bluuebunny/crossref_metadata_2025 huggingface dataset:
Current Mud Practices in Coastal Louisiana
Authors: Gill J.A. , Carnicom W.M.
Published: June 2009

Approximately 70% of the muds in use in coastal Louisiana are calcium treated, and the majority of these are of the recently introduced, more highly inhibited type. The terminology of inhibition is reviewed. Examples of South Louisiana well records and their mud costs are given for the different types of mud. A curve for flow properties vs. mud weight is presented. Centrifuge economics are discussed. Special muds, mud additives and techniques are described.

At the invitation of the Evangeline Section, Society of Petroleum Engineers of AIME, this paper was prepared to present a brief review of recent innovations and current mud practices along the Gulf Coast of Louisiana. The authors feel that the last two years have been significant ones for the drilling mud industry, in that mud costs have been drastically reduced and practical field muds and techniques have been developed which enable the drilling of deeper wells with less trouble than has heretofore been possible.

Mud Types Currently in Use

First in order of interest is a survey of the types of mud currently being used in South Louisiana (Table I).

As indicated statistically in the survey, the low pH red mud is the most economical type for drilling wells which do not require a heavily weighted mud or anticipate salt water contamination. The cost of chemicals for maintaining deflocculation of the mud is very low in the absence of inhibiting ions. The non-inhibited mud has little tolerance for solids, however, and the flow properties become costly to manage at mud densities in excess of 12.0 ppg. The wells which can be drilled in South Louisiana with this type of mud are in the minority.

At the time this survey was taken, 70% of the muds in use were calcium treated — either with lime, calcium chloride, gypsum, or seawater. These more or less inhibited muds have proven themselves very practical for Gulf Coast drilling, where good filtration and flow properties are required at heavy mud weights and in the presence of contaminants.
The Retrievable Valve Testing System Used in Well Evaluation and Completion Operations
Authors: Farley D.L.
Published: June 2009

The retrievable valve testing system has been developed for use with a retrievable multi-purpose packer to provide a means for obtaining a formation test and subsequently performing treating, squeeze cementing, perforating, or further testing operations without removing the tubing from the well. This technique permits the removal or the retrievable valve and pressure recording device from inside the tubing at the completion or the test, leaving an unobstructed opening through the string for further operations. The primary advantage or this system is realized in eliminating many or the usual round trips with the tubing between operations, thereby resulting in considerable saving or costly rig time.

There is a definite demand for this type or service and field results have been successful. On many jobs there have been various combinations or several operations performed on one or more formations with only one trip with the tubing. In some instances the same operations could not be duplicated by conventional means.

There are various techniques which have been developed in the three years or its use which increase the versatility or the system. The system has been successfully used in many areas and will eventually supplement conventional methods in many more areas or the oil industry.

Introduction

In every phase of the oil industry there has been continuous efforts to develop more economical methods for the recovery of oil. Particular attention has been given to reducing the time necessary for a drilling rig or workover rig to remain on the well location for well evaluation and completion operations.
Modern Logging Programs and Interpretation Methods
Authors: Alger R.P.
Published: June 2009

Recent logging developments have provided more dependable data for reservoir evaluation. These new methods, which include both resistivity and porosity measuring devices, have now been adequately checked against older techniques, core analysis, and production results. Their responses with respect to varied borehole and formation conditions are sufficiently understood to permit the proper selection of logs for most efficient interpretation.

These devices, including the Induction Log (medium and deep), Laterolog, Proximity Log, Sonic Log, and Gamma-Gamma Density, have largely solved the problems of thin-bed resolution and borehole effects. All are essentially focused devices and have improved and predictable response where flushing or invasion is a problem. Their utility is such that any logging program today is likely to include one or several of them. when detailed reservoir information is required, where reservoir conditions are complex, and when wildcats or outposts are drilled the best available logging combination should be used.

The first and most important use of logs is to identify zones for testing or further evaluation. Although the discussion to follow presupposes that logs will provide complete information, it must be remembered that additional data, such as sidewall cores, conventional cores, drill-stem and wire-line formation tests, and cuttings, will assist in the final analysis.

The objectives of this paper are twofold: first, to discuss the new logs, briefly indicating where each fits in the several families of logging devices, and, second, to outline essential logging combinations or programs by mud and formation type.

The basic requirements of any logging program should be:Correlation -the program should include curves that may be reliably correlated with logs(sometimes old logs) from nearby wells. The SP, Short Normal, and Gamma Ray curves are normally used for this purpose. The Laterolog is often used in saltmuds. The Sonic Log can give unique correlations in carbonate reservoirs, evaporite sequences, or in lignite or coal.Depth control - the tops and bottoms of beds should be accurately defined.

Pad devices, such as the Microlog and Microlaterolog, pinpoint bed boundaries. 3. Net pay definition - the net thickness of the productive zones (the sand count) is required for recovery computations. The oldest, and still useful, method involves the SP. The modern combination of the Microlog with a caliper gives maximum efficiency.
Solution of a Typical Reservoir Problem on a Large Scale Computer
Authors: Warren J.E. , Mueller T.D.
Published: June 2009

Introduction

High speed digital computing machines, in spite of their wide publicity as magic brains, can only add, subtract, multiply, and divide. With this in mind, considerable detailed mathematical analysis and planning work is required on a problem before the machine will perform its job. The purpose of this paper is to show how a typical reservoir problem is put in a form for solution on a high speed digital computer. The problem we have chosen for illustration is prediction of recovery and gas-oil-ratio trend of a solution gas-drive reservoir by the Muskat equation.

