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Sample records for a1c-derived average glucose

  1. A semi-mechanistic model of the relationship between average glucose and HbA1c in healthy and diabetic subjects.

    PubMed

    Lledó-García, Rocío; Mazer, Norman A; Karlsson, Mats O

    2013-04-01

    HbA1c is the most commonly used biomarker for the adequacy of glycemic management in diabetic patients and a surrogate endpoint for anti-diabetic drug approval. In spite of an empirical description for the relationship between average glucose (AG) and HbA1c concentrations, obtained from the A1c-derived average glucose (ADAG) study by Nathan et al., a model for the non-steady-state relationship is still lacking. Using data from the ADAG study, we here develop such models that utilize literature information on (patho)physiological processes and assay characteristics. The model incorporates the red blood cell (RBC) aging description, and uses prior values of the glycosylation rate constant (KG), mean RBC life-span (LS) and mean RBC precursor LS obtained from the literature. Different hypothesis were tested to explain the observed non-proportional relationship between AG and HbA1c. Both an inverse dependence of LS on AG and a non-specificity of the National Glycohemoglobin Standardization Program assay used could well describe the data. Both explanations have mechanistic support and could be incorporated, alone or in combination, in models allowing prediction of the time-course of HbA1c changes associated with changes in AG from, for example dietary or therapeutic interventions, and vice versa, to infer changes in AG from observed changes in HbA1c. The selection between the alternative mechanistic models require gathering of new information.

  2. Hemoglobin A1c and Self-Monitored Average Glucose

    PubMed Central

    Kovatchev, Boris P.; Breton, Marc D.

    2015-01-01

    Background: Previously we have introduced the eA1c—a new approach to real-time tracking of average glycemia and estimation of HbA1c from infrequent self-monitoring (SMBG) data, which was developed and tested in type 2 diabetes. We now test eA1c in type 1 diabetes and assess its relationship to the hemoglobin glycation index (HGI)—an established predictor of complications and treatment effect. Methods: Reanalysis of previously published 12-month data from 120 patients with type 1 diabetes, age 39.15 (14.35) years, 51/69 males/females, baseline HbA1c = 7.99% (1.48), duration of diabetes 20.28 (12.92) years, number SMBG/day = 4.69 (1.84). Surrogate fasting BG and 7-point daily profiles were derived from these unstructured SMBG data and the previously reported eA1c method was applied without any changes. Following the literature, we calculated HGI = HbA1c – (0.009 × Fasting BG + 6.8). Results: The correlation of eA1c with reference HbA1c was r = .75, and its deviation from reference was MARD = 7.98%; 95% of all eA1c values fell within ±20% from reference. The HGI was well approximated by a linear combination of the eA1c calibration factors: HGI = 0.007552*θ1 + 0.007645*θ2 – 3.154 (P < .0001); 73% of low versus moderate-high HGIs were correctly classified by the same factors as well. Conclusions: The eA1c procedure developed in type 2 diabetes to track in real-time changes in average glycemia and present the results in HbA1c-equivalent units has shown similar performance in type 1 diabetes. The eA1c calibration factors are highly predictive of the HGI, thereby explaining partially the biological variation causing discrepancies between HbA1c and its linear estimates from SMBG data. PMID:26553023

  3. Translating the A1C assay into estimated average glucose values.

    PubMed

    Nathan, David M; Kuenen, Judith; Borg, Rikke; Zheng, Hui; Schoenfeld, David; Heine, Robert J

    2008-08-01

    The A1C assay, expressed as the percent of hemoglobin that is glycated, measures chronic glycemia and is widely used to judge the adequacy of diabetes treatment and adjust therapy. Day-to-day management is guided by self-monitoring of capillary glucose concentrations (milligrams per deciliter or millimoles per liter). We sought to define the mathematical relationship between A1C and average glucose (AG) levels and determine whether A1C could be expressed and reported as AG in the same units as used in self-monitoring. A total of 507 subjects, including 268 patients with type 1 diabetes, 159 with type 2 diabetes, and 80 nondiabetic subjects from 10 international centers, was included in the analyses. A1C levels obtained at the end of 3 months and measured in a central laboratory were compared with the AG levels during the previous 3 months. AG was calculated by combining weighted results from at least 2 days of continuous glucose monitoring performed four times, with seven-point daily self-monitoring of capillary (fingerstick) glucose performed at least 3 days per week. Approximately 2,700 glucose values were obtained by each subject during 3 months. Linear regression analysis between the A1C and AG values provided the tightest correlations (AG(mg/dl) = 28.7 x A1C - 46.7, R(2) = 0.84, P < 0.0001), allowing calculation of an estimated average glucose (eAG) for A1C values. The linear regression equations did not differ significantly across subgroups based on age, sex, diabetes type, race/ethnicity, or smoking status. A1C levels can be expressed as eAG for most patients with type 1 and type 2 diabetes.

  4. Development of diagnotors based on time-average values of plasma glucose and immunoreactive insulin levels during intravenous glucose tolerance testing

    NASA Astrophysics Data System (ADS)

    Denisova, Tatyana P.; Malinov, Igor A.; Malinova, Lidia I.; Brook, Sergey B.

    2000-04-01

    The diagnostic algorithm of glucose-insulinic violations for the patients with a clinically obvious atherosclerosis of coronary arteries, non-insulin dependent diabetes mellitus and persons with the heritable predisposition to these forms of pathology was designed. The realization of intravenous glucose tolerance test in specially fitted groups of patients served as basis of the algorithm.

  5. Does glucose variability influence the relationship between mean plasma glucose and HbA1c levels in type 1 and type 2 diabetic patients?

    PubMed

    Kuenen, Judith C; Borg, Rikke; Kuik, Dirk J; Zheng, Hui; Schoenfeld, David; Diamant, Michaela; Nathan, David M; Heine, Robert J

    2011-08-01

    The A1C-Derived Average Glucose (ADAG) study demonstrated a linear relationship between HbA(1c) and mean plasma glucose (MPG). As glucose variability (GV) may contribute to glycation, we examined the association of several glucose variability indices and the MPG-HbA(1c) relationship. Analyses included 268 patients with type 1 diabetes and 159 with type 2 diabetes. MPG during 3 months was calculated from 7-point self-monitored plasma glucose and continuous glucose monitoring. We calculated three different measures of GV and used a multiple-step regression model to determine the contribution of the respective GV measures to the MPG-HbA(1c) relationship. GV, as reflected by SD and continuous overlapping net glycemic action, had a significant effect on the MPG-HbA(1c) relationship in type 1 diabetic patients so that high GV led to a higher HbA(1c) level for the same MPG. In type 1 diabetes, the impact of confounding and effect modification of a low versus high SD at an MPG level of 160 mg/dL on the HbA(1c) level is 7.02 vs. 7.43 and 6.96 vs. 7.41. All GV measures showed the same tendency. In only type 1 diabetic patients, GV shows a significant interaction with MPG in the association with HbA(1c). This effect is more pronounced at higher HbA(1c) levels. However, the impact of GV on the HbA(1c) level in type 1 diabetes is modest, particularly when HbA(1c) is close to the treatment target of 7%.

  6. Quaternion Averaging

    NASA Technical Reports Server (NTRS)

    Markley, F. Landis; Cheng, Yang; Crassidis, John L.; Oshman, Yaakov

    2007-01-01

    Many applications require an algorithm that averages quaternions in an optimal manner. For example, when combining the quaternion outputs of multiple star trackers having this output capability, it is desirable to properly average the quaternions without recomputing the attitude from the the raw star tracker data. Other applications requiring some sort of optimal quaternion averaging include particle filtering and multiple-model adaptive estimation, where weighted quaternions are used to determine the quaternion estimate. For spacecraft attitude estimation applications, derives an optimal averaging scheme to compute the average of a set of weighted attitude matrices using the singular value decomposition method. Focusing on a 4-dimensional quaternion Gaussian distribution on the unit hypersphere, provides an approach to computing the average quaternion by minimizing a quaternion cost function that is equivalent to the attitude matrix cost function Motivated by and extending its results, this Note derives an algorithm that deterniines an optimal average quaternion from a set of scalar- or matrix-weighted quaternions. Rirthermore, a sufficient condition for the uniqueness of the average quaternion, and the equivalence of the mininiization problem, stated herein, to maximum likelihood estimation, are shown.

  7. Glucose Tests

    MedlinePlus

    ... AACC products and services. Advertising & Sponsorship: Policy | Opportunities Glucose Tests Share this page: Was this page helpful? ... the meaning of other test results. Fasting Blood Glucose Glucose Level Indication From 70 to 99 mg/ ...

  8. Glucose Variability

    PubMed Central

    Le Floch, Jean-Pierre; Kessler, Laurence

    2016-01-01

    Background: Glucose variability has been suspected to be a major factor of diabetic complications. Several indices have been proposed for measuring glucose variability, but their interest remains discussed. Our aim was to compare different indices. Methods: Glucose variability was studied in 150 insulin-treated diabetic patients (46% men, 42% type 1 diabetes, age 52 ± 11 years) using a continuous glucose monitoring system (668 ± 564 glucose values; mean glucose value 173 ± 38 mg/dL). Results from the mean, the median, different indices (SD, MAGE, MAG, glucose fluctuation index (GFI), and percentages of low [<60 mg/dL] and high [>180 mg/dL] glucose values), and ratios (CV = SD/m, MAGE/m, MAG/m, and GCF = GFI/m) were compared using Pearson linear correlations and a multivariate principal component analysis (PCA). Results: CV, MAGE/m (ns), GCF and GFI (P < .05), MAG and MAG/m (P < .01) were not strongly correlated with the mean. The percentage of high glucose values was mainly correlated with indices. The percentage of low glucose values was mainly correlated with ratios. PCA showed 3 main axes; the first was associated with descriptive data (mean, SD, CV, MAGE, MAGE/m, and percentage of high glucose values); the second with ratios MAG/m and GCF and with the percentage of low glucose values; and the third with MAG, GFI, and the percentage of high glucose values. Conclusions: Indices and ratios provide complementary pieces of information associated with high and low glucose values, respectively. The pairs MAG+MAG/m and GFI+GCF appear to be the most reliable markers of glucose variability in diabetic patients. PMID:26880391

  9. Neutron resonance averaging

    SciTech Connect

    Chrien, R.E.

    1986-10-01

    The principles of resonance averaging as applied to neutron capture reactions are described. Several illustrations of resonance averaging to problems of nuclear structure and the distribution of radiative strength in nuclei are provided. 30 refs., 12 figs.

  10. PCK and Average

    ERIC Educational Resources Information Center

    Watson, Jane; Callingham, Rosemary

    2013-01-01

    This paper considers the responses of 26 teachers to items exploring their pedagogical content knowledge (PCK) about the concept of average. The items explored teachers' knowledge of average, their planning of a unit on average, and their understanding of students as learners in devising remediation for two student responses to a problem. Results…

  11. Areal Average Albedo (AREALAVEALB)

    DOE Data Explorer

    Riihimaki, Laura; Marinovici, Cristina; Kassianov, Evgueni

    2008-01-01

    he Areal Averaged Albedo VAP yields areal averaged surface spectral albedo estimates from MFRSR measurements collected under fully overcast conditions via a simple one-line equation (Barnard et al., 2008), which links cloud optical depth, normalized cloud transmittance, asymmetry parameter, and areal averaged surface albedo under fully overcast conditions.

  12. Glucose metabolism and hyperglycemia.

    PubMed

    Giugliano, Dario; Ceriello, Antonio; Esposito, Katherine

    2008-01-01

    Islet dysfunction and peripheral insulin resistance are both present in type 2 diabetes and are both necessary for the development of hyperglycemia. In both type 1 and type 2 diabetes, large, prospective clinical studies have shown a strong relation between time-averaged mean values of glycemia, measured as glycated hemoglobin (HbA1c), and vascular diabetic complications. These studies are the basis for the American Diabetes Association's current recommended treatment goal that HbA1c should be <7%. The measurement of the HbA1c concentration is considered the gold standard for assessing long-term glycemia; however, it does not reveal any information on the extent or frequency of blood glucose excursions, but provides an overall mean value only. Postprandial hyperglycemia occurs frequently in patients with diabetes receiving active treatment and can occur even when metabolic control is apparently good. Interventional studies indicate that reducing postmeal glucose excursions is as important as controlling fasting plasma glucose in persons with diabetes and impaired glucose tolerance. Evidence exists for a causal relation between postmeal glucose increases and microvascular and macrovascular outcomes; therefore, it is not surprising that treatment with different compounds that have specific effects on postprandial glucose regulation is accompanied by a significant improvement of many pathways supposed to be involved in diabetic complications, including oxidative stress, endothelial dysfunction, inflammation, and nuclear factor-kappaB activation. The goal of therapy should be to achieve glycemic status as near to normal as safely possible in all 3 components of glycemic control: HbA1c, fasting glucose, and postmeal glucose peak.

  13. States' Average College Tuition.

    ERIC Educational Resources Information Center

    Eglin, Joseph J., Jr.; And Others

    This report presents statistical data on trends in tuition costs from 1980-81 through 1995-96. The average tuition for in-state undergraduate students of 4-year public colleges and universities for academic year 1995-96 was approximately 8.9 percent of median household income. This figure was obtained by dividing the students' average annual…

  14. Aggregation and Averaging.

    ERIC Educational Resources Information Center

    Siegel, Irving H.

    The arithmetic processes of aggregation and averaging are basic to quantitative investigations of employment, unemployment, and related concepts. In explaining these concepts, this report stresses need for accuracy and consistency in measurements, and describes tools for analyzing alternative measures. (BH)

  15. Averaging Schwarzschild spacetime

    NASA Astrophysics Data System (ADS)

    Tegai, S. Ph.; Drobov, I. V.

    2017-07-01

    We tried to average the Schwarzschild solution for the gravitational point source by analogy with the same problem in Newtonian gravity or electrostatics. We expected to get a similar result, consisting of two parts: the smoothed interior part being a sphere filled with some matter content and an empty exterior part described by the original solution. We considered several variants of generally covariant averaging schemes. The averaging of the connection in the spirit of Zalaletdinov's macroscopic gravity gave unsatisfactory results. With the transport operators proposed in the literature it did not give the expected Schwarzschild solution in the exterior part of the averaged spacetime. We were able to construct a transport operator that preserves the Newtonian analogy for the outward region but such an operator does not have a clear geometrical meaning. In contrast, using the curvature as the primary averaged object instead of the connection does give the desired result for the exterior part of the problem in a fine way. However for the interior part, this curvature averaging does not work because the Schwarzschild curvature components diverge as 1 /r3 near the center and therefore are not integrable.

  16. Threaded average temperature thermocouple

    NASA Technical Reports Server (NTRS)

    Ward, Stanley W. (Inventor)

    1990-01-01

    A threaded average temperature thermocouple 11 is provided to measure the average temperature of a test situs of a test material 30. A ceramic insulator rod 15 with two parallel holes 17 and 18 through the length thereof is securely fitted in a cylinder 16, which is bored along the longitudinal axis of symmetry of threaded bolt 12. Threaded bolt 12 is composed of material having thermal properties similar to those of test material 30. Leads of a thermocouple wire 20 leading from a remotely situated temperature sensing device 35 are each fed through one of the holes 17 or 18, secured at head end 13 of ceramic insulator rod 15, and exit at tip end 14. Each lead of thermocouple wire 20 is bent into and secured in an opposite radial groove 25 in tip end 14 of threaded bolt 12. Resulting threaded average temperature thermocouple 11 is ready to be inserted into cylindrical receptacle 32. The tip end 14 of the threaded average temperature thermocouple 11 is in intimate contact with receptacle 32. A jam nut 36 secures the threaded average temperature thermocouple 11 to test material 30.

  17. The average enzyme principle

    PubMed Central

    Reznik, Ed; Chaudhary, Osman; Segrè, Daniel

    2013-01-01

    The Michaelis-Menten equation for an irreversible enzymatic reaction depends linearly on the enzyme concentration. Even if the enzyme concentration changes in time, this linearity implies that the amount of substrate depleted during a given time interval depends only on the average enzyme concentration. Here, we use a time re-scaling approach to generalize this result to a broad category of multi-reaction systems, whose constituent enzymes have the same dependence on time, e.g. they belong to the same regulon. This “average enzyme principle” provides a natural methodology for jointly studying metabolism and its regulation. PMID:23892076

  18. Average Revisited in Context

    ERIC Educational Resources Information Center

    Watson, Jane; Chick, Helen

    2012-01-01

    This paper analyses the responses of 247 middle school students to items requiring the concept of average in three different contexts: a city's weather reported in maximum daily temperature, the number of children in a family, and the price of houses. The mixed but overall disappointing performance on the six items in the three contexts indicates…

  19. Averaging of TNTC counts.

    PubMed Central

    Haas, C N; Heller, B

    1988-01-01

    When plate count methods are used for microbial enumeration, if too-numerous-to-count results occur, they are commonly discarded. In this paper, a method for consideration of such results in computation of an average microbial density is developed, and its use is illustrated by example. PMID:3178211

  20. Determining average yarding distance.

    Treesearch

    Roger H. Twito; Charles N. Mann

    1979-01-01

    Emphasis on environmental and esthetic quality in timber harvesting has brought about increased use of complex boundaries of cutting units and a consequent need for a rapid and accurate method of determining the average yarding distance and area of these units. These values, needed for evaluation of road and landing locations in planning timber harvests, are easily and...

  1. Covariant approximation averaging

    NASA Astrophysics Data System (ADS)

    Shintani, Eigo; Arthur, Rudy; Blum, Thomas; Izubuchi, Taku; Jung, Chulwoo; Lehner, Christoph

    2015-06-01

    We present a new class of statistical error reduction techniques for Monte Carlo simulations. Using covariant symmetries, we show that correlation functions can be constructed from inexpensive approximations without introducing any systematic bias in the final result. We introduce a new class of covariant approximation averaging techniques, known as all-mode averaging (AMA), in which the approximation takes account of contributions of all eigenmodes through the inverse of the Dirac operator computed from the conjugate gradient method with a relaxed stopping condition. In this paper we compare the performance and computational cost of our new method with traditional methods using correlation functions and masses of the pion, nucleon, and vector meson in Nf=2 +1 lattice QCD using domain-wall fermions. This comparison indicates that AMA significantly reduces statistical errors in Monte Carlo calculations over conventional methods for the same cost.

  2. Implantable continuous glucose sensors.

    PubMed

    Renard, Eric

    2008-08-01

    Because of the limits of wearable needle-type or microdialysis-based enzymatic sensors in clinical use, fully implantable glucose monitoring systems (IGMS) represent a promising alternative. Long-term use reducing impact of invasiveness due to implantation, less frequent calibration needs because of a more stable tissue environment around the sensor and potential easier inclusion in a closed-loop insulin delivery system are the expected benefits of IGMS. First experiences with subcutaneous and intravenous IGMS have been recently collected in pilot studies. While no severe adverse events have been reported, biointerface issues have been responsible for the failures of IGMS. Tissue reactions around implanted subcutaneous devices and damages of intravenous sensors due to shearing forces of blood flow impaired IGMS function and longevity. In functioning systems, accuracy of glucose measurement reached satisfactory levels for average durations of about 120 days with subcutaneous IGMS and 259 days with intravenous sensors. Moreover, sensor information could help to improve time spent in normal glucose range when provided to patients wearing subcutaneous IGMS and allowed safe and effective closed-loop glucose control when intravenous sensors were connected to implanted pumps using intra-peritoneal insulin delivery. These data could open a favourable perspective for IGMS after improvement of biointerface conditions and if compatible with an affordable cost.

  3. Americans' Average Radiation Exposure

    SciTech Connect

    NA

    2000-08-11

    We live with radiation every day. We receive radiation exposures from cosmic rays, from outer space, from radon gas, and from other naturally radioactive elements in the earth. This is called natural background radiation. It includes the radiation we get from plants, animals, and from our own bodies. We also are exposed to man-made sources of radiation, including medical and dental treatments, television sets and emission from coal-fired power plants. Generally, radiation exposures from man-made sources are only a fraction of those received from natural sources. One exception is high exposures used by doctors to treat cancer patients. Each year in the United States, the average dose to people from natural and man-made radiation sources is about 360 millirem. A millirem is an extremely tiny amount of energy absorbed by tissues in the body.

  4. Temperature averaging thermal probe

    NASA Technical Reports Server (NTRS)

    Kalil, L. F.; Reinhardt, V. (Inventor)

    1985-01-01

    A thermal probe to average temperature fluctuations over a prolonged period was formed with a temperature sensor embedded inside a solid object of a thermally conducting material. The solid object is held in a position equidistantly spaced apart from the interior surfaces of a closed housing by a mount made of a thermally insulating material. The housing is sealed to trap a vacuum or mass of air inside and thereby prevent transfer of heat directly between the environment outside of the housing and the solid object. Electrical leads couple the temperature sensor with a connector on the outside of the housing. Other solid objects of different sizes and materials may be substituted for the cylindrically-shaped object to vary the time constant of the probe.

  5. Temperature averaging thermal probe

    NASA Astrophysics Data System (ADS)

    Kalil, L. F.; Reinhardt, V.

    1985-12-01

    A thermal probe to average temperature fluctuations over a prolonged period was formed with a temperature sensor embedded inside a solid object of a thermally conducting material. The solid object is held in a position equidistantly spaced apart from the interior surfaces of a closed housing by a mount made of a thermally insulating material. The housing is sealed to trap a vacuum or mass of air inside and thereby prevent transfer of heat directly between the environment outside of the housing and the solid object. Electrical leads couple the temperature sensor with a connector on the outside of the housing. Other solid objects of different sizes and materials may be substituted for the cylindrically-shaped object to vary the time constant of the probe.

  6. Neuroscience of glucose homeostasis.

    PubMed

    La Fleur, S E; Fliers, E; Kalsbeek, A

    2014-01-01

    Plasma glucose concentrations are homeostatically regulated and maintained within strict boundaries. Several mechanisms are in place to increase glucose output when glucose levels in the circulation drop as a result of glucose utilization, or to decrease glucose output and increase tissue glucose uptake to prevent hyperglycemia. Although the term homeostasis mostly refers to stable levels, the blood glucose concentrations fluctuate over the day/night cycle, with the highest concentrations occurring just prior to the activity period in anticipation of increased caloric need. In this chapter we describe how the brain, particularly the hypothalamus, is involved in both the daily rhythm of plasma glucose concentrations and acute glucose challenges.

  7. Dissociating Averageness and Attractiveness: Attractive Faces Are Not Always Average

    ERIC Educational Resources Information Center

    DeBruine, Lisa M.; Jones, Benedict C.; Unger, Layla; Little, Anthony C.; Feinberg, David R.

    2007-01-01

    Although the averageness hypothesis of facial attractiveness proposes that the attractiveness of faces is mostly a consequence of their averageness, 1 study has shown that caricaturing highly attractive faces makes them mathematically less average but more attractive. Here the authors systematically test the averageness hypothesis in 5 experiments…

  8. Low Blood Glucose (Hypoglycemia)

    MedlinePlus

    ... Dental Problems Diabetes & Sexual & Urologic Problems Low Blood Glucose (Hypoglycemia) What is hypoglycemia? Hypoglycemia, also called low ... actions can also help prevent hypoglycemia: Check blood glucose levels Knowing your blood glucose level can help ...

  9. Monitoring breath during oral glucose tolerance tests.

    PubMed

    Ghimenti, S; Tabucchi, S; Lomonaco, T; Di Francesco, F; Fuoco, R; Onor, M; Lenzi, S; Trivella, M G

    2013-03-01

    The evolution of breath composition during oral glucose tolerance tests (OGTTs) was analysed by thermal desorption/gas chromatography/mass spectrometry in 16 subjects and correlated to blood glucose levels. The glucose tolerance tests classified five of the subjects as diabetics, eight as affected by impaired glucose tolerance and three as normoglycaemic. Acetone levels were generally higher in diabetics (average concentration values: diabetics, 300 ± 40 ppbv; impaired glucose tolerance, 350 ± 30 ppbv; normoglycaemic, 230 ± 20 ppbv) but the large inter-individual variability did not allow us to identify the three groups by this parameter alone. The exhalation of 3-hydroxy-butan-2-one and butane-2,3-dione, likely due to the metabolization of glucose by bacteria in the mouth, was also observed. Future work will involve the extension of the analyses to other volatile compounds by attempting to improve the level of discrimination between the various classes of subjects.

  10. Blood Test: Glucose

    MedlinePlus

    ... Your 1- to 2-Year-Old Blood Test: Glucose KidsHealth > For Parents > Blood Test: Glucose A A A What's in this article? What ... de sangre: glucosa What It Is A blood glucose test measures the amount of glucose (the main ...

  11. Blood Test: Glucose

    MedlinePlus

    ... TV, Video Games, and the Internet Blood Test: Glucose KidsHealth > For Parents > Blood Test: Glucose Print A A A What's in this article? ... de sangre: glucosa What It Is A blood glucose test measures the amount of glucose (the main ...

  12. CSF glucose test

    MedlinePlus

    Glucose test - CSF; Cerebrospinal fluid glucose test ... The glucose level in the CSF should be 50 to 80 mg/100 mL (or greater than 2/3 ... Abnormal results include higher and lower glucose levels. Abnormal ... or fungus) Inflammation of the central nervous system Tumor

  13. Alternatives to the Moving Average

    Treesearch

    Paul C. van Deusen

    2001-01-01

    There are many possible estimators that could be used with annual inventory data. The 5-year moving average has been selected as a default estimator to provide initial results for states having available annual inventory data. User objectives for these estimates are discussed. The characteristics of a moving average are outlined. It is shown that moving average...

  14. Toward a Continuous Intravascular Glucose Monitoring System

    PubMed Central

    Beier, Brooke; Musick, Katherine; Matsumoto, Akira; Panitch, Alyssa; Nauman, Eric; Irazoqui, Pedro

    2011-01-01

    Proof-of-concept studies that display the potential of using a glucose-sensitive hydrogel as a continuous glucose sensor are presented. The swelling ratio, porosity, and diffusivity of the hydrogel increased with glucose concentration. In glucose solutions of 50, 100, 200, and 300 mg/dL, the hydrogel swelling ratios were 4.9, 12.3, 15.9, and 21.7, respectively, and the swelling was reversible. The impedance across the hydrogel depended solely on the thickness and had an average increase of 47 Ω/mm. The hydrogels exposed to a hyperglycemic solution were more porous than the hydrogels exposed to a normal glycemic solution. The diffusivity of 390 Da MW fluorescein isothiocyanate in hydrogels exposed to normal and hyperglycemic solutions was examined using fluorescence recovery after photobleaching and was found to be 9.3 × 10−14 and 41.4 × 10−14 m2/s, respectively, compared to 6.2 × 10−10 m2/s in glucose solution. There was no significant difference between the permeability of hydrogels in normal and hyperglycemic glucose solutions with averages being 5.26 × 10−17 m2 and 5.80 × 10−17 m2, respectively, which resembles 2–4% agarose gels. A prototype design is presented for continuous intravascular glucose monitoring by attaching a glucose sensor to an FDA-approved stent. PMID:22344366

  15. Averaging Models: Parameters Estimation with the R-Average Procedure

    ERIC Educational Resources Information Center

    Vidotto, G.; Massidda, D.; Noventa, S.

    2010-01-01

    The Functional Measurement approach, proposed within the theoretical framework of Information Integration Theory (Anderson, 1981, 1982), can be a useful multi-attribute analysis tool. Compared to the majority of statistical models, the averaging model can account for interaction effects without adding complexity. The R-Average method (Vidotto &…

  16. The Average of Rates and the Average Rate.

    ERIC Educational Resources Information Center

    Lindstrom, Peter

    1988-01-01

    Defines arithmetic, harmonic, and weighted harmonic means, and discusses their properties. Describes the application of these properties in problems involving fuel economy estimates and average rates of motion. Gives example problems and solutions. (CW)

  17. The Average of Rates and the Average Rate.

    ERIC Educational Resources Information Center

    Lindstrom, Peter

    1988-01-01

    Defines arithmetic, harmonic, and weighted harmonic means, and discusses their properties. Describes the application of these properties in problems involving fuel economy estimates and average rates of motion. Gives example problems and solutions. (CW)

  18. Your Glucose Meter

    MedlinePlus

    ... Audience For Women Women's Health Topics Your Glucose Meter Share Tweet Linkedin Pin it More sharing options ... Testing Your Blood Sugar and Caring for Your Meter Glucose meters test and record how much sugar ( ...

  19. Glucose test (image)

    MedlinePlus

    ... person with diabetes constantly manages their blood's sugar (glucose) levels. After a blood sample is taken and tested, it is determined whether the glucose levels are low or high. Following your health ...

  20. Glucose-6-phosphate dehydrogenase

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003671.htm Glucose-6-phosphate dehydrogenase test To use the sharing features on this page, please enable JavaScript. Glucose-6-phosphate dehydrogenase (G6PD) is a protein that ...

  1. All about Blood Glucose

    MedlinePlus

    Toolkit No. 15 All About Blood Glucose Keeping your blood glucose (sugar)in your target range can prevent or delay the health problems ... Diabetes Association, Inc. 1/15 Toolkit No.15: All About Blood Glucose continued team about when and ...

  2. Ambulatory glucose profile: Flash glucose monitoring.

    PubMed

    Kalra, Sanjay; Gupta, Yashdeep

    2015-12-01

    Ambulatory glucose profile (AGP) is a novel way of assessing glycaemic levels on a 24 hour basis, through a minimally invasive method, known as flash glucose monitoring. This review describes the unique features of AGP, differentiates it from existing methods of glucose monitoring, and explains how it helps pursue the glycaemic pentad. The review suggests pragmatic usage of this technology, including pre-test, intra-test, and post-test counselling, and lists specific clinical scenarios where the investigation seems to be of immense benefit.

  3. High average power pockels cell

    DOEpatents

    Daly, Thomas P.

    1991-01-01

    A high average power pockels cell is disclosed which reduces the effect of thermally induced strains in high average power laser technology. The pockels cell includes an elongated, substantially rectangular crystalline structure formed from a KDP-type material to eliminate shear strains. The X- and Y-axes are oriented substantially perpendicular to the edges of the crystal cross-section and to the C-axis direction of propagation to eliminate shear strains.

  4. The correlation of hemoglobin A1c to blood glucose.

    PubMed

    Sikaris, Ken

    2009-05-01

    The understanding that hemoglobin A1c (HbA1c) represents the average blood glucose level of patients over the previous 120 days underlies the current management of diabetes. Even in making such a statement, we speak of "average blood glucose" as though "blood glucose" were itself a simple idea. When we consider all the blood glucose forms-arterial versus venous versus capillary, whole blood versus serum versus fluoride-preserved plasma, fasting versus nonfasting-we can start to see that this is not a simple issue. Nevertheless, it seems as though HbA1c correlates to any single glucose measurement. Having more than one measurement and taking those measurements in the preceding month improves the correlation further. In particular, by having glucose measurements that reflect both the relatively lower overnight glucose levels and measurements that reflect the postprandial peaks improves not only our ability to manage diabetes patients, but also our understanding of how HbA1c levels are determined. Modern continuous glucose monitoring (CGM) devices may take thousands of glucose results over a week. Several studies have shown that CGM glucose averages account for the vast proportion of the variation of HbA1c. The ability to relate HbA1c to average glucose may become a popular method for reporting HbA1c, eliminating current concerns regarding differences in HbA1c standardization. Hemoglobin A1c expressed as an average glucose may be more understandable to patients and improve not only their understanding, but also their ability to improve their diabetes management. 2009 Diabetes Technology Society.

  5. Determining GPS average performance metrics

    NASA Technical Reports Server (NTRS)

    Moore, G. V.

    1995-01-01

    Analytic and semi-analytic methods are used to show that users of the GPS constellation can expect performance variations based on their location. Specifically, performance is shown to be a function of both altitude and latitude. These results stem from the fact that the GPS constellation is itself non-uniform. For example, GPS satellites are over four times as likely to be directly over Tierra del Fuego than over Hawaii or Singapore. Inevitable performance variations due to user location occur for ground, sea, air and space GPS users. These performance variations can be studied in an average relative sense. A semi-analytic tool which symmetrically allocates GPS satellite latitude belt dwell times among longitude points is used to compute average performance metrics. These metrics include average number of GPS vehicles visible, relative average accuracies in the radial, intrack and crosstrack (or radial, north/south, east/west) directions, and relative average PDOP or GDOP. The tool can be quickly changed to incorporate various user antenna obscuration models and various GPS constellation designs. Among other applications, tool results can be used in studies to: predict locations and geometries of best/worst case performance, design GPS constellations, determine optimal user antenna location and understand performance trends among various users.

  6. Vocal attractiveness increases by averaging.

    PubMed

    Bruckert, Laetitia; Bestelmeyer, Patricia; Latinus, Marianne; Rouger, Julien; Charest, Ian; Rousselet, Guillaume A; Kawahara, Hideki; Belin, Pascal

    2010-01-26

    Vocal attractiveness has a profound influence on listeners-a bias known as the "what sounds beautiful is good" vocal attractiveness stereotype [1]-with tangible impact on a voice owner's success at mating, job applications, and/or elections. The prevailing view holds that attractive voices are those that signal desirable attributes in a potential mate [2-4]-e.g., lower pitch in male voices. However, this account does not explain our preferences in more general social contexts in which voices of both genders are evaluated. Here we show that averaging voices via auditory morphing [5] results in more attractive voices, irrespective of the speaker's or listener's gender. Moreover, we show that this phenomenon is largely explained by two independent by-products of averaging: a smoother voice texture (reduced aperiodicities) and a greater similarity in pitch and timbre with the average of all voices (reduced "distance to mean"). These results provide the first evidence for a phenomenon of vocal attractiveness increases by averaging, analogous to a well-established effect of facial averaging [6, 7]. They highlight prototype-based coding [8] as a central feature of voice perception, emphasizing the similarity in the mechanisms of face and voice perception. Copyright 2010 Elsevier Ltd. All rights reserved.

  7. Determining GPS average performance metrics

    NASA Technical Reports Server (NTRS)

    Moore, G. V.

    1995-01-01

    Analytic and semi-analytic methods are used to show that users of the GPS constellation can expect performance variations based on their location. Specifically, performance is shown to be a function of both altitude and latitude. These results stem from the fact that the GPS constellation is itself non-uniform. For example, GPS satellites are over four times as likely to be directly over Tierra del Fuego than over Hawaii or Singapore. Inevitable performance variations due to user location occur for ground, sea, air and space GPS users. These performance variations can be studied in an average relative sense. A semi-analytic tool which symmetrically allocates GPS satellite latitude belt dwell times among longitude points is used to compute average performance metrics. These metrics include average number of GPS vehicles visible, relative average accuracies in the radial, intrack and crosstrack (or radial, north/south, east/west) directions, and relative average PDOP or GDOP. The tool can be quickly changed to incorporate various user antenna obscuration models and various GPS constellation designs. Among other applications, tool results can be used in studies to: predict locations and geometries of best/worst case performance, design GPS constellations, determine optimal user antenna location and understand performance trends among various users.

  8. Evaluations of average level spacings

    SciTech Connect

    Liou, H.I.

    1980-01-01

    The average level spacing for highly excited nuclei is a key parameter in cross section formulas based on statistical nuclear models, and also plays an important role in determining many physics quantities. Various methods to evaluate average level spacings are reviewed. Because of the finite experimental resolution, to detect a complete sequence of levels without mixing other parities is extremely difficult, if not totally impossible. Most methods derive the average level spacings by applying a fit, with different degrees of generality, to the truncated Porter-Thomas distribution for reduced neutron widths. A method that tests both distributions of level widths and positions is discussed extensivey with an example of /sup 168/Er data. 19 figures, 2 tables.

  9. Vibrational averages along thermal lines

    NASA Astrophysics Data System (ADS)

    Monserrat, Bartomeu

    2016-01-01

    A method is proposed for the calculation of vibrational quantum and thermal expectation values of physical properties from first principles. Thermal lines are introduced: these are lines in configuration space parametrized by temperature, such that the value of any physical property along them is approximately equal to the vibrational average of that property. The number of sampling points needed to explore the vibrational phase space is reduced by up to an order of magnitude when the full vibrational density is replaced by thermal lines. Calculations of the vibrational averages of several properties and systems are reported, namely, the internal energy and the electronic band gap of diamond and silicon, and the chemical shielding tensor of L-alanine. Thermal lines pave the way for complex calculations of vibrational averages, including large systems and methods beyond semilocal density functional theory.

  10. Polyhedral Painting with Group Averaging

    ERIC Educational Resources Information Center

    Farris, Frank A.; Tsao, Ryan

    2016-01-01

    The technique of "group-averaging" produces colorings of a sphere that have the symmetries of various polyhedra. The concepts are accessible at the undergraduate level, without being well-known in typical courses on algebra or geometry. The material makes an excellent discovery project, especially for students with some background in…

  11. Polyhedral Painting with Group Averaging

    ERIC Educational Resources Information Center

    Farris, Frank A.; Tsao, Ryan

    2016-01-01

    The technique of "group-averaging" produces colorings of a sphere that have the symmetries of various polyhedra. The concepts are accessible at the undergraduate level, without being well-known in typical courses on algebra or geometry. The material makes an excellent discovery project, especially for students with some background in…

  12. Averaging inhomogenous cosmologies - a dialogue

    NASA Astrophysics Data System (ADS)

    Buchert, T.

    The averaging problem for inhomogeneous cosmologies is discussed in the form of a disputation between two cosmologists, one of them (RED) advocating the standard model, the other (GREEN) advancing some arguments against it. Technical explanations of these arguments as well as the conclusions of this debate are given by BLUE.

  13. Averaging inhomogeneous cosmologies - a dialogue.

    NASA Astrophysics Data System (ADS)

    Buchert, T.

    The averaging problem for inhomogeneous cosmologies is discussed in the form of a disputation between two cosmologists, one of them (RED) advocating the standard model, the other (GREEN) advancing some arguments against it. Technical explanations of these arguments as well as the conclusions of this debate are given by BLUE.

  14. Spatial moving average risk smoothing.

    PubMed

    Botella-Rocamora, P; López-Quílez, A; Martinez-Beneito, M A

    2013-07-10

    This paper introduces spatial moving average risk smoothing (SMARS) as a new way of carrying out disease mapping. This proposal applies the moving average ideas of time series theory to the spatial domain, making use of a spatial moving average process of unknown order to define dependence on the risk of a disease occurring. Correlation of the risks for different locations will be a function of m values (m being unknown), providing a rich class of correlation functions that may be reproduced by SMARS. Moreover, the distance (in terms of neighborhoods) that should be covered for two units to be found to make the correlation of their risks 0 is a quantity to be fitted by the model. This way, we reproduce patterns that range from spatially independent to long-range spatially dependent. We will also show a theoretical study of the correlation structure induced by SMARS, illustrating the wide variety of correlation functions that this proposal is able to reproduce. We will also present three applications of SMARS to both simulated and real datasets. These applications will show SMARS to be a competitive disease mapping model when compared with alternative proposals that have already appeared in the literature. Finally, the application of SMARS to the study of mortality for 21 causes of death in the Comunitat Valenciana will allow us to identify some qualitative differences in the patterns of those diseases. Copyright © 2012 John Wiley & Sons, Ltd.

  15. GLUT2, glucose sensing and glucose homeostasis.

    PubMed

    Thorens, Bernard

    2015-02-01

    The glucose transporter isoform GLUT2 is expressed in liver, intestine, kidney and pancreatic islet beta cells, as well as in the central nervous system, in neurons, astrocytes and tanycytes. Physiological studies of genetically modified mice have revealed a role for GLUT2 in several regulatory mechanisms. In pancreatic beta cells, GLUT2 is required for glucose-stimulated insulin secretion. In hepatocytes, suppression of GLUT2 expression revealed the existence of an unsuspected glucose output pathway that may depend on a membrane traffic-dependent mechanism. GLUT2 expression is nevertheless required for the physiological control of glucose-sensitive genes, and its inactivation in the liver leads to impaired glucose-stimulated insulin secretion, revealing a liver-beta cell axis, which is likely to be dependent on bile acids controlling beta cell secretion capacity. In the nervous system, GLUT2-dependent glucose sensing controls feeding, thermoregulation and pancreatic islet cell mass and function, as well as sympathetic and parasympathetic activities. Electrophysiological and optogenetic techniques established that Glut2 (also known as Slc2a2)-expressing neurons of the nucleus tractus solitarius can be activated by hypoglycaemia to stimulate glucagon secretion. In humans, inactivating mutations in GLUT2 cause Fanconi-Bickel syndrome, which is characterised by hepatomegaly and kidney disease; defects in insulin secretion are rare in adult patients, but GLUT2 mutations cause transient neonatal diabetes. Genome-wide association studies have reported that GLUT2 variants increase the risks of fasting hyperglycaemia, transition to type 2 diabetes, hypercholesterolaemia and cardiovascular diseases. Individuals with a missense mutation in GLUT2 show preference for sugar-containing foods. We will discuss how studies in mice help interpret the role of GLUT2 in human physiology.

  16. The glucose oxidase-peroxidase assay for glucose

    USDA-ARS?s Scientific Manuscript database

    The glucose oxidase-peroxidase assay for glucose has served as a very specific, sensitive, and repeatable assay for detection of glucose in biological samples. It has been used successfully for analysis of glucose in samples from blood and urine, to analysis of glucose released from starch or glycog...

  17. Averaging Robertson-Walker cosmologies

    SciTech Connect

    Brown, Iain A.; Robbers, Georg; Behrend, Juliane E-mail: G.Robbers@thphys.uni-heidelberg.de

    2009-04-15

    The cosmological backreaction arises when one directly averages the Einstein equations to recover an effective Robertson-Walker cosmology, rather than assuming a background a priori. While usually discussed in the context of dark energy, strictly speaking any cosmological model should be recovered from such a procedure. We apply the scalar spatial averaging formalism for the first time to linear Robertson-Walker universes containing matter, radiation and dark energy. The formalism employed is general and incorporates systems of multiple fluids with ease, allowing us to consider quantitatively the universe from deep radiation domination up to the present day in a natural, unified manner. Employing modified Boltzmann codes we evaluate numerically the discrepancies between the assumed and the averaged behaviour arising from the quadratic terms, finding the largest deviations for an Einstein-de Sitter universe, increasing rapidly with Hubble rate to a 0.01% effect for h = 0.701. For the {Lambda}CDM concordance model, the backreaction is of the order of {Omega}{sub eff}{sup 0} Almost-Equal-To 4 Multiplication-Sign 10{sup -6}, with those for dark energy models being within a factor of two or three. The impacts at recombination are of the order of 10{sup -8} and those in deep radiation domination asymptote to a constant value. While the effective equations of state of the backreactions in Einstein-de Sitter, concordance and quintessence models are generally dust-like, a backreaction with an equation of state w{sub eff} < -1/3 can be found for strongly phantom models.

  18. Glucose: detection and analysis

    USDA-ARS?s Scientific Manuscript database

    Glucose is an aldosic monosaccharide that is centrally entrenched in the processes of photosynthesis and respiration, serving as an energy reserve and metabolic fuel in most organisms. As both a monomer and as part of more complex structures such as polysaccharides and glucosides, glucose also pla...

  19. Capillary blood glucose monitoring.

    PubMed

    Wallymahmed, M

    This article, the first in a series of articles relating to clinical skills in nursing, outlines the procedure of capillary blood glucose monitoring. This is a convenient way of monitoring blood glucose patterns and can be a useful aid in guiding treatment changes in patients with type 1 and type 2 diabetes, especially during periods of illness or frequent hypoglycaemia.

  20. The Correlation of Hemoglobin A1c to Blood Glucose

    PubMed Central

    Sikaris, Ken

    2009-01-01

    The understanding that hemoglobin A1c (HbA1c) represents the average blood glucose level of patients over the previous 120 days underlies the current management of diabetes. Even in making such a statement, we speak of “average blood glucose” as though “blood glucose” were itself a simple idea. When we consider all the blood glucose forms—arterial versus venous versus capillary, whole blood versus serum versus fluoride-preserved plasma, fasting versus nonfasting—we can start to see that this is not a simple issue. Nevertheless, it seems as though HbA1c correlates to any single glucose measurement. Having more than one measurement and taking those measurements in the preceding month improves the correlation further. In particular, by having glucose measurements that reflect both the relatively lower overnight glucose levels and measurements that reflect the postprandial peaks improves not only our ability to manage diabetes patients, but also our understanding of how HbA1c levels are determined. Modern continuous glucose monitoring (CGM) devices may take thousands of glucose results over a week. Several studies have shown that CGM glucose averages account for the vast proportion of the variation of HbA1c. The ability to relate HbA1c to average glucose may become a popular method for reporting HbA1c, eliminating current concerns regarding differences in HbA1c standardization. Hemoglobin A1c expressed as an average glucose may be more understandable to patients and improve not only their understanding, but also their ability to improve their diabetes management. PMID:20144279

  1. Pathogenesis of glucose intolerance in uremia.

    PubMed

    DeFronzo, R A

    1978-12-01

    The pathogenesis of glucose intolerance in uremia was examined with the glucose clamp technique. Hyperglycemic clamp (n = 8): The plasma glucose concentration is acutely raised and maintained at 125 mg/dl above basal levels. Under these steady state conditions the glucose infusion rate, M, equals the amount of glucose metabolized: Predialysis M averaged 4.23 +/- 0.36 mg/kg/min and increased to 7.71 +/- 0.43 postdialysis (p less than 0.001). The plasma insulin response predialysis was 90 +/- 20 microU/ml and decreased to 80 +/- 23 microU/ml following dialysis. Consequently the M/l ratio, a measure of tissue sensitivity to insulin, increased by 80% +/- 25% (p less than 0.001) but still remained less than controls (p less than 0.01). Euglycemic insulin clamp (n = 10): The plasma insulin concentration is acutely raised by 100 microU/ml and the plasma glucose concentration is held constant at the basal level. Predialysis both M (3.37 +/- 0.36 mg/kg/min) and M/l (3.56 +/- 0.33 mg/kg/min per microU/ml X 100) were significantly less than controls (p less than 0.01). Postdialysis both M and M/l increased significantly (p less than 0.01) to a mean that was not significantly different from controls. Basal hepatic glucose production (n = 6), 2.15 +/- 0.09 mg/kg/min, was similar to controls and fell (87% +/- 4%) normally during the insulin clamp. In five uremic subjects in wom insulin binding to monocytes was measured, there was no correlation with tissue sensitivity to insulin (M/l). Significant abnormalities in both growth hormone and glucagon physiology were present in uremic individuals, but no correlation with either the presence or degree of glucose intolerance was demonstrable. In conclusion, glucose intolerance is universally present in uremic subjects and results primarily from peripheral tissue insensitivity to insulin. Insulin secretion is usually enhanced in an attempt to compensate for this insulin resistance but in occasional subjects uremia also inhibits beta

  2. Achronal averaged null energy condition

    SciTech Connect

    Graham, Noah; Olum, Ken D.

    2007-09-15

    The averaged null energy condition (ANEC) requires that the integral over a complete null geodesic of the stress-energy tensor projected onto the geodesic tangent vector is never negative. This condition is sufficient to prove many important theorems in general relativity, but it is violated by quantum fields in curved spacetime. However there is a weaker condition, which is free of known violations, requiring only that there is no self-consistent spacetime in semiclassical gravity in which ANEC is violated on a complete, achronal null geodesic. We indicate why such a condition might be expected to hold and show that it is sufficient to rule out closed timelike curves and wormholes connecting different asymptotically flat regions.

  3. Flexible time domain averaging technique

    NASA Astrophysics Data System (ADS)

    Zhao, Ming; Lin, Jing; Lei, Yaguo; Wang, Xiufeng

    2013-09-01

    Time domain averaging(TDA) is essentially a comb filter, it cannot extract the specified harmonics which may be caused by some faults, such as gear eccentric. Meanwhile, TDA always suffers from period cutting error(PCE) to different extent. Several improved TDA methods have been proposed, however they cannot completely eliminate the waveform reconstruction error caused by PCE. In order to overcome the shortcomings of conventional methods, a flexible time domain averaging(FTDA) technique is established, which adapts to the analyzed signal through adjusting each harmonic of the comb filter. In this technique, the explicit form of FTDA is first constructed by frequency domain sampling. Subsequently, chirp Z-transform(CZT) is employed in the algorithm of FTDA, which can improve the calculating efficiency significantly. Since the signal is reconstructed in the continuous time domain, there is no PCE in the FTDA. To validate the effectiveness of FTDA in the signal de-noising, interpolation and harmonic reconstruction, a simulated multi-components periodic signal that corrupted by noise is processed by FTDA. The simulation results show that the FTDA is capable of recovering the periodic components from the background noise effectively. Moreover, it can improve the signal-to-noise ratio by 7.9 dB compared with conventional ones. Experiments are also carried out on gearbox test rigs with chipped tooth and eccentricity gear, respectively. It is shown that the FTDA can identify the direction and severity of the eccentricity gear, and further enhances the amplitudes of impulses by 35%. The proposed technique not only solves the problem of PCE, but also provides a useful tool for the fault symptom extraction of rotating machinery.

  4. Glucose screening tests during pregnancy

    MedlinePlus

    Oral glucose tolerance test - pregnancy; OGTT - pregnancy; Glucose challenge test - pregnancy; Gestational diabetes - glucose screening ... screening test between 24 and 28 weeks of pregnancy. The test may be done earlier if you ...

  5. The average Indian female nose.

    PubMed

    Patil, Surendra B; Kale, Satish M; Jaiswal, Sumeet; Khare, Nishant; Math, Mahantesh

    2011-12-01

    This study aimed to delineate the anthropometric measurements of the noses of young women of an Indian population and to compare them with the published ideals and average measurements for white women. This anthropometric survey included a volunteer sample of 100 young Indian women ages 18 to 35 years with Indian parents and no history of previous surgery or trauma to the nose. Standardized frontal, lateral, oblique, and basal photographs of the subjects' noses were taken, and 12 standard anthropometric measurements of the nose were determined. The results were compared with published standards for North American white women. In addition, nine nasal indices were calculated and compared with the standards for North American white women. The nose of Indian women differs significantly from the white nose. All the nasal measurements for the Indian women were found to be significantly different from those for North American white women. Seven of the nine nasal indices also differed significantly. Anthropometric analysis suggests differences between the Indian female nose and the North American white nose. Thus, a single aesthetic ideal is inadequate. Noses of Indian women are smaller and wider, with a less projected and rounded tip than the noses of white women. This study established the nasal anthropometric norms for nasal parameters, which will serve as a guide for cosmetic and reconstructive surgery in Indian women.

  6. Monitor blood glucose - slideshow

    MedlinePlus

    ... Series—Monitoring blood glucose: Using a self-test meter To use the sharing features on this page, ... 5 out of 5 Overview Set up the meter according to the specific directions that come with ...

  7. Hyperglycemia (High Blood Glucose)

    MedlinePlus

    ... Doctors, Nurses & More Oral Health & Hygiene Women A1C Insulin Pregnancy 8 Tips for Caregivers Health Insurance Health ... glucose happens when the body has too little insulin or when the body can't use insulin ...

  8. Glucose urine test

    MedlinePlus

    Urine sugar test; Urine glucose test; Glucosuria test; Glycosuria test ... After you provide a urine sample, it is tested right away. The health care provider uses a dipstick made with a color-sensitive pad. The ...

  9. Continuous Glucose Monitoring

    MedlinePlus

    ... to download data from the devices to a computer for tracking and analysis of patterns and trends, ... use CGM systems can download data to a computer to see patterns and trends in their glucose ...

  10. Glucose: Detection and analysis.

    PubMed

    Galant, A L; Kaufman, R C; Wilson, J D

    2015-12-01

    Glucose is an aldosic monosaccharide that is centrally entrenched in the processes of photosynthesis and respiration, serving as an energy reserve and metabolic fuel in most organisms. As both a monomer and as part of more complex structures such as polysaccharides and glucosides, glucose also plays a major role in modern food products, particularly where flavor and or structure are concerned. Over the years, many diverse methods for detecting and quantifying glucose have been developed; this review presents an overview of the most widely employed and historically significant, including copper iodometry, HPLC, GC, CZE, and enzyme based systems such as glucose meters. The relative strengths and limitations of each method are evaluated, and examples of their recent application in the realm of food chemistry are discussed.

  11. Vascular Glucose Sensor Symposium

    PubMed Central

    Joseph, Jeffrey I; Torjman, Marc C.; Strasma, Paul J.

    2015-01-01

    Hyperglycemia, hypoglycemia, and glycemic variability have been associated with increased morbidity, mortality, length of stay, and cost in a variety of critical care and non–critical care patient populations in the hospital. The results from prospective randomized clinical trials designed to determine the risks and benefits of intensive insulin therapy and tight glycemic control have been confusing; and at times conflicting. The limitations of point-of-care blood glucose (BG) monitoring in the hospital highlight the great clinical need for an automated real-time continuous glucose monitoring system (CGMS) that can accurately measure the concentration of glucose every few minutes. Automation and standardization of the glucose measurement process have the potential to significantly improve BG control, clinical outcome, safety and cost. PMID:26078254

  12. Recombinant glucose uptake system

    DOEpatents

    Ingrahm, Lonnie O.; Snoep, Jacob L.; Arfman, Nico

    1997-01-01

    Recombinant organisms are disclosed that contain a pathway for glucose uptake other than the pathway normally utilized by the host cell. In particular, the host cell is one in which glucose transport into the cell normally is coupled to PEP production. This host cell is transformed so that it uses an alternative pathway for glucose transport that is not coupled to PEP production. In a preferred embodiment, the host cell is a bacterium other than Z. mobilis that has been transformed to contain the glf and glk genes of Z. mobilis. By uncoupling glucose transport into the cell from PEP utilization, more PEP is produced for synthesis of products of commercial importance from a given quantity of biomass supplied to the host cells.

  13. An acoustic glucose sensor.

    PubMed

    Hu, Ruifen; Stevenson, Adrian C; Lowe, Christopher R

    2012-05-15

    In vivo glucose monitoring is required for tighter glycaemic control. This report describes a new approach to construct a miniature implantable device based on a magnetic acoustic resonance sensor (MARS). A ≈ 600-800 nm thick glucose-responsive poly(acrylamide-co-3-acrylamidophenylboronic acid) (poly(acrylamide-co-3-APB)) film was polymerised on the quartz disc (12 mm in diameter and 0.25 mm thick) of the MARS. The swelling/shrinking of the polymer film induced by the glucose binding to the phenylboronate caused changes in the resonance amplitude of the quartz disc in the MARS. A linear relationship between the response of the MARS and the glucose concentration in the range ≈ 0-15 mM was observed, with the optimum response of the MARS sensor being obtained when the polymer films contained ≈ 20 mol% 3-APB. The MARS glucose sensor also functioned under flow conditions (9 μl/min) with a response almost identical to the sensor under static or non-flow conditions. The results suggest that the MARS could offer a promising strategy for developing a small subcutaneously implanted continuous glucose monitor.

  14. Benefits of glucose and oxygen in multidose cold cardioplegia.

    PubMed

    Doherty, N E; Turocy, J F; Geffin, G A; O'Keefe, D D; Titus, J S; Daggett, W M

    1992-02-01

    We tested the effects of glucose and oxygen in cardioplegic solutions on myocardial protection in the isolated perfused working rat heart. Recovery from 2 hours' hypothermic (8 degrees C) cardioplegic arrest was examined in 93 hearts. Cardioplegic solution, which was delivered every 15 minutes, was supplemented with glucose 28 mmol/L as a substrate or sucrose 28 mmol/L as a nonmetabolizable osmotic control; it was equilibrated with either 98% oxygen or 98% nitrogen, both with 2% carbon dioxide. Four combinations of hyperkalemic cardioplegic solution were studied: nitrogen-sucrose, nitrogen-glucose, oxygen-sucrose, and oxygen-glucose. During hypothermic arrest, oxygenation of cardioplegic solution greatly reduced myocardial lactate production and prevented ischemic contracture as indicated by coronary vascular resistance. Glucose increased lactate production modestly but significantly only when the cardioplegic solution was nitrogenated. Although end-arrest myocardial adenosine triphosphate and creatine phosphate were greatly increased by oxygenation of cardioplegic solution (p less than 0.005), we could not detect improved preservation of these high-energy phosphates by glucose. Averaged over reperfusion, percent recovery of cardiac output for the nitrogen-sucrose, nitrogen-glucose, oxygen-sucrose, and oxygen-glucose solutions was 32.3% +/- 6.1%, 45.9% +/- 4.6%, 44.5% +/- 4.6%, and 62.2% +/- 4.5%, respectively. Oxygenation of the glucose solution or addition of glucose to the oxygenated solution significantly improved recovery of cardiac output. The benefits of glucose and oxygen were additive, so that the oxygen-glucose cardioplegic solution provided the best functional recovery. We conclude that the addition of glucose to the fully oxygenated multidose cold cardioplegic solution improves functional recovery without increasing lactate production during arrest.

  15. A glucose sensor protein for continuous glucose monitoring.

    PubMed

    Veetil, Jithesh V; Jin, Sha; Ye, Kaiming

    2010-12-15

    In vivo continuous glucose monitoring has posed a significant challenge to glucose sensor development due to the lack of reliable techniques that are non- or at least minimally-invasive. In this proof-of-concept study, we demonstrated the development of a new glucose sensor protein, AcGFP1-GBPcys-mCherry, and an optical sensor assembly, capable of generating quantifiable FRET (fluorescence resonance energy transfer) signals for glucose monitoring. Our experimental data showed that the engineered glucose sensor protein can generate measurable FRET signals in response to glucose concentrations varying from 25 to 800 μM. The sensor developed based on this protein had a shelf-life of up to 3 weeks. The sensor response was devoid of interference from compounds like galactose, fructose, lactose, mannose, and mannitol when tested at physiologically significant concentrations of these compounds. This new glucose sensor protein can potentially be used to develop implantable glucose sensors for continuous glucose monitoring.

  16. Sodium-glucose cotransport

    PubMed Central

    Poulsen, Søren Brandt; Fenton, Robert A.; Rieg, Timo

    2017-01-01

    Purpose of review Sodium-glucose cotransporters (SGLTs) are important mediators of glucose uptake across apical cell membranes. SGLT1 mediates almost all sodium-dependent glucose uptake in the small intestine, while in the kidney SGLT2, and to a lesser extent SGLT1, account for more than 90% and nearly 3%, respectively, of glucose reabsorption from the glomerular ultrafiltrate. Although the recent availability of SGLT2 inhibitors for the treatment of diabetes mellitus has increased the number of clinical studies, this review has a focus on mechanisms contributing to the cellular regulation of SGLTs. Recent findings Studies have focused on the regulation of SGLT expression under different physiological/pathophysiological conditions, for example diet, age or diabetes mellitus. Several studies provide evidence of SGLT regulation via cyclic adenosine monophosphate/protein kinase A, protein kinase C, glucagon-like peptide 2, insulin, leptin, signal transducer and activator of transcription-3 (STAT3), phosphoinositide-3 kinase (PI3K)/Akt, mitogen-activated protein kinases (MAPKs), nuclear factor-kappaB (NF-kappaB), with-no-K[Lys] kinases/STE20/SPS1-related proline/alanine-rich kinase (Wnk/SPAK) and regulatory solute carrier protein 1 (RS1) pathways. Summary SGLT inhibitors are important drugs for glycemic control in diabetes mellitus. Although the contribution of SGLT1 for absorption of glucose from the intestine as well as SGLT2/SGLT1 for renal glucose reabsorption has been comprehensively defined, this review provides an up-to-date outline for the mechanistic regulation of SGLT1/SGLT2. PMID:26125647

  17. Continuous Glucose Monitoring

    PubMed Central

    Fritschi, Cynthia; Quinn, Laurie; Penckofer, Sue; Surdyk, Patricia M.

    2010-01-01

    Purpose The purpose of this descriptive study was to document the experience of wearing a continuous glucose monitoring (CGM) device in women with type 2 diabetes (T2DM). The availability of CGM has provided patients and clinicians with the opportunity to describe the immediate effects of diet, exercise, and medications on blood glucose levels; however, there are few data examining patients’ experiences and acceptability of using CGM. Methods Thirty-five women with T2DM wore a CGM for 3 days. Semistructured interviews were conducted to capture the self-described experience of wearing a CGM. Three open-ended questions were used to guide the participants’ self-reflection. Interviews were transcribed and analyzed. Results The women verbalized both positive and negative aspects of needing to check their blood glucose more frequently and wearing the monitor. After viewing the results, most women were surprised by the magnitude and frequency of blood glucose excursions. They immediately examined their behaviors during the time they wore the CGM. Independent problem-solving skills became apparent as they attempted to identify reasons for hyperglycemia by retracing food intake, physical activity, and stress experiences during the period of CGM. Most important, the majority of women stated they were interested in changing their diabetes-related self-care behaviors, especially eating and exercise behaviors, after reviewing their CGM results. Conclusions CGM is generally acceptable to women with T2DM and offers patients and their health care practitioners a possible alternative to routine glucose monitoring for assessing the effects of real-life events on blood glucose levels. PMID:20016057

  18. Redundancy in Glucose Sensing

    PubMed Central

    Sharifi, Amin; Varsavsky, Andrea; Ulloa, Johanna; Horsburgh, Jodie C.; McAuley, Sybil A.; Krishnamurthy, Balasubramanian; Jenkins, Alicia J.; Colman, Peter G.; Ward, Glenn M.; MacIsaac, Richard J.; Shah, Rajiv; O’Neal, David N.

    2015-01-01

    Background: Current electrochemical glucose sensors use a single electrode. Multiple electrodes (redundancy) may enhance sensor performance. We evaluated an electrochemical redundant sensor (ERS) incorporating two working electrodes (WE1 and WE2) onto a single subcutaneous insertion platform with a processing algorithm providing a single real-time continuous glucose measure. Methods: Twenty-three adults with type 1 diabetes each wore two ERSs concurrently for 168 hours. Post-insertion a frequent sampling test (FST) was performed with ERS benchmarked against a glucose meter (Bayer Contour Link). Day 4 and 7 FSTs were performed with a standard meal and venous blood collected for reference glucose measurements (YSI and meter). Between visits, ERS was worn with capillary blood glucose testing ≥8 times/day. Sensor glucose data were processed prospectively. Results: Mean absolute relative deviation (MARD) for ERS day 1-7 (3,297 paired points with glucose meter) was (mean [SD]) 10.1 [11.5]% versus 11.4 [11.9]% for WE1 and 12.0 [11.9]% for WE2; P < .0001. ERS Clarke A and A+B were 90.2% and 99.8%, respectively. ERS day 4 plus day 7 MARD (1,237 pairs with YSI) was 9.4 [9.5]% versus 9.6 [9.7]% for WE1 and 9.9 [9.7]% for WE2; P = ns. ERS day 1-7 precision absolute relative deviation (PARD) was 9.9 [3.6]% versus 11.5 [6.2]% for WE1 and 10.1 [4.4]% for WE2; P = ns. ERS sensor display time was 97.8 [6.0]% versus 91.0 [22.3]% for WE1 and 94.1 [14.3]% for WE2; P < .05. Conclusions: Electrochemical redundancy enhances glucose sensor accuracy and display time compared with each individual sensing element alone. ERS performance compares favorably with ‘best-in-class’ of non-redundant sensors. PMID:26499476

  19. Weighted south-wide average pulpwood prices

    Treesearch

    James E. Granskog; Kevin D. Growther

    1991-01-01

    Weighted average prices provide a more accurate representation of regional pulpwood price trends when production volumes valy widely by state. Unweighted South-wide average delivered prices for pulpwood, as reported by Timber Mart-South, were compared to average annual prices weighted by each state's pulpwood production from 1977 to 1986. Weighted average prices...

  20. SY 10-1 RENAL GLUCOSE HANDLING AND SGLT2.

    PubMed

    Poudel, Resham

    2016-09-01

    The kidneys maintain glucose homeostasis through its utilization, gluconeogenesis, and reabsorption. Glucose is freely filtered and reabsorbed in order to retain energy essential between meals. The amount of glucose reabsorbed by the kidneys is equivalent to the amount entering the filtration system. With a daily glomerular filtration rate of 180 L, approximately 180 g (180 L/day × 100 mg/dL) of glucose must be reabsorbed each day to maintain an average fasting plasma glucose concentration of 5.6 mmol/L (100 mg/dL). The reabsorption increases with increase in plasma glucose concentration up to approximately 11 mmol/L (198 mg/dL). At this threshold level, the system becomes saturated and the maximal resabsorption rate-the glucose transport maximum (Tm G ) is reached. No more glucose can be absorbed, and the kidneys begin excreting it in the urine-the beginning of glycosuria. Reabsorption of glucose occurs mainly in the proximal tubule and is mediated by 2 different transport proteins, Sodium Glucose Cotransporter (SGLT)1 and SGLT2. SGLT1, which are found in the straight section of the proximal tubule (S3), are responsible for approximately 10% of glucose reabsorption. The other 90% of filtered glucose is reabsorbed through by SGLT2, which are located in the convoluted section on the proximal tubule (S1). The SGLT2 are located on the luminal side of the early proximal tubule S1 segment. Absorption of sodium across the cell membrane creates an energy gradient that in turn allows glucose to be absorbed. On the other side of the cell, sodium is reabsorbed through sodium-potassium ATPase pump into the bloodstream. The concentration gradient within the cell, resulting from this exchange drives glucose reabsorption into the bloodstream via the Glucose transporter (GLUT) 2. The role of kidneys in glucose regulation has been well recognized in the recent years, and inhibition of glucose reabsorption by SGLT2 inhibitors has evolved as a promising target for

  1. Glucose Tolerance and Hyperkinesis.

    ERIC Educational Resources Information Center

    Langseth, Lillian; Dowd, Judith

    Examined were medical records of 265 hyperkinetic children (7-9 years old). Clinical blood chemistries, hematology, and 5-hour glucose tolerance test (GTT) results indicated that hematocrit levels were low in 27% of the Ss, eosinophil levels were abnormally high in 86% of the Ss, and GTT results were abnormal in a maority of Ss. (CL)

  2. Glucose Tolerance and Hyperkinesis.

    ERIC Educational Resources Information Center

    Langseth, Lillian; Dowd, Judith

    Examined were medical records of 265 hyperkinetic children (7-9 years old). Clinical blood chemistries, hematology, and 5-hour glucose tolerance test (GTT) results indicated that hematocrit levels were low in 27% of the Ss, eosinophil levels were abnormally high in 86% of the Ss, and GTT results were abnormal in a maority of Ss. (CL)

  3. Continuous Glucose Monitoring

    MedlinePlus

    ... to reduce the burden of monitoring and managing blood glucose. An artificial pancreas based on mechanical devices requires at least ... MiniMed Paradigm REAL-Time System—is not an artificial pancreas, but it does ... pricking a fingertip to obtain a blood sample and using a glu cose meter to ...

  4. Below-Average, Average, and Above-Average Readers Engage Different and Similar Brain Regions while Reading

    ERIC Educational Resources Information Center

    Molfese, Dennis L.; Key, Alexandra Fonaryova; Kelly, Spencer; Cunningham, Natalie; Terrell, Shona; Ferguson, Melissa; Molfese, Victoria J.; Bonebright, Terri

    2006-01-01

    Event-related potentials (ERPs) were recorded from 27 children (14 girls, 13 boys) who varied in their reading skill levels. Both behavior performance measures recorded during the ERP word classification task and the ERP responses themselves discriminated between children with above-average, average, and below-average reading skills. ERP…

  5. Below-Average, Average, and Above-Average Readers Engage Different and Similar Brain Regions while Reading

    ERIC Educational Resources Information Center

    Molfese, Dennis L.; Key, Alexandra Fonaryova; Kelly, Spencer; Cunningham, Natalie; Terrell, Shona; Ferguson, Melissa; Molfese, Victoria J.; Bonebright, Terri

    2006-01-01

    Event-related potentials (ERPs) were recorded from 27 children (14 girls, 13 boys) who varied in their reading skill levels. Both behavior performance measures recorded during the ERP word classification task and the ERP responses themselves discriminated between children with above-average, average, and below-average reading skills. ERP…

  6. Fluorescence lifetime-based glucose sensor using NADH

    NASA Astrophysics Data System (ADS)

    von Ketteler, A.; Siegberg, D.; Herten, D. P.; Horn, C.; Petrich, W.

    2012-03-01

    Fluorescence lifetime-based glucose sensing does not depend on fluctuations of the intensity of the light source, light scattering, or changes in the transmission of optical components. Here we demonstrate the sensing of glucose based on the fluorescence lifetime properties of dihydro nicotinamide adenine dinucleotide (NADH), which is reduced from NAD in the presence of glucose and glucose dehydrogenase. In particular we use the difference in the fluorescence properties of free and protein-bound NADH and calculate an average fluorescence lifetime, which arises from the two short lifetimes τ1=0.28ns and τ2=0.60ns (representing free NADH) and the longer lifetime of τ3=2.9ns (for the protein-bound NADH). While initial results were derived from measurements in aqueous solution, we also demonstrate the suitability of this method for determining the concentration of glucose in blood using test strips. We find that the average fluorescence lifetime changes linearly by a factor of 0.17 per 100mg/dl change in glucose concentration. As an alternative the ratio between free and protein-bound components Rs/l may also be used for quantification. Rs/l increases by a factor of 0.74 per 100mg/dl change in glucose concentration.

  7. 40 CFR 76.11 - Emissions averaging.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.11 Emissions averaging. (a) General... averaging plan is in compliance with the Acid Rain emission limitation for NOX under the plan only if the...

  8. 40 CFR 76.11 - Emissions averaging.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.11 Emissions averaging. (a) General... averaging plan is in compliance with the Acid Rain emission limitation for NOX under the plan only if the...

  9. RHIC BPM system average orbit calculations

    SciTech Connect

    Michnoff,R.; Cerniglia, P.; Degen, C.; Hulsart, R.; et al.

    2009-05-04

    RHIC beam position monitor (BPM) system average orbit was originally calculated by averaging positions of 10000 consecutive turns for a single selected bunch. Known perturbations in RHIC particle trajectories, with multiple frequencies around 10 Hz, contribute to observed average orbit fluctuations. In 2006, the number of turns for average orbit calculations was made programmable; this was used to explore averaging over single periods near 10 Hz. Although this has provided an average orbit signal quality improvement, an average over many periods would further improve the accuracy of the measured closed orbit. A new continuous average orbit calculation was developed just prior to the 2009 RHIC run and was made operational in March 2009. This paper discusses the new algorithm and performance with beam.

  10. Effects of exercise and metformin on the prevention of glucose intolerance: a comparative study

    PubMed Central

    Molena-Fernandes, C.; Bersani-Amado, C. A.; Ferraro, Z. M.; Hintze, L. J.; Nardo, N.; Cuman, R. K. N.

    2015-01-01

    We aimed to evaluate the effects of aerobic exercise training (4 days) and metformin exposure on acute glucose intolerance after dexamethasone treatment in rats. Forty-two adult male Wistar rats (8 weeks old) were divided randomly into four groups: sedentary control (SCT), sedentary dexamethasone-treated (SDX), training dexamethasone-treated (DPE), and dexamethasone and metformin treated group (DMT). Glucose tolerance tests and in situ liver perfusion were undertaken on fasting rats to obtain glucose profiles. The DPE group displayed a significant decrease in glucose values compared with the SDX group. Average glucose levels in the DPE group did not differ from those of the DMT group, so we suggest that exercise training corrects dexamethasone-induced glucose intolerance and improves glucose profiles in a similar manner to that observed with metformin. These data suggest that exercise may prevent the development of glucose intolerance induced by dexamethasone in rats to a similar magnitude to that observed after metformin treatment. PMID:26421869

  11. Ketosis proportionately spares glucose utilization in brain.

    PubMed

    Zhang, Yifan; Kuang, Youzhi; Xu, Kui; Harris, Donald; Lee, Zhenghong; LaManna, Joseph; Puchowicz, Michelle A

    2013-08-01

    The brain is dependent on glucose as a primary energy substrate, but is capable of utilizing ketones such as β-hydroxybutyrate and acetoacetate, as occurs with fasting, starvation, or chronic feeding of a ketogenic diet. The relationship between changes in cerebral metabolic rates of glucose (CMRglc) and degree or duration of ketosis remains uncertain. To investigate if CMRglc decreases with chronic ketosis, 2-[(18)F]fluoro-2-deoxy-D-glucose in combination with positron emission tomography, was applied in anesthetized young adult rats fed 3 weeks of either standard or ketogenic diets. Cerebral metabolic rates of glucose (μmol/min per 100 g) was determined in the cerebral cortex and cerebellum using Gjedde-Patlak analysis. The average CMRglc significantly decreased in the cerebral cortex (23.0±4.9 versus 32.9±4.7) and cerebellum (29.3±8.6 versus 41.2±6.4) with increased plasma ketone bodies in the ketotic rats compared with standard diet group. The reduction of CMRglc in both brain regions correlates linearly by ∼9% for each 1 mmol/L increase of total plasma ketone bodies (0.3 to 6.3 mmol/L). Together with our meta-analysis, these data revealed that the degree and duration of ketosis has a major role in determining the corresponding change in CMRglc with ketosis.

  12. Glucose-induced inhibition of in vitro bone mineralization.

    PubMed

    Balint, E; Szabo, P; Marshall, C F; Sprague, S M

    2001-01-01

    Patients with diabetes tend to have an increased incidence of osteopenia that may be related to hyperglycemia. However, little is known about how glucose may alter bone formation and osteoblast maturation. To determine whether glucose affects osteoblastic calcium deposition, MC3T3-E1 cells were incubated in media containing either a normal (5.5 mmol/L) or high glucose concentration (15 mmol/L) or mannitol (15 mmol/L), and bone nodule formation was examined. Net calcium flux was measured thrice weekly and cumulative calcium uptake was determined. Compared with control incubations, glucose significantly inhibited daily and cumulative calcium uptake into the nodules. At the time of matrix maturation, cultures undergo a rapid phase of increased calcium deposition; this was significantly inhibited by the presence of glucose. Total calcium uptake, determined by acid digestion, was also significantly inhibited by glucose. Area and number of nodules were quantitated at the end of the incubation period (day 30) by staining with Alizarin Red S calcium stain. Compared with both control and mannitol-treated cultures, the number of nodules was increased by incubation with glucose. Furthermore, both the average total nodular area and calcified nodular area of large nodules were increased by glucose. Cellular proliferation as well as the release of markers of osteoblast activity (osteocalcin and alkaline phosphatase) were determined at the end of the experimental period (day 30). Cellular proliferation and alkaline phosphatase activity was significantly increased in the presence of glucose, however, the release of osteocalcin into culture media was similar in all three groups. In conclusion, the present study shows that elevated glucose concentration present throughout the development of murine osteoblasts stimulates cellular proliferation while inhibiting calcium uptake. The result of glucose inhibition of calcium uptake suggests that bone could be structurally altered in

  13. Capillary blood glucose screening for gestational diabetes: a preliminary investigation.

    PubMed

    Landon, M B; Cembrowski, G S; Gabbe, S G

    1986-10-01

    Home glucose monitoring with the use of reflectance meters is an important adjunct in the care of pregnant women with insulin-dependent diabetes. The accuracy of reflectance meters for the assay of capillary glucose specimens has been well documented. The present preliminary study was undertaken to determine the utility of outpatient screening for gestational diabetes mellitus with the use of a reflectance meter (Accu-Chek, Boehringer Mannheim Co.). One hundred twenty-five patients in our high-risk practice had a standard 50 gm glucose load at 26 to 28 weeks' gestation. Capillary glucose values were measured on site with the Accu-Chek. Venous plasma glucose levels were measured by the central laboratory chemistry analyzer. While the laboratory (x) and meter (y) glucose determinations between the two sets of values were highly correlated (R = 0.89, p less than 0.001), there was a significant difference in their average values (x = 111.74, y = 136.35, p less than 0.0001). With the use of a receiver operator characteristic curve, a meter value of 160 mg/dl was determined as the optimal threshold for performing a 3-hour glucose tolerance test. The sensitivity and specificity with the use of a meter value of 160 mg/dl were 93% and 96%, respectively, for detecting an abnormal screening test in venous plasma (greater than or equal to 135 mg/dl). A total of 32 glucose tolerance tests were performed, with four patients included who had venous values less than 135 mg/dl. All eight patients with gestational diabetes mellitus were correctly identified. These data suggest that a glucose reflectance meter can be used for accurate outpatient screening of gestational diabetes mellitus. The potential advantages of capillary blood glucose screening include both cost and efficiency. Patients with abnormal screening values can be promptly identified and scheduled for a follow-up 3-hour glucose tolerance test.

  14. Averaging and Adding in Children's Worth Judgements

    ERIC Educational Resources Information Center

    Schlottmann, Anne; Harman, Rachel M.; Paine, Julie

    2012-01-01

    Under the normative Expected Value (EV) model, multiple outcomes are additive, but in everyday worth judgement intuitive averaging prevails. Young children also use averaging in EV judgements, leading to a disordinal, crossover violation of utility when children average the part worths of simple gambles involving independent events (Schlottmann,…

  15. 40 CFR 1037.710 - Averaging.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... family's deficit by the due date for the final report required in § 1037.730. The emission credits used... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF... Averaging. (a) Averaging is the exchange of emission credits among your vehicle families. You may average...

  16. 40 CFR 1037.710 - Averaging.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... family's deficit by the due date for the final report required in § 1037.730. The emission credits used... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF... Averaging. (a) Averaging is the exchange of emission credits among your vehicle families. You may average...

  17. 40 CFR 89.204 - Averaging.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... are defined as follows: (1) Eligible engines rated at or above 19 kW, other than marine diesel engines, constitute an averaging set. (2) Eligible engines rated under 19 kW, other than marine diesel engines, constitute an averaging set. (3) Marine diesel engines rated at or above 19 kW constitute an averaging...

  18. 40 CFR 89.204 - Averaging.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... are defined as follows: (1) Eligible engines rated at or above 19 kW, other than marine diesel engines, constitute an averaging set. (2) Eligible engines rated under 19 kW, other than marine diesel engines, constitute an averaging set. (3) Marine diesel engines rated at or above 19 kW constitute an averaging...

  19. 40 CFR 89.204 - Averaging.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... are defined as follows: (1) Eligible engines rated at or above 19 kW, other than marine diesel engines, constitute an averaging set. (2) Eligible engines rated under 19 kW, other than marine diesel engines, constitute an averaging set. (3) Marine diesel engines rated at or above 19 kW constitute an averaging...

  20. 40 CFR 89.204 - Averaging.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... are defined as follows: (1) Eligible engines rated at or above 19 kW, other than marine diesel engines, constitute an averaging set. (2) Eligible engines rated under 19 kW, other than marine diesel engines, constitute an averaging set. (3) Marine diesel engines rated at or above 19 kW constitute an averaging...

  1. 40 CFR 89.204 - Averaging.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... are defined as follows: (1) Eligible engines rated at or above 19 kW, other than marine diesel engines, constitute an averaging set. (2) Eligible engines rated under 19 kW, other than marine diesel engines, constitute an averaging set. (3) Marine diesel engines rated at or above 19 kW constitute an averaging...

  2. Designing Digital Control Systems With Averaged Measurements

    NASA Technical Reports Server (NTRS)

    Polites, Michael E.; Beale, Guy O.

    1990-01-01

    Rational criteria represent improvement over "cut-and-try" approach. Recent development in theory of control systems yields improvements in mathematical modeling and design of digital feedback controllers using time-averaged measurements. By using one of new formulations for systems with time-averaged measurements, designer takes averaging effect into account when modeling plant, eliminating need to iterate design and simulation phases.

  3. Glucose and Aging

    NASA Astrophysics Data System (ADS)

    Ely, John T. A.

    2008-04-01

    When a human's enzymes attach glucose to proteins they do so at specific sites on a specific molecule for a specific purpose that also can include ascorbic acid (AA) at a high level such as 1 gram per hour during exposure. In an AA synthesizing animal the manifold increase of AA produced in response to illness is automatic. In contrast, the human non-enzymatic process adds glucose haphazardly to any number of sites along available peptide chains. As Cerami clarified decades ago, extensive crosslinking of proteins contributes to loss of elasticity in aging tissues. Ascorbic acid reduces the random non-enyzmatic glycation of proteins. Moreover, AA is a cofactor for hydroxylase enzymes that are necessary for the production and replacement of collagen and other structural proteins. We will discuss the relevance of ``aging is scurvy'' to the biochemistry of human aging.

  4. Liver glucose metabolism in humans

    PubMed Central

    Adeva-Andany, María M.; Pérez-Felpete, Noemi; Fernández-Fernández, Carlos; Donapetry-García, Cristóbal; Pazos-García, Cristina

    2016-01-01

    Information about normal hepatic glucose metabolism may help to understand pathogenic mechanisms underlying obesity and diabetes mellitus. In addition, liver glucose metabolism is involved in glycosylation reactions and connected with fatty acid metabolism. The liver receives dietary carbohydrates directly from the intestine via the portal vein. Glucokinase phosphorylates glucose to glucose 6-phosphate inside the hepatocyte, ensuring that an adequate flow of glucose enters the cell to be metabolized. Glucose 6-phosphate may proceed to several metabolic pathways. During the post-prandial period, most glucose 6-phosphate is used to synthesize glycogen via the formation of glucose 1-phosphate and UDP–glucose. Minor amounts of UDP–glucose are used to form UDP–glucuronate and UDP–galactose, which are donors of monosaccharide units used in glycosylation. A second pathway of glucose 6-phosphate metabolism is the formation of fructose 6-phosphate, which may either start the hexosamine pathway to produce UDP-N-acetylglucosamine or follow the glycolytic pathway to generate pyruvate and then acetyl-CoA. Acetyl-CoA may enter the tricarboxylic acid (TCA) cycle to be oxidized or may be exported to the cytosol to synthesize fatty acids, when excess glucose is present within the hepatocyte. Finally, glucose 6-phosphate may produce NADPH and ribose 5-phosphate through the pentose phosphate pathway. Glucose metabolism supplies intermediates for glycosylation, a post-translational modification of proteins and lipids that modulates their activity. Congenital deficiency of phosphoglucomutase (PGM)-1 and PGM-3 is associated with impaired glycosylation. In addition to metabolize carbohydrates, the liver produces glucose to be used by other tissues, from glycogen breakdown or from de novo synthesis using primarily lactate and alanine (gluconeogenesis). PMID:27707936

  5. PROFESSIONAL CONTINUOUS FLASH GLUCOSE MONITORING WITH AMBULATORY GLUCOSE PROFILE REPORTING TO SUPPLEMENT A1C: RATIONALE AND PRACTICAL IMPLEMENTATION.

    PubMed

    Hirsch, Irl B; Verderese, Carol A

    2017-08-17

    Recent consensus statements strongly advocate downloading and interpretation of continuous glucose data for diabetes management in patients with type 1 or type 2 diabetes. Supplementing periodic A1C testing with intermittent continuous glucose monitoring (CGM) using a standardized report form known as the ambulatory glucose profile (AGP) is an evolving standard of care. The rationale for this approach and its implementation with a recently approved novel monitoring technology are explored. Search of the medical literature, professional guidelines, and realworld evidence guided this introduction of an integrative practice framework that uses AGP in conjunction with intermittent continuous "flash" glucose monitoring (CFGM) as a supplement to A1C testing. The combination of intermittent continuous glucose pattern analysis, standardized glucose metrics, and a readily interpretable data report, as discussed in this review, has the potential to practically extend the recognized benefits of CGM to more patients, and clarify the relationship between A1C and average glucose levels in individual cases. Novel CFGM technologies portend greater use of continuous forms of glucose monitoring and wider adoption of AGP report analysis. Additional formal and empirical evidence is needed to more fully characterize best practice.

  6. Bayesian Model Averaging for Propensity Score Analysis.

    PubMed

    Kaplan, David; Chen, Jianshen

    2014-01-01

    This article considers Bayesian model averaging as a means of addressing uncertainty in the selection of variables in the propensity score equation. We investigate an approximate Bayesian model averaging approach based on the model-averaged propensity score estimates produced by the R package BMA but that ignores uncertainty in the propensity score. We also provide a fully Bayesian model averaging approach via Markov chain Monte Carlo sampling (MCMC) to account for uncertainty in both parameters and models. A detailed study of our approach examines the differences in the causal estimate when incorporating noninformative versus informative priors in the model averaging stage. We examine these approaches under common methods of propensity score implementation. In addition, we evaluate the impact of changing the size of Occam's window used to narrow down the range of possible models. We also assess the predictive performance of both Bayesian model averaging propensity score approaches and compare it with the case without Bayesian model averaging. Overall, results show that both Bayesian model averaging propensity score approaches recover the treatment effect estimates well and generally provide larger uncertainty estimates, as expected. Both Bayesian model averaging approaches offer slightly better prediction of the propensity score compared with the Bayesian approach with a single propensity score equation. Covariate balance checks for the case study show that both Bayesian model averaging approaches offer good balance. The fully Bayesian model averaging approach also provides posterior probability intervals of the balance indices.

  7. Development of a fluorescent method for simultaneous measurement of glucose concentrations in interstitial fluid and blood

    NASA Astrophysics Data System (ADS)

    Shi, Ting; Li, Dachao; Li, Guoqing; Chen, Limin; Lin, Yuan; Xu, Kexin; Lu, Luo

    2013-12-01

    Continuous blood glucose monitoring is of great clinical significance to patients with diabetes. One of the effective methods to monitor blood glucose is to measure glucose concentrations of interstitial fluid (ISF). However, a time-delay problem exists between ISF and blood glucose concentrations, which results in difficulty in indicating real-time blood glucose concentrations. Therefore, we developed a fluorescent method to verify the accuracy and reliability of simultaneous ISF and blood glucose measurement, especially incorporating it into research on the delay relationship between blood and ISF glucose changes. This method is based on a competitive reaction among borate polymer, alizarin and glucose. When glucose molecules combine with borate polymers in alizarin-borate polymer competitively, changes in fluorescence intensity demonstrate changes in glucose concentrations. By applying the measured results to the blood and ISF glucose delay relationship, we were able to calculate the time delay as an average of 2.16 ± 2.05 min for ISF glucose changes with reference to blood glucose concentrations.

  8. Is Low Blood Glucose (Hypoglycemia) Dangerous?

    MedlinePlus

    ... Please leave this field empty Is Low Blood Glucose (Hypoglycemia) Dangerous? Low blood glucose or hypoglycemia is one of the most common ... In general, hypoglycemia is defined as a blood glucose level below 70 mg/dl. Low blood glucose ...

  9. Gliotransmission and Brain Glucose Sensing

    PubMed Central

    Lanfray, Damien; Arthaud, Sébastien; Ouellet, Johanne; Compère, Vincent; Do Rego, Jean-Luc; Leprince, Jérôme; Lefranc, Benjamin; Castel, Hélène; Bouchard, Cynthia; Monge-Roffarello, Boris; Richard, Denis; Pelletier, Georges; Vaudry, Hubert; Tonon, Marie-Christine; Morin, Fabrice

    2013-01-01

    Hypothalamic glucose sensing is involved in the control of feeding behavior and peripheral glucose homeostasis, and glial cells are suggested to play an important role in this process. Diazepam-binding inhibitor (DBI) and its processing product the octadecaneuropeptide (ODN), collectively named endozepines, are secreted by astroglia, and ODN is a potent anorexigenic factor. Therefore, we investigated the involvement of endozepines in brain glucose sensing. First, we showed that intracerebroventricular administration of glucose in rats increases DBI expression in hypothalamic glial-like tanycytes. We then demonstrated that glucose stimulates endozepine secretion from hypothalamic explants. Feeding experiments indicate that the anorexigenic effect of central administration of glucose was blunted by coinjection of an ODN antagonist. Conversely, the hyperphagic response elicited by central glucoprivation was suppressed by an ODN agonist. The anorexigenic effects of centrally injected glucose or ODN agonist were suppressed by blockade of the melanocortin-3/4 receptors, suggesting that glucose sensing involves endozepinergic control of the melanocortin pathway. Finally, we found that brain endozepines modulate blood glucose levels, suggesting their involvement in a feedback loop controlling whole-body glucose homeostasis. Collectively, these data indicate that endozepines are a critical relay in brain glucose sensing and potentially new targets in treatment of metabolic disorders. PMID:23160530

  10. Average-cost based robust structural control

    NASA Technical Reports Server (NTRS)

    Hagood, Nesbitt W.

    1993-01-01

    A method is presented for the synthesis of robust controllers for linear time invariant structural systems with parameterized uncertainty. The method involves minimizing quantities related to the quadratic cost (H2-norm) averaged over a set of systems described by real parameters such as natural frequencies and modal residues. Bounded average cost is shown to imply stability over the set of systems. Approximations for the exact average are derived and proposed as cost functionals. The properties of these approximate average cost functionals are established. The exact average and approximate average cost functionals are used to derive dynamic controllers which can provide stability robustness. The robustness properties of these controllers are demonstrated in illustrative numerical examples and tested in a simple SISO experiment on the MIT multi-point alignment testbed.

  11. Statistics of time averaged atmospheric scintillation

    SciTech Connect

    Stroud, P.

    1994-02-01

    A formulation has been constructed to recover the statistics of the moving average of the scintillation Strehl from a discrete set of measurements. A program of airborne atmospheric propagation measurements was analyzed to find the correlation function of the relative intensity over displaced propagation paths. The variance in continuous moving averages of the relative intensity was then found in terms of the correlation functions. An empirical formulation of the variance of the continuous moving average of the scintillation Strehl has been constructed. The resulting characterization of the variance of the finite time averaged Strehl ratios is being used to assess the performance of an airborne laser system.

  12. Spatial limitations in averaging social cues

    PubMed Central

    Florey, Joseph; Clifford, Colin W. G.; Dakin, Steven; Mareschal, Isabelle

    2016-01-01

    The direction of social attention from groups provides stronger cueing than from an individual. It has previously been shown that both basic visual features such as size or orientation and more complex features such as face emotion and identity can be averaged across multiple elements. Here we used an equivalent noise procedure to compare observers’ ability to average social cues with their averaging of a non-social cue. Estimates of observers’ internal noise (uncertainty associated with processing any individual) and sample-size (the effective number of gaze-directions pooled) were derived by fitting equivalent noise functions to discrimination thresholds. We also used reverse correlation analysis to estimate the spatial distribution of samples used by participants. Averaging of head-rotation and cone-rotation was less noisy and more efficient than averaging of gaze direction, though presenting only the eye region of faces at a larger size improved gaze averaging performance. The reverse correlation analysis revealed greater sampling areas for head rotation compared to gaze. We attribute these differences in averaging between gaze and head cues to poorer visual processing of faces in the periphery. The similarity between head and cone averaging are examined within the framework of a general mechanism for averaging of object rotation. PMID:27573589

  13. Cell averaging Chebyshev methods for hyperbolic problems

    NASA Technical Reports Server (NTRS)

    Wei, Cai; Gottlieb, David; Harten, Ami

    1990-01-01

    A cell averaging method for the Chebyshev approximations of first order hyperbolic equations in conservation form is described. Formulas are presented for transforming between pointwise data at the collocation points and cell averaged quantities, and vice-versa. This step, trivial for the finite difference and Fourier methods, is nontrivial for the global polynomials used in spectral methods. The cell averaging methods presented are proven stable for linear scalar hyperbolic equations and present numerical simulations of shock-density wave interaction using the new cell averaging Chebyshev methods.

  14. Cosmological ensemble and directional averages of observables

    SciTech Connect

    Bonvin, Camille; Clarkson, Chris; Durrer, Ruth; Maartens, Roy; Umeh, Obinna E-mail: chris.clarkson@gmail.com E-mail: roy.maartens@gmail.com

    2015-07-01

    We show that at second order, ensemble averages of observables and directional averages do not commute due to gravitational lensing—observing the same thing in many directions over the sky is not the same as taking an ensemble average. In principle this non-commutativity is significant for a variety of quantities that we often use as observables and can lead to a bias in parameter estimation. We derive the relation between the ensemble average and the directional average of an observable, at second order in perturbation theory. We discuss the relevance of these two types of averages for making predictions of cosmological observables, focusing on observables related to distances and magnitudes. In particular, we show that the ensemble average of the distance in a given observed direction is increased by gravitational lensing, whereas the directional average of the distance is decreased. For a generic observable, there exists a particular function of the observable that is not affected by second-order lensing perturbations. We also show that standard areas have an advantage over standard rulers, and we discuss the subtleties involved in averaging in the case of supernova observations.

  15. Comparison of daily glucose excursion by continuous glucose monitoring between type 2 diabetic patients receiving preprandial insulin aspart or postprandial insulin glulisine.

    PubMed

    Ohta, Akio; Arai, Kaori; Nishine, Ami; Sada, Yoshiyuki; Kato, Hiroyuki; Fukuda, Hisashi; Asai, Shiko; Nagai, Yoshio; Katabami, Takuyuki; Tanaka, Yasushi

    2013-01-01

    Insulin glulisine (Glu) is a rapidly-acting insulin analog with a faster onset of action than the other insulin analogs of its class, which are insulin aspart (Asp) and insulin lispro (Lisp). While insulin Glu is usually injected just before meals, postprandial injection may help to avoid unexpected postprandial hypoglycemia or hyperglycemia by adjusting the insulin dosage according to food intake. However, the effect of postprandial insulin Glu on the glucose profile has not been evaluated. The aim of this study was to compare daily glucose excursion by continuous glucose monitoring (CGM) between multiple daily doses of preprandial insulin Asp or postprandial insulin Glu. In a randomized cross-over trial, we performed CGM to evaluate the 48-hour glucose profile during treatment with the same dosage of insulin Asp just before each meal in 12 hospitalized patients with type 2 diabetes. Patients also received the same dosage of long-acting insulin glargine at bedtime. The average glucose level, standard deviation of the glucose level, mean amplitude of glucose excursion, and daily glucose profile did not differ between preprandial Asp and postprandial Glu. The incidence of hypoglycemic episodes (glucose level<70 mg/dL with or without symptoms) and the area under the curve of glucose<70 mg/dL also did not differ between the two insulin regimens. Multiple daily injections of preprandial Asp and postprandial Glu achieved the same daily glucose excursion profile. Postprandial injection of Glu may provide greater flexibility for patients who require insulin therapy.

  16. Glucose transporters in the transepithelial transport of glucose.

    PubMed

    Takata, K

    1996-08-01

    Glucose transporters are integral membrane proteins that mediate the transport of glucose and structurally-related substances across the cellular membranes. Two families of glucose transporter have been identified: the facilitated-diffusion glucose transporter family (GLUT family), and the NA(+)-dependent glucose transporter one (SGLT family). These transporters play a pivotal role in the transfer of glucose across the epithelial cell layers that separate distinct compartments in the mammalian body. In the small intestine, a Na(+)-dependent glucose transporter, SGLT1, is localized at the apical plasma membrane of the absorptive epithelial cells, whereas a facilitated-diffusion glucose transporter, GLUT2, is at the basolateral membrane of the cells. Similar localization is seen in the kidney proximal tubules in the reabsorption of glucose. For the absorption of fructose in the small intestine, fructose transporter GLUT5 is localized at the apical membrane. The expressed GLUT5 in polarized cultured cells is targeted to the apical membrane, showing that the GLUT5 molecule itself has sufficient information to determine its cellular localization. In the blood-tissue barriers, such as the blood-brain barrier, blood-ocular barrier, and placental barrier, either endothelial or epithelial cell layers constitute the barrier. GLUT1 is abundant at the plasma membrane of these barrier cells, and plays a crucial role in the specific transfer of glucose across the barrier. When the barrier is composed of a two-cell layer, gap junctions connecting them could serve as intercellular channels for glucose transfer in addition to GLUT1. Proper localization of glucose transporters and gap junctions is a prerequisite for the successful transepithelial transport of sugars.

  17. Dynamic Multiscale Averaging (DMA) of Turbulent Flow

    SciTech Connect

    Richard W. Johnson

    2012-09-01

    A new approach called dynamic multiscale averaging (DMA) for computing the effects of turbulent flow is described. The new method encompasses multiple applications of temporal and spatial averaging, that is, multiscale operations. Initially, a direct numerical simulation (DNS) is performed for a relatively short time; it is envisioned that this short time should be long enough to capture several fluctuating time periods of the smallest scales. The flow field variables are subject to running time averaging during the DNS. After the relatively short time, the time-averaged variables are volume averaged onto a coarser grid. Both time and volume averaging of the describing equations generate correlations in the averaged equations. These correlations are computed from the flow field and added as source terms to the computation on the next coarser mesh. They represent coupling between the two adjacent scales. Since they are computed directly from first principles, there is no modeling involved. However, there is approximation involved in the coupling correlations as the flow field has been computed for only a relatively short time. After the time and spatial averaging operations are applied at a given stage, new computations are performed on the next coarser mesh using a larger time step. The process continues until the coarsest scale needed is reached. New correlations are created for each averaging procedure. The number of averaging operations needed is expected to be problem dependent. The new DMA approach is applied to a relatively low Reynolds number flow in a square duct segment. Time-averaged stream-wise velocity and vorticity contours from the DMA approach appear to be very similar to a full DNS for a similar flow reported in the literature. Expected symmetry for the final results is produced for the DMA method. The results obtained indicate that DMA holds significant potential in being able to accurately compute turbulent flow without modeling for practical

  18. A photonic crystal fiber glucose sensor filled with silver nanowires

    NASA Astrophysics Data System (ADS)

    Yang, X. C.; Lu, Y.; Wang, M. T.; Yao, J. Q.

    2016-01-01

    We report a photonic crystal fiber glucose sensor filled with silver nanowires in this paper. The proposed sensor is both analyzed by COMSOL multiphysics software and demonstrated by experiments. The extremely high average spectral sensitivity 19009.17 nm/RIU for experimental measurement is obtained, equivalent to 44.25 mg/dL of glucose in water, which is lower than 70 mg/dL for efficient detection of hypoglycemia episodes. The silver nanowires diameter which may affect the sensor's spectral sensitivity is also discussed and an optimal range of silver nanowires diameter 90-120 nm is obtained. We expect that the sensor can provide an effective platform for glucose sensing and potentially leading to a further development towards minimal-invasive glucose measurement.

  19. Thermoresponsive amperometric glucose biosensor.

    PubMed

    Pinyou, Piyanut; Ruff, Adrian; Pöller, Sascha; Barwe, Stefan; Nebel, Michaela; Alburquerque, Natalia Guerrero; Wischerhoff, Erik; Laschewsky, André; Schmaderer, Sebastian; Szeponik, Jan; Plumeré, Nicolas; Schuhmann, Wolfgang

    2015-03-24

    The authors report on the fabrication of a thermoresponsive biosensor for the amperometric detection of glucose. Screen printed electrodes with heatable gold working electrodes were modified by a thermoresponsive statistical copolymer [polymer I: poly(ω-ethoxytriethylenglycol methacrylate-co-3-(N,N-dimethyl-N-2-methacryloyloxyethyl ammonio) propanesulfonate-co-ω-butoxydiethylenglycol methacrylate-co-2-(4-benzoyl-phenoxy)ethyl methacrylate)] with a lower critical solution temperature of around 28 °C in aqueous solution via electrochemically induced codeposition with a pH-responsive redox-polymer [polymer II: poly(glycidyl methacrylate-co-allyl methacrylate-co-poly(ethylene glycol)methacrylate-co-butyl acrylate-co-2-(dimethylamino)ethyl methacrylate)-[Os(bpy)2(4-(((2-(2-(2-aminoethoxy)ethoxy)ethyl)amino)methyl)-N,N-dimethylpicolinamide)](2+)] and pyrroloquinoline quinone-soluble glucose dehydrogenase acting as biological recognition element. Polymer II bears covalently bound Os-complexes that act as redox mediators for shuttling electrons between the enzyme and the electrode surface. Polymer I acts as a temperature triggered immobilization matrix. Probing the catalytic current as a function of the working electrode temperature shows that the activity of the biosensor is dramatically reduced above the phase transition temperature of polymer I. Thus, the local modulation of the temperature at the interphase between the electrode and the bioactive layer allows switching the biosensor from an on- to an off-state without heating of the surrounding analyte solution.

  20. Average Transmission Probability of a Random Stack

    ERIC Educational Resources Information Center

    Lu, Yin; Miniatura, Christian; Englert, Berthold-Georg

    2010-01-01

    The transmission through a stack of identical slabs that are separated by gaps with random widths is usually treated by calculating the average of the logarithm of the transmission probability. We show how to calculate the average of the transmission probability itself with the aid of a recurrence relation and derive analytical upper and lower…

  1. 40 CFR 1036.710 - Averaging.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...'s deficit by the due date for the final report required in § 1036.730. The emission credits used to... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF... § 1036.710 Averaging. (a) Averaging is the exchange of emission credits among your engine families. You...

  2. 40 CFR 1036.710 - Averaging.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...'s deficit by the due date for the final report required in § 1036.730. The emission credits used to... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF... § 1036.710 Averaging. (a) Averaging is the exchange of emission credits among your engine families. You...

  3. Determinants of College Grade Point Averages

    ERIC Educational Resources Information Center

    Bailey, Paul Dean

    2012-01-01

    Chapter 2: The Role of Class Difficulty in College Grade Point Averages. Grade Point Averages (GPAs) are widely used as a measure of college students' ability. Low GPAs can remove a students from eligibility for scholarships, and even continued enrollment at a university. However, GPAs are determined not only by student ability but also by the…

  4. 40 CFR 63.846 - Emission averaging.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... operator may average TF emissions from potlines and demonstrate compliance with the limits in Table 1 of... operator also may average POM emissions from potlines and demonstrate compliance with the limits in Table 2... limit in Table 1 of this subpart (for TF emissions) and/or Table 2 of this subpart (for POM emissions...

  5. 40 CFR 63.846 - Emission averaging.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... operator may average TF emissions from potlines and demonstrate compliance with the limits in Table 1 of... operator also may average POM emissions from potlines and demonstrate compliance with the limits in Table 2... limit in Table 1 of this subpart (for TF emissions) and/or Table 2 of this subpart (for POM emissions...

  6. 40 CFR 63.846 - Emission averaging.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... operator may average TF emissions from potlines and demonstrate compliance with the limits in Table 1 of... operator also may average POM emissions from potlines and demonstrate compliance with the limits in Table 2... limit in Table 1 of this subpart (for TF emissions) and/or Table 2 of this subpart (for POM emissions...

  7. Whatever Happened to the Average Student?

    ERIC Educational Resources Information Center

    Krause, Tom

    2005-01-01

    Mandated state testing, college entrance exams and their perceived need for higher and higher grade point averages have raised the anxiety levels felt by many of the average students. Too much focus is placed on state test scores and college entrance standards with not enough focus on the true level of the students. The author contends that…

  8. Determinants of College Grade Point Averages

    ERIC Educational Resources Information Center

    Bailey, Paul Dean

    2012-01-01

    Chapter 2: The Role of Class Difficulty in College Grade Point Averages. Grade Point Averages (GPAs) are widely used as a measure of college students' ability. Low GPAs can remove a students from eligibility for scholarships, and even continued enrollment at a university. However, GPAs are determined not only by student ability but also by the…

  9. 40 CFR 90.204 - Averaging.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Averaging. 90.204 Section 90.204... Trading Provisions § 90.204 Averaging. (a) Negative credits from engine families with FELs above the... manner is used to determine compliance under § 90.207(b). A manufacturer may have a negative balance of...

  10. 40 CFR 90.204 - Averaging.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Averaging. 90.204 Section 90.204... Trading Provisions § 90.204 Averaging. (a) Negative credits from engine families with FELs above the... manner is used to determine compliance under § 90.207(b). A manufacturer may have a negative balance of...

  11. Average Transmission Probability of a Random Stack

    ERIC Educational Resources Information Center

    Lu, Yin; Miniatura, Christian; Englert, Berthold-Georg

    2010-01-01

    The transmission through a stack of identical slabs that are separated by gaps with random widths is usually treated by calculating the average of the logarithm of the transmission probability. We show how to calculate the average of the transmission probability itself with the aid of a recurrence relation and derive analytical upper and lower…

  12. 40 CFR 90.204 - Averaging.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Averaging. 90.204 Section 90.204 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF... credits as allowed under § 90.207(c)(2). (b) Cross-class averaging of credits is allowed across all...

  13. 40 CFR 90.204 - Averaging.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Averaging. 90.204 Section 90.204 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF... credits as allowed under § 90.207(c)(2). (b) Cross-class averaging of credits is allowed across all...

  14. Analogue Divider by Averaging a Triangular Wave

    NASA Astrophysics Data System (ADS)

    Selvam, Krishnagiri Chinnathambi

    2017-03-01

    A new analogue divider circuit by averaging a triangular wave using operational amplifiers is explained in this paper. The triangle wave averaging analog divider using operational amplifiers is explained here. The reference triangular waveform is shifted from zero voltage level up towards positive power supply voltage level. Its positive portion is obtained by a positive rectifier and its average value is obtained by a low pass filter. The same triangular waveform is shifted from zero voltage level to down towards negative power supply voltage level. Its negative portion is obtained by a negative rectifier and its average value is obtained by another low pass filter. Both the averaged voltages are combined in a summing amplifier and the summed voltage is given to an op-amp as negative input. This op-amp is configured to work in a negative closed environment. The op-amp output is the divider output.

  15. Analogue Divider by Averaging a Triangular Wave

    NASA Astrophysics Data System (ADS)

    Selvam, Krishnagiri Chinnathambi

    2017-08-01

    A new analogue divider circuit by averaging a triangular wave using operational amplifiers is explained in this paper. The triangle wave averaging analog divider using operational amplifiers is explained here. The reference triangular waveform is shifted from zero voltage level up towards positive power supply voltage level. Its positive portion is obtained by a positive rectifier and its average value is obtained by a low pass filter. The same triangular waveform is shifted from zero voltage level to down towards negative power supply voltage level. Its negative portion is obtained by a negative rectifier and its average value is obtained by another low pass filter. Both the averaged voltages are combined in a summing amplifier and the summed voltage is given to an op-amp as negative input. This op-amp is configured to work in a negative closed environment. The op-amp output is the divider output.

  16. The Hubble rate in averaged cosmology

    SciTech Connect

    Umeh, Obinna; Larena, Julien; Clarkson, Chris E-mail: julien.larena@gmail.com

    2011-03-01

    The calculation of the averaged Hubble expansion rate in an averaged perturbed Friedmann-Lemaître-Robertson-Walker cosmology leads to small corrections to the background value of the expansion rate, which could be important for measuring the Hubble constant from local observations. It also predicts an intrinsic variance associated with the finite scale of any measurement of H{sub 0}, the Hubble rate today. Both the mean Hubble rate and its variance depend on both the definition of the Hubble rate and the spatial surface on which the average is performed. We quantitatively study different definitions of the averaged Hubble rate encountered in the literature by consistently calculating the backreaction effect at second order in perturbation theory, and compare the results. We employ for the first time a recently developed gauge-invariant definition of an averaged scalar. We also discuss the variance of the Hubble rate for the different definitions.

  17. Glucose repression in Saccharomyces cerevisiae

    PubMed Central

    Kayikci, Ömur; Nielsen, Jens

    2015-01-01

    Glucose is the primary source of energy for the budding yeast Saccharomyces cerevisiae. Although yeast cells can utilize a wide range of carbon sources, presence of glucose suppresses molecular activities involved in the use of alternate carbon sources as well as it represses respiration and gluconeogenesis. This dominant effect of glucose on yeast carbon metabolism is coordinated by several signaling and metabolic interactions that mainly regulate transcriptional activity but are also effective at post-transcriptional and post-translational levels. This review describes effects of glucose repression on yeast carbon metabolism with a focus on roles of the Snf3/Rgt2 glucose-sensing pathway and Snf1 signal transduction in establishment and relief of glucose repression. PMID:26205245

  18. Glucose Catabolism of Erysipelothrix rhusiopathiae

    PubMed Central

    Robertson, D. C.; McCullough, W. G.

    1968-01-01

    The pathways of glucose catabolism in Erysipelothrix rhusiopathiae have been identified by the radiorespirometric technique. The radiorespirometric data showed that 96% of the glucose catabolism was via the Embden-Meyerhof-Parnas pathway with the remaining 4% dissimilated by the hexose monophosphate pathway. The products of the anaerobic dissimilation of glucose were determined. Lactic acid was the major product; ethyl alcohol, acetic acid, formic acid, and carbon dioxide were formed in smaller amounts. Images PMID:4877823

  19. Optoelectronic Apparatus Measures Glucose Noninvasively

    NASA Technical Reports Server (NTRS)

    Ansari, Rafat R.; Rovati, Luigi L.

    2003-01-01

    An optoelectronic apparatus has been invented as a noninvasive means of measuring the concentration of glucose in the human body. The apparatus performs polarimetric and interferometric measurements of the human eye to acquire data from which the concentration of glucose in the aqueous humor can be computed. Because of the importance of the concentration of glucose in human health, there could be a large potential market for instruments based on this apparatus.

  20. Light propagation in the averaged universe

    SciTech Connect

    Bagheri, Samae; Schwarz, Dominik J. E-mail: dschwarz@physik.uni-bielefeld.de

    2014-10-01

    Cosmic structures determine how light propagates through the Universe and consequently must be taken into account in the interpretation of observations. In the standard cosmological model at the largest scales, such structures are either ignored or treated as small perturbations to an isotropic and homogeneous Universe. This isotropic and homogeneous model is commonly assumed to emerge from some averaging process at the largest scales. We assume that there exists an averaging procedure that preserves the causal structure of space-time. Based on that assumption, we study the effects of averaging the geometry of space-time and derive an averaged version of the null geodesic equation of motion. For the averaged geometry we then assume a flat Friedmann-Lemaître (FL) model and find that light propagation in this averaged FL model is not given by null geodesics of that model, but rather by a modified light propagation equation that contains an effective Hubble expansion rate, which differs from the Hubble rate of the averaged space-time.

  1. Cosmic inhomogeneities and averaged cosmological dynamics.

    PubMed

    Paranjape, Aseem; Singh, T P

    2008-10-31

    If general relativity (GR) describes the expansion of the Universe, the observed cosmic acceleration implies the existence of a "dark energy." However, while the Universe is on average homogeneous on large scales, it is inhomogeneous on smaller scales. While GR governs the dynamics of the inhomogeneous Universe, the averaged homogeneous Universe obeys modified Einstein equations. Can such modifications alone explain the acceleration? For a simple generic model with realistic initial conditions, we show the answer to be "no." Averaging effects negligibly influence the cosmological dynamics.

  2. Average-passage flow model development

    NASA Technical Reports Server (NTRS)

    Adamczyk, John J.; Celestina, Mark L.; Beach, Tim A.; Kirtley, Kevin; Barnett, Mark

    1989-01-01

    A 3-D model was developed for simulating multistage turbomachinery flows using supercomputers. This average passage flow model described the time averaged flow field within a typical passage of a bladed wheel within a multistage configuration. To date, a number of inviscid simulations were executed to assess the resolution capabilities of the model. Recently, the viscous terms associated with the average passage model were incorporated into the inviscid computer code along with an algebraic turbulence model. A simulation of a stage-and-one-half, low speed turbine was executed. The results of this simulation, including a comparison with experimental data, is discussed.

  3. GROUP ACTION INDUCED AVERAGING FOR HARDI PROCESSING

    PubMed Central

    Çetingül, H. Ertan; Afsari, Bijan; Wright, Margaret J.; Thompson, Paul M.; Vidal, Rene

    2012-01-01

    We consider the problem of processing high angular resolution diffusion images described by orientation distribution functions (ODFs). Prior work showed that several processing operations, e.g., averaging, interpolation and filtering, can be reduced to averaging in the space of ODFs. However, this approach leads to anatomically erroneous results when the ODFs to be processed have very different orientations. To address this issue, we propose a group action induced distance for averaging ODFs, which leads to a novel processing framework on the spaces of orientation (the space of 3D rotations) and shape (the space of ODFs with the same orientation). Experiments demonstrate that our framework produces anatomically meaningful results. PMID:22903055

  4. Average shape of transport-limited aggregates.

    PubMed

    Davidovitch, Benny; Choi, Jaehyuk; Bazant, Martin Z

    2005-08-12

    We study the relation between stochastic and continuous transport-limited growth models. We derive a nonlinear integro-differential equation for the average shape of stochastic aggregates, whose mean-field approximation is the corresponding continuous equation. Focusing on the advection-diffusion-limited aggregation (ADLA) model, we show that the average shape of the stochastic growth is similar, but not identical, to the corresponding continuous dynamics. Similar results should apply to DLA, thus explaining the known discrepancies between average DLA shapes and viscous fingers in a channel geometry.

  5. Random plasma glucose in serendipitous screening for glucose intolerance: screening for impaired glucose tolerance study 2.

    PubMed

    Ziemer, David C; Kolm, Paul; Foster, Jovonne K; Weintraub, William S; Vaccarino, Viola; Rhee, Mary K; Varughese, Rincy M; Tsui, Circe W; Koch, David D; Twombly, Jennifer G; Narayan, K M Venkat; Phillips, Lawrence S

    2008-05-01

    With positive results from diabetes prevention studies, there is interest in convenient ways to incorporate screening for glucose intolerance into routine care and to limit the need for fasting diagnostic tests. The aim of this study is to determine whether random plasma glucose (RPG) could be used to screen for glucose intolerance. This is a cross-sectional study. The participants of this study include a voluntary sample of 990 adults not known to have diabetes. RPG was measured, and each subject had a 75-g oral glucose tolerance test several weeks later. Glucose intolerance targets included diabetes, impaired glucose tolerance (IGT), and impaired fasting glucose(110) (IFG(110); fasting glucose, 110-125 mg/dl, and 2 h glucose < 140 mg/dl). Screening performance was measured by area under receiver operating characteristic curves (AROC). Mean age was 48 years, and body mass index (BMI) was 30.4 kg/m(2); 66% were women, and 52% were black; 5.1% had previously unrecognized diabetes, and 24.0% had any "high-risk" glucose intolerance (diabetes or IGT or IFG(110)). The AROC was 0.80 (95% CI 0.74-0.86) for RPG to identify diabetes and 0.72 (0.68-0.75) to identify any glucose intolerance, both highly significant (p < 0.001). Screening performance was generally consistent at different times of the day, regardless of meal status, and across a range of risk factors such as age, BMI, high density lipoprotein cholesterol, triglycerides, and blood pressure. RPG values should be considered by health care providers to be an opportunistic initial screening test and used to prompt further evaluation of patients at risk of glucose intolerance. Such "serendipitous screening" could help to identify unrecognized diabetes and prediabetes.

  6. Rotational averaging of multiphoton absorption cross sections

    NASA Astrophysics Data System (ADS)

    Friese, Daniel H.; Beerepoot, Maarten T. P.; Ruud, Kenneth

    2014-11-01

    Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

  7. Rotational averaging of multiphoton absorption cross sections.

    PubMed

    Friese, Daniel H; Beerepoot, Maarten T P; Ruud, Kenneth

    2014-11-28

    Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

  8. 40 CFR 86.449 - Averaging provisions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... calculations of projected emission credits (zero, positive, or negative) based on production projections. If..., rounding to the nearest tenth of a gram: Deficit = (Emission Level − Average Standard) × (Total...

  9. 40 CFR 86.449 - Averaging provisions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... calculations of projected emission credits (zero, positive, or negative) based on production projections. If..., rounding to the nearest tenth of a gram: Deficit = (Emission Level − Average Standard) × (Total...

  10. 40 CFR 86.449 - Averaging provisions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... calculations of projected emission credits (zero, positive, or negative) based on production projections. If..., rounding to the nearest tenth of a gram: Deficit = (Emission Level − Average Standard) × (Total...

  11. 40 CFR 86.449 - Averaging provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... calculations of projected emission credits (zero, positive, or negative) based on production projections. If..., rounding to the nearest tenth of a gram: Deficit = (Emission Level − Average Standard) × (Total...

  12. 40 CFR 86.449 - Averaging provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... calculations of projected emission credits (zero, positive, or negative) based on production projections. If..., rounding to the nearest tenth of a gram: Deficit = (Emission Level − Average Standard) × (Total...

  13. 40 CFR 76.11 - Emissions averaging.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.11 Emissions averaging. (a) General... compliance with the Acid Rain emission limitation for NOX under the plan only if the following requirements...

  14. 40 CFR 76.11 - Emissions averaging.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.11 Emissions averaging. (a) General... compliance with the Acid Rain emission limitation for NOX under the plan only if the following requirements...

  15. 40 CFR 76.11 - Emissions averaging.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.11 Emissions averaging. (a) General... compliance with the Acid Rain emission limitation for NOX under the plan only if the following requirements...

  16. Total pressure averaging in pulsating flows

    NASA Technical Reports Server (NTRS)

    Krause, L. N.; Dudzinski, T. J.; Johnson, R. C.

    1972-01-01

    A number of total-pressure tubes were tested in a non-steady flow generator in which the fraction of period that pressure is a maximum is approximately 0.8, thereby simulating turbomachine-type flow conditions. Most of the tubes indicated a pressure which was higher than the true average. Organ-pipe resonance which further increased the indicated pressure was encountered within the tubes at discrete frequencies. There was no obvious combination of tube diameter, length, and/or geometry variation used in the tests which resulted in negligible averaging error. A pneumatic-type probe was found to measure true average pressure, and is suggested as a comparison instrument to determine whether nonlinear averaging effects are serious in unknown pulsation profiles. The experiments were performed at a pressure level of 1 bar, for Mach number up to near 1, and frequencies up to 3 kHz.

  17. Spacetime Average Density (SAD) cosmological measures

    NASA Astrophysics Data System (ADS)

    Page, Don N.

    2014-11-01

    The measure problem of cosmology is how to obtain normalized probabilities of observations from the quantum state of the universe. This is particularly a problem when eternal inflation leads to a universe of unbounded size so that there are apparently infinitely many realizations or occurrences of observations of each of many different kinds or types, making the ratios ambiguous. There is also the danger of domination by Boltzmann Brains. Here two new Spacetime Average Density (SAD) measures are proposed, Maximal Average Density (MAD) and Biased Average Density (BAD), for getting a finite number of observation occurrences by using properties of the Spacetime Average Density (SAD) of observation occurrences to restrict to finite regions of spacetimes that have a preferred beginning or bounce hypersurface. These measures avoid Boltzmann brain domination and appear to give results consistent with other observations that are problematic for other widely used measures, such as the observation of a positive cosmological constant.

  18. Bimetal sensor averages temperature of nonuniform profile

    NASA Technical Reports Server (NTRS)

    Dittrich, R. T.

    1968-01-01

    Instrument that measures an average temperature across a nonuniform temperature profile under steady-state conditions has been developed. The principle of operation is an application of the expansion of a solid material caused by a change in temperature.

  19. Spacetime Average Density (SAD) cosmological measures

    SciTech Connect

    Page, Don N.

    2014-11-01

    The measure problem of cosmology is how to obtain normalized probabilities of observations from the quantum state of the universe. This is particularly a problem when eternal inflation leads to a universe of unbounded size so that there are apparently infinitely many realizations or occurrences of observations of each of many different kinds or types, making the ratios ambiguous. There is also the danger of domination by Boltzmann Brains. Here two new Spacetime Average Density (SAD) measures are proposed, Maximal Average Density (MAD) and Biased Average Density (BAD), for getting a finite number of observation occurrences by using properties of the Spacetime Average Density (SAD) of observation occurrences to restrict to finite regions of spacetimes that have a preferred beginning or bounce hypersurface. These measures avoid Boltzmann brain domination and appear to give results consistent with other observations that are problematic for other widely used measures, such as the observation of a positive cosmological constant.

  20. [Glucose homeostasis in children. I. Regulation of blood glucose].

    PubMed

    Otto Buczkowska, E; Szirer, G; Jarosz-Chobot, P

    2001-01-01

    The amount of glucose in the circulation depends on its absorption from the intestine, uptake by and release from the liver and uptake by peripheral tissues. Insulin and glucagon together control the metabolities required by peripheral tissues and both are involved in maintaining glucose homeostasis. Insulin is considered to be an anabolic hormone in that it promotes the synthesis of protein, lipid and glycogen. The key target tissues for insulin are liver, muscles and adipose tissue. Glucagon acts largely to increase catabolic processes. Between meals or during fast, the most tightly regulated process is the release of glucose from the liver. During fasting glucose is produced from glycogen and is formed by enzymes on the gluconeogenic pathway. Fetal metabolism is directed to ensure anabolism with formation of glycogen, fat and protein. Glucogen is stored in the liver and serves as the immediate source of new glucose during first few hours after birth. Glucose is the most important substrate for brain metabolism. Due to the large size of neonatal brain in relation to body weight cerebral glucose consumption is particularly high. Postnatal hormonal changes have a central role in regulating glucose mobilization through glycogenolysis and gluconeogenesis. The initial glucagon surge is the key adaptive change which triggers the switch to glucose production. The control of insulin and glucagon secretion is of fundamental importance during first hours after birth. Children have a decreased tolerance to starvation when compared with adults, they are more prone to develop hypoglycaemia after short fasting. The faster rate in the fall of blood glucose and gluconeogenic substrates and rapid rate of ketogenesis are characteristic features of fasting adaptation in children.

  1. Monthly average polar sea-ice concentration

    USGS Publications Warehouse

    Schweitzer, Peter N.

    1995-01-01

    The data contained in this CD-ROM depict monthly averages of sea-ice concentration in the modern polar oceans. These averages were derived from the Scanning Multichannel Microwave Radiometer (SMMR) and Special Sensor Microwave/Imager (SSM/I) instruments aboard satellites of the U.S. Air Force Defense Meteorological Satellite Program from 1978 through 1992. The data are provided as 8-bit images using the Hierarchical Data Format (HDF) developed by the National Center for Supercomputing Applications.

  2. Radial averages of astigmatic TEM images.

    PubMed

    Fernando, K Vince

    2008-10-01

    The Contrast Transfer Function (CTF) of an image, which modulates images taken from a Transmission Electron Microscope (TEM), is usually determined from the radial average of the power spectrum of the image (Frank, J., Three-dimensional Electron Microscopy of Macromolecular Assemblies, Oxford University Press, Oxford, 2006). The CTF is primarily defined by the defocus. If the defocus estimate is accurate enough then it is possible to demodulate the image, which is popularly known as the CTF correction. However, it is known that the radial average is somewhat attenuated if the image is astigmatic (see Fernando, K.V., Fuller, S.D., 2007. Determination of astigmatism in TEM images. Journal of Structural Biology 157, 189-200) but this distortion due to astigmatism has not been fully studied or understood up to now. We have discovered the exact mathematical relationship between the radial averages of TEM images with and without astigmatism. This relationship is determined by a zeroth order Bessel function of the first kind and hence we can exactly quantify this distortion in the radial averages of signal and power spectra of astigmatic images. The argument to this Bessel function is similar to an aberration function (without the spherical aberration term) except that the defocus parameter is replaced by the differences of the defoci in the major and minor axes of astigmatism. The ill effects due this Bessel function are twofold. Since the zeroth order Bessel function is a decaying oscillatory function, it introduces additional zeros to the radial average and it also attenuates the CTF signal in the radial averages. Using our analysis, it is possible to simulate the effects of astigmatism in radial averages by imposing Bessel functions on idealized radial averages of images which are not astigmatic. We validate our theory using astigmatic TEM images.

  3. Symmetric Euler orientation representations for orientational averaging.

    PubMed

    Mayerhöfer, Thomas G

    2005-09-01

    A new kind of orientation representation called symmetric Euler orientation representation (SEOR) is presented. It is based on a combination of the conventional Euler orientation representations (Euler angles) and Hamilton's quaternions. The properties of the SEORs concerning orientational averaging are explored and compared to those of averaging schemes that are based on conventional Euler orientation representations. To that aim, the reflectance of a hypothetical polycrystalline material with orthorhombic crystal symmetry was calculated. The calculation was carried out according to the average refractive index theory (ARIT [T.G. Mayerhöfer, Appl. Spectrosc. 56 (2002) 1194]). It is shown that the use of averaging schemes based on conventional Euler orientation representations leads to a dependence of the result from the specific Euler orientation representation that was utilized and from the initial position of the crystal. The latter problem can be overcome partly by the introduction of a weighing factor, but only for two-axes-type Euler orientation representations. In case of a numerical evaluation of the average, a residual difference remains also if a two-axes type Euler orientation representation is used despite of the utilization of a weighing factor. In contrast, this problem does not occur if a symmetric Euler orientation representation is used as a matter of principle, while the result of the averaging for both types of orientation representations converges with increasing number of orientations considered in the numerical evaluation. Additionally, the use of a weighing factor and/or non-equally spaced steps in the numerical evaluation of the average is not necessary. The symmetrical Euler orientation representations are therefore ideally suited for the use in orientational averaging procedures.

  4. Heuristic approach to capillary pressures averaging

    SciTech Connect

    Coca, B.P.

    1980-10-01

    Several methods are available to average capillary pressure curves. Among these are the J-curve and regression equations of the wetting-fluid saturation in porosity and permeability (capillary pressure held constant). While the regression equation seem completely empiric, the J-curve method seems to be theoretically sound due to its expression based on a relation between the average capillary radius and the permeability-porosity ratio. An analysis is given of each of these methods.

  5. Instrument to average 100 data sets

    NASA Technical Reports Server (NTRS)

    Tuma, G. B.; Birchenough, A. G.; Rice, W. J.

    1977-01-01

    An instrumentation system is currently under development which will measure many of the important parameters associated with the operation of an internal combustion engine. Some of these parameters include mass-fraction burn rate, ignition energy, and the indicated mean effective pressure. One of the characteristics of an internal combustion engine is the cycle-to-cycle variation of these parameters. A curve-averaging instrument has been produced which will generate the average curve, over 100 cycles, of any engine parameter. the average curve is described by 2048 discrete points which are displayed on an oscilloscope screen to facilitate recording and is available in real time. Input can be any parameter which is expressed as a + or - 10-volt signal. Operation of the curve-averaging instrument is defined between 100 and 6000 rpm. Provisions have also been made for averaging as many as four parameters simultaneously, with a subsequent decrease in resolution. This provides the means to correlate and perhaps interrelate the phenomena occurring in an internal combustion engine. This instrument has been used successfully on a 1975 Chevrolet V8 engine, and on a Continental 6-cylinder aircraft engine. While this instrument was designed for use on an internal combustion engine, with some modification it can be used to average any cyclically varying waveform.

  6. Average variograms to guide soil sampling

    NASA Astrophysics Data System (ADS)

    Kerry, R.; Oliver, M. A.

    2004-10-01

    To manage land in a site-specific way for agriculture requires detailed maps of the variation in the soil properties of interest. To predict accurately for mapping, the interval at which the soil is sampled should relate to the scale of spatial variation. A variogram can be used to guide sampling in two ways. A sampling interval of less than half the range of spatial dependence can be used, or the variogram can be used with the kriging equations to determine an optimal sampling interval to achieve a given tolerable error. A variogram might not be available for the site, but if the variograms of several soil properties were available on a similar parent material and or particular topographic positions an average variogram could be calculated from these. Averages of the variogram ranges and standardized average variograms from four different parent materials in southern England were used to suggest suitable sampling intervals for future surveys in similar pedological settings based on half the variogram range. The standardized average variograms were also used to determine optimal sampling intervals using the kriging equations. Similar sampling intervals were suggested by each method and the maps of predictions based on data at different grid spacings were evaluated for the different parent materials. Variograms of loss on ignition (LOI) taken from the literature for other sites in southern England with similar parent materials had ranges close to the average for a given parent material showing the possible wider application of such averages to guide sampling.

  7. Alginate cryogel based glucose biosensor

    NASA Astrophysics Data System (ADS)

    Fatoni, Amin; Windy Dwiasi, Dian; Hermawan, Dadan

    2016-02-01

    Cryogel is macroporous structure provides a large surface area for biomolecule immobilization. In this work, an alginate cryogel based biosensor was developed to detect glucose. The cryogel was prepared using alginate cross-linked by calcium chloride under sub-zero temperature. This porous structure was growth in a 100 μL micropipette tip with a glucose oxidase enzyme entrapped inside the cryogel. The glucose detection was based on the colour change of redox indicator, potassium permanganate, by the hydrogen peroxide resulted from the conversion of glucose. The result showed a porous structure of alginate cryogel with pores diameter of 20-50 μm. The developed glucose biosensor was showed a linear response in the glucose detection from 1.0 to 5.0 mM with a regression of y = 0.01x+0.02 and R2 of 0.994. Furthermore, the glucose biosensor was showed a high operational stability up to 10 times of uninterrupted glucose detections.

  8. Antihypertensive drugs and glucose metabolism

    PubMed Central

    Rizos, Christos V; Elisaf, Moses S

    2014-01-01

    Hypertension plays a major role in the development and progression of micro- and macrovascular disease. Moreover, increased blood pressure often coexists with additional cardiovascular risk factors such as insulin resistance. As a result the need for a comprehensive management of hypertensive patients is critical. However, the various antihypertensive drug categories have different effects on glucose metabolism. Indeed, angiotensin receptor blockers as well as angiotensin converting enzyme inhibitors have been associated with beneficial effects on glucose homeostasis. Calcium channel blockers (CCBs) have an overall neutral effect on glucose metabolism. However, some members of the CCBs class such as azelnidipine and manidipine have been shown to have advantageous effects on glucose homeostasis. On the other hand, diuretics and β-blockers have an overall disadvantageous effect on glucose metabolism. Of note, carvedilol as well as nebivolol seem to differentiate themselves from the rest of the β-blockers class, being more attractive options regarding their effect on glucose homeostasis. The adverse effects of some blood pressure lowering drugs on glucose metabolism may, to an extent, compromise their cardiovascular protective role. As a result the effects on glucose homeostasis of the various blood pressure lowering drugs should be taken into account when selecting an antihypertensive treatment, especially in patients which are at high risk for developing diabetes. PMID:25068013

  9. The generic modeling fallacy: Average biomechanical models often produce non-average results!

    PubMed

    Cook, Douglas D; Robertson, Daniel J

    2016-11-07

    Computational biomechanics models constructed using nominal or average input parameters are often assumed to produce average results that are representative of a target population of interest. To investigate this assumption a stochastic Monte Carlo analysis of two common biomechanical models was conducted. Consistent discrepancies were found between the behavior of average models and the average behavior of the population from which the average models׳ input parameters were derived. More interestingly, broadly distributed sets of non-average input parameters were found to produce average or near average model behaviors. In other words, average models did not produce average results, and models that did produce average results possessed non-average input parameters. These findings have implications on the prevalent practice of employing average input parameters in computational models. To facilitate further discussion on the topic, the authors have termed this phenomenon the "Generic Modeling Fallacy". The mathematical explanation of the Generic Modeling Fallacy is presented and suggestions for avoiding it are provided. Analytical and empirical examples of the Generic Modeling Fallacy are also given. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Random Plasma Glucose in Serendipitous Screening for Glucose Intolerance: Screening for Impaired Glucose Tolerance Study 2

    PubMed Central

    Ziemer, David C.; Kolm, Paul; Foster, Jovonne K.; Weintraub, William S.; Vaccarino, Viola; Rhee, Mary K.; Varughese, Rincy M.; Tsui, Circe W.; Koch, David D.; Twombly, Jennifer G.; Venkat Narayan, K. M.

    2008-01-01

    Background With positive results from diabetes prevention studies, there is interest in convenient ways to incorporate screening for glucose intolerance into routine care and to limit the need for fasting diagnostic tests. Objective The aim of this study is to determine whether random plasma glucose (RPG) could be used to screen for glucose intolerance. Design This is a cross-sectional study. Participants The participants of this study include a voluntary sample of 990 adults not known to have diabetes. Measurements RPG was measured, and each subject had a 75-g oral glucose tolerance test several weeks later. Glucose intolerance targets included diabetes, impaired glucose tolerance (IGT), and impaired fasting glucose110 (IFG110; fasting glucose, 110–125 mg/dl, and 2 h glucose < 140 mg/dl). Screening performance was measured by area under receiver operating characteristic curves (AROC). Results Mean age was 48 years, and body mass index (BMI) was 30.4 kg/m2; 66% were women, and 52% were black; 5.1% had previously unrecognized diabetes, and 24.0% had any “high-risk” glucose intolerance (diabetes or IGT or IFG110). The AROC was 0.80 (95% CI 0.74–0.86) for RPG to identify diabetes and 0.72 (0.68–0.75) to identify any glucose intolerance, both highly significant (p < 0.001). Screening performance was generally consistent at different times of the day, regardless of meal status, and across a range of risk factors such as age, BMI, high density lipoprotein cholesterol, triglycerides, and blood pressure. Conclusions RPG values should be considered by health care providers to be an opportunistic initial screening test and used to prompt further evaluation of patients at risk of glucose intolerance. Such “serendipitous screening” could help to identify unrecognized diabetes and prediabetes. PMID:18335280

  11. Averaged controllability of parameter dependent conservative semigroups

    NASA Astrophysics Data System (ADS)

    Lohéac, Jérôme; Zuazua, Enrique

    2017-02-01

    We consider the problem of averaged controllability for parameter depending (either in a discrete or continuous fashion) control systems, the aim being to find a control, independent of the unknown parameters, so that the average of the states is controlled. We do it in the context of conservative models, both in an abstract setting and also analysing the specific examples of the wave and Schrödinger equations. Our first result is of perturbative nature. Assuming the averaging probability measure to be a small parameter-dependent perturbation (in a sense that we make precise) of an atomic measure given by a Dirac mass corresponding to a specific realisation of the system, we show that the averaged controllability property is achieved whenever the system corresponding to the support of the Dirac is controllable. Similar tools can be employed to obtain averaged versions of the so-called Ingham inequalities. Particular attention is devoted to the 1d wave equation in which the time-periodicity of solutions can be exploited to obtain more precise results, provided the parameters involved satisfy Diophantine conditions ensuring the lack of resonances.

  12. Influence of ketamine on regional brain glucose use

    SciTech Connect

    Davis, D.W.; Mans, A.M.; Biebuyck, J.F.; Hawkins, R.A.

    1988-08-01

    The purpose of this study was to determine the effect of different doses of ketamine on cerebral function at the level of individual brain structures as reflected by glucose use. Rats received either 5 or 30 mg/kg ketamine intravenously as a loading dose, followed by an infusion to maintain a steady-state level of the drug. An additional group received 30 mg/kg as a single injection only, and was studied 20 min later, by which time they were recovering consciousness (withdrawal group). Regional brain energy metabolism was evaluated with (6-/sup 14/C)glucose and quantitative autoradiography during a 5-min experimental period. A subhypnotic, steady-state dose (5 mg/kg) of ketamine caused a stimulation of glucose use in most brain areas, with an average increase of 20%. At the larger steady-state dose (30 mg/kg, which is sufficient to cause anesthesia), there was no significant effect on most brain regions; some sensory nuclei were depressed (inferior colliculus, -29%; cerebellar dentate nucleus, -18%; vestibular nucleus, -16%), but glucose use in the ventral posterior hippocampus was increased by 33%. In contrast, during withdrawal from a 30-mg/kg bolus, there was a stimulation of glucose use throughout the brain (21-78%), at a time when plasma ketamine levels were similar to the levels in the 5 mg/kg group. At each steady-state dose, as well as during withdrawal, ketamine caused a notable stimulation of glucose use by the hippocampus.

  13. Books Average Previous Decade of Economic Misery

    PubMed Central

    Bentley, R. Alexander; Acerbi, Alberto; Ormerod, Paul; Lampos, Vasileios

    2014-01-01

    For the 20th century since the Depression, we find a strong correlation between a ‘literary misery index’ derived from English language books and a moving average of the previous decade of the annual U.S. economic misery index, which is the sum of inflation and unemployment rates. We find a peak in the goodness of fit at 11 years for the moving average. The fit between the two misery indices holds when using different techniques to measure the literary misery index, and this fit is significantly better than other possible correlations with different emotion indices. To check the robustness of the results, we also analysed books written in German language and obtained very similar correlations with the German economic misery index. The results suggest that millions of books published every year average the authors' shared economic experiences over the past decade. PMID:24416159

  14. Books average previous decade of economic misery.

    PubMed

    Bentley, R Alexander; Acerbi, Alberto; Ormerod, Paul; Lampos, Vasileios

    2014-01-01

    For the 20(th) century since the Depression, we find a strong correlation between a 'literary misery index' derived from English language books and a moving average of the previous decade of the annual U.S. economic misery index, which is the sum of inflation and unemployment rates. We find a peak in the goodness of fit at 11 years for the moving average. The fit between the two misery indices holds when using different techniques to measure the literary misery index, and this fit is significantly better than other possible correlations with different emotion indices. To check the robustness of the results, we also analysed books written in German language and obtained very similar correlations with the German economic misery index. The results suggest that millions of books published every year average the authors' shared economic experiences over the past decade.

  15. Average length of stay in hospitals.

    PubMed

    Egawa, H

    1984-03-01

    The average length of stay is essentially an important and appropriate index for hospital bed administration. However, from the position that it is not necessarily an appropriate index in Japan, an analysis is made of the difference in the health care facility system between the United States and Japan. Concerning the length of stay in Japanese hospitals, the median appeared to better represent the situation. It is emphasized that in order for the average length of stay to become an appropriate index, there is need to promote regional health, especially facility planning.

  16. The modulated average structure of mullite.

    PubMed

    Birkenstock, Johannes; Petříček, Václav; Pedersen, Bjoern; Schneider, Hartmut; Fischer, Reinhard X

    2015-06-01

    Homogeneous and inclusion-free single crystals of 2:1 mullite (Al(4.8)Si(1.2)O(9.6)) grown by the Czochralski technique were examined by X-ray and neutron diffraction methods. The observed diffuse scattering together with the pattern of satellite reflections confirm previously published data and are thus inherent features of the mullite structure. The ideal composition was closely met as confirmed by microprobe analysis (Al(4.82 (3))Si(1.18 (1))O(9.59 (5))) and by average structure refinements. 8 (5) to 20 (13)% of the available Si was found in the T* position of the tetrahedra triclusters. The strong tendencey for disorder in mullite may be understood from considerations of hypothetical superstructures which would have to be n-fivefold with respect to the three-dimensional average unit cell of 2:1 mullite and n-fourfold in case of 3:2 mullite. In any of these the possible arrangements of the vacancies and of the tetrahedral units would inevitably be unfavorable. Three directions of incommensurate modulations were determined: q1 = [0.3137 (2) 0 ½], q2 = [0 0.4021 (5) 0.1834 (2)] and q3 = [0 0.4009 (5) -0.1834 (2)]. The one-dimensional incommensurately modulated crystal structure associated with q1 was refined for the first time using the superspace approach. The modulation is dominated by harmonic occupational modulations of the atoms in the di- and the triclusters of the tetrahedral units in mullite. The modulation amplitudes are small and the harmonic character implies that the modulated structure still represents an average structure in the overall disordered arrangement of the vacancies and of the tetrahedral structural units. In other words, when projecting the local assemblies at the scale of a few tens of average mullite cells into cells determined by either one of the modulation vectors q1, q2 or q3 a weak average modulation results with slightly varying average occupation factors for the tetrahedral units. As a result, the real

  17. An improved moving average technical trading rule

    NASA Astrophysics Data System (ADS)

    Papailias, Fotis; Thomakos, Dimitrios D.

    2015-06-01

    This paper proposes a modified version of the widely used price and moving average cross-over trading strategies. The suggested approach (presented in its 'long only' version) is a combination of cross-over 'buy' signals and a dynamic threshold value which acts as a dynamic trailing stop. The trading behaviour and performance from this modified strategy are different from the standard approach with results showing that, on average, the proposed modification increases the cumulative return and the Sharpe ratio of the investor while exhibiting smaller maximum drawdown and smaller drawdown duration than the standard strategy.

  18. Average power meter for laser radiation

    NASA Astrophysics Data System (ADS)

    Shevnina, Elena I.; Maraev, Anton A.; Ishanin, Gennady G.

    2016-04-01

    Advanced metrology equipment, in particular an average power meter for laser radiation, is necessary for effective using of laser technology. In the paper we propose a measurement scheme with periodic scanning of a laser beam. The scheme is implemented in a pass-through average power meter that can perform continuous monitoring during the laser operation in pulse mode or in continuous wave mode and at the same time not to interrupt the operation. The detector used in the device is based on the thermoelastic effect in crystalline quartz as it has fast response, long-time stability of sensitivity, and almost uniform sensitivity dependence on the wavelength.

  19. Polarized electron beams at milliampere average current

    SciTech Connect

    Poelker, Matthew

    2013-11-01

    This contribution describes some of the challenges associated with developing a polarized electron source capable of uninterrupted days-long operation at milliAmpere average beam current with polarization greater than 80%. Challenges will be presented in the context of assessing the required level of extrapolation beyond the performance of today's CEBAF polarized source operating at ~ 200 uA average current. Estimates of performance at higher current will be based on hours-long demonstrations at 1 and 4 mA. Particular attention will be paid to beam-related lifetime-limiting mechanisms, and strategies to construct a photogun that operate reliably at bias voltage > 350kV.

  20. Attractors and Time Averages for Random Maps

    NASA Astrophysics Data System (ADS)

    Araujo, Vitor

    2006-07-01

    Considering random noise in finite dimensional parameterized families of diffeomorphisms of a compact finite dimensional boundaryless manifold M, we show the existence of time averages for almost every orbit of each point of M, imposing mild conditions on the families. Moreover these averages are given by a finite number of physical absolutely continuous stationary probability measures. We use this result to deduce that situations with infinitely many sinks and Henon-like attractors are not stable under random perturbations, e.g., Newhouse's and Colli's phenomena in the generic unfolding of a quadratic homoclinic tangency by a one-parameter family of diffeomorphisms.

  1. Average: the juxtaposition of procedure and context

    NASA Astrophysics Data System (ADS)

    Watson, Jane; Chick, Helen; Callingham, Rosemary

    2014-09-01

    This paper presents recent data on the performance of 247 middle school students on questions concerning average in three contexts. Analysis includes considering levels of understanding linking definition and context, performance across contexts, the relative difficulty of tasks, and difference in performance for male and female students. The outcomes lead to a discussion of the expectations of the curriculum and its implementation, as well as assessment, in relation to students' skills in carrying out procedures and their understanding about the meaning of average in context.

  2. SOURCE TERMS FOR AVERAGE DOE SNF CANISTERS

    SciTech Connect

    K. L. Goluoglu

    2000-06-09

    The objective of this calculation is to generate source terms for each type of Department of Energy (DOE) spent nuclear fuel (SNF) canister that may be disposed of at the potential repository at Yucca Mountain. The scope of this calculation is limited to generating source terms for average DOE SNF canisters, and is not intended to be used for subsequent calculations requiring bounding source terms. This calculation is to be used in future Performance Assessment calculations, or other shielding or thermal calculations requiring average source terms.

  3. Investigation of Arterial Waves using Phase Averaging.

    PubMed

    Johnston, Clifton; Martinuzzi, Robert; Schaefer, Matthew

    2005-01-01

    In this paper the development of objective criteria for data reduction, parameter estimations and phenomenological description of arterial pressure pulses are presented. The additional challenge of distinguishing between the cyclical and incoherent contributions to the wave form is also considered. By applying the technique of phase averaging to a series of heart beats, a characteristic pulse was determined. It was shown that the beats from a paced heart are very similar and while beats from an unpaced heart will vary significantly in time and amplitude. The appropriate choice of a reference point is critical in generating phase averages that embody the characteristic behaviour.

  4. Model averaging and muddled multimodel inferences

    USGS Publications Warehouse

    Cade, Brian S.

    2015-01-01

    Three flawed practices associated with model averaging coefficients for predictor variables in regression models commonly occur when making multimodel inferences in analyses of ecological data. Model-averaged regression coefficients based on Akaike information criterion (AIC) weights have been recommended for addressing model uncertainty but they are not valid, interpretable estimates of partial effects for individual predictors when there is multicollinearity among the predictor variables. Multicollinearity implies that the scaling of units in the denominators of the regression coefficients may change across models such that neither the parameters nor their estimates have common scales, therefore averaging them makes no sense. The associated sums of AIC model weights recommended to assess relative importance of individual predictors are really a measure of relative importance of models, with little information about contributions by individual predictors compared to other measures of relative importance based on effects size or variance reduction. Sometimes the model-averaged regression coefficients for predictor variables are incorrectly used to make model-averaged predictions of the response variable when the models are not linear in the parameters. I demonstrate the issues with the first two practices using the college grade point average example extensively analyzed by Burnham and Anderson. I show how partial standard deviations of the predictor variables can be used to detect changing scales of their estimates with multicollinearity. Standardizing estimates based on partial standard deviations for their variables can be used to make the scaling of the estimates commensurate across models, a necessary but not sufficient condition for model averaging of the estimates to be sensible. A unimodal distribution of estimates and valid interpretation of individual parameters are additional requisite conditions. The standardized estimates or equivalently the

  5. Model averaging and muddled multimodel inferences.

    PubMed

    Cade, Brian S

    2015-09-01

    Three flawed practices associated with model averaging coefficients for predictor variables in regression models commonly occur when making multimodel inferences in analyses of ecological data. Model-averaged regression coefficients based on Akaike information criterion (AIC) weights have been recommended for addressing model uncertainty but they are not valid, interpretable estimates of partial effects for individual predictors when there is multicollinearity among the predictor variables. Multicollinearity implies that the scaling of units in the denominators of the regression coefficients may change across models such that neither the parameters nor their estimates have common scales, therefore averaging them makes no sense. The associated sums of AIC model weights recommended to assess relative importance of individual predictors are really a measure of relative importance of models, with little information about contributions by individual predictors compared to other measures of relative importance based on effects size or variance reduction. Sometimes the model-averaged regression coefficients for predictor variables are incorrectly used to make model-averaged predictions of the response variable when the models are not linear in the parameters. I demonstrate the issues with the first two practices using the college grade point average example extensively analyzed by Burnham and Anderson. I show how partial standard deviations of the predictor variables can be used to detect changing scales of their estimates with multicollinearity. Standardizing estimates based on partial standard deviations for their variables can be used to make the scaling of the estimates commensurate across models, a necessary but not sufficient condition for model averaging of the estimates to be sensible. A unimodal distribution of estimates and valid interpretation of individual parameters are additional requisite conditions. The standardized estimates or equivalently the t

  6. Glucose tolerance test - non-pregnant

    MedlinePlus

    ... gov/ency/article/003466.htm Glucose tolerance test - non-pregnant To use the sharing features on this ... is broken) Alternative Names Oral glucose tolerance test - non-pregnant; OGTT - non-pregnant; Diabetes - glucose tolerance test; ...

  7. Genetics Home Reference: glucose-galactose malabsorption

    MedlinePlus

    ... Facebook Twitter Home Health Conditions glucose-galactose malabsorption glucose-galactose malabsorption Printable PDF Open All Close All ... Javascript to view the expand/collapse boxes. Description Glucose-galactose malabsorption is a condition in which the ...

  8. Glucose Suppression of Glucagon Secretion

    PubMed Central

    Le Marchand, Sylvain J.; Piston, David W.

    2010-01-01

    Glucagon is released from α-cells present in intact pancreatic islets at glucose concentrations below 4 mm, whereas higher glucose levels inhibit its secretion. The mechanisms underlying the suppression of α-cell secretory activity are poorly understood, but two general types of models have been proposed as follows: direct inhibition by glucose or paracrine inhibition from non-α-cells within the islet of Langerhans. To identify α-cells for analysis, we utilized transgenic mice expressing fluorescent proteins targeted specifically to these cells. Measurements of glucagon secretion from pure populations of flow-sorted α-cells show that contrary to its effect on intact islets, glucose does stimulate glucagon secretion from isolated α-cells. This observation argues against a direct inhibition of glucagon secretion by glucose and supports the paracrine inhibition model. Imaging of cellular metabolism by two-photon excitation of NAD(P)H autofluorescence indicates that glucose is metabolized in α-cells and that glucokinase is the likely rate-limiting step in this process. Imaging calcium dynamics of α-cells in intact islets reveals that inhibiting concentrations of glucose increase the intracellular calcium concentration and the frequency of α-cell calcium oscillations. Application of candidate paracrine inhibitors leads to reduced glucagon secretion but did not decrease the α-cell calcium activity. Taken together, the data suggest that suppression occurs downstream from α-cell calcium signaling, presumably at the level of vesicle trafficking or exocytotic machinery. PMID:20231269

  9. The glucose-6-phosphatase system.

    PubMed Central

    van Schaftingen, Emile; Gerin, Isabelle

    2002-01-01

    Glucose-6-phosphatase (G6Pase), an enzyme found mainly in the liver and the kidneys, plays the important role of providing glucose during starvation. Unlike most phosphatases acting on water-soluble compounds, it is a membrane-bound enzyme, being associated with the endoplasmic reticulum. In 1975, W. Arion and co-workers proposed a model according to which G6Pase was thought to be a rather unspecific phosphatase, with its catalytic site oriented towards the lumen of the endoplasmic reticulum [Arion, Wallin, Lange and Ballas (1975) Mol. Cell. Biochem. 6, 75--83]. Substrate would be provided to this enzyme by a translocase that is specific for glucose 6-phosphate, thereby accounting for the specificity of the phosphatase for glucose 6-phosphate in intact microsomes. Distinct transporters would allow inorganic phosphate and glucose to leave the vesicles. At variance with this substrate-transport model, other models propose that conformational changes play an important role in the properties of G6Pase. The last 10 years have witnessed important progress in our knowledge of the glucose 6-phosphate hydrolysis system. The genes encoding G6Pase and the glucose 6-phosphate translocase have been cloned and shown to be mutated in glycogen storage disease type Ia and type Ib respectively. The gene encoding a G6Pase-related protein, expressed specifically in pancreatic islets, has also been cloned. Specific potent inhibitors of G6Pase and of the glucose 6-phosphate translocase have been synthesized or isolated from micro-organisms. These as well as other findings support the model initially proposed by Arion. Much progress has also been made with regard to the regulation of the expression of G6Pase by insulin, glucocorticoids, cAMP and glucose. PMID:11879177

  10. Average Annual Rainfall Over the Globe

    NASA Astrophysics Data System (ADS)

    Agrawal, D. C.

    2013-12-01

    The atmospheric recycling of water is a very important phenomenon on the globe because it not only refreshes the water but it also redistributes it over land and oceans/rivers/lakes throughout the globe. This is made possible by the solar energy intercepted by the Earth. The half of the globe facing the Sun, on the average, intercepts 1.74×1017 J of solar radiation per second and it is divided over various channels as given in Table 1. It keeps our planet warm and maintains its average temperature2 of 288 K with the help of the atmosphere in such a way that life can survive. It also recycles the water in the oceans/rivers/ lakes by initial evaporation and subsequent precipitation; the average annual rainfall over the globe is around one meter. According to M. King Hubbert the amount of solar power going into the evaporation and precipitation channel is 4.0×1016 W. Students can verify the value of average annual rainfall over the globe by utilizing this part of solar energy. This activity is described in the next section.

  11. Averaging on Earth-Crossing Orbits

    NASA Astrophysics Data System (ADS)

    Gronchi, G. F.; Milani, A.

    The orbits of planet-crossing asteroids (and comets) can undergo close approaches and collisions with some major planet. This introduces a singularity in the N-body Hamiltonian, and the averaging of the equations of motion, traditionally used to compute secular perturbations, is undefined. We show that it is possible to define in a rigorous way some generalised averaged equations of motion, in such a way that the generalised solutions are unique and piecewise smooth. This is obtained, both in the planar and in the three-dimensional case, by means of the method of extraction of the singularities by Kantorovich. The modified distance used to approximate the singularity is the one used by Wetherill in his method to compute probability of collision. Some examples of averaged dynamics have been computed; a systematic exploration of the averaged phase space to locate the secular resonances should be the next step. `Alice sighed wearily. ``I think you might do something better with the time'' she said, ``than waste it asking riddles with no answers'' (Alice in Wonderland, L. Carroll)

  12. Attendance and Grade Point Average: A Study.

    ERIC Educational Resources Information Center

    Strickland, Vinnie P.

    This study investigated the correlation between attendance and grade point average among high school juniors, hypothesizing that there would not be a significant correlation between the two. The sample consisted of 32 students randomly selected from among 172 high school students enrolled in a Chicago public school during school years 1995-1996…

  13. Average thermal characteristics of solar wind electrons

    NASA Technical Reports Server (NTRS)

    Montgomery, M. D.

    1972-01-01

    Average solar wind electron properties based on a 1 year Vela 4 data sample-from May 1967 to May 1968 are presented. Frequency distributions of electron-to-ion temperature ratio, electron thermal anisotropy, and thermal energy flux are presented. The resulting evidence concerning heat transport in the solar wind is discussed.

  14. Initial Conditions in the Averaging Cognitive Model

    ERIC Educational Resources Information Center

    Noventa, S.; Massidda, D.; Vidotto, G.

    2010-01-01

    The initial state parameters s[subscript 0] and w[subscript 0] are intricate issues of the averaging cognitive models in Information Integration Theory. Usually they are defined as a measure of prior information (Anderson, 1981; 1982) but there are no general rules to deal with them. In fact, there is no agreement as to their treatment except in…

  15. Bayesian Model Averaging for Propensity Score Analysis

    ERIC Educational Resources Information Center

    Kaplan, David; Chen, Jianshen

    2013-01-01

    The purpose of this study is to explore Bayesian model averaging in the propensity score context. Previous research on Bayesian propensity score analysis does not take into account model uncertainty. In this regard, an internally consistent Bayesian framework for model building and estimation must also account for model uncertainty. The…

  16. Why Johnny Can Be Average Today.

    ERIC Educational Resources Information Center

    Sturrock, Alan

    1997-01-01

    During a (hypothetical) phone interview with a university researcher, an elementary principal reminisced about a lifetime of reading groups with unmemorable names, medium-paced math problems, patchworked social studies/science lessons, and totally "average" IQ and batting scores. The researcher hung up at the mention of bell-curved assembly lines…

  17. Why Johnny Can Be Average Today.

    ERIC Educational Resources Information Center

    Sturrock, Alan

    1997-01-01

    During a (hypothetical) phone interview with a university researcher, an elementary principal reminisced about a lifetime of reading groups with unmemorable names, medium-paced math problems, patchworked social studies/science lessons, and totally "average" IQ and batting scores. The researcher hung up at the mention of bell-curved assembly lines…

  18. World average top-quark mass

    SciTech Connect

    Glenzinski, D.; /Fermilab

    2008-01-01

    This paper summarizes a talk given at the Top2008 Workshop at La Biodola, Isola d Elba, Italy. The status of the world average top-quark mass is discussed. Some comments about the challanges facing the experiments in order to further improve the precision are offered.

  19. Measuring Time-Averaged Blood Pressure

    NASA Technical Reports Server (NTRS)

    Rothman, Neil S.

    1988-01-01

    Device measures time-averaged component of absolute blood pressure in artery. Includes compliant cuff around artery and external monitoring unit. Ceramic construction in monitoring unit suppresses ebb and flow of pressure-transmitting fluid in sensor chamber. Transducer measures only static component of blood pressure.

  20. Conceptual Analysis of System Average Water Stability

    NASA Astrophysics Data System (ADS)

    Zhang, H.

    2016-12-01

    Averaging over time and area, the precipitation in an ecosystem (SAP - system average precipitation) depends on the average surface temperature and relative humidity (RH) in the system if uniform convection is assumed. RH depends on the evapotranspiration of the system (SAE - system average evapotranspiration). There is a non-linear relationship between SAP and SAE. Studying this relationship can lead mechanistic understanding of the ecosystem health status and trend under different setups. If SAP is higher than SAE, the system will have a water runoff which flows out through rivers. If SAP is lower than SAE, irrigation is needed to maintain the vegetation status. This presentation will give a conceptual analysis of the stability in this relationship under different assumed areas, water or forest coverages, elevations and latitudes. This analysis shows that desert is a stable system. Water circulation in basins is also stabilized at a specific SAP based on the basin profile. It further shows that deforestation will reduce SAP, and can flip the system to an irrigation required status. If no irrigation is provided, the system will automatically reduce to its stable point - desert, which is extremely difficult to turn around.

  1. Measuring Time-Averaged Blood Pressure

    NASA Technical Reports Server (NTRS)

    Rothman, Neil S.

    1988-01-01

    Device measures time-averaged component of absolute blood pressure in artery. Includes compliant cuff around artery and external monitoring unit. Ceramic construction in monitoring unit suppresses ebb and flow of pressure-transmitting fluid in sensor chamber. Transducer measures only static component of blood pressure.

  2. 40 CFR 91.1304 - Averaging.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... EMISSIONS FROM MARINE SPARK-IGNITION ENGINES In-Use Credit Program for New Marine Engines § 91.1304... credit balance for a model year. Positive credits to be used in averaging may be obtained from credits... positive credit balance must be used at a rate of 1.1 to 1. ...

  3. 40 CFR 63.846 - Emission averaging.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 11 2012-07-01 2012-07-01 false Emission averaging. 63.846 Section 63...) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES (CONTINUED) National Emission Standards for Hazardous Air Pollutants for Primary Aluminum Reduction Plants § 63.846...

  4. 40 CFR 63.846 - Emission averaging.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 11 2014-07-01 2014-07-01 false Emission averaging. 63.846 Section 63...) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES (CONTINUED) National Emission Standards for Hazardous Air Pollutants for Primary Aluminum Reduction Plants § 63.846...

  5. A Functional Measurement Study on Averaging Numerosity

    ERIC Educational Resources Information Center

    Tira, Michael D.; Tagliabue, Mariaelena; Vidotto, Giulio

    2014-01-01

    In two experiments, participants judged the average numerosity between two sequentially presented dot patterns to perform an approximate arithmetic task. In Experiment 1, the response was given on a 0-20 numerical scale (categorical scaling), and in Experiment 2, the response was given by the production of a dot pattern of the desired numerosity…

  6. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.

    SciTech Connect

    BEN-ZVI, ILAN, DAYRAN, D.; LITVINENKO, V.

    2005-08-21

    Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department.

  7. How Young Is Standard Average European?

    ERIC Educational Resources Information Center

    Haspelmath, Martin

    1998-01-01

    An analysis of Standard Average European, a European linguistic area, looks at 11 of its features (definite, indefinite articles, have-perfect, participial passive, antiaccusative prominence, nominative experiencers, dative external possessors, negation/negative pronouns, particle comparatives, A-and-B conjunction, relative clauses, verb fronting…

  8. Conversion of glucose to sorbose

    DOEpatents

    Davis, Mark E.; Gounder, Rajamani

    2016-02-09

    The present invention is directed to methods for preparing sorbose from glucose, said method comprising: (a) contacting the glucose with a silica-containing structure comprising a zeolite having a topology of a 12 membered-ring or larger, an ordered mesoporous silica material, or an amorphous silica, said structure containing Lewis acidic Ti.sup.4+ or Zr.sup.4+ or both Ti.sup.4+ and Zr.sup.4+ framework centers, said contacting conducted under reaction conditions sufficient to isomerize the glucose to sorbose. The sorbose may be (b) separated or isolated; or (c) converted to ascorbic acid.

  9. Orbit Averaging in Perturbed Planetary Rings

    NASA Astrophysics Data System (ADS)

    Stewart, Glen R.

    2015-11-01

    The orbital period is typically much shorter than the time scale for dynamical evolution of large-scale structures in planetary rings. This large separation in time scales motivates the derivation of reduced models by averaging the equations of motion over the local orbit period (Borderies et al. 1985, Shu et al. 1985). A more systematic procedure for carrying out the orbit averaging is to use Lie transform perturbation theory to remove the dependence on the fast angle variable from the problem order-by-order in epsilon, where the small parameter epsilon is proportional to the fractional radial distance from exact resonance. This powerful technique has been developed and refined over the past thirty years in the context of gyrokinetic theory in plasma physics (Brizard and Hahm, Rev. Mod. Phys. 79, 2007). When the Lie transform method is applied to resonantly forced rings near a mean motion resonance with a satellite, the resulting orbit-averaged equations contain the nonlinear terms found previously, but also contain additional nonlinear self-gravity terms of the same order that were missed by Borderies et al. and by Shu et al. The additional terms result from the fact that the self-consistent gravitational potential of the perturbed rings modifies the orbit-averaging transformation at nonlinear order. These additional terms are the gravitational analog of electrostatic ponderomotive forces caused by large amplitude waves in plasma physics. The revised orbit-averaged equations are shown to modify the behavior of nonlinear density waves in planetary rings compared to the previously published theory. This reserach was supported by NASA's Outer Planets Reserach program.

  10. Glucose-responsive hydrogel electrode for biocompatible glucose transistor

    PubMed Central

    Kajisa, Taira; Sakata, Toshiya

    2017-01-01

    Abstract In this paper, we propose a highly sensitive and biocompatible glucose sensor using a semiconductor-based field effect transistor (FET) with a functionalized hydrogel. The principle of the FET device contributes to the easy detection of ionic charges with high sensitivity, and the hydrogel coated on the electrode enables the specific detection of glucose with biocompatibility. The copolymerized hydrogel on the Au gate electrode of the FET device is optimized by controlling the mixture ratio of biocompatible 2-hydroxyethylmethacrylate (HEMA) as the main monomer and vinylphenylboronic acid (VPBA) as a glucose-responsive monomer. The gate surface potential of the hydrogel FETs shifts in the negative direction with increasing glucose concentration from 10 μM to 40 mM, which results from the increase in the negative charges on the basis of the diol-binding of PBA derivatives with glucose molecules in the hydrogel. Moreover, the hydrogel coated on the gate suppresses the signal noise caused by the nonspecific adsorption of proteins such as albumin. The hydrogel FET can serve as a highly sensitive and biocompatible glucose sensor in in vivo or ex vivo applications such as eye contact lenses and sheets adhering to the skin. PMID:28179956

  11. Glucose-responsive hydrogel electrode for biocompatible glucose transistor.

    PubMed

    Kajisa, Taira; Sakata, Toshiya

    2017-01-01

    In this paper, we propose a highly sensitive and biocompatible glucose sensor using a semiconductor-based field effect transistor (FET) with a functionalized hydrogel. The principle of the FET device contributes to the easy detection of ionic charges with high sensitivity, and the hydrogel coated on the electrode enables the specific detection of glucose with biocompatibility. The copolymerized hydrogel on the Au gate electrode of the FET device is optimized by controlling the mixture ratio of biocompatible 2-hydroxyethylmethacrylate (HEMA) as the main monomer and vinylphenylboronic acid (VPBA) as a glucose-responsive monomer. The gate surface potential of the hydrogel FETs shifts in the negative direction with increasing glucose concentration from 10 μM to 40 mM, which results from the increase in the negative charges on the basis of the diol-binding of PBA derivatives with glucose molecules in the hydrogel. Moreover, the hydrogel coated on the gate suppresses the signal noise caused by the nonspecific adsorption of proteins such as albumin. The hydrogel FET can serve as a highly sensitive and biocompatible glucose sensor in in vivo or ex vivo applications such as eye contact lenses and sheets adhering to the skin.

  12. Catalase-conjugated liposomes encapsulating glucose oxidase for controlled oxidation of glucose with decomposition of hydrogen peroxide produced.

    PubMed

    Yoshimoto, Makoto; Takaki, Noriyuki; Yamasaki, Miku

    2010-09-01

    The catalase-conjugated liposome encapsulating glucose oxidase (CLG) was prepared for developing a novel liposomal system for glucose oxidation with controllable enzyme activities. The catalase molecules were conjugated to the surface of liposome with 100 nm in mean diameter through coupling with the membrane-incorporated 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(glutaryl) (NGPE) at its mole fraction f(G) of 0.05 or 0.15. The average number of enzyme molecules per CLG with f(G) of 0.15 was 8.7 for glucose oxidase and 6.5 for catalase. The CLG-catalyzed oxidation of glucose was performed at 40 degrees C for prolonged period up to 99 h. The CLG with f(G) of 0.15 gave larger oxidation rate than that with f(G) of 0.05. In the fed-batch oxidation of glucose catalyzed by the former CLG, the stable oxidation rate was observed for 75 h with negligible accumulation of H(2)O(2) produced because of the durable catalytic actions of the liposomal enzymes. The oxidation rate of the CLG reaction increased to 1.1 mM-glucose/(hmM-lipid) at the acidic pH in the internal phase of liposome and the neutral pH in the external one corresponding to the optimal pH conditions for the activities of glucose oxidase and catalase, respectively. The oxidation rate catalyzed by the CLG could be controlled by adding sublytic concentrations of cholate to increase permeability of the liposome membrane to glucose. The catalase-conjugated liposomal system is potentially utilized for controlling the rate of reactions catalyzed by a variety of oxidases. Copyright 2010 Elsevier B.V. All rights reserved.

  13. Apparent and average accelerations of the Universe

    SciTech Connect

    Bolejko, Krzysztof; Andersson, Lars E-mail: larsa@math.miami.edu

    2008-10-15

    In this paper we consider the relation between the volume deceleration parameter obtained within the Buchert averaging scheme and the deceleration parameter derived from supernova observation. This work was motivated by recent findings that showed that there are models which despite having {Lambda} = 0 have volume deceleration parameter q{sup vol}<0. This opens the possibility that back-reaction and averaging effects may be used as an interesting alternative explanation to the dark energy phenomenon. We have calculated q{sup vol} in some Lemaitre-Tolman models. For those models which are chosen to be realistic and which fit the supernova data, we find that q{sup vol}>0, while those models which we have been able to find which exhibit q{sup vol}<0 turn out to be unrealistic. This indicates that care must be exercised in relating the deceleration parameter to observations.

  14. New applications for high average power beams

    SciTech Connect

    Neau, E.L.; Turman, B.N.; Patterson, E.L.

    1993-08-01

    The technology base formed by the development of high peak power simulators, laser drivers, FEL`s, and ICF drivers from the early 60`s through the late 80`s is being extended to high average power short-pulse machines with the capabilities of supporting new types of manufacturing processes and performing new roles in environmental cleanup applications. This paper discusses a process for identifying and developing possible commercial applications, specifically those requiring very high average power levels of hundreds of kilowatts to perhaps megawatts. The authors discuss specific technology requirements and give examples of application development efforts. The application development work is directed at areas that can possibly benefit from the high specific energies attainable with short pulse machines.

  15. Rigid shape matching by segmentation averaging.

    PubMed

    Wang, Hongzhi; Oliensis, John

    2010-04-01

    We use segmentations to match images by shape. The new matching technique does not require point-to-point edge correspondence and is robust to small shape variations and spatial shifts. To address the unreliability of segmentations computed bottom-up, we give a closed form approximation to an average over all segmentations. Our method has many extensions, yielding new algorithms for tracking, object detection, segmentation, and edge-preserving smoothing. For segmentation, instead of a maximum a posteriori approach, we compute the "central" segmentation minimizing the average distance to all segmentations of an image. For smoothing, instead of smoothing images based on local structures, we smooth based on the global optimal image structures. Our methods for segmentation, smoothing, and object detection perform competitively, and we also show promising results in shape-based tracking.

  16. Time-average dynamic speckle interferometry

    NASA Astrophysics Data System (ADS)

    Vladimirov, A. P.

    2014-05-01

    For the study of microscopic processes occurring at structural level in solids and thin biological objects, a method of dynamic speckle interferometry successfully applied. However, the method has disadvantages. The purpose of the report is to acquaint colleagues with the method of averaging in time in dynamic speckle - interferometry of microscopic processes, allowing eliminating shortcomings. The main idea of the method is the choice the averaging time, which exceeds the characteristic time correlation (relaxation) the most rapid process. The method theory for a thin phase and the reflecting object is given. The results of the experiment on the high-cycle fatigue of steel and experiment to estimate the biological activity of a monolayer of cells, cultivated on a transparent substrate is given. It is shown that the method allows real-time visualize the accumulation of fatigue damages and reliably estimate the activity of cells with viruses and without viruses.

  17. Polarized electron beams at milliampere average current

    SciTech Connect

    Poelker, M.

    2013-11-07

    This contribution describes some of the challenges associated with developing a polarized electron source capable of uninterrupted days-long operation at milliAmpere average beam current with polarization greater than 80%. Challenges will be presented in the context of assessing the required level of extrapolation beyond the performance of today’s CEBAF polarized source operating at ∼ 200 uA average current. Estimates of performance at higher current will be based on hours-long demonstrations at 1 and 4 mA. Particular attention will be paid to beam-related lifetime-limiting mechanisms, and strategies to construct a photogun that operate reliably at bias voltage > 350kV.

  18. Warp-averaging event-related potentials.

    PubMed

    Wang, K; Begleiter, H; Porjesz, B

    2001-10-01

    To align the repeated single trials of the event-related potential (ERP) in order to get an improved estimate of the ERP. A new implementation of the dynamic time warping is applied to compute a warp-average of the single trials. The trilinear modeling method is applied to filter the single trials prior to alignment. Alignment is based on normalized signals and their estimated derivatives. These features reduce the misalignment due to aligning the random alpha waves, explaining amplitude differences in latency differences, or the seemingly small amplitudes of some components. Simulations and applications to visually evoked potentials show significant improvement over some commonly used methods. The new implementation of the dynamic time warping can be used to align the major components (P1, N1, P2, N2, P3) of the repeated single trials. The average of the aligned single trials is an improved estimate of the ERP. This could lead to more accurate results in subsequent analysis.

  19. Models of space averaged energetics of plates

    NASA Technical Reports Server (NTRS)

    Bouthier, O. M.; Bernhard, R. J.

    1990-01-01

    The analysis of high frequency vibrations in plates is of particular interest in the study of structure borne noise in aircrafts. The current methods of analysis are either too expensive (finite element method) or may have a confidence band wider than desirable (Statistical Energy Analysis). An alternative technique to model the space and time averaged response of structural acoustics problems with enough detail to include all significant mechanisms of energy generation, transmission, and absorption is highly desirable. The focus of this paper is the development of a set of equations which govern the space and time averaged energy density in plates. To solve this equation, a new type of boundary value problem must be treated in terms of energy density variables using energy and intensity boundary conditions. A computer simulation verification study of the energy governing equation is performed. A finite element formulation of the new equations is also implemented and several test cases are analyzed and compared to analytical solutions.

  20. [Contribution of the kidney to glucose homeostasis].

    PubMed

    Segura, Julián; Ruilope, Luis Miguel

    2013-09-01

    The kidney is involved in glucose homeostasis through three major mechanisms: renal gluconeogenesis, renal glucose consumption, and glucose reabsorption in the proximal tubule. Glucose reabsorption is one of the most important physiological functions of the kidney, allowing full recovery of filtered glucose, elimination of glucose from the urine, and prevention of calorie loss. Approximately 90% of the glucose is reabsorbed in the S1 segment of the proximal tubule, where glucose transporter-2 (GLUT2) and sodium-glucose transporter-2 (SGLT2) are located, while the remaining 10% is reabsorbed in the S3 segment by SGLT1 and GLUT1 transporters. In patients with hyperglycemia, the kidney continues to reabsorb glucose, thus maintaining hyperglycemia. Most of the renal glucose reabsorption is mediated by SGLT2. Several experimental and clinical studies suggest that pharmacological blockade of this transporter might be beneficial in the management of hyperglycemia in patients with type 2 diabetes.

  1. Area-average rainfall and lightning activity

    NASA Astrophysics Data System (ADS)

    ChèZe, Jean-Luc; Sauvageot, Henri

    1997-01-01

    The aim of the paper is to discuss the statistical relations between the average rainfall parameters for an ensemble of convective cells and the mean lightning occurrence inside this area. The study is based on a data set gathered in France using C and S band radars and two different lightning detection networks. One of them is used to measure L, the cloud to ground flash number. The other one is used to measure Sa, the total cloud to ground and intracloud flash number. The rainfall parameters are and F(τ), the mean areal rain rate and the fractional rainfall area above a threshold τ, respectively. The results demonstrate that for a single event (i.e., on the spatiotemporal scale of a rain system), significant correlations (1) between the average rainfall parameters, (2) between L and Sa, and (3) between the lightning and the average rainfall parameters are observed. As expected, the correlation between and F(τ) (1) is very tight for the individual cases as well as for the cluster of the data. The correlations between L and Sa and between the lightning and the average rainfall parameters (i.e., 2 and 3) can be tight in convectively and electrically very active systems (the correlation coefficient between L and F(τ) reaches 0.96). Yet, the parameters of the relations change from one case to another. So, when considered on a climatological scale (i.e., all the data for a season processed together), the 2 and 3 types of correlation diminish or even vanish. However, it is suggested that for homogeneous climatological conditions associated with very active convective clouds, such as, for example, the conditions observed in some tropical areas, and for a homogeneous regime of convection, a tight relation with stable parameters could be expected.

  2. Average Annual Rainfall over the Globe

    ERIC Educational Resources Information Center

    Agrawal, D. C.

    2013-01-01

    The atmospheric recycling of water is a very important phenomenon on the globe because it not only refreshes the water but it also redistributes it over land and oceans/rivers/lakes throughout the globe. This is made possible by the solar energy intercepted by the Earth. The half of the globe facing the Sun, on the average, intercepts 1.74 ×…

  3. Stochastic Games with Average Payoff Criterion

    SciTech Connect

    Ghosh, M. K.; Bagchi, A.

    1998-11-15

    We study two-person stochastic games on a Polish state and compact action spaces and with average payoff criterion under a certain ergodicity condition. For the zero-sum game we establish the existence of a value and stationary optimal strategies for both players. For the nonzero-sum case the existence of Nash equilibrium in stationary strategies is established under certain separability conditions.

  4. Average Annual Rainfall over the Globe

    ERIC Educational Resources Information Center

    Agrawal, D. C.

    2013-01-01

    The atmospheric recycling of water is a very important phenomenon on the globe because it not only refreshes the water but it also redistributes it over land and oceans/rivers/lakes throughout the globe. This is made possible by the solar energy intercepted by the Earth. The half of the globe facing the Sun, on the average, intercepts 1.74 ×…

  5. Average chemical composition of the lunar surface

    NASA Technical Reports Server (NTRS)

    Turkevich, A. L.

    1973-01-01

    The available data on the chemical composition of the lunar surface at eleven sites (3 Surveyor, 5 Apollo and 3 Luna) are used to estimate the amounts of principal chemical elements (those present in more than about 0.5% by atom) in average lunar surface material. The terrae of the moon differ from the maria in having much less iron and titanium and appreciably more aluminum and calcium.

  6. Iterative methods based upon residual averaging

    NASA Technical Reports Server (NTRS)

    Neuberger, J. W.

    1980-01-01

    Iterative methods for solving boundary value problems for systems of nonlinear partial differential equations are discussed. The methods involve subtracting an average of residuals from one approximation in order to arrive at a subsequent approximation. Two abstract methods in Hilbert space are given and application of these methods to quasilinear systems to give numerical schemes for such problems is demonstrated. Potential theoretic matters related to the iteration schemes are discussed.

  7. The Average Velocity in a Queue

    ERIC Educational Resources Information Center

    Frette, Vidar

    2009-01-01

    A number of cars drive along a narrow road that does not allow overtaking. Each driver has a certain maximum speed at which he or she will drive if alone on the road. As a result of slower cars ahead, many cars are forced to drive at speeds lower than their maximum ones. The average velocity in the queue offers a non-trivial example of a mean…

  8. The Average Velocity in a Queue

    ERIC Educational Resources Information Center

    Frette, Vidar

    2009-01-01

    A number of cars drive along a narrow road that does not allow overtaking. Each driver has a certain maximum speed at which he or she will drive if alone on the road. As a result of slower cars ahead, many cars are forced to drive at speeds lower than their maximum ones. The average velocity in the queue offers a non-trivial example of a mean…

  9. Modern average global sea-surface temperature

    USGS Publications Warehouse

    Schweitzer, Peter N.

    1993-01-01

    The data contained in this data set are derived from the NOAA Advanced Very High Resolution Radiometer Multichannel Sea Surface Temperature data (AVHRR MCSST), which are obtainable from the Distributed Active Archive Center at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. The JPL tapes contain weekly images of SST from October 1981 through December 1990 in nine regions of the world ocean: North Atlantic, Eastern North Atlantic, South Atlantic, Agulhas, Indian, Southeast Pacific, Southwest Pacific, Northeast Pacific, and Northwest Pacific. This data set represents the results of calculations carried out on the NOAA data and also contains the source code of the programs that made the calculations. The objective was to derive the average sea-surface temperature of each month and week throughout the whole 10-year series, meaning, for example, that data from January of each year would be averaged together. The result is 12 monthly and 52 weekly images for each of the oceanic regions. Averaging the images in this way tends to reduce the number of grid cells that lack valid data and to suppress interannual variability.

  10. On the ensemble averaging of PIC simulations

    NASA Astrophysics Data System (ADS)

    Codur, R. J. B.; Tsung, F. S.; Mori, W. B.

    2016-10-01

    Particle-in-cell simulations are used ubiquitously in plasma physics to study a variety of phenomena. They can be an efficient tool for modeling the Vlasov or Vlasov Fokker Planck equations in multi-dimensions. However, the PIC method actually models the Klimontovich equation for finite size particles. The Vlasov Fokker Planck equation can be derived as the ensemble average of the Klimontovich equation. We present results of studying Landau damping and Stimulated Raman Scattering using PIC simulations where we use identical ``drivers'' but change the random number generator seeds. We show that even for cases where a plasma wave is excited below the noise in a single simulation that the plasma wave can clearly be seen and studied if an ensemble average over O(10) simulations is made. Comparison between the results from an ensemble average and the subtraction technique are also presented. In the subtraction technique two simulations, one with the other without the ``driver'' are conducted with the same random number generator seed and the results are subtracted. This work is supported by DOE, NSF, and ENSC (France).

  11. Disk-averaged synthetic spectra of Mars.

    PubMed

    Tinetti, Giovanna; Meadows, Victoria S; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather

    2005-08-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin.

  12. Digital Averaging Phasemeter for Heterodyne Interferometry

    NASA Technical Reports Server (NTRS)

    Johnson, Donald; Spero, Robert; Shaklan, Stuart; Halverson, Peter; Kuhnert, Andreas

    2004-01-01

    A digital averaging phasemeter has been built for measuring the difference between the phases of the unknown and reference heterodyne signals in a heterodyne laser interferometer. This phasemeter performs well enough to enable interferometric measurements of distance with accuracy of the order of 100 pm and with the ability to track distance as it changes at a speed of as much as 50 cm/s. This phasemeter is unique in that it is a single, integral system capable of performing three major functions that, heretofore, have been performed by separate systems: (1) measurement of the fractional-cycle phase difference, (2) counting of multiple cycles of phase change, and (3) averaging of phase measurements over multiple cycles for improved resolution. This phasemeter also offers the advantage of making repeated measurements at a high rate: the phase is measured on every heterodyne cycle. Thus, for example, in measuring the relative phase of two signals having a heterodyne frequency of 10 kHz, the phasemeter would accumulate 10,000 measurements per second. At this high measurement rate, an accurate average phase determination can be made more quickly than is possible at a lower rate.

  13. Disk-averaged synthetic spectra of Mars

    NASA Technical Reports Server (NTRS)

    Tinetti, Giovanna; Meadows, Victoria S.; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather

    2005-01-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin.

  14. Disk-Averaged Synthetic Spectra of Mars

    NASA Astrophysics Data System (ADS)

    Tinetti, Giovanna; Meadows, Victoria S.; Crisp, David; Fong ,William; Velusamy, Thangasamy; Snively, Heather

    2005-08-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin.

  15. BAEPs averaging analysis using autoregressive modelling.

    PubMed

    Vannier, E; Naït-Ali, A

    2004-06-01

    The present paper introduces a new perspective on the classical ensemble averaging which can be useful to analyse the Brainstem Auditory Evoked Potentials (BAEPs). The analysis of the dynamics, related to the BAEP, is performed directly after its acquisition from the electroencephalogram (EEG). The method primarily consists of dynamically modelling the averaged potential, obtained during the acquisition mode. Each averaging of signal at a given instant is considered as an autoregressive (AR) process. It has been shown that the predicting error power of AR modelling can be useful to provide an efficient tool to analyse the BAEPs. It has also been shown that the method is capable of taking the non-stationarities of both the BAEP and the EEG into account. In order to validate our approach, the proposed technique has been implemented for both simulated and real signals. This approach can also be employed in the context of estimating other evoked potentials and shows rich promise for potential clinical applications in future.

  16. A simple algorithm for averaging spike trains.

    PubMed

    Julienne, Hannah; Houghton, Conor

    2013-02-25

    Although spike trains are the principal channel of communication between neurons, a single stimulus will elicit different spike trains from trial to trial. This variability, in both spike timings and spike number can obscure the temporal structure of spike trains and often means that computations need to be run on numerous spike trains in order to extract features common across all the responses to a particular stimulus. This can increase the computational burden and obscure analytical results. As a consequence, it is useful to consider how to calculate a central spike train that summarizes a set of trials. Indeed, averaging responses over trials is routine for other signal types. Here, a simple method for finding a central spike train is described. The spike trains are first mapped to functions, these functions are averaged, and a greedy algorithm is then used to map the average function back to a spike train. The central spike trains are tested for a large data set. Their performance on a classification-based test is considerably better than the performance of the medoid spike trains.

  17. Disk-averaged synthetic spectra of Mars

    NASA Technical Reports Server (NTRS)

    Tinetti, Giovanna; Meadows, Victoria S.; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather

    2005-01-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin.

  18. Orienteering performance and ingestion of glucose and glucose polymers.

    PubMed

    Kujala, U M; Heinonen, O J; Kvist, M; Kärkkäinen, O P; Marniemi, J; Niittymäki, K; Havas, E

    1989-06-01

    The benefit of glucose polymer ingestion in addition to 2.5 per cent glucose before and during a prolonged orienteering competition was studied. The final time in the competition in the group ingesting 2.5 per cent glucose (group G, n = 10) was 113 min 37 s +/- 8 min 11 s, and in the group which had additionally ingested glucose polymer (group G + GP, n = 8) 107 min 18s +/- 4 min 41 s (NS). One fifth (21 per cent) of the time difference between the two groups was due to difference in orienteering errors. Group G + GP orienteered the last third of the competition faster than group G (p less than 0.05). The time ratio between the last third of the competition and the first third of the competition was lower in group G + GP than in group G (p less than 0.05). After the competition, there was statistically insignificant tendency to higher serum glucose and lower serum free fatty acid concentrations in group G + GP, and serum insulin concentration was higher in group G + GP than in group G (p less than 0.05). Three subjects reported that they exhausted during the competition. These same three subjects had the lowest serum glucose concentrations after the competition (2.9 mmol.1(-1), 2.9 mmol.1(-1), 3.5 mmol.1(-1] and all of them were from group G. It is concluded that glucose polymer syrup ingestion is beneficial for prolonged psychophysical performance.

  19. Single Glucose Biofuel Cells Implanted in Rats Power Electronic Devices

    PubMed Central

    Zebda, A.; Cosnier, S.; Alcaraz, J.-P.; Holzinger, M.; Le Goff, A.; Gondran, C.; Boucher, F.; Giroud, F.; Gorgy, K.; Lamraoui, H.; Cinquin, P.

    2013-01-01

    We describe the first implanted glucose biofuel cell (GBFC) that is capable of generating sufficient power from a mammal's body fluids to act as the sole power source for electronic devices. This GBFC is based on carbon nanotube/enzyme electrodes, which utilize glucose oxidase for glucose oxidation and laccase for dioxygen reduction. The GBFC, implanted in the abdominal cavity of a rat, produces an average open-circuit voltage of 0.57 V. This implanted GBFC delivered a power output of 38.7 μW, which corresponded to a power density of 193.5 μW cm−2 and a volumetric power of 161 μW mL−1. We demonstrate that one single implanted enzymatic GBFC can power a light-emitting diode (LED), or a digital thermometer. In addition, no signs of rejection or inflammation were observed after 110 days implantation in the rat. PMID:23519113

  20. Whole body glucose kinetics in type I diabetes studied with (6,6-/sup 2/H) and (U-/sup 13/C)-glucose and the artificial B-cell

    SciTech Connect

    Darmaun, D.; Cirillo, D.; Koziet, J.; Chauvet, D.; Young, V.R.; Robert, J.J.

    1988-05-01

    Dynamic aspects of whole body glucose metabolism were assessed in ten young adult insulin-dependent (type I) diabetic men. Using a primed, continuous intravenous infusion of (6,6-/sup 2/H)glucose and (U-/sup 13/C)glucose, endogenous production, tissue uptake, carbon recycling, and oxidation of glucose were measured in the postabsorptive state. These studies were undertaken after blood glucose had been maintained overnight at 5.9 +/- 0.4 mmol/L (n = 10), and on another night at 10.5 +/- 0.4 mmol/L (n = 4) or 15.2 +/- 0.6 mmol/L (n = 6). In the normoglycemic state, endogenous glucose production averaged 2.15 +/- 0.13 mg x kg-1 x min-1. This value, as well as the rate of glucose carbon recycling (0.16 +/- 0.04 mg x kg-1 x min-1) and glucose oxidation (1.52 +/- 0.16 mg x kg-1 x min-1) are comparable to those found in nondiabetic controls. In the hyperglycemic states at 10 or 15 mmol/L, endogenous glucose production was increased by 11% (P less than .01) and 60% (P less than .01) compared to the normoglycemic states, respectively. Glucose carbon recycling contributed only a small percentage to this variation in glucose production (15% at the 15 mmol/L glucose level). This suggests that if gluconeogenesis participates in the increased glucose output, it is not dependent on a greater systemic supply of three-carbon precursors. The increased rate of glucose production in the hyperglycemic state was quantitatively offset by a rise in urinary glucose excretion. Glucose tissue uptake, as well as glucose oxidation, did not vary between normoglycemic and hyperglycemic states.

  1. Continuous glucose monitoring, oral glucose tolerance, and insulin - glucose parameters in adolescents with simple obesity.

    PubMed

    El Awwa, A; Soliman, A; Al-Ali, M; Yassin, M; De Sanctis, V

    2012-09-01

    In obese adolescents pancreatic beta-cells may not be able to cope with insulin resistance leading to hyperglycemia and type2 diabetes (T2DM To assess oral glucose tolerance, 72-h continuous blood glucose concentrations (CGM) and calculate homeostatic model assessment (HOMA), and the quantitative insulin sensitivity check index (QUICKI) in 13 adolescents with simple obesity (BMI SDS=4 ± 1.06). OGTT performed in 13 obese adolescents (13.47 ± 3 years) revealed 3 cases (23%) with impaired fasting glucose (IFG: fasting glucose >5.6 mmol/L), 4 cases (30%) with impaired glucose tolerance (IGT: 2h blood glucose >7.8 <11.1 mmol/L), and none with diabetes. Using the continuous glucose monitoring system ( CGMS), IFG was detected in 4 cases, the maximum serum blood glucose (BG : 2h or more after meal) was >7.8 and <11.1 mmol/L (IGT) in 9 children (69%) and >11.1 mmol/L (diabetes) in one case (7.6%). Five cases had a minimum BG recorded of <2.7 mmol/L (hypoglycemia). No glycemic abnormality was detected using HbA1C (5.7 ± 0.3%). 11/13 patients had HOMA values >2.6 and QUICKI values <0.35 denoting insulin resistance. Beta cell mass percent (B %) = 200 ± 94.8% and insulin sensitivity values (IS)=50.4 ± 45.5% denoted insulin resistance with hyper-insulinaemia and preserved beta cell mass. In obese adolescents, CGMS is superior to OGTT and HbA1C in detecting glycemic abnormalities, which appears to be secondary to insulin resistance.

  2. Average Temperatures in the Southwestern United States, 2000-2015 Versus Long-Term Average

    EPA Pesticide Factsheets

    This indicator shows how the average air temperature from 2000 to 2015 has differed from the long-term average (1895??2015). To provide more detailed information, each state has been divided into climate divisions, which are zones that share similar climate features. For more information: www.epa.gov/climatechange/science/indicators

  3. Average characteristics of partially coherent electromagnetic beams.

    PubMed

    Seshadri, S R

    2000-04-01

    Average characteristics of partially coherent electromagnetic beams are treated with the paraxial approximation. Azimuthally or radially polarized, azimuthally symmetric beams and linearly polarized dipolar beams are used as examples. The change in the mean squared width of the beam from its value at the location of the beam waist is found to be proportional to the square of the distance in the propagation direction. The proportionality constant is obtained in terms of the cross-spectral density as well as its spatial spectrum. The use of the cross-spectral density has advantages over the use of its spatial spectrum.

  4. Basin average rainfall and its sampling error

    NASA Astrophysics Data System (ADS)

    Yoo, Chulsang; Ha, Eunho

    2002-11-01

    The sampling error from the randomly located rain gauge network has a significant meaning, especially for hydrologic applications where the basin average rainfall estimated using point measurements is used as an input for various rainfall-runoff analyses. In this paper we derived an equation for the sampling error from the randomly located rain gauge network of a basin and compared it with that from the evenly spaced rain gauge network derived by [1989], also implemented by [2000]. To make the analytical derivation of the sampling error equation available, we assumed that the locations of the rain gauges planted through years in a given basin follow the uniform distribution and the rainfall field is weakly statistically homogeneous in space and time. The derived equation is neatly factored with the rainfall spectrum and the design filter, which considers the second-order statistics of a rainfall field and sampling design characteristics such as the basin size, the basin shape, and the number of rain gauges within the basin. The derived equation is also flexible enough to consider various shapes of the basins such as circles, ellipses, and rectangles as well. We applied the two equations for the sampling errors from evenly spaced and randomly located rain gauge network cases to the GATE data field using the rainfall model of [1989] and then compared the results. As a result of the study, we found that the sampling errors from the randomly located and evenly spaced rain gauge networks are more or less the same as the standard deviation of the m gauge averages until some threshold number of rain gauges is reached. With more rain gauges the sampling error from the evenly spaced rain gauge network decreases much faster, while that from the randomly located rain gauge networks stagnates. However, if considering the typical rain gauge density in a natural basin, we may conclude that the sampling error involved in the estimation of basin average rainfall using point

  5. Time-averaged MSD of Brownian motion

    NASA Astrophysics Data System (ADS)

    Andreanov, Alexei; Grebenkov, Denis S.

    2012-07-01

    We study the statistical properties of the time-averaged mean-square displacements (TAMSD). This is a standard non-local quadratic functional for inferring the diffusion coefficient from an individual random trajectory of a diffusing tracer in single-particle tracking experiments. For Brownian motion, we derive an exact formula for the Laplace transform of the probability density of the TAMSD by mapping the original problem onto chains of coupled harmonic oscillators. From this formula, we deduce the first four cumulant moments of the TAMSD, the asymptotic behavior of the probability density and its accurate approximation by a generalized Gamma distribution.

  6. A Green's function quantum average atom model

    DOE PAGES

    Starrett, Charles Edward

    2015-05-21

    A quantum average atom model is reformulated using Green's functions. This allows integrals along the real energy axis to be deformed into the complex plane. The advantage being that sharp features such as resonances and bound states are broadened by a Lorentzian with a half-width chosen for numerical convenience. An implementation of this method therefore avoids numerically challenging resonance tracking and the search for weakly bound states, without changing the physical content or results of the model. A straightforward implementation results in up to a factor of 5 speed-up relative to an optimized orbital based code.

  7. The averaging method in applied problems

    NASA Astrophysics Data System (ADS)

    Grebenikov, E. A.

    1986-04-01

    The totality of methods, allowing to research complicated non-linear oscillating systems, named in the literature "averaging method" has been given. THe author is describing the constructive part of this method, or a concrete form and corresponding algorithms, on mathematical models, sufficiently general , but built on concrete problems. The style of the book is that the reader interested in the Technics and algorithms of the asymptotic theory of the ordinary differential equations, could solve individually such problems. For specialists in the area of applied mathematics and mechanics.

  8. Glucose polymer molecular weight does not affect exogenous carbohydrate oxidation.

    PubMed

    Rowlands, David S; Wallis, Gareth A; Shaw, Chris; Jentjens, Roy L P G; Jeukendrup, Asker E

    2005-09-01

    To compare the effects of high (HMW) versus low molecular weight (LMW) glucose polymer solutions on the pattern of substrate oxidation during exercise. Eight cyclists (VO(2max): 63 +/- 8 mL.kg(-1).min(-1)) performed three 150-min cycling trials at 64 +/- 5% VO(2max) while ingesting 11.25% HMW (500-750 kg.mol(-1), 21 mOsm.kg(-1)) or LMW (8 kg.mol(-1), 110 mOsm.kg(-1)) solutions providing 1.8 g of carbohydrate per minute, or plain water. Substrate oxidation was determined using stable-isotope methods and indirect calorimetry. Exogenous carbohydrate oxidation rate was not affected by carbohydrate molecular weight (P = 0.89, peak rate: 0.93 x// 1.37 g.min(-1)). There was no effect of carbohydrate molecular weight on endogenous carbohydrate or fat oxidation rates (P = 0.30), plasma free fatty acid (P = 0.14), lactate (P = 0.38), or glucose concentrations (P = 0.98), nor were there any serious gastrointestinal complaints reported for either of the two solutions during exercise. Despite previous reports of faster gastric emptying and glycogen resynthesis suggesting enhanced glucose delivery, a markedly hypotonic HMW glucose polymer solution had no effect on exogenous and endogenous substrate oxidation rates during exercise, relative to a LMW glucose polymer solution. These data are consistent with there being no effect of carbohydrate structure or solution osmolality or viscosity on exogenous glucose oxidation and that ingested glucose polymers can only be oxidized on average up to 1.0 g.min during exercise.

  9. Meal related glucose monitoring is a method of diagnosing glucose intolerance in pregnancies with high probability of gestational diabetes but normal glucose tolerance by oral glucose tolerance test.

    PubMed

    John, Mathew; Gopinath, Deepa

    2013-06-01

    Gestational diabetes mellitus diagnosed by classical oral glucose tolerance test can result in fetal complications like macrosomia and polyhydramnios. Guidelines exist on management of patients diagnose by abnormal oral glucose tolerance test with diet modification followed by insulin. Even patients with abnormal oral glucose tolerance test maintaining apparently normal blood sugars with diet are advised insulin if there is accelerated fetal growth. But patients with normal oral glucose tolerance test can present with macrosomia and polyhydramnios. These patients are labelled as not having gestational diabetes mellitus and are followed up with repeat oral glucose tolerance test. We hypothesise that these patients may have an altered placental threshold to glucose or abnormal sensitivity of fetal tissues to glucose. Meal related glucose monitoring in these patients can identify minor abnormalities in glucose disturbance and should be treated to targets similar to physiological levels of glucose in non pregnant adults.

  10. Local average height distribution of fluctuating interfaces.

    PubMed

    Smith, Naftali R; Meerson, Baruch; Sasorov, Pavel V

    2017-01-01

    Height fluctuations of growing surfaces can be characterized by the probability distribution of height in a spatial point at a finite time. Recently there has been spectacular progress in the studies of this quantity for the Kardar-Parisi-Zhang (KPZ) equation in 1+1 dimensions. Here we notice that, at or above a critical dimension, the finite-time one-point height distribution is ill defined in a broad class of linear surface growth models unless the model is regularized at small scales. The regularization via a system-dependent small-scale cutoff leads to a partial loss of universality. As a possible alternative, we introduce a local average height. For the linear models, the probability density of this quantity is well defined in any dimension. The weak-noise theory for these models yields the "optimal path" of the interface conditioned on a nonequilibrium fluctuation of the local average height. As an illustration, we consider the conserved Edwards-Wilkinson (EW) equation, where, without regularization, the finite-time one-point height distribution is ill defined in all physical dimensions. We also determine the optimal path of the interface in a closely related problem of the finite-time height-difference distribution for the nonconserved EW equation in 1+1 dimension. Finally, we discuss a UV catastrophe in the finite-time one-point distribution of height in the (nonregularized) KPZ equation in 2+1 dimensions.

  11. Local average height distribution of fluctuating interfaces

    NASA Astrophysics Data System (ADS)

    Smith, Naftali R.; Meerson, Baruch; Sasorov, Pavel V.

    2017-01-01

    Height fluctuations of growing surfaces can be characterized by the probability distribution of height in a spatial point at a finite time. Recently there has been spectacular progress in the studies of this quantity for the Kardar-Parisi-Zhang (KPZ) equation in 1 +1 dimensions. Here we notice that, at or above a critical dimension, the finite-time one-point height distribution is ill defined in a broad class of linear surface growth models unless the model is regularized at small scales. The regularization via a system-dependent small-scale cutoff leads to a partial loss of universality. As a possible alternative, we introduce a local average height. For the linear models, the probability density of this quantity is well defined in any dimension. The weak-noise theory for these models yields the "optimal path" of the interface conditioned on a nonequilibrium fluctuation of the local average height. As an illustration, we consider the conserved Edwards-Wilkinson (EW) equation, where, without regularization, the finite-time one-point height distribution is ill defined in all physical dimensions. We also determine the optimal path of the interface in a closely related problem of the finite-time height-difference distribution for the nonconserved EW equation in 1 +1 dimension. Finally, we discuss a UV catastrophe in the finite-time one-point distribution of height in the (nonregularized) KPZ equation in 2 +1 dimensions.

  12. Averaged null energy condition from causality

    NASA Astrophysics Data System (ADS)

    Hartman, Thomas; Kundu, Sandipan; Tajdini, Amirhossein

    2017-07-01

    Unitary, Lorentz-invariant quantum field theories in flat spacetime obey mi-crocausality: commutators vanish at spacelike separation. For interacting theories in more than two dimensions, we show that this implies that the averaged null energy, ∫ duT uu , must be non-negative. This non-local operator appears in the operator product expansion of local operators in the lightcone limit, and therefore contributes to n-point functions. We derive a sum rule that isolates this contribution and is manifestly positive. The argument also applies to certain higher spin operators other than the stress tensor, generating an infinite family of new constraints of the form ∫ duX uuu··· u ≥ 0. These lead to new inequalities for the coupling constants of spinning operators in conformal field theory, which include as special cases (but are generally stronger than) the existing constraints from the lightcone bootstrap, deep inelastic scattering, conformal collider methods, and relative entropy. We also comment on the relation to the recent derivation of the averaged null energy condition from relative entropy, and suggest a more general connection between causality and information-theoretic inequalities in QFT.

  13. Average neutronic properties of prompt fission products

    SciTech Connect

    Foster, D.G. Jr.; Arthur, E.D.

    1982-02-01

    Calculations of the average neutronic properties of the ensemble of fission products producted by fast-neutron fission of /sup 235/U and /sup 239/Pu, where the properties are determined before the first beta decay of any of the fragments, are described. For each case we approximate the ensemble by a weighted average over 10 selected nuclides, whose properties we calculate using nuclear-model parameters deduced from the systematic properties of other isotopes of the same elements as the fission fragments. The calculations were performed primarily with the COMNUC and GNASH statistical-model codes. The results, available in ENDF/B format, include cross sections, angular distributions of neutrons, and spectra of neutrons and photons, for incident-neutron energies between 10/sup -5/ eV and 20 MeV. Over most of this energy range, we find that the capture cross section of /sup 239/Pu fission fragments is systematically a factor of two to five greater than for /sup 235/U fission fragments.

  14. Global atmospheric circulation statistics: Four year averages

    NASA Technical Reports Server (NTRS)

    Wu, M. F.; Geller, M. A.; Nash, E. R.; Gelman, M. E.

    1987-01-01

    Four year averages of the monthly mean global structure of the general circulation of the atmosphere are presented in the form of latitude-altitude, time-altitude, and time-latitude cross sections. The numerical values are given in tables. Basic parameters utilized include daily global maps of temperature and geopotential height for 18 pressure levels between 1000 and 0.4 mb for the period December 1, 1978 through November 30, 1982 supplied by NOAA/NMC. Geopotential heights and geostrophic winds are constructed using hydrostatic and geostrophic formulae. Meridional and vertical velocities are calculated using thermodynamic and continuity equations. Fields presented in this report are zonally averaged temperature, zonal, meridional, and vertical winds, and amplitude of the planetary waves in geopotential height with zonal wave numbers 1-3. The northward fluxes of sensible heat and eastward momentum by the standing and transient eddies along with their wavenumber decomposition and Eliassen-Palm flux propagation vectors and divergences by the standing and transient eddies along with their wavenumber decomposition are also given. Large interhemispheric differences and year-to-year variations are found to originate in the changes in the planetary wave activity.

  15. Detrending moving average algorithm for multifractals.

    PubMed

    Gu, Gao-Feng; Zhou, Wei-Xing

    2010-07-01

    The detrending moving average (DMA) algorithm is a widely used technique to quantify the long-term correlations of nonstationary time series and the long-range correlations of fractal surfaces, which contains a parameter θ determining the position of the detrending window. We develop multifractal detrending moving average (MFDMA) algorithms for the analysis of one-dimensional multifractal measures and higher-dimensional multifractals, which is a generalization of the DMA method. The performance of the one-dimensional and two-dimensional MFDMA methods is investigated using synthetic multifractal measures with analytical solutions for backward (θ=0), centered (θ=0.5), and forward (θ=1) detrending windows. We find that the estimated multifractal scaling exponent τ(q) and the singularity spectrum f(α) are in good agreement with the theoretical values. In addition, the backward MFDMA method has the best performance, which provides the most accurate estimates of the scaling exponents with lowest error bars, while the centered MFDMA method has the worse performance. It is found that the backward MFDMA algorithm also outperforms the multifractal detrended fluctuation analysis. The one-dimensional backward MFDMA method is applied to analyzing the time series of Shanghai Stock Exchange Composite Index and its multifractal nature is confirmed.

  16. Detrending moving average algorithm for multifractals

    NASA Astrophysics Data System (ADS)

    Gu, Gao-Feng; Zhou, Wei-Xing

    2010-07-01

    The detrending moving average (DMA) algorithm is a widely used technique to quantify the long-term correlations of nonstationary time series and the long-range correlations of fractal surfaces, which contains a parameter θ determining the position of the detrending window. We develop multifractal detrending moving average (MFDMA) algorithms for the analysis of one-dimensional multifractal measures and higher-dimensional multifractals, which is a generalization of the DMA method. The performance of the one-dimensional and two-dimensional MFDMA methods is investigated using synthetic multifractal measures with analytical solutions for backward (θ=0) , centered (θ=0.5) , and forward (θ=1) detrending windows. We find that the estimated multifractal scaling exponent τ(q) and the singularity spectrum f(α) are in good agreement with the theoretical values. In addition, the backward MFDMA method has the best performance, which provides the most accurate estimates of the scaling exponents with lowest error bars, while the centered MFDMA method has the worse performance. It is found that the backward MFDMA algorithm also outperforms the multifractal detrended fluctuation analysis. The one-dimensional backward MFDMA method is applied to analyzing the time series of Shanghai Stock Exchange Composite Index and its multifractal nature is confirmed.

  17. MACHINE PROTECTION FOR HIGH AVERAGE CURRENT LINACS

    SciTech Connect

    Jordan, Kevin; Allison, Trent; Evans, Richard; Coleman, James; Grippo, Albert

    2003-05-01

    A fully integrated Machine Protection System (MPS) is critical to efficient commissioning and safe operation of all high current accelerators. The Jefferson Lab FEL [1,2] has multiple electron beam paths and many different types of diagnostic insertion devices. The MPS [3] needs to monitor both the status of these devices and the magnet settings which define the beam path. The matrix of these devices and beam paths are programmed into gate arrays, the output of the matrix is an allowable maximum average power limit. This power limit is enforced by the drive laser for the photocathode gun. The Beam Loss Monitors (BLMs), RF status, and laser safety system status are also inputs to the control matrix. There are 8 Machine Modes (electron path) and 8 Beam Modes (average power limits) that define the safe operating limits for the FEL. Combinations outside of this matrix are unsafe and the beam is inhibited. The power limits range from no beam to 2 megawatts of electron beam power.

  18. Averaged null energy condition from causality

    DOE PAGES

    Hartman, Thomas; Kundu, Sandipan; Tajdini, Amirhossein

    2017-07-14

    Unitary, Lorentz-invariant quantum field theories in at spacetime obey mi-crocausality: commutators vanish at spacelike separation. For interacting theories in more than two dimensions, we show that this implies that the averaged null energy,more » $$\\int$$duTuu, must be non-negative. This non-local operator appears in the operator product expansion of local operators in the lightcone limit, and therefore contributes to n-point functions. We derive a sum rule that isolates this contribution and is manifestly positive. The argument also applies to certain higher spin operators other than the stress tensor, generating an infinite family of new constraints of the form RduX uuu∙∙∙u ≥ 0. These lead to new inequalities for the coupling constants of spinning operators in conformal field theory, which include as special cases (but are generally stronger than) the existing constraints from the lightcone bootstrap, deep inelastic scattering, conformal collider methods, and relative entropy. We also comment on the relation to the recent derivation of the averaged null energy condition from relative entropy, and suggest a more general connection between causality and information-theoretic inequalities in QFT.« less

  19. Glucose metabolism and cardiac hypertrophy

    PubMed Central

    Kolwicz, Stephen C.; Tian, Rong

    2011-01-01

    The most notable change in the metabolic profile of hypertrophied hearts is an increased reliance on glucose with an overall reduced oxidative metabolism, i.e. a reappearance of the foetal metabolic pattern. In animal models, this change is attributed to the down-regulation of the transcriptional cascades promoting gene expression for fatty acid oxidation and mitochondrial oxidative phosphorylation in adult hearts. Impaired myocardial energetics in cardiac hypertrophy also triggers AMP-activated protein kinase (AMPK), leading to increased glucose uptake and glycolysis. Aside from increased reliance on glucose as an energy source, changes in other glucose metabolism pathways, e.g. the pentose phosphate pathway, the glucosamine biosynthesis pathway, and anaplerosis, are also noted in the hypertrophied hearts. Studies using transgenic mouse models and pharmacological compounds to mimic or counter the switch of substrate preference in cardiac hypertrophy have demonstrated that increased glucose metabolism in adult heart is not harmful and can be beneficial when it provides sufficient fuel for oxidative metabolism. However, improvement in the oxidative capacity and efficiency rather than the selection of the substrate is likely the ultimate goal for metabolic therapies. PMID:21502371

  20. Ketones suppress brain glucose consumption.

    PubMed

    LaManna, Joseph C; Salem, Nicolas; Puchowicz, Michelle; Erokwu, Bernadette; Koppaka, Smruta; Flask, Chris; Lee, Zhenghong

    2009-01-01

    The brain is dependent on glucose as a primary energy substrate, but is capable of utilizing ketones such as beta-hydroxybutyrate (beta HB) and acetoacetate (AcAc), as occurs with fasting, prolonged starvation or chronic feeding of a high fat/low carbohydrate diet (ketogenic diet). In this study, the local cerebral metabolic rate of glucose consumption (CMRglu; microM/min/100g) was calculated in the cortex and cerebellum of control and ketotic rats using Patlak analysis. Rats were imaged on a rodent PET scanner and MRI was performed on a 7-Tesla Bruker scanner for registration with the PET images. Plasma glucose and beta HB concentrations were measured and 90-minute dynamic PET scans were started simultaneously with bolus injection of 2-Deoxy-2[18F]Fluoro-D-Glucose (FDG). The blood radioactivity concentration was automatically sampled from the tail vein for 3 min following injection and manual periodic blood samples were taken. The calculated local CMRGlu decreased with increasing plasma BHB concentration in the cerebellum (CMRGlu = -4.07*[BHB] + 61.4, r2 = 0.3) and in the frontal cortex (CMRGlu = -3.93*[BHB] + 42.7, r2 = 0.5). These data indicate that, under conditions of ketosis, glucose consumption is decreased in the cortex and cerebellum by about 10% per each mM of plasma ketone bodies.

  1. Glucose Monitoring in Individuals with Diabetes using a Long-Term Implanted Sensor/Telemetry System and Model

    PubMed Central

    Lucisano, Joseph Y.; Routh, Timothy L.; Lin, Joe T.; Gough, David A.

    2017-01-01

    Objective The use of a fully implanted, first-generation prototype sensor/telemetry system is described for long-term monitoring of subcutaneous tissue glucose in a small cohort of people with diabetes. Methods Sensors are based on a membrane containing immobilized glucose oxidase and catalase coupled to oxygen electrodes and a telemetry system, integrated as an implant. The devices remained implanted for up to 180 days, with signals transmitted every 2 minutes to external receivers. Results The data include signal recordings from glucose clamps and spontaneous glucose excursions, matched respectively to reference blood glucose and finger-stick values. The sensor signals indicate dynamic tissue glucose, for which there is no independent standard, and a model describing the relationship between blood glucose and the signal is therefore included. The values of all model parameters have been estimated, including the permeability of adjacent tissues to glucose, and equated to conventional mass transfer parameters. As a group, the sensor calibration varied randomly at an average rate of −2.6%/week. Statistical correlation indicated strong association between the sensor signals and reference glucose values. Conclusions Continuous, long-term glucose monitoring in individuals with diabetes is feasible with this system. Significance All therapies for diabetes are based on glucose control and therefore require glucose monitoring. This fully implanted, long-term sensor/telemetry system may facilitate a new era of management of the disease. PMID:27775510

  2. Lagrangian averaging, nonlinear waves, and shock regularization

    NASA Astrophysics Data System (ADS)

    Bhat, Harish S.

    In this thesis, we explore various models for the flow of a compressible fluid as well as model equations for shock formation, one of the main features of compressible fluid flows. We begin by reviewing the variational structure of compressible fluid mechanics. We derive the barotropic compressible Euler equations from a variational principle in both material and spatial frames. Writing the resulting equations of motion requires certain Lie-algebraic calculations that we carry out in detail for expository purposes. Next, we extend the derivation of the Lagrangian averaged Euler (LAE-alpha) equations to the case of barotropic compressible flows. The derivation in this thesis involves averaging over a tube of trajectories etaepsilon centered around a given Lagrangian flow eta. With this tube framework, the LAE-alpha equations are derived by following a simple procedure: start with a given action, expand via Taylor series in terms of small-scale fluid fluctuations xi, truncate, average, and then model those terms that are nonlinear functions of xi. We then analyze a one-dimensional subcase of the general models derived above. We prove the existence of a large family of traveling wave solutions. Computing the dispersion relation for this model, we find it is nonlinear, implying that the equation is dispersive. We carry out numerical experiments that show that the model possesses smooth, bounded solutions that display interesting pattern formation. Finally, we examine a Hamiltonian partial differential equation (PDE) that regularizes the inviscid Burgers equation without the addition of standard viscosity. Here alpha is a small parameter that controls a nonlinear smoothing term that we have added to the inviscid Burgers equation. We show the existence of a large family of traveling front solutions. We analyze the initial-value problem and prove well-posedness for a certain class of initial data. We prove that in the zero-alpha limit, without any standard viscosity

  3. Quetelet, the average man and medical knowledge.

    PubMed

    Caponi, Sandra

    2013-01-01

    Using two books by Adolphe Quetelet, I analyze his theory of the 'average man', which associates biological and social normality with the frequency with which certain characteristics appear in a population. The books are Sur l'homme et le développement de ses facultés and Du systeme social et des lois qui le régissent. Both reveal that Quetelet's ideas are permeated by explanatory strategies drawn from physics and astronomy, and also by discursive strategies drawn from theology and religion. The stability of the mean as opposed to the dispersion of individual characteristics and events provided the basis for the use of statistics in social sciences and medicine.

  4. High average power switching for linear accelerators

    NASA Astrophysics Data System (ADS)

    Dicapua, M. S.

    This report summarizes the presentations and the findings of the Workshop on High Average Power Switching (WHAPS) that took place in Livermore, California, on October 10 to 11, 1990. The WHAPS discussed switching technologies that could meet requirements that arise in applications of linear induction accelerators also known as induction linacs. Induction linacs require a switch that will hold-off 250 kV, conduct 30 kA for 150 to 200 ns, operate at 1 to 2 kHz for several second bursts, have better than 1 ns jitter, and last in excess of 10(exp 8) pulses. The workshop reviewed the state-of-the-art of Super-Emissive Cathode Switches, Magnetically Delayed Vacuum Switches and Solid State Switches and considered research and development steps that would allow these technologies to meet these requirements.

  5. The Average-Value Correspondence Principle

    NASA Astrophysics Data System (ADS)

    Goyal, Philip

    2007-12-01

    In previous work [1], we have presented an attempt to derive the finite-dimensional abstract quantum formalism from a set of physically comprehensible assumptions. In this paper, we continue the derivation of the quantum formalism by formulating a correspondence principle, the Average-Value Correspondence Principle, that allows relations between measurement outcomes which are known to hold in a classical model of a system to be systematically taken over into the quantum model of the system, and by using this principle to derive many of the correspondence rules (such as operator rules, commutation relations, and Dirac's Poisson bracket rule) that are needed to apply the abstract quantum formalism to model particular physical systems.

  6. Average deployments versus missile and defender parameters

    SciTech Connect

    Canavan, G.H.

    1991-03-01

    This report evaluates the average number of reentry vehicles (RVs) that could be deployed successfully as a function of missile burn time, RV deployment times, and the number of space-based interceptors (SBIs) in defensive constellations. Leakