bluuebunny/crossref_metadata_2025 huggingface dataset:
Significant Improvement in the Accuracy of Pressure Transient Analysis Using Total Least Squares
Authors: Dastan Aysegul , Horne Roland N.
Published: October 2009

In this study we show significant improvements over conventional pressure transient analysis based on nonlinear regression, by using total least squares (TLS). The TLS algorithm we have developed estimates reservoir parameters by minimizing errors in both pressure and time simultaneously. Our technique is in contrast to other approaches that also have been named TLS but which considered errors in flow rates and pressures simultaneously, rather than errors in time.

TLS regression, which is based on minimization of orthogonal distances of measured data points to the fitted curve, is not an easy problem to solve mathematically, especially for nonlinear pressure transient model functions. To our knowledge, TLS has not been applied to pressure transient analysis before in this sense. In our work, we formulated a robust approximation of the TLS solution, which can handle a variety of tests and reservoir models yet does not compromise the performance of the analysis. We used our TLS algorithm on various different reservoirs and transient tests successfully, including dual-porosity and fractured reservoirs, reservoirs with rectangular boundaries, cyclic buildup-drawdown tests, and general multirate data. We show that our technique reduces ambiguity in the estimation of parameters to a large extent, especially in the presence of noise. Using our TLS algorithm we obtained much narrower confidence intervals on the parameter estimates compared to the regular least squares approach used conventionally today.

In this paper we compare four different versions of total least squares: (1) errors in time and pressure (horizontal error and vertical error) summed in the same objective function; (2) orthogonal distance regression in linear p vs. linear t, (3) orthogonal distance regression in linear p vs. log t, (4) orthogonal distance regression in log p vs. log t. We have observed much greater robustness against noise in the estimation of reservoir parameters. In the presence of errors in pressure only, the confidence intervals were at least as good as regular least squares. However, in the presence of errors in time in addition to pressure, the performance of TLS algorithms was substantially better. On a variety of both real and synthetic data sets, we have observed much narrower confidence intervals on the estimated parameters, even for large noise. For synthetic data sets, we observed that the reservoir parameter estimates from TLS are often closer to the true values than estimates made with conventional least squares, especially for poorly determined problems. We therefore expect that our technique will provide more accurate estimation of reservoir parameters, allowing for better forecasting of reservoir performance.
Geomechanical Risk Mitigation for CO2 Sequestration in Saline Aquifers
Authors: Tran David , Shrivastava Vijay , Nghiem Long , Kohse Bruce
Published: October 2009

Saline aquifers are the most promising target for underground CO2 sequestration since they have the largest capacity compared to other possible locations, for example coal seams or depleted gas and oil fields. One of the major risks associated with sequestration in aquifers is the potential leakage of CO2 through cap rock and overburden leading to escape of CO2 into shallow potable aquifers or to the atmosphere. Factors responsible for rock failure need to be investigated before starting a CO2 injection program to avoid potential leakage problems.

This paper presents a novel approach for assessing and mitigating the risk of CO2 leakage caused by geomechanical effects. An equation-of-state compositional and GHG (Green-House Gas) simulator has been modified to incorporate iterative coupling with an in-house geomechanical code (geomechanics module). The coupled model is used to predict possible leakage events during an injection process. The following steps are taken to solve the problem: The reservoir simulator computes the amount of CO2 dissolution and flow in the formation, geochemical reactions, and changes in pressure, temperature and compositions.Based on the values of pressure and temperature at the end of every time step, the geomechanics module computes stress change and deformation in the formation and its surroundings to determine if and where rock failure might occur.A Barton-Bandis model is used to simulate opening and closing of fractures in the cap or country rock due to development of stresses caused by high injection pressure.

Example cases are presented to demonstrate the workflow and to show how injection scenarios may be altered to mitigate the risk of leakage. Both isothermal and non-isothermal situations are examined.
Automatic Detection of Pressure-Buildup Intervals From Permanent Downhole Pressure Data Using Filter Convolution
Authors: Suzuki Satomi , Chorneyko David
Published: October 2009

The availability of permanent downhole pressure data has become a rich source of information for reservoir surveillance and production optimization. Permanent downhole gauges continuously provide near real-time data without well intervention. The data can lead to timely and proactive reservoir surveillance and management decisions if effectively utilized. However, challenges lie in processing and analyzing the overwhelming volume of data. The development of tools and software for automatic data processing will facilitate interpretation and application of the data from permanent downhole gauges.

Pressure transient analysis from permanent downhole pressure data is an example of such an application. By analyzing pressure buildup behavior observed during unintentional shut-ins of wells, engineers can frequently develop insight into reservoirs without conducting scheduled buildup tests. However, manual identification and selection of each pressure buildup interval for analysis is often a time-consuming and labor intensive job as the amount of pressure data can amount to millions of sets of information. This time and effort often precludes the acquired data from being utilized. The problem has already been realized in the industry and some software offers the capability to automatically detect buildup intervals from continuous pressure data. The issue is the robustness and tolerance of detection methods to noisy data.

This paper proposes a new method to automatically detect pressure buildup intervals from permanent downhole pressure data. The buildup intervals are detected by convolving a filter with permanent gauge data. The filter is designed to detect a particular pattern of pressure response rather than merely to detect a frequency change. Also, it can be easily combined with noise-removal filters. These features of the method enhance the tolerance to noise. The method is demonstrated through the application to real data. An example of field application is also presented.
Cultural Factors Related to Smoking in San Francisco's Irish Bars
Authors: Satterlund Travis D. , Antin Tamar M. J. , Lee Juliet P. , Moore Roland S.
Published: October 2009

California's Smoke-Free Workplace Act was extended to include bars in 1998. While the majority of bars in the state have become smoke free, in many bars patrons and staff continue to smoke despite the law. The authors present findings from a study which assessed cultural factors related to continued smoking in bars in the city of San Francisco. In bars serving primarily Irish migrants, tight-knit relations within the local Irish bar community together with a reluctance to be the first Irish bar to ban smoking were found to contribute to continued indoor smoking. The findings illustrate challenges to implementing tobacco control policies within ethnic subpopulations and particularly highlight the importance of considering how cultural dynamics within subpopulations may help or hinder such policies.
The Influence of Race and Ethnicity on Substance Use and Negative Activity Involvement among Monoracial and Multiracial Adolescents of the Southwest
Authors: Jackson Kelly F. , Lecroy Craig W.
Published: October 2009

This study examined predictors of substance use and negative activity involvement among a diverse sample of European American, African American, Hispanic, Native American, and multiracial early adolescents ( n = 749) living in a large urban city in the Southwest United States. This study investigated a broad set of predictor variables that tap sociodemographic, peer, family, community, and school influences. Overall, findings from this study confirm that lifetime substance use remains high among youth of color. Of particular concern is this study's finding that multiracial adolescents are at elevated risk to use substances and engage in negative activities. The implications of this study for understanding how risk factors are influenced by race and other variables on different measures of problem behavior are discussed.
Effectiveness of Skill-Based Substance Abuse Intervention among Male Adolescents in an Islamic Country: Case of the Islamic Republic of Iran
Authors: Allahverdipour Hamid , Bazargan Mohsen , Farhadinasab Abdollah , Hidarnia Alireza , Bashirian Saeed
Published: October 2009

The prevalence of substance abuse among adolescents from low- and middle-income countries is increasing drastically and requires immediate intervention. The objective of this longitudinal quasi-experimental panel study was to design and implement a skill-based intervention to prevent and reduce substance use among urban adolescents who attended 2 randomly selected high-schools in Tehran, Iran. One-year post intervention data show that substance abuse, knowledge, attitudes, peer resistance skills, level of self-control, self-efficacy, and perceived susceptibility among intervention group were significantly improved, whereas level of self control and attitudes against substance abuse among the control group deteriorated. To efficiently prevent substance abuse among youth primary preventive interventions should be implemented before onset of substance abuse to improve resistance skills and provide adolescents with information and skills needed to develop anti-drug norms.
Developing Critical Implementations of Technology-Rich Innovations: A Cross-Case Study of the Implementation of Quest Atlantis
Authors: Thomas Michael K. , Barab Sasha A. , Tuzun Hakan
Published: October 2009

This study examined the tensions surrounding the implementation of a technology-rich educational innovation called Quest Atlantis (QA) in a local public elementary school. Three qualitative case studies of three classrooms implementing the innovation and a subsequent cross-case analysis were undertaken to illuminate: 1) the reasons why teachers chose to implement the innovation in their classrooms; 2) the core challenges and tensions of implementing this innovation; 3) the supports necessary to successfully implement the innovation; and 4) the adaptation that the innovation underwent in the course of its implementation. The results of this study indicated that teachers implemented QA because of its alignment with their existing curricular goals, its flexible adaptivity, and its emphasis on social commitments. Findings also indicated that teachers persisted in using QA because the students enjoyed it and were enthusiastic for its continued use. Core challenges and tensions in the implementation included security concerns related to QA's use of web-based communication features, providing appropriate technical and social support for implementation, and balancing the innovation's intended use and its actual use.
Critical Thinking in a Collaborative Online PBL Tutorial
Authors: Schell Robyn , Kaufman David
Published: October 2009

The web has the potential to offer an environment that can support standardized medical education to students dispersed in time or place and, in the process, respond to reduced availability of patients for practice. This exploratory article describes how we evaluated critical thinking in an online collaborative Problem-based Learning (PBL) tutorial built on a platform integrating a well-known course management system and a voice-over the Internet communications tool. We discuss the process and results of evaluating the tutorials by adapting and applying an earlier framework used to measure the level of critical thinking taking place in collaborative online PBL tutorials. Our results indicate that this framework could be used as a method to compare levels of critical thinking between tutorial groups as well as tutorial variables such as case study formats and the types of technology used to support the sessions.
Predictive Validity of Measures of the Pathfinder Scaling Algorithm on Programming Performance: Alternative Assessment Strategy for Programming Education
Authors: Lau Wilfred W. F. , Yuen Allan H. K.
Published: October 2009

Recent years have seen a shift in focus from assessment of learning to assessment for learning and the emergence of alternative assessment methods. However, the reliability and validity of these methods as assessment tools are still questionable. In this article, we investigated the predictive validity of measures of the Pathfinder Scaling Algorithm (PSA), a concept mapping assessment utility, using the referent-free and referent-based approaches on programming performance of a group of secondary school students. Results suggest that the predictive validity of both approaches was more or less the same. Among the three similarity measures applied for the referent-based approach, PRX appeared to be the most predictive one whereas PFC and GTD were similar in terms of predictive power. The correlations between the referent-free measure C and the three previously mentioned referent-based measures with the programming performance measures were not as strong as reported in the literature. In the light of these results, we argue that there is a need to reform assessment in programming education.
Combined Risk Allele Score of Eight Type 2 Diabetes Genes Is Associated With Reduced First-Phase Glucose-Stimulated Insulin Secretion During Hyperglycemic Clamps
Authors: ‘t Hart Leen M. , Simonis-Bik Annemarie M. , Nijpels Giel , van Haeften Timon W. , Schäfer Silke A. , Houwing-Duistermaat Jeanine J. , Boomsma Dorret I. , Groenewoud Marlous J. , Reiling Erwin , van Hove Els C. , Diamant Michaela , Kramer Mark H.H. , Heine Robert J. , Maassen J. Antonie , Kirchhoff Kerstin , Machicao Fausto , Häring Hans-Ulrich , Slagboom P. Eline , Willemsen Gonneke , Eekhoff Elisabeth M. , de Geus Eco J. , Dekker Jacqueline M. , Fritsche Andreas
Published: October 2009

OBJECTIVE

At least 20 type 2 diabetes loci have now been identified, and several of these are associated with altered β-cell function. In this study, we have investigated the combined effects of eight known β-cell loci on insulin secretion stimulated by three different secretagogues during hyperglycemic clamps.

RESEARCH DESIGN AND METHODS

A total of 447 subjects originating from four independent studies in the Netherlands and Germany (256 with normal glucose tolerance [NGT]/191 with impaired glucose tolerance [IGT]) underwent a hyperglycemic clamp. A subset had an extended clamp with additional glucagon-like peptide (GLP)-1 and arginine (n = 224). We next genotyped single nucleotide polymorphisms in TCF7L2, KCNJ11, CDKAL1, IGF2BP2, HHEX/IDE, CDKN2A/B, SLC30A8, and MTNR1B and calculated a risk allele score by risk allele counting.

RESULTS

The risk allele score was associated with lower first-phase glucose-stimulated insulin secretion (GSIS) (P = 7.1 × 10−6). The effect size was equal in subjects with NGT and IGT. We also noted an inverse correlation with the disposition index (P = 1.6 × 10−3). When we stratified the study population according to the number of risk alleles into three groups, those with a medium- or high-risk allele score had 9 and 23% lower first-phase GSIS. Second-phase GSIS, insulin sensitivity index and GLP-1, or arginine-stimulated insulin release were not significantly different.

CONCLUSIONS

A combined risk allele score for eight known β-cell genes is associated with the rapid first-phase GSIS and the disposition index. The slower second-phase GSIS, GLP-1, and arginine-stimulated insulin secretion are not associated, suggesting that especially processes involved in rapid granule recruitment and exocytosis are affected in the majority of risk loci.
Attenuated Purinergic Receptor Function in Patients With Type 2 Diabetes
Authors: Thaning Pia , Bune Laurids T. , Hellsten Ylva , Pilegaard Henriette , Saltin Bengt , Rosenmeier Jaya B.
Published: October 2009

OBJECTIVE

Extracellular nucleotides and nucleosides are involved in regulation of skeletal muscle blood flow. Diabetes induces cardiovascular dysregulation, but the extent to which the vasodilatatory capacity of nucleotides and nucleosides is affected in type 2 diabetes is unknown. The present study investigated 1) the vasodilatatory effect of ATP, uridine-triphosphate (UTP), and adenosine (ADO) and 2) the expression and distribution of P2Y2 and P2X1 receptors in skeletal muscles of diabetic subjects.

RESEARCH DESIGN AND METHODS

In 10 diabetic patients and 10 age-matched control subjects, leg blood flow (LBF) was measured during intrafemoral artery infusion of ATP, UTP, and ADO, eliciting a blood flow equal to knee-extensor exercise at 12 W (∼2.6 l/min).

RESULTS

The vasodilatatory effect of the purinergic system was 50% lower in the diabetic group as exemplified by an LBF increase of 274 ± 37 vs. 143 ± 26 ml/μmol ATP × kg, 494 ± 80 vs. 234 ± 39 ml/μmol UTP × kg, and 14.9 ± 2.7 vs. 7.5 ± 0.6 ml/μmol ADO × kg in control and diabetic subjects, respectively, thus making the vasodilator potency as follows: UTP control subjects (100) > ATP control subjects (55) > UTP diabetic subjects (47) > ATP diabetic subjects (29) > ADO control subjects (3) > ADO diabetic subjects (1.5). The distribution and mRNA expression of receptors were similar in the two groups.

CONCLUSIONS

The vasodilatatory effect of the purinergic system is severely reduced in type 2 diabetic patients. The potency of nucleotides varies with the following rank order: UTP > ATP > ADO. This is not due to alterations in receptor distribution and mRNA expression, but may be due to differences in receptor sensitivity.
ATP-Sensitive K+ Channel Mediates the Zinc Switch-Off Signal for Glucagon Response During Glucose Deprivation
Authors: Slucca Michela , Harmon Jamie S. , Oseid Elizabeth A. , Bryan Joseph , Robertson R. Paul
Published: October 2009

OBJECTIVE

The intraislet insulin hypothesis proposes that glucagon secretion during hypoglycemia is triggered by a decrease in intraislet insulin secretion. A more recent hypothesis based on in vivo data from hypoglycemic rats is that it is the decrease in zinc cosecreted with insulin from β-cells, rather than the decrease in insulin itself, that signals glucagon secretion from α-cells during hypoglycemia. These studies were designed to determine whether closure of the α-cell ATP-sensitive K+ channel (KATP channel) is the mechanism through which the zinc switch-off signal triggers glucagon secretion during glucose deprivation.

RESEARCH DESIGN AND METHODS

All studies were performed using perifused isolated islets.

RESULTS

In control experiments, the expected glucagon response to an endogenous insulin switch-off signal during glucose deprivation was observed in wild-type mouse islets. In experiments with streptozotocin-treated wild-type islets, a glucagon response to an exogenous zinc switch-off signal was observed during glucose deprivation. However, this glucagon response to the zinc switch-off signal during glucose deprivation was not seen in the presence of nifedipine, diazoxide, or tolbutamide or if KATP channel knockout mouse islets were used. All islets had intact glucagon responses to epinephrine.

CONCLUSIONS

These data demonstrate that closure of KATP channels and consequent opening of calcium channels is the mechanism through which the zinc switch-off signal triggers glucagon secretion during glucose deprivation.
Many Americans Have Pre-Diabetes and Should Be Considered for Metformin Therapy
Authors: Rhee Mary K. , Herrick Kirsten , Ziemer David C. , Vaccarino Viola , Weintraub William S. , Narayan K.M. Venkat , Kolm Paul , Twombly Jennifer G. , Phillips Lawrence S.
Published: October 2009

OBJECTIVE

To determine the proportion of the American population who would merit metformin treatment, according to recent American Diabetes Association (ADA) consensus panel recommendations to prevent or delay the development of diabetes.

RESEARCH DESIGN AND METHODS

Risk factors were evaluated in 1,581 Screening for Impaired Glucose Tolerance (SIGT), 2,014 Third National Health and Nutrition Examination Survey (NHANES III), and 1,111 National Health and Nutrition Examination Survey 2005–2006 (NHANES 2005–2006) subjects, who were non-Hispanic white and black, without known diabetes. Criteria for consideration of metformin included the presence of both impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), with ≥1 additional diabetes risk factor: age <60 years, BMI ≥35 kg/m2, family history of diabetes, elevated triglycerides, reduced HDL cholesterol, hypertension, or A1C >6.0%.

RESULTS

Isolated IFG, isolated IGT, and IFG and IGT were found in 18.0, 7.2, and 8.2% of SIGT; 22.3, 6.4, and 9.4% of NHANES III; and 21.8, 5.0, and 9.0% of NHANES 2005–2006 subjects, respectively. In SIGT, NHANES III, and NHANES 2005–2006, criteria for metformin consideration were met in 99, 96, and 96% of those with IFG and IGT; 31, 29, and 28% of all those with IFG; and 53, 57, and 62% of all those with IGT (8.1, 9.1, and 8.7% of all subjects), respectively.

CONCLUSIONS

More than 96% of individuals with both IFG and IGT are likely to meet ADA consensus criteria for consideration of metformin. Because >28% of all those with IFG met the criteria, providers should perform oral glucose tolerance tests to find concomitant IGT in all patients with IFG. To the extent that our findings are representative of the U.S. population, ∼1 in 12 adults has a combination of pre-diabetes and risk factors that may justify consideration of metformin treatment for diabetes prevention.
Postprandial Vascular Effects of VIAject Compared With Insulin Lispro and Regular Human Insulin in Patients With Type 2 Diabetes
Authors: Forst Thomas , Pfützner Andreas , Flacke Frank , Krasner Alan , Hohberg Cloth , Tarakci Eda , Pichotta Philip , Forst Senait , Steiner Solomon
Published: October 2009

OBJECTIVE

Recent studies suggested an impact of prandial insulin delivery on postprandial regulation of tissue blood flow. This study compared the effect of VIAject with human regular insulin and insulin lispro on postprandial oxidative stress and endothelial function in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Fourteen patients (seven men; aged 61.5 ± 1.8 years; duration of diabetes 6.6 ± 4.6 years; A1C 7.2 ± 0.5% [mean ± SEM]) received a prandial injection of VIAject, human regular insulin, and insulin lispro. At baseline and after a standardized liquid meal test (Ensure Plus), the postprandial increases in asymmetric dimethylarginine (ADMA) and nitrotyrosine levels were investigated. In addition, the postprandial effects on microvascular blood flow, skin oxygenation, and vascular elasticity were measured.

RESULTS

Treatment with VIAject resulted in a significant reduction in the peak postprandial generation of ADMA compared with human insulin and insulin lispro (VIAject −27.3 ± 22.6, human insulin 97.7 ± 24.4, and insulin lispro 66.9 ± 33.9 nmol/l; P < 0.05, respectively). The postprandial increases in nitrotyrosine levels were significantly less after VIAject than after human regular insulin (VIAject −0.22 ± 0.17 vs. human insulin 0.25 ± 0.15 μg/ml; P < 0.05), whereas nitrotyrosine after insulin lispro was in between (insulin lispro 0.09 ± 0.07 μg/ml; NS). In parallel, earlier and more pronounced increases in microvascular blood flow and skin oxygenation were obtained after VIAject compared with those after human insulin or insulin lispro (P < 0.05, respectively). All insulin formulations resulted in comparable improvements in central arterial elasticity.

CONCLUSIONS

Treatment with VIAject reduced postprandial oxidative stress and improved endothelial function compared with human regular insulin or insulin lispro.
Psychometric Findings for a Spanish Translation of the Diabetes Self-Management Profile (DSMP-Parent-Sp)
Authors: Valenzuela Jessica M. , Fernandez Michelle Castro , Hsin Olivia , Harris Michael A. , Taylor Cortney , La Greca Annette M. , Delamater Alan M.
Published: October 2009

OBJECTIVE

Few validated measures exist to evaluate self-management of diabetes in families with limited English proficiency. The present study evaluated the psychometric properties and the factorial equivalence of a Spanish translation of the parent report version of the Diabetes Self-Management Profile (DSMP-Parent-Sp).