The process of obtaining solutions on a high speed computer may be divided into six specific steps:Formulation of the physical behavior to be studied into mathematical terms(construction of the mathematical model);Selection of a suitable mathematical technique for solving the equations governing behavior of the proposed mathematical model;Application of the selected mathematical technique to the model equations(developing a flow diagram which separates the total calculation into particular computing sequences and blocks of computation);Interpretation of the mathematical and logical operations into machine language (done for each computation block and is called coding or programming);Preparation of data needed in the calculation so that the computer can use the data (usually entails entering the data into paper cards or tape);Application of the computer program to a specific problem, listing of results, and verification of the machine program.

In the sections to follow, we plan to discuss each step as it applies to predicting the behavior of a solution gas drive reservoir using the Muskat equation.

Construction of the Mathematical Model

The physical mechanisms by which oil is produced from a reservoir are complex and even today not understood in their entirety. Thus, the engineer or mathematician whose job it is to construct a mathematical model of an oil reservoir is forced to make assumptions regarding the reservoir so as to reduce the problem to one he can formulate in mathematical terms. In addition, he must devise or choose his model so it will retain the particular features of reservoir behavior that he wishes to study.
Preharvest Neutral Detergent Fiber Concentration of Alfalfa as Influenced by Stubble Height
Authors: Parsons David , Cherney Jerome H. , Peterson Paul R.
Published: June 2009

Regression equations can be used to estimate the preharvest neutral detergent fiber (NDF) concentration of alfalfa. In New York, where the stubble height of alfalfa varies due to terrain, predictive accuracy of existing equations may be reduced. The objectives of this experiment were to develop and evaluate alfalfa NDF equations that incorporate intended stubble height. Stands of first‐cut alfalfa were sampled in producers' fields in New York in 2007, and cut into 5‐cm segments. Predictive NDF equations were developed for each segment and for the whole plant. To develop whole‐plant equations, it was necessary to develop and use equations describing the change, with alfalfa height, in the contribution of each segment to the overall dry matter (DM). The r2 values ranged from 0.90 to 0.93 for the individual segments and 0.93 for the whole‐plant equations. The whole‐plant equations performed comparably to existing models when evaluated using a dataset of 109 alfalfa samples cut at 10 cm, from 19 New York counties in 2004 and 2005. The derived equations were also fitted to samples collected at a range of stubble heights from New York and Minnesota in 2008. For the New York dataset, the r2 values for whole‐plant equations ranged from 0.86 to 0.87, compared with 0.66 to 0.68 for existing equations, which were also biased. The r2 values for the Minnesota dataset were also high, but with some translational bias. The equations could be used by New York producers to obtain a more accurate estimate of preharvest NDF concentration.
Cover Crop and Liquid Manure Effects on Soil Quality Indicators in a Corn Silage System
Authors: Jokela William E. , Grabber John H. , Karlen Douglas L. , Balser Teri C. , Palmquist Debra E.
Published: June 2009

Due to a lack of surface residue and organic matter inputs, continuous corn (Zea mays L.) silage production is one of the most demanding cropping systems imposed on our soil resources. In this study, our objective was to determine if using cover/companion crops and/or applying low‐solids liquid dairy manure could improve physical, chemical, and biological soil properties and overall soil quality. Corn was grown for 4 yr on a Bertrand silt loam in rotation with a living mulch of kura clover (KC, Trifolium ambiguum L.) or June‐interseeded red clover (Trifolium pratese L.), and continuously with June‐interseeded Italian ryegrass (IR, Lolium multiflorum L.), September‐seeded winter rye (Secale cereale L.), or no cover crop. Extractable P and K, pH, soil organic matter (SOM), active C, water‐stable aggregates, bulk density, penetrometer resistance, and microbial biomass/diversity were measured, and the Soil Management Assessment Framework (SMAF) soil quality index (SQI) was determined. Cover/companion crop treatments generally had more large macroaggregates, greater aggregate mean‐weight diameter, and larger quantities of total microbial biomass and most lipid/microbial groups than no‐cover treatments. Manure and starter fertilizer additions resulted in significant cover/companion crop treatment effects on extractable P and K. Liquid dairy manure alone did not improve any soil quality indicators. Although soil quality benefits of cover crops and manure are typically attributed to additions of organic C, we found no significant treatment effects on SOM content. However, the active, or labile, C fraction, was significantly increased by cover crops and showed good relationships with aggregate stability and microbial biomass. Overall, use of cover/companion crops appears beneficial for corn silage systems, but it may take more than 4 yr for some soil quality indicators to fully respond.
Dietary Forage Impacts on Dairy Slurry Nitrogen Availability to Corn
Authors: Powell J. M. , Grabber J. H.
Published: June 2009

Precise feeding of protein and mineral supplement can maintain high levels of milk production and reduce nutrient excretion in dairy manure and losses to the environment. No information is available on the impacts of feeding different silages to dairy cattle (Bos taurus) on manure N cycling in soils. Slurry from dairy cattle fed rations containing alfalfa (Medicago sativa L.; ALF), red clover (Trifolium pratense L.; RCL), low‐tannin birdsfoot trefoil (Lotus corniculatus L.; LTBT), or high‐tannin birdsfoot trefoil (HTBT) silages were applied to field plots during spring or spring + fall. After spring application, slurry type did not significantly impact soil pH, and only periodically impacted soil NH4–N and NO3–N. Corn (Zea mays L.) N uptake after spring application of ALF slurry was greater than after LBFT slurry application and control plots. Residual ALF slurry plots had 35% greater yield and 49% greater N uptake than control plots, followed by other slurries, which had from 17 to 22% greater yield and 29 to 36% greater N uptake than control plots. Corn yield and N uptake were not impacted by slurry types applied the previous fall. Average residual N recovery by corn in spring slurry‐amended plots ranged from 20% (ALF) to 13% (RCL and LTBT). Total‐N recovery was highest in ALF plots followed by HTBT and RCL. Low impact of applied slurry types was likely due to several interactive factors, including low rainfall, high indigenous soil N availability, and high response variability associated with indirect estimates of slurry N recovery.
Mesophilic and Thermophilic Anaerobic Digestion of Municipal Sludge and Fat, Oil, and Grease
Authors: Kabouris John C. , Tezel Ulas , Pavlostathis Spyros G. , Engelmann Michael , Dulaney James A. , Todd Allen C. , Gillette Robert A.
Published: June 2009

The anaerobic biodegradability of municipal primary sludge, thickened waste activated sludge (TWAS), and fat, oil, and grease (FOG) was assessed using semi‐continuous‐feed, laboratory‐scale anaerobic digesters and compared with the ultimate degradability obtained from 120‐day batch digestion at 35°C. In run 1, combined primary sludge and TWAS (40/60%, volatile solids [VS] basis) were fed to digesters operated at mesophilic (35°C) and thermophilic (52°C) temperatures at loading rates of 0.99 and 1.46 g‐VS/L · d for primary sludge and TWAS, respectively, and a hydraulic retention time (HRT) of 12 days. The volatile solids destruction values were 25.3 and 30.7% (69 and 83% biodegradable volatile solids destruction) at 35°C and 52°C, respectively. The methane (CH 4) yields were 159 and 197 mL at the standard temperature and pressure (STP) conditions of 0°C and 1 atm/g‐VS added or 632 and 642 mL @ STP/g‐VS destroyed at 35°C and 52°C, respectively. In run 2, a mix of primary sludge, TWAS, and FOG (21/31/48%, volatile solids basis) was fed to an acid digester operated at a 1‐day HRT, at 35°C, and a loading rate of 52.5 g‐VS/L · d. The acid‐reactor effluent was fed to two parallel methane‐phase reactors operated at an HRT of 12 days and maintained at 35°C and 52°C, respectively. After an initial period of 20 days with near‐zero gas production in the acid reactor, biogas production increased and stabilized to approximately 2 mL CH 4 @ STP/g‐VS added, corresponding to a volatile solids destruction of 0.4%. The acid‐phase reactor achieved a 43% decrease in nonsaturated fat and a 16, 26, and 20% increase of soluble COD, volatile fatty acids, and ammonia, respectively. The methane‐phase volatile solids destruction values in run 2 were 45 and 51% (85 and 97% biodegradable volatile solids destruction) at 35°C and 52°C, respectively. The methane yields for the methane‐phase reactors were 473 and 551 mL @ STP/g‐VS added, which is approximately 3 times larger compared with run 1, or 1040 and 1083 mL @ STP/g‐VS destroyed, at 35°C and 52°C, respectively. The results indicate that, when co‐digesting municipal sludge and FOG, a large FOG organic load fraction could have a profound effect on the methane gas yield.
Relationships between Computer and Video Game Play and Creativity among Upper Elementary School Students
Authors: Hamlen Karla R.
Published: June 2009

This study explored relationships between time spent playing video games in a typical week and general creativity, as measured by a common assessment. One hundred eighteen students in 4th and 5th grades answered questions about their video game play and completed the Torrance Tests of Creative Thinking (Torrance, Orlow, & Safter, 1990). While significant relationships were found between creativity and two variables (gender and grade), no significant relationship was found between time spent playing video games in a typical week and creativity, when controlling for gender and grade. Additional analyses examined relationships of creativity with skills used in video games and context in which the games were typically played and these also did not reveal significant relationships. This study provides initial evidence that video game play may not, in fact, influence children's general creativity levels.
The Effects of Electronic Books on Pre-Kindergarten-to-Grade 5 Students' Literacy and Language Outcomes: A Research Synthesis
Authors: Zucker Tricia A. , Moody Amelia K. , McKenna Michael C.
Published: June 2009

Electronic books (e-books) are a prevalent method for integrating technology in preschool and elementary classrooms; however, there is a lack of consensus concerning the extent to which e-books increase literacy skills in the domains of comprehension and decoding. This article assesses the efficacy of e-books with a comprehensive review method, including a systematic literature search, comparison of outcomes with effect sizes, and discussion of individual studies that met either (a) randomized-trial synthesis criteria, or (b) quasi-experimental/observational narrative synthesis criteria. Seven studies met the randomized-trial criteria and 20 studies met the quasi-experimental/observational narrative review criteria. Results from the randomized trials indicate that the effects of e-books on comprehension-related outcomes were small to medium in size. Only two randomized trials examined decoding-related outcomes, thereby preventing firm conclusions. The narrative review suggests some interactive e-book features support comprehension, whereas other incongruent features may hinder comprehension. Educational implications and future research directions are discussed.
The Impact of Subjective Norm and Facilitating Conditions on Pre-Service Teachers' Attitude toward Computer Use: A Structural Equation Modeling of an Extended Technology Acceptance Model
Authors: Teo Timothy
Published: June 2009

This study examined pre-service teachers' self-report on their attitude toward computer use. Participants were 285 pre-service teachers at a teacher training institution in Singapore. They completed a survey questionnaire measuring their responses to five constructs which formed a research model using the Technology Acceptance Model (TAM) as a framework. Structural Equation Modeling (SEM) was used as the main technique for data analysis. Results showed that attitude toward computer use was significantly explained by perceived usefulness and perceived ease of use, and two external variables, subjective norm and facilitating conditions. Overall, perceived usefulness, perceived ease of use, subjective norm, and facilitating conditions model accounts for 67.1% of the variance in the attitude toward computer use among pre-service teachers. The results of this study suggest that the TAM is a valid and efficient model in explaining attitude toward computer use among educational users.
Students' Problem Solving as Mediated by Their Cognitive Tool Use: A Study of Tool Use Patterns
Authors: Liu M. , Horton L. R. , Corliss S. B. , Svinicki M. D. , Bogard T. , Kim J. , Chang M.
Published: June 2009

The purpose of this study was to use multiple data sources, both objective and subjective, to capture students' thinking processes as they were engaged in problem solving, examine the cognitive tool use patterns, and understand what tools were used and why they were used. The findings of this study confirmed previous research and provided clear empirical evidence supporting the theoretical notion that technology-based cognitive tools play an important role in assisting students' problem solving. Students' tool use patterns were discussed in the context of their problem solving.
Cross Modality Correlations in the Imagery of Adults and 5-Year-Old Children
Authors: Mannering Anne M. , Taylor Marjorie
Published: June 2009

This research examined visual and auditory imagery in adults and 5-year-old children. We focused on 3 broad issues: 1) parallels between visual and auditory imagery; 2) static and dynamic imagery processes within the visual and auditory modalities; and 3) individual differences in these imagery processes. In Experiments 1 and 2, adults completed a set of four tasks of visual and auditory imagery and self-report measures of imagery. In Experiment 3, the set of imagery tasks was presented to 83 5-year-old children. Although children were less consistent in their imagery use than adults, there were interesting parallels between the children's and adults' performance. Across the 3 experiments, we found little or no relationship between static and dynamic imagery processes within the visual and auditory modalities. In contrast, significant correlations were observed across modality for dynamic imagery. These findings highlight the importance of examining cross-modality parallels in the development of imagery processes.
Emotional Intelligence and Emotional Responses to Hypothetical and Actual Frustrating Stressors
Authors: Yoo Seung Hee , Salovey Peter
Published: June 2009

The relationship between emotional intelligence (EI)measured as an ability and an individual's initial emotional responses to hypothetical and actual frustrating stressors was examined in 2 studies. In Study 1, participants imagined they had to repeat an experiment due to an error by the experimenter. In Study 2, participants experienced the situation described in Study 1. In both studies, higher scores on the MSCEIT, an ability-based measure of EI, were associated with greater self-reported frustration. The present studies provide the first step in understanding how individuals high in EI react to frustrating stressors.
The Effect of Shape and Color Symmetry on the Aesthetic Value of Dayak Masks from Borneo
Authors: Swami Viren
Published: June 2009

In both human and non-human species, as well as in artistic designs, symmetry has been found to enhance judgments of attractiveness. To explore the effects of symmetry on tribal designs, this study designed a set of stimuli using Dayak masks from Borneo, in which shape and color symmetry were manipulated. When British women and men rated the images, there was a significantly greater preference for symmetrically-shaped over asymmetrically-shaped masks, but not for symmetrically-colored masks. However, in a 2-alternative forced-choice experiment, the symmetric mask was significantly preferred for both shape and color manipulations. The results suggest a role for symmetry in the perception of tribal art.
Market Competition and Lower Tier Incentives
Authors: Theilen Bernd
Published: June 2009

The relationship between competition and performancerelated pay has been analyzed in singleprincipalsingleagent models. While this approach yields good predictions for managerial pay schemes, the predictions fail to apply for employees at lower tiers of a firm's hierarchy. This paper describes a principal multi-agent model of incentive pay that analyzes the effect of changes in the competitiveness of markets on lower tier incentive payment schemes. The results explain why the payment schemes of agents located at low and mid tiers are less sensitive to changes in competition when aggregated firm data is used.
Involvement of Per-Arnt-Sim Kinase and Extracellular-Regulated Kinases-1/2 in Palmitate Inhibition of Insulin Gene Expression in Pancreatic β-Cells
Authors: Fontés Ghislaine , Semache Meriem , Hagman Derek K. , Tremblay Caroline , Shah Ramila , Rhodes Christopher J. , Rutter Jared , Poitout Vincent
Published: June 2009

OBJECTIVE

Prolonged exposure of pancreatic β-cells to simultaneously elevated levels of fatty acids and glucose (glucolipotoxicity) impairs insulin gene transcription. However, the intracellular signaling pathways mediating these effects are mostly unknown. This study aimed to ascertain the role of extracellular-regulated kinases (ERKs)1/2, protein kinase B (PKB), and Per-Arnt-Sim kinase (PASK) in palmitate inhibition of insulin gene expression in pancreatic β-cells.

RESEARCH DESIGN AND METHODS

MIN6 cells and isolated rat islets were cultured in the presence of elevated glucose, with or without palmitate or ceramide. ERK1/2 phosphorylation, PKB phosphorylation, and PASK expression were examined by immunoblotting and real-time PCR. The role of these kinases in insulin gene expression was assessed using pharmacological and molecular approaches.

RESULTS

Exposure of MIN6 cells and islets to elevated glucose induced ERK1/2 and PKB phosphorylation, which was further enhanced by palmitate. Inhibition of ERK1/2, but not of PKB, partially prevented the inhibition of insulin gene expression in the presence of palmitate or ceramide. Glucose-induced expression of PASK mRNA and protein levels was reduced in the presence of palmitate. Overexpression of wild-type PASK increased insulin and pancreatic duodenal homeobox-1 gene expression in MIN6 cells and rat islets incubated with glucose and palmitate, whereas overexpression of a kinase-dead PASK mutant in rat islets decreased expression of insulin and pancreatic duodenal homeobox-1 and increased C/EBPβ expression.

CONCLUSIONS

Both the PASK and ERK1/2 signaling pathways mediate palmitate inhibition of insulin gene expression. These findings identify PASK as a novel mediator of glucolipotoxicity on the insulin gene in pancreatic β-cells.
Islet-1 is Required for the Maturation, Proliferation, and Survival of the Endocrine Pancreas
Authors: Du Aiping , Hunter Chad S. , Murray Johanna , Noble Daniel , Cai Chen-Leng , Evans Sylvia M. , Stein Roland , May Catherine Lee
Published: June 2009

OBJECTIVE

The generation of mature cell types during pancreatic development depends on the expression of many regulatory and signaling proteins. In this study, we tested the hypothesis that the transcriptional regulator Islet-1 (Isl-1), whose expression is first detected in the mesenchyme and epithelium of the developing pancreas and is later restricted to mature islet cells, is involved in the terminal differentiation of islet cells and maintenance of islet mass.

RESEARCH DESIGN AND METHODS

To investigate the role of Isl-1 in the pancreatic epithelium during the secondary transition, Isl-1 was conditionally and specifically deleted from embryonic day 13.5 onward using Cre/LoxP technology.

RESULTS

Isl-1–deficient endocrine precursors failed to mature into functional islet cells. The postnatal expansion of endocrine cell mass was impaired, and consequently Isl-1 deficient mice were diabetic. In addition, MafA, a potent regulator of the Insulin gene and β-cell function, was identified as a direct transcriptional target of Isl-1.

CONCLUSIONS

These results demonstrate the requirement for Isl-1 in the maturation, proliferation, and survival of the second wave of hormone-producing islet cells.
Activation of AMP-Activated Protein Kinase by Interleukin-6 in Rat Skeletal Muscle
Authors: Kelly Meghan , Gauthier Marie-Soleil , Saha Asish K. , Ruderman Neil B.
Published: June 2009

OBJECTIVE

Interleukin-6 (IL-6) directly activates AMP-activated protein kinase (AMPK) in vivo and in vitro; however, the mechanism by which it does so is unknown.

RESEARCH DESIGN AND METHODS

We examined this question in skeletal muscle using an incubated rat extensor digitorum longus (EDL) muscle preparation as a tool.

RESULTS

AMPK activation by IL-6 coincided temporally with a nearly threefold increase in the AMP:ATP ratio in the EDL. The effects of IL-6 on both AMPK activity and energy state were inhibited by coincubation with propranolol, suggesting involvement of β-adrenergic signaling. In keeping with this notion, IL-6 concurrently induced a transient increase in cAMP, and its ability to activate AMPK was blocked by the adenyl cyclase inhibitor 2′5′-dideoxyadenosine. In addition, like other β-adrenergic stimuli, IL-6 increased glycogen breakdown and lipolysis in the EDL. Similar effects of IL-6 on AMPK, energy state, and cAMP content were observed in C2C12 myotubes and gastrocnemius muscle in vivo, indicating that they were not unique to the incubated EDL.

CONCLUSIONS

These studies demonstrate that IL-6 activates AMPK in skeletal muscle by increasing the concentration of cAMP and, secondarily, the AMP:ATP ratio. They also suggest that substantial increases in IL-6 concentrations, such as those that can result from its synthesis by muscles during exercise, may play a role in the mobilization of fuel stores within skeletal muscle as an added means of restoring energy balance.
Adipose Tissue Expression and Genetic Variants of the Bone Morphogenetic Protein Receptor 1A Gene (BMPR1A) Are Associated With Human Obesity
Authors: Böttcher Yvonne , Unbehauen Hanne , Klöting Nora , Ruschke Karen , Körner Antje , Schleinitz Dorit , Tönjes Anke , Enigk Beate , Wolf Sara , Dietrich Kerstin , Koriath Moritz , Scholz Gerhard Harry , Tseng Yu-Hua , Dietrich Arne , Schön Michael R. , Kiess Wieland , Stumvoll Michael , Blüher Matthias , Kovacs Peter
Published: June 2009

OBJECTIVE

Members of the family of bone morphogenetic proteins (BMPs) are important regulators of adipogenesis. We examined the role of the BMP receptor 1A gene (BMPR1A) in the pathophysiology of human obesity.

RESEARCH DESIGN AND METHODS

We measured BMPR1A mRNA expression in paired samples of visceral and subcutaneous adipose tissue from 297 subjects and sequenced the BMPR1A in 48 nonrelated white subjects. Twenty-one representative variants including HapMap tagging single nucleotide polymorphisms (SNPs) were then genotyped for association studies in German whites (n = 1,907). For replication analyses, we used a population of Sorbs from Germany (n = 900) and German childhood cohorts (n = 1,029 schoolchildren and 270 obese children).

RESULTS

mRNA expression of the BMPR1A was significantly increased in both visceral and subcutaneous adipose tissue of overweight and obese subjects compared with lean subjects (P < 0.05). In a case-control study, four SNPs (rs7095025, rs11202222, rs10788528, and rs7922846) were nominally associated with obesity (adjusted P < 0.05). For three SNPs (rs7095025, rs11202222, and rs10788528), the association with obesity was confirmed in the independent cohort of Sorbs (adjusted P < 0.005). Consistent with this, BMPR1A SNPs were nominally associated with obesity-related quantitative traits in nondiabetic subjects in both adult cohorts. Furthermore, homozygous carriers of the obesity risk alleles had higher BMPR1A mRNA expression in fat than noncarriers.

CONCLUSIONS

Our data suggest that genetic variation in the BMPR1A may play a role in the pathophysiology of human obesity, possibly mediated through effects on mRNA expression.
Insulin and Metformin Regulate Circulating and Adipose Tissue Chemerin
Authors: Tan Bee K. , Chen Jing , Farhatullah Syed , Adya Raghu , Kaur Jaspreet , Heutling Dennis , Lewandowski Krzysztof C. , O'Hare J. Paul , Lehnert Hendrik , Randeva Harpal S.
Published: June 2009

OBJECTIVE

To assess chemerin levels and regulation in sera and adipose tissue from women with polycystic ovary syndrome (PCOS) and matched control subjects.

RESEARCH DESIGN AND METHODS

Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of chemerin. Serum chemerin was measured by enzyme-linked immunosorbent assay. We investigated the in vivo effects of insulin on serum chemerin levels via a prolonged insulin-glucose infusion. Ex vivo effects of insulin, metformin, and steroid hormones on adipose tissue chemerin protein production and secretion into conditioned media were assessed by Western blotting and enzyme-linked immunosorbent assay, respectively.

RESULTS

Serum chemerin, subcutaneous, and omental adipose tissue chemerin were significantly higher in women with PCOS (n = 14; P < 0.05, P < 0.01). Hyperinsulinemic induction in human subjects significantly increased serum chemerin levels (n = 6; P < 0.05, P < 0.01). In adipose tissue explants, insulin significantly increased (n = 6; P < 0.05, P < 0.01) whereas metformin significantly decreased (n = 6; P < 0.05, P < 0.01) chemerin protein production and secretion into conditioned media, respectively. After 6 months of metformin treatment, there was a significant decrease in serum chemerin (n = 21; P < 0.01). Importantly, changes in homeostasis model assessment–insulin resistance were predictive of changes in serum chemerin (P = 0.046).

CONCLUSIONS

Serum and adipose tissue chemerin levels are increased in women with PCOS and are upregulated by insulin. Metformin treatment decreases serum chemerin in these women.
Resistin-Like Molecule-β Inhibits SGLT-1 Activity and Enhances GLUT2-Dependent Jejunal Glucose Transport
Authors: Krimi Rim Belharbi , Letteron Philippe , Chedid Pia , Nazaret Corinne , Ducroc Robert , Marie Jean-Claude
Published: June 2009

OBJECTIVE

An increased expression of RELM-β (resistin-like molecule-β), a gut-derived hormone, is observed in animal models of insulin resistance/obesity and intestinal inflammation. Intestinal sugar absorption is modulated by dietary environment and hormones/cytokines. The aim of this study was to investigate the effect of RELM-β on intestinal glucose absorption.

RESEARCH DESIGN AND METHODS

Oral glucose tolerance test was performed in mice and rats in the presence and the absence of RELM-β. The RELM-β action on glucose transport in rat jejunal sacs, everted rings, and mucosal strips was explored as well as downstream kinases modulating SGLT-1 and GLUT2 glucose transporters.

RESULTS

Oral glucose tolerance test carried out in rodents showed that oral administration of RELM-β increased glycemia. Studies in rat jejunal tissue indicated that mucosal RELM-β promoted absorption of glucose from the gut lumen. RELM-β had no effect on paracellular mannitol transport, suggesting a transporter-mediated transcellular mechanism. In studies with jejunal mucosa mounted in Ussing chamber, luminal RELM-β inhibited SGLT-1 activity in line with a diminished SGLT-1 abundance in brush border membranes (BBMs). Further, the potentiating effect of RELM-β on jejunal glucose uptake was associated with an increased abundance of GLUT2 at BBMs. The effects of RELM-β were associated with an increased amount of protein kinase C βII in BBMs and an increased phosphorylation of AMP-activated protein kinase (AMPK).

CONCLUSIONS

The regulation of SGLT-1 and GLUT2 by RELM-β expands the role of gut hormones in short-term AMPK/protein kinase C mediated control of energy balance.
Association of 18 Confirmed Susceptibility Loci for Type 2 Diabetes With Indices of Insulin Release, Proinsulin Conversion, and Insulin Sensitivity in 5,327 Nondiabetic Finnish Men
Authors: Stančáková Alena , Kuulasmaa Teemu , Paananen Jussi , Jackson Anne U. , Bonnycastle Lori L. , Collins Francis S. , Boehnke Michael , Kuusisto Johanna , Laakso Markku
Published: June 2009

OBJECTIVE

We investigated the effects of 18 confirmed type 2 diabetes risk single nucleotide polymorphisms (SNPs) on insulin sensitivity, insulin secretion, and conversion of proinsulin to insulin.

RESEARCH DESIGN AND METHODS

A total of 5,327 nondiabetic men (age 58 ± 7 years, BMI 27.0 ± 3.8 kg/m2) from a large population-based cohort were included. Oral glucose tolerance tests and genotyping of SNPs in or near PPARG, KCNJ11, TCF7L2, SLC30A8, HHEX, LOC387761, CDKN2B, IGF2BP2, CDKAL1, HNF1B, WFS1, JAZF1, CDC123, TSPAN8, THADA, ADAMTS9, NOTCH2, KCNQ1, and MTNR1B were performed. HNF1B rs757210 was excluded because of failure to achieve Hardy-Weinberg equilibrium.

RESULTS

Six SNPs (TCF7L2, SLC30A8, HHEX, CDKN2B, CDKAL1, and MTNR1B) were significantly (P < 6.9 × 10−4) and two SNPs (KCNJ11 and IGF2BP2) were nominally (P < 0.05) associated with early-phase insulin release (InsAUC0–30/GluAUC0–30), adjusted for age, BMI, and insulin sensitivity (Matsuda ISI). Combined effects of these eight SNPs reached −32% reduction in InsAUC0–30/GluAUC0–30 in carriers of ≥11 vs. ≤3 weighted risk alleles. Four SNPs (SLC30A8, HHEX, CDKAL1, and TCF7L2) were significantly or nominally associated with indexes of proinsulin conversion. Three SNPs (KCNJ11, HHEX, and TSPAN8) were nominally associated with Matsuda ISI (adjusted for age and BMI). The effect of HHEX on Matsuda ISI became significant after additional adjustment for InsAUC0–30/GluAUC0–30. Nine SNPs did not show any associations with examined traits.

CONCLUSIONS

Eight type 2 diabetes–related loci were significantly or nominally associated with impaired early-phase insulin release. Effects of SLC30A8, HHEX, CDKAL1, and TCF7L2 on insulin release could be partially explained by impaired proinsulin conversion. HHEX might influence both insulin release and insulin sensitivity.
Human Brain Glycogen Metabolism During and After Hypoglycemia
Authors: Öz Gülin , Kumar Anjali , Rao Jyothi P. , Kodl Christopher T. , Chow Lisa , Eberly Lynn E. , Seaquist Elizabeth R.
Published: June 2009

OBJECTIVE

We tested the hypotheses that human brain glycogen is mobilized during hypoglycemia and its content increases above normal levels (“supercompensates”) after hypoglycemia.

RESEARCH DESIGN AND METHODS

We utilized in vivo 13C nuclear magnetic resonance spectroscopy in conjunction with intravenous infusions of [13C]glucose in healthy volunteers to measure brain glycogen metabolism during and after euglycemic and hypoglycemic clamps.

RESULTS

After an overnight intravenous infusion of 99% enriched [1-13C]glucose to prelabel glycogen, the rate of label wash-out from [1-13C]glycogen was higher (0.12 ± 0.05 vs. 0.03 ± 0.06 μmol · g−1 · h−1, means ± SD, P < 0.02, n = 5) during a 2-h hyperinsulinemic-hypoglycemic clamp (glucose concentration 57.2 ± 9.7 mg/dl) than during a hyperinsulinemic-euglycemic clamp (95.3 ± 3.3 mg/dl), indicating mobilization of glucose units from glycogen during moderate hypoglycemia. Five additional healthy volunteers received intravenous 25–50% enriched [1-13C]glucose over 22–54 h after undergoing hyperinsulinemic-euglycemic (glucose concentration 92.4 ± 2.3 mg/dl) and hyperinsulinemic-hypoglycemic (52.9 ± 4.8 mg/dl) clamps separated by at least 1 month. Levels of newly synthesized glycogen measured from 4 to 80 h were higher after hypoglycemia than after euglycemia (P ≤ 0.01 for each subject), indicating increased brain glycogen synthesis after moderate hypoglycemia.

CONCLUSIONS

These data indicate that brain glycogen supports energy metabolism when glucose supply from the blood is inadequate and that its levels rebound to levels higher than normal after a single episode of moderate hypoglycemia in humans.
Relationships Between Circulating Metabolic Intermediates and Insulin Action in Overweight to Obese, Inactive Men and Women
Authors: Huffman Kim M. , Shah Svati H. , Stevens Robert D. , Bain James R. , Muehlbauer Michael , Slentz Cris A. , Tanner Charles J. , Kuchibhatla Maragatha , Houmard Joseph A. , Newgard Christopher B. , Kraus William E.
Published: June 2009

OBJECTIVE

To determine whether circulating metabolic intermediates are related to insulin resistance and β-cell dysfunction in individuals at risk for type 2 diabetes.

RESEARCH DESIGN AND METHODS

In 73 sedentary, overweight to obese, dyslipidemic individuals, insulin action was derived from a frequently sampled intravenous glucose tolerance test. Plasma concentrations of 75 amino acids, acylcarnitines, free fatty acids, and conventional metabolites were measured with a targeted, mass spectrometry–based platform. Principal components analysis followed by backward stepwise linear regression was used to explore relationships between measures of insulin action and metabolic intermediates.

RESULTS

The 75 metabolic intermediates clustered into 19 factors comprising biologically related intermediates. A factor containing large neutral amino acids was inversely related to insulin sensitivity (SI) (R2 = 0.26). A factor containing fatty acids was inversely related to the acute insulin response to glucose (R2 = 0.12). Both of these factors, age, and a factor containing medium-chain acylcarnitines and glucose were inversely and independently related to the disposition index (DI) (R2 = 0.39). Sex differences were found for metabolic predictors of SI and DI.

CONCLUSIONS

In addition to the well-recognized risks for insulin resistance, elevated concentrations of large, neutral amino acids were independently associated with insulin resistance. Fatty acids were inversely related to the pancreatic response to glucose. Both large neutral amino acids and fatty acids were related to an appropriate pancreatic response, suggesting that these metabolic intermediates might play a role in the progression to type 2 diabetes, one by contributing to insulin resistance and the other to pancreatic failure. These intermediates might exert sex-specific effects on insulin action.
Postprandial Glucose Improves the Risk Prediction of Cardiovascular Death Beyond the Metabolic Syndrome in the Nondiabetic Population
Authors: Lin Hung-Ju , Lee Bai-Chin , Ho Yi-Lwun , Lin Yen-Hung , Chen Ching-Yi , Hsu Hsiu-Ching , Lin Mao-Shin , Chien Kuo-Liong , Chen Ming-Fong
Published: June 2009

OBJECTIVE

With increasing evidence about the cardiovascular risk associated with postprandial nonfasting glucose and lipid dysmetabolism, it remains uncertain whether the postprandial glucose concentration increases the ability of metabolic syndrome to predict cardiovascular events.

RESEARCH DESIGN AND METHODS

This was an observational study of 15,145 individuals aged 35–75 years without diabetes or cardiovascular diseases. Postprandial glucose was obtained 2 h after a lunch meal. Metabolic syndrome was diagnosed using the criteria of the U.S. National Cholesterol Education Program Adult Treatment Panel III. Cardiovascular and all-cause deaths were primary outcomes.

RESULTS

During a median follow-up of 6.7 years, 410 individuals died, including 82 deaths from cardiovascular causes. In a Cox model adjusting for metabolic syndrome status as well as age, sex, smoking, systolic blood pressure, LDL, and HDL cholesterol levels, elevated 2-h postprandial glucose increased the risk of cardiovascular and all-cause death (per millimole per liter increase, hazard ratio 1.26 [95% CI 1.11–1.42] and 1.10 [1.04–1.16], respectively), with significant trends across the postprandial glucose quintiles. Including 2-h postprandial glucose into a metabolic syndrome–included multivariate risk prediction model conferred a discernible improvement of the model in discriminating between those who died of cardiovascular causes and who did not (integrated discrimination improvement 0.4, P = 0.005; net reclassification improvement 13.4%, P = 0.03); however, the improvement was only marginal for all-cause death.

CONCLUSIONS

Given the risk prediction based on metabolic syndrome and established cardiovascular risk factors, 2-h postprandial glucose improves the predictive ability to identity nondiabetic individuals at increased risk of cardiovascular death.
A1C Underestimates Glycemia in HIV Infection
Authors: Kim Peter S. , Woods Christian , Georgoff Patrick , Crum Dana , Rosenberg Alice , Smith Margo , Hadigan Colleen
Published: June 2009

OBJECTIVE

The objective of this study was to determine the relationship between A1C and glycemia in HIV infection.

RESEARCH DESIGN AND METHODS

We completed a prospective cross-sectional study of 100 HIV-infected adults with type 2 diabetes (77%) or fasting hyperglycemia (23%) with measured glucose, A1C, mean corpuscular volume (MCV), and fructosamine. A total of 200 HIV-uninfected type 2 diabetic subjects matched for key demographic characteristics served as control subjects.

RESULTS

Relative to the control subjects, A1C underestimated glucose by 29 ± 4 mg/dl in the HIV-infected subjects. Current nucleoside reverse transcriptase inhibitors (NRTIs), higher MCV and hemoglobin, and lower HIV RNA and haptoglobin were associated with greater A1C-glucose discordance. However, only MCV and current NTRI use, in particular abacavir, remained significant predictors in multivariate analyses. Fructosamine more closely reflected glycemia in the HIV-infected subjects.

CONCLUSIONS

A1C underestimates glycemia in HIV-infected patients and is related to NRTI use. Use of abacavir and increased MCV were key correlates in multivariate analyses. Fructosamine may be more appropriate in this setting.
Metformin for Obesity in Children and Adolescents: A Systematic Review
Authors: Park Min Hae , Kinra Sanjay , Ward Kirsten J. , White Billy , Viner Russell M.
Published: June 2009

OBJECTIVE

To summarize the efficacy of metformin in reducing BMI and cardiometabolic risk in obese children and adolescents without diabetes.

RESEARCH DESIGN AND METHODS

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs). Double-blind RCTs of ≥6 months duration in obese subjects age ≤19 years without diabetes were included. Our primary outcomes of interest include changes in BMI and measures of insulin sensitivity.

RESULTS

Five trials met inclusion criteria (n = 320 individuals). Compared with placebo, metformin reduced BMI by 1.42 kg/m2 (95% CI 0.83–2.02) and homeostasis model assessment insulin of resistance (HOMA-IR) score by 2.01 (95% CI 0.75–3.26).

CONCLUSIONS

Metformin appears to be moderately efficacious in reducing BMI and insulin resistance in hyperinsulinemic obese children and adolescents in the short term. Larger, longer-term studies in different populations are needed to establish its role in the treatment of overweight children.