention are also highlighted.
ABSTRACT
When conventional vehicles (eg, methylcellulose and water) impart inadequate physical, chemical, and/or biological properties for proper toxicological assessment of test article formulations, nonconventional vehicles may be considered. Often toxicity data for nonconventional vehicle formulations are limited. Studies were conducted to collect toxicity data from a rodent and a non-rodent species given 2 nonconventional vehicles, Solutol HS15/polyethylene glycol (PEG) 400 and Cremophor RH40/PEG 400, with differing formulations and dose volumes (10 mL/kg for rats; 2 or 5 mL/kg for dogs). In rats, both vehicles caused increase in kidney weights (males only) and decrease in thymic weights (males only) without concurrent microscopic findings; altered urine electrolytes, minimally decreased serum electrolytes (males only), and increased serum total cholesterol (females only) were also present. The Cremophor formulation was also associated with increased serum urea (males only) and urine phosphorus: creatinine. For rats given the Solutol formulation, both genders had decreased urine glucose parameters and males had increased urine volume. In dogs, loose/watery feces and emesis were present given either vehicle, and mucus-cell hyperplasia of the ileum was present given the Solutol formulation. Increased red blood cell mass and decreased urine volume in dogs given 30% Solutol/70% PEG 400 (5 mL/kg/d) were likely due to subclinical dehydration and hemoconcentration. For the Cremophor formulations, dose volume-dependent increased incidence of minimal subepithelial gastric hemorrhage was noted in dogs, and dogs given 5 mL/kg/d showed increased serum urea nitrogen. Overall, regardless of the formulation or dose volume, neither vehicle produced overt toxicity in either species, but the Solutol formulation produced fewer effects in rats. Generally, lower dose volumes minimized the severity and/or incidence of findings.
Subject(s)
Polyethylene Glycols/chemistry , Stearic Acids/toxicity , Animals , Dogs , Female , Male , Polyethylene Glycols/toxicity , Random Allocation , Rats , Rats, Sprague-Dawley , Specific Pathogen-Free Organisms , Stearic Acids/chemistryABSTRACT
Obesity is associated with insulin resistance, a major risk factor for type 2 diabetes and cardiovascular disease. However, not all obese individuals are insulin resistant, which confounds our understanding of the mechanistic link between these conditions. We conducted transcriptome analyses on 835 obese subjects with mean BMI of 48.8, on which we have previously reported genetic associations of gene expression. Here, we selected ~320 nondiabetic (HbA(1c) <7.0) subjects and further stratified the cohort into insulin-resistant versus insulin-sensitive subgroups based on homeostasis model assessment-insulin resistance. An unsupervised informatics analysis revealed that immune response and inflammation-related genes were significantly downregulated in the omental adipose tissue of obese individuals with extreme insulin sensitivity and, to a much lesser extent, in subcutaneous adipose tissue. In contrast, genes related to ß-oxidation and the citric acid cycle were relatively overexpressed in adipose of insulin-sensitive patients. These observations were verified by querying an independent cohort of our published dataset of 37 subjects whose subcutaneous adipose tissue was sampled before and after treatment with thiazolidinediones. Whereas the immune response and inflammation pathway genes were downregulated by thiazolidinedione treatment, ß-oxidation and citric acid cycle genes were upregulated. This work highlights the critical role that omental adipose inflammatory pathways might play in the pathophysiology of insulin resistance, independent of body weight.
Subject(s)
Gene Expression Regulation, Enzymologic , Insulin Resistance , Intra-Abdominal Fat/immunology , Mitochondria/metabolism , Obesity, Morbid/immunology , Adult , Biopsy , Body Mass Index , Citric Acid Cycle/drug effects , Cohort Studies , Diabetes Mellitus, Type 2/complications , Gene Expression Profiling , Gene Expression Regulation, Enzymologic/drug effects , Humans , Hypoglycemic Agents/therapeutic use , Intra-Abdominal Fat/drug effects , Intra-Abdominal Fat/metabolism , Intra-Abdominal Fat/pathology , Mitochondria/drug effects , Mitochondria/pathology , Mitochondrial Proteins/genetics , Mitochondrial Proteins/metabolism , Obesity, Morbid/complications , Obesity, Morbid/metabolism , Obesity, Morbid/pathology , Oligonucleotide Array Sequence Analysis , Oxidative Phosphorylation/drug effects , RNA, Messenger/metabolism , Subcutaneous Fat, Abdominal/drug effects , Subcutaneous Fat, Abdominal/immunology , Subcutaneous Fat, Abdominal/metabolism , Subcutaneous Fat, Abdominal/pathology , Thiazolidinediones/therapeutic useABSTRACT
The cytoprotective stress response factor HSF1 regulates the transcription of the chaperone HSP70, which exhibits anti-inflammatory effects and improves insulin sensitivity. We tested the therapeutic potential of this pathway in rodent models of diabetes using pharmacological tools. Activation of the HSF1 pathway was achieved using potent inhibitors of the upstream regulatory protein, HSP90. Treatment with AUY922, a selective HSP90 inhibitor led to robust inhibition of JNK1 phosphorylation, cytoprotection and improved insulin signaling in cells, consistent with effects observed with HSP70 treatment. Chronic dosing with HSP90 inhibitors reversed hyperglycemia in the diabetic db/db mouse model, and improved insulin sensitivity in the diet-induced obese mouse model of insulin resistance, further supporting the concept that the HSF1 pathway is a potentially viable anti-diabetes target.
Subject(s)
Blood Glucose/drug effects , DNA-Binding Proteins/agonists , Diabetes Mellitus, Type 2/drug therapy , HSP90 Heat-Shock Proteins/antagonists & inhibitors , Hypoglycemic Agents/administration & dosage , Isoxazoles/administration & dosage , Resorcinols/administration & dosage , Transcription Factors/agonists , Animals , Benzoquinones/pharmacology , Blood Glucose/metabolism , Cells, Cultured , Cytoprotection , Diabetes Mellitus, Type 2/metabolism , Heat Shock Transcription Factors , Heat-Shock Response , Isoxazoles/chemistry , Lactams, Macrocyclic/pharmacology , Male , Mice , Mice, Inbred Strains , Myoblasts/drug effects , Myoblasts/metabolism , Resorcinols/chemistryABSTRACT
Complex diseases result from molecular changes induced by multiple genetic factors and the environment. To derive a systems view of how genetic loci interact in the context of tissue-specific molecular networks, we constructed an F2 intercross comprised of >500 mice from diabetes-resistant (B6) and diabetes-susceptible (BTBR) mouse strains made genetically obese by the Leptin(ob/ob) mutation (Lep(ob)). High-density genotypes, diabetes-related clinical traits, and whole-transcriptome expression profiling in five tissues (white adipose, liver, pancreatic islets, hypothalamus, and gastrocnemius muscle) were determined for all mice. We performed an integrative analysis to investigate the inter-relationship among genetic factors, expression traits, and plasma insulin, a hallmark diabetes trait. Among five tissues under study, there are extensive protein-protein interactions between genes responding to different loci in adipose and pancreatic islets that potentially jointly participated in the regulation of plasma insulin. We developed a novel ranking scheme based on cross-loci protein-protein network topology and gene expression to assess each gene's potential to regulate plasma insulin. Unique candidate genes were identified in adipose tissue and islets. In islets, the Alzheimer's gene App was identified as a top candidate regulator. Islets from 17-week-old, but not 10-week-old, App knockout mice showed increased insulin secretion in response to glucose or a membrane-permeant cAMP analog, in agreement with the predictions of the network model. Our result provides a novel hypothesis on the mechanism for the connection between two aging-related diseases: Alzheimer's disease and type 2 diabetes.
Subject(s)
Alzheimer Disease , Amyloid Precursor Protein Secretases , Diabetes Mellitus, Experimental , Diabetes Mellitus, Type 2 , Insulin , Adipose Tissue/metabolism , Alzheimer Disease/genetics , Alzheimer Disease/metabolism , Amyloid Precursor Protein Secretases/deficiency , Amyloid Precursor Protein Secretases/genetics , Amyloid Precursor Protein Secretases/metabolism , Animals , Diabetes Mellitus, Experimental/genetics , Diabetes Mellitus, Experimental/metabolism , Diabetes Mellitus, Type 2/blood , Diabetes Mellitus, Type 2/genetics , Diabetes Mellitus, Type 2/metabolism , Gene Expression Profiling , Gene Regulatory Networks , Glucose/metabolism , Humans , Insulin/blood , Insulin/genetics , Insulin/metabolism , Insulin Secretion , Islets of Langerhans/metabolism , Leptin/genetics , Mice , Mice, Knockout , Mice, Obese/genetics , Protein Interaction MapsABSTRACT
Complex diseases such as obesity and type II diabetes can result from a failure in multiple organ systems including the central nervous system and tissues involved in partitioning and disposal of nutrients. Studying the genetics of gene expression in tissues that are involved in the development of these diseases can provide insights into how these tissues interact within the context of disease. Expression quantitative trait locus (eQTL) studies identify mRNA expression changes linked to proximal genetic signals (cis eQTLs) that have been shown to affect disease. Given the high impact of recent eQTL studies, it is important to understand what role sample size and environment plays in identification of cis eQTLs. Here we show in a genotyped obese human population that the number of cis eQTLs obey precise scaling laws as a function of sample size in three profiled tissues, i.e. omental adipose, subcutaneous adipose and liver. Also, we show that genes (or transcripts) with cis eQTL associations detected in a small population are detected at approximately 90% rate in the largest population available for our study, indicating that genes with strong cis acting regulatory elements can be identified with relatively high confidence in smaller populations. However, by increasing the sample size we allow for better detection of weaker and more distantly located cis-regulatory elements. Yet, we determined that the number of tissue specific cis eQTLs saturates in a modestly sized cohort while the number of cis eQTLs common to all tissues fails to reach a maximum value. Understanding the power laws that govern the number and specificity of eQTLs detected in different tissues, will allow a better utilization of genetics of gene expression to inform the molecular mechanism underlying complex disease traits.
Subject(s)
Computational Biology , Gene Expression Regulation/genetics , Regulatory Sequences, Nucleic Acid/genetics , DNA/chemistry , DNA/genetics , Disease/genetics , Humans , Models, Molecular , Nucleic Acid Conformation , Organ Specificity , Quantitative Trait Loci/geneticsABSTRACT
BACKGROUND: Prior to bioanalysis, sample transport and storage are critical considerations in any pharmacokinetic or toxicokinetic study design. Care must be taken to ensure the shipment is properly packaged and tracked to make certain it arrives at the desired, final destination in the appropriate timeframe, and that the integrity of the sample is not compromised. When dealing with biological specimens, environmental conditions may have a deleterious effect on the stability and conditions of the sample. RESULTS: Currently, frozen plasma or blood samples are the matrix of choice within the pharmaceutical industry for analysis within both preclinical and clinical trials. Liquid samples are shipped and received frozen and, therefore, the assumption is made that the frozen conditions are maintained throughout the entire transit process. Dried blood spot and dried matrix spot samples are becoming popular alternatives to plasma sampling in many small- and even large-molecule applications. With the implementation of dried blood spot and dried matrix spot samples, shipping and storage occurs under ambient conditions. CONCLUSION: In this article we discuss various shipping containers for these samples, illustrate the environmental extremes encountered during the shipping process, demonstrate a cost-effective method of monitoring both temperature and humidity, and discuss validation steps that may be implemented to minimize the impact of these variables on your study design.
Subject(s)
Dried Blood Spot Testing/methods , Specimen Handling/methods , Environment , Humans , Specimen Handling/instrumentationABSTRACT
To map the genetics of gene expression in metabolically relevant tissues and investigate the diversity of expression SNPs (eSNPs) in multiple tissues from the same individual, we collected four tissues from approximately 1000 patients undergoing Roux-en-Y gastric bypass (RYGB) and clinical traits associated with their weight loss and co-morbidities. We then performed high-throughput genotyping and gene expression profiling and carried out a genome-wide association analyses for more than 100,000 gene expression traits representing four metabolically relevant tissues: liver, omental adipose, subcutaneous adipose, and stomach. We successfully identified 24,531 eSNPs corresponding to about 10,000 distinct genes. This represents the greatest number of eSNPs identified to our knowledge by any study to date and the first study to identify eSNPs from stomach tissue. We then demonstrate how these eSNPs provide a high-quality disease map for each tissue in morbidly obese patients to not only inform genetic associations identified in this cohort, but in previously published genome-wide association studies as well. These data can aid in elucidating the key networks associated with morbid obesity, response to RYGB, and disease as a whole.
Subject(s)
Gastric Mucosa/metabolism , Liver/metabolism , Obesity, Morbid/epidemiology , Obesity, Morbid/genetics , Adiposity/genetics , Adult , Cohort Studies , Comorbidity , Databases, Genetic , Female , Gastric Bypass , Gene Expression Profiling , Genome-Wide Association Study/methods , Genotype , Humans , Male , Middle Aged , Obesity, Morbid/surgery , Polymorphism, Single Nucleotide , Weight LossABSTRACT
Alcohol typically has a detrimental impact on memory across a variety of encoding and retrieval conditions (e.g., Mintzer, 2007; Ray & Bates, 2006). No research has addressed alcohol's effect on memory for lengthy and interactive events and little has tested alcohol's effect on free recall. In this study 94 participants were randomly assigned to alcohol, placebo, or control groups and consumed drinks in a bar-lab setting while interacting with a "bartender". Immediately afterwards all participants freely recalled the bar interaction. Consistent with alcohol myopia theory, intoxicated participants only differed from placebo and control groups when recalling peripheral information. Expanding on the original hypervigilance hypothesis, placebo participants showed more conservative reporting behaviour than the alcohol or control groups by providing more uncertain and "don't know" responses. Thus, alcohol intoxication had confined effects on memory for events, supporting and extending current theories.
Subject(s)
Alcoholic Intoxication/psychology , Arousal/drug effects , Attention/drug effects , Memory/drug effects , Mental Recall/drug effects , Adult , Alcoholic Intoxication/blood , Central Nervous System Depressants/blood , Ethanol/blood , Female , Field Dependence-Independence , Humans , Male , Reference Values , Young AdultABSTRACT
Second-order Møller-Plesset perturbation theory (MP2) is used to perform geometry optimizations on XHX(-).(H(2)O)(n) for X = Br, I, with n = 1 to 6 water molecules. Of particular interest is the manner in which the solvent molecules orient themselves around the solute and which configurations are lowest in energy. Although for most values of n, water molecules may donate all of their hydrogen atoms for hydrogen bonding to the solute, this type of structure is the lowest in energy only for n = 0 to 2 and is only a local minimum for n = 3, 4, and 6. For n = 5, this type of structure is a saddle point. Coupled cluster single-point calculations at the MP2 geometries are used to obtain accurate relative energies for all stationary points.
ABSTRACT
Structural properties of large NO(3)(-).(H(2)O)(n) (n = 15-500) clusters are studied by Monte Carlo simulations using effective fragment potentials (EFPs) and by classical molecular dynamics simulations using a polarizable empirical force field. The simulation results are analyzed with a focus on the description of hydrogen bonding and solvation in the clusters. In addition, a comparison between the electronic structure based EFP and the classical force field description of the 32 water cluster system is presented. The EFP simulations, which focused on the cases of n = 15 and 32, show an internal, fully solvated structure and a "surface adsorbed" structure for the 32 water cluster at 300 K, with the latter configuration being more probable. The internal solvated structure and the "surface adsorbed" structure differ considerably in their hydrogen bonding coordination numbers. The force field based simulations agree qualitatively with these results, and the local geometry of NO(3)(-) and solvation at the surface-adsorbed site in the force field simulations are similar to those predicted using EFPs. Differences and similarities between the description of hydrogen bonding of the anion in the two approaches are discussed. Extensive classical force field based simulations at 250 K predict that long time scale stability of "internal" NO(3)(-), which is characteristic of extended bulk aqueous interfaces, emerges only for n > 300. Ab initio Møller-Plesset perturbation theory is used to test the geometries of selected surface and interior anions for n = 32, and the results are compared to the EFP and MD simulations. Qualitatively, all approaches agree that surface structures are preferred over the interior structures for clusters of this size. The relatively large aqueous clusters of NO(3)(-) studied here are of comparable size to clusters that lead to new particle formation in air. Nitrate ions on the surface of such clusters may have significantly different photochemistry than the internal species. The possible implications of surface-adsorbed nitrate ions for atmospheric chemistry are discussed.
Subject(s)
Computer Simulation , Models, Chemical , Nitrates/chemistry , Temperature , Water/chemistry , Atmosphere , Hydrogen Bonding , Molecular Structure , Monte Carlo Method , Particle Size , Surface PropertiesABSTRACT
Assigned from data sets measured in water at 2, 25, and 60 degrees C containing (13)C=O NMR chemical shifts and [theta](222) ellipticities, helical propensities are reported for the 20 genetically coded amino acids, as well as for norvaline and norleucine. These have been introduced by chemical synthesis at central sites within length-optimized, spaced, solubilized Ala(19) hosts. The resulting polyalanine-derived, quantitative propensity sets express for each residue its temperature-dependent but context-independent tendency to forego a coil state and join a preexisting helical conformation. At 2 degrees C their rank ordering is: P << G < H < C, T, N < S < Y, F, W < V, D < K < Q < I < R, M < L < E < A; at 60 degrees C the rank becomes: H, P < G < C < R, K < T, Y, F < N, V < S < Q < W, D < I, M < E < A < L. The DeltaDeltaG values, kcal/mol, relative to alanine, for the cluster T, N, S, Y, F, W, V, D, Q, imply that at 2 degrees C all are strong breakers: DeltaDeltaG(mean) = +0.63 +/- 0.11, but at 60 degrees C their breaking tendencies are dramatically attenuated and converge toward the mean: DeltaDeltaG(mean) = +0.25 +/- 0.07. Accurate modeling of helix-rich proteins found in thermophiles, mesophiles, and organisms that flourish near 0 degrees C thus requires appropriately matched propensity sets. Comparisons are offered between the temperature-dependent propensity assignments of this study and those previously assigned by the Scheraga group; the special problems that attend propensity assignments for charged residues are illustrated by lysine guest data; and comparisons of errors in helicity assignments from shifts and ellipticity data show that the former provide superior precision and accuracy.
Subject(s)
Amino Acids/chemistry , Peptides/chemistry , Amino Acid Sequence , Models, Molecular , Nuclear Magnetic Resonance, Biomolecular , Protein Structure, Secondary , TemperatureABSTRACT
To investigate the genetic architecture of severe obesity, we performed a genome-wide association study of 775 cases and 3197 unascertained controls at approximately 550,000 markers across the autosomal genome. We found convincing association to the previously described locus including the FTO gene. We also found evidence of association at a further six of 12 other loci previously reported to influence body mass index (BMI) in the general population and one of three associations to severe childhood and adult obesity and that cases have a higher proportion of risk-conferring alleles than controls. We found no evidence of homozygosity at any locus due to identity-by-descent associating with phenotype which would be indicative of rare, penetrant alleles, nor was there excess genome-wide homozygosity in cases relative to controls. Our results suggest that variants influencing BMI also contribute to severe obesity, a condition at the extreme of the phenotypic spectrum rather than a distinct condition.