RESEARCH DESIGN AND METHODS

Hispanic families of youth (mean 13.7 years old) with type 1 diabetes were recruited from three clinics in South Florida and represented a wide range of nationalities and acculturation levels. A total of 127 parents reported on their child's self-management behaviors using either the original DSMP-Parent (59.8%) or the DSMP-Parent-Sp (40.2%). In addition, youth reported their self-management using the original DSMP in English, and physicians rated their perceptions of the youth's self-management. Glycemic control was indexed by A1C in the past 3 months and collected from medical chart review.

RESULTS

Item analysis confirmed that the DSMP-Parent-Sp items related to the overall composite score in expected ways, and internal consistency estimates were adequate. Paired correlations demonstrated strong parent-child concordance and a significant relationship with physician perceptions of self-management. Evidence of concurrent and convergent validity, as well as “strict factorial invariance,” was demonstrated.

CONCLUSIONS

These preliminary findings indicate that the DSMP-Parent-Sp is a reliable and valid parent report measure of the diabetes self-management behaviors of Hispanic youths. In addition, there is preliminary evidence that the translated measure may be considered equivalent to the original English measure when used to measure self-management in Hispanic youth with diabetes.
Insulin Glargine Safety in Pregnancy
Authors: Pollex Erika K. , Feig Denice S. , Lubetsky Angelika , Yip Paul M. , Koren Gideon
Published: October 2009

OBJECTIVE

Insulin glargine (Lantus) is an extended-action insulin analog with greater stability and duration of action than regular human insulin. The long duration of action and decreased incidence of hypoglycemia provide potential advantages for its use in pregnancy. However, the placental pharmacokinetics of insulin glargine have not been studied. Therefore, the objective of this study was to determine whether insulin glargine crosses the human placenta using the human perfused placental lobule technique.

RESEARCH DESIGN AND METHODS

Placentae were obtained with informed consent after elective cesarean section delivery of noncomplicated term pregnancies. Insulin glargine, at a therapeutic concentration of 150 pmol/l (20 μU/ml) was added to the maternal circulation. Additional experiments were carried out at insulin glargine concentrations 1,000-fold higher than therapeutic levels (150, 225, and 300 nmol/l). A subsequent perfusion for which the maternal circuit remained open and insulin glargine was continuously infused at 150 pmol/l was completed for further confirmation of findings. The appearance of insulin glargine in the fetal circulation was analyzed by a chemiluminescence immunoassay.

RESULTS

Results from perfusions carried out at therapeutic concentrations (150 pmol/l) of insulin glargine showed no detectable insulin glargine in the fetal circuit. After perfusion with very high insulin glargine concentrations of 150, 225, and 300 nmol/l, the rate of transfer remained low at 0.079 ± 0.01, 0.14, and 0.064 pmol · min−1 · g tissue−1, respectively.

CONCLUSIONS

Insulin glargine, when used at therapeutic concentrations, is not likely to cross the placenta.
Ingestion of Diet Soda Before a Glucose Load Augments Glucagon-Like Peptide-1 Secretion
Authors: Brown Rebecca J. , Walter Mary , Rother Kristina I.
Published: October 2009

OBJECTIVE

The goal of this study was to determine the effect of artificial sweeteners on glucose, insulin, and glucagon-like peptide (GLP)-1 in humans.

RESEARCH DESIGN AND METHODS

For this study, 22 healthy volunteers (mean age 18.5 ± 4.2 years) underwent two 75-g oral glucose tolerance tests with frequent measurements of glucose, insulin, and GLP-1 for 180 min. Subjects drank 240 ml of diet soda or carbonated water, in randomized order, 10 min prior to the glucose load.

RESULTS

Glucose excursions were similar after ingestion of carbonated water and diet soda. Serum insulin levels tended to be higher after diet soda, without statistical significance. GLP-1 peak and area under the curve (AUC) were significantly higher with diet soda (AUC 24.0 ± 15.2 pmol/l per 180 min) versus carbonated water (AUC 16.2 ± 9.0 pmol/l per 180 min; P = 0.003).

CONCLUSIONS

Artificial sweeteners synergize with glucose to enhance GLP-1 release in humans. This increase in GLP-1 secretion may be mediated via stimulation of sweet-taste receptors on L-cells by artificial sweetener.
Comparison of A1C and Fasting Glucose Criteria to Diagnose Diabetes Among U.S. Adults
Authors: Carson April P. , Reynolds Kristi , Fonseca Vivian A. , Muntner Paul
Published: October 2009

OBJECTIVE

To compare A1C and fasting glucose for the diagnosis of diabetes among U.S. adults.

RESEARCH DESIGN AND METHODS

This study included 6,890 adults (≥20 years of age) from the 1999–2006 National Health and Nutrition Examination Survey without a self-reported history of diabetes who had fasted ≥9 h. A1C ≥6.5% and fasting glucose ≥126 mg/dl were used, separately, to define diabetes.

RESULTS

Overall, 1.8% of U.S. adults had A1C ≥6.5% and fasting glucose ≥126 mg/dl, 0.5% had A1C ≥6.5% and fasting glucose <126 mg/dl, and 1.8% had A1C <6.5% and fasting glucose ≥126 mg/dl. Compared with individuals with A1C <6.5% and fasting glucose ≥126 mg/dl, individuals with A1C ≥6.5% and fasting glucose <126 mg/dl were younger, more likely to be non-Hispanic black, had lower Hb levels, and had higher C-reactive protein.

CONCLUSIONS

A1C ≥6.5% demonstrates reasonable agreement with fasting glucose for diagnosing diabetes among U.S. adults.
Diabetes Interactive Diary: A New Telemedicine System Enabling Flexible Diet and Insulin Therapy While Improving Quality of Life
Authors: Rossi Maria C.E. , Nicolucci Antonio , Di Bartolo Paolo , Bruttomesso Daniela , Girelli Angela , Ampudia Francisco J. , Kerr David , Ceriello Antonio , Mayor Carmen De La Questa , Pellegrini Fabio , Horwitz David , Vespasiani Giacomo
Published: October 2009

OBJECTIVE

Widespread use of carbohydrate counting is limited by its complex education. In this study we compared a Diabetes Interactive Diary (DID) with standard carbohydrate counting in terms of metabolic and weight control, time required for education, quality of life, and treatment satisfaction.

RESEARCH DESIGN AND METHODS

Adults with type 1 diabetes were randomly assigned to DID (group A, n = 67) or standard education (group B, n = 63) and followed for 6 months. A subgroup also completed the SF-36 Health Survey (SF-36) and World Health Organization-Diabetes Treatment Satisfaction Questionnaire (WHO-DTSQ) at each visit.

RESULTS

Of 130 patients (aged 35.7 ± 9.4 years; diabetes duration 16.5 ± 10.5 years), 11 dropped out. Time for education was 6 h (range 2–15 h) in group A and 12 h (2.5–25 h) in group B (P = 0.07). A1C reduction was similar in both groups (group A from 8.2 ± 0.8 to 7.8 ± 0.8% and group B from 8.4 ± 0.7 to 7.9 ± 1.1%; P = 0.68). Nonsignificant differences in favor of group A were documented for fasting blood glucose and body weight. No severe hypoglycemic episode occurred. WHO-DTSQ scores increased significantly more in group A (from 26.7 ± 4.4 to 30.3 ± 4.5) than in group B (from 27.5 ± 4.8 to 28.6 ± 5.1) (P = 0.04). Role Physical, General Health, Vitality, and Role Emotional SF-36 scores improved significantly more in group A than in group B.

CONCLUSIONS

DID is at least as effective as traditional carbohydrate counting education, allowing dietary freedom for a larger proportion of type 1 diabetic patients. DID is safe, requires less time for education, and is associated with lower weight gain. DID significantly improved treatment satisfaction and several quality-of-life dimensions.
Analysis of spectinomycin in fermentation broth by reversed-phase chromatography
Authors: Yan Hong , Xu Pei , Huang Hai , Qiu Juan
Published: October 2009

A pre-column derivatized high-performance liquid chromatographic (HPLC) method with ultraviolet-visible detection was developed to measure the concentrations of spectinomycin in fermentation broth. Derivatization reagents, 2,4-dinitrophenylhydrazine in acetonitrile (5 mg mL−1) and trifluoroacetic acid in acetonitrile (0.8 mol L−1), were added to an aliquot of the fermentation broth, and the mixture was incubated for 60 min at 70°C. The resulting derivative was separated from other compounds by isocratic elution in a reversed-phase column Zorbax SB-C18 (250 mm × 4.6 mm, 5 µm). Mobile phase consisted of acetonitrile, tetrahydrofuran, and water (φ r = 40: 35: 25) and the flow rate was 1.0 mL min−1. The detection wavelength was 415 nm. The standard curve for spectinomycin sulfate was linear with correlation coefficients of 0.9997 in the range of 25 µg mL−1 to 600 µg mL−1. The relative standard deviation values ranged from 0.43 % to 2.18 % depending on the concentration of samples. The average recovery was 101.5 %. The limit of detection was 50 ng mL−1.
Selection of a method for determination of activity of pectinolytic enzymes in berry fruit materials
Authors: Jakób Alina , Bryjak Jolanta , Polakovič Milan
Published: October 2009

The goal of the study was to find the most accurate and sensitive method for the determination of activity of pectinolytic enzymes in complex mixtures obtained from fruit materials such as raw cloudberry and raspberry juices. Several assay methods based on enzymatic reactions using viscometric, colourimetric, spectrophotometric, or pH-titration detection of the reaction products were tested. Problems with the application of the selected methods, such as very low detection signal or very large background signal, were observed. Among the tested methods, only a modified method based on the continuous recording of the released carboxyl groups titration allowed to assay the activity of exogenous pectin methylesterase with a good linearity, sensitivity, accuracy, and minimised the interference of other fruit components.
Synthesis and characterization of mesoporous molecular sieves
Authors: Horňáček Michal , Hudec Pavol , Smiešková Agáta
Published: October 2009

In the synthesis of mesoporous molecular sieves of the type MCM-41, different cationactive surfactants and sources of silicon were used. Moreover, Al-MCM-41 samples with different content of aluminium were synthesized. MCM-41 and Al-MCM-41 were synthesized at elevated temperature in stainless-steel autoclaves. Prepared mesoporous molecular sieves were characterized by powder X-ray diffraction (XRD), physical adsorption of nitrogen at the temperature of −197°C, sorption capacity of benzene, and by infrared spectroscopy (FTIR). Acidity was measured for Al-MCM-41 by temperature programmed desorption of ammonia (TPDA) and by FTIR of adsorbed pyridine. Acid catalytic activity of Al-MCM-41 was tested by isomerization of o-xylene. Influence of the synthesis reproducibility, surfactant used, source of silicon, synthesis time, source of aluminium, and Si to Al mole ratio on the properties of mesoporous molecular sieves were evaluated.
Effect of anthraquinone on brightness value and crystalline structure of pulp during soda processes
Authors: Gümüşkaya Esat , Kalyoncu Evren , Kirci Hüseyin
Published: October 2009

The dependence of crystalline structure and optical properties of pulp on anthraquinone (AQ) added to the soda process at different cooking times was determined in this study. Wheat (Triticum aestevum L.) straw was used as the raw material for pulp. Soda and soda-AQ processes were selected for pulping at 80 min and 120 min. The soda-AQ process improved the yield and viscosity of pulp delignification ratio for pulping in comparison with the soda process. Crystallinity of pulp samples decreased by adding anthraquinone to the soda process because of stabilized less ordered cellulose and amorphous hemicelluloses in pulp. It was determined that crystallinity of pulp samples decreased with longer cooking time, from 80 min to 120 min, in both soda and soda-AQ processes. Monoclinic structure was dominant in pulp samples; however, the triclinic structure ratio increased in both soda and soda-AQ processes compared to raw material. It was found that brightness and lightness values in pulp samples decreased when using anthraquinone depending on the changes of the crystalline structure.
Study on polymeric micelles of poly(γ-benzyl l-glutamate)-graft-poly(ethylene glycol) copolymer and its mixtures with poly(γ-benzyl l-glutamate) homopolymer in ethanol
Authors: Zhu Guo-Quan
Published: October 2009

Poly(γ-benzyl l-glutamate)-graft-poly(ethylene glycol) (PBLG-graft-PEG) copolymer was synthesized by the ester exchange reaction of the PBLG homopolymer with PEG. NMR spectroscopy was used to confirm the composition of the PBLG-graft-PEG copolymer. FTIR spectroscopy was used to characterize the chain conformation of polypeptide segments in the PBLG-graft-PEG copolymer in solid state. The self-assembly behavior of PBLG-graft-PEG and its mixtures with PBLG in ethanol were investigated by transmission electron microscopy (TEM) and viscometry. Experimental results showed that the PBLG-graft-PEG copolymer can self-assemble to form polymeric micelles with a core-shell structure of a thin shuttle-like shape. The introduction of the PBLG homopolymer into the mixed system not only decreases the critical micelle concentration (CMC) but also changes the morphology of the micelles from their shuttle-like shape to cylindrical shape. The effects of test temperature on the critical micelle concentration of PBLG-graft-PEG were also studied.
Novel use of silicon nanocrystals and nanodiamonds in biology
Authors: Fucikova Anna , Valenta Jan , Pelant Ivan , Brezina Vitezslav
Published: October 2009

The presented work is aimed at the development of nontoxic nanocrystalline silicon fluorescence labels, biodegradable in living body and long-term stable, and of fluorescent nanodiamonds mainly for in vitro use. These novel fluorescence labels could be very good substitutes for commercially used quantum dots (e.g. cadmium compound quantum dots) which can be toxic according to the latest results. In this work, manufacturing of porous nanocrystalline silicon (por-Si) is described, several basic optical properties of por-Si are presented and the influence of Si nanocrystals, nanodiamonds, and milled silicon on the growth of a cell culture of L929 mouse fibroblast and HeLa cells is compared. Bio-interaction of nanoparticles was studied by optical transmission microscopy, time-lapse microphotography of cell culture evolution, fluorescence microscopy, fluorescence microspectroscopy, and scanning electron microscopy. The size and shape of nanocrystals were determined using atomic force microscopy (AFM).
An amperometric sensor for uric acid based on ordered mesoporous carbon-modified pyrolytic graphite electrode
Authors: Ma Yonggen , Hu Guangzhi , Shao Shijun , Guo Yong
Published: October 2009

A novel amperometric sensor for uric acid based on ordered mesoporous carbon modified pyrolytic graphite electrode was developed. Uric acid oxidation was easily catalyzed by this electrode in a phosphate buffer solution at pH 7.0, with an anodic potential decrease about 140 mV compared to bare pyrolytic graphite electrode. The uric acid level was determined by the amperometric method, at a constant potential of 0.31 mV, the catalytic current of uric acid vs. its concentration showed a good linearity in the range of 1.0 × 10−6−1.0 × 10−4 mol L−1, with a correlation coefficient of 0.999. The detection limit was 4.0 × 10−7 mol L−1. The proposed method could be effectively used for uric acid amperometric sensing in human urine.
Fluoride anion sensing using colorimetric reagents containing binaphthyl moiety and urea binding site
Authors: Mikláš Roman , Kasák Peter , Devínsky Ferdinand , Putala Martin
Published: October 2009

Four 1,1′-binaphthalene based bis-urea derivatives bearing aryl groups at end-on nitrogen atoms IIIa–d were synthesized as potential sensor molecules. These receptors show characteristic UV-VIS spectral changes on complexation with anions and they exhibit selective recognition of F− over other halide anions. Interaction of a fluoride anion with urea NH groups was confirmed by 1H NMR data. The presence of an electron-withdrawing nitro group in N′-aryls (receptors IIIa and IIIb) appeared to be necessary for naked-eye colorimetric detection. These receptors show dramatic color change from light-yellow to orange (IIIa) or to orange-red (IIIb) in the presence of guest fluoride anions already at concentrations of 10−5 mol dm−3 of the receptor and host.
Study of physicochemical properties-antitubercular activity relationship of naphthalene-1,4-dione analogs: A QSAR approach
Authors: Gupta Revathi , Gupta Arun , Soni Love , Kaskhedikar Satish
Published: October 2009

Enduring pandemic nature of tuberculosis urges to explore novel antimycobacterial agents with different mechanism of actions. Plant containing 1,4-naphthoquinone derivatives showed promising antitubercular activity with novel mode of action and their synthetic/semi-synthetic derivatives devoid of toxicity. Structural requirements of naphthalene-1,4-dione derivatives towards antitubercular activity and cytotoxicity were explored using a mathematical model in order to understand their physicochemical parameters. A quantitative structure activity relationship study furnished some important structural insights for antitubercular activity, i.e. average connectivity index, information content index of neighborhood symmetry, aromatic ratio, and path/walk 3 Randic shape index. Similarly it also provides drivers for the cytotoxicity of compounds. These drivers will be helpful in further development of safer and potent 1,4-naphthoquinone derivatives.
Aquaculture by-product: a source of proteolytic enzymes for detergent additives
Authors: Mendes Chirleanny , Brito Marília , Porto Tatiana , Porto Ana , Bezerra Ranilson , Carvalho Luiz , Caneiro-Leão Ana , Carneiro-da-Cunha Maria
Published: October 2009

Intestine proteases of Nile tilapia (Oreochromis niloticus) were partially purified by heat treatment (purification factor of 3.5, enzyme activity remained almost constant) to reach the maximum activity and stability within an alkaline pH range of 7.2–11.0. The optimum temperature and stability over a 120 min period were found to be at 55°C and at 35–45°C, respectively. The proteases’ activity was not affected by a 1 vol. % saponin surfactant, inactivated by 0.01 g mL−1 sodium dodecylsulphate after 120 min, and it remained stable for 30 min in a 5 vol. % and 10 vol. % hydrogen peroxide solutions. The proteases were slightly activated by Ca2+, Mg2+, and K+ and the substrate most effectively hydrolysed was casein (40.0 U mg−1). A 24 full factorial design used to evaluated the influence of independent variables showed that the enzyme extract, detergent concentration and the incubation time had a significant influence on the enzymatic activity. The best conditions to be used concerning detergent additive were found with 0.3 mg mL−1 of protein and 3.0 mg mL−1 of detergent for 30 min in the presence of Astrus® detergent.
Utility of π-acceptor reagents for spectrophotometric determination of sulphonamide drugs via charge-transfer complex formation
Authors: Nour El-Dien Faten , Mohamed Gehad , Frag Eman
Published: October 2009

A simple, sensitive and accurate spectrophotometric method for the determination of sulphonamides (sulphamethoxazole (SMZ), sulphaguanidine (SGD), sulphaquinoxaline sodium (SQX), sulphametrole (SMR), and sulphadimidine sodium (SDD)) has been developed. The charge-transfer reactions between sulphonamides as n-electron donors and 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, p-CLA) as π-acceptors resulting in highly coloured complexes were studied. Experimental conditions for these CT reactions were carefully optimised. Beer’s law is valid over the concentration ranges from 4–280 µg mL−1, 4–260 µg mL−1, 4–200 µg mL−1, and 4–200 µg mL−1 of SMZ, SGD, SQX, and SDD using DDQ reagent, respectively. While the calibration curves are linear in the concentration ranges from 4–180 µg mL−1, 4–80 µg mL−1, 4–60 µg mL−1, 4–180 µg mL−1, and 4–60 µg mL−1 of SMZ, SGD, SQX, SMR, and SDD, respectively, using TCNQ reagent and from 4–380 µg mL−1 and 4–300 µg mL−1 of SQX and SDD, respectively, using p-CLA reagent, respectively. Different analytical parameters, namely molar absorptivity (ε), standard deviation, relative standard deviation, correlation coefficient, limit of detection, and limit of quantification, were calculated. The results obtained by the proposed methods are in good agreement with those obtained by the official method as indicated by the percent recovery values.
Evaluation of the Pattern of Human Serum Glycoproteins in Prostate Cancer
Authors: Kosanović Maja , Janković Miroslava
Published: October 2009

Evaluation of the Pattern of Human Serum Glycoproteins in Prostate Cancer

Glycoprotein profiling at the level of cells, tissues and biological fluids is aimed at discovering new cancer biomarkers and also at finding specific cancer-related structural alterations of known tumor markers. In this study we comparatively evaluated the glycoprotein patterns of human prostate cancer (PCa)- and normal human sera regarding sialylation and fucosylation as structural characteristics relevant for cancer progression. Glycoproteins were isolated using affinity chromatography on Sambucus nigra agglutinin- and Lens culinaris agglutinin-columns and subsequently characterized by SDS-PAGE and on-chip normal phase-surface capture combined with surface-enhanced laser/desorption ionization time of flight mass spectrometry. Comparative analysis of the glycoproteins purified from healthy and PCa sera indicated differences and redundancy of the isolated molecules in terms of the microheterogeneity of counterpart glycans, the relative abundance and the presence/absence of particular molecular species. In PCa there was a general increase in sialylation and decrease in fucosylation of human serum glycans compared to normal sera. Taken together, the results obtained indicated that an affinity-approach based on the use of lectins of narrow specificity reduced the complexity of the examined samples and at this discovery-phase of our study pointed to specific glyco-changes that may be relevant for improving the monitoring of PCa progression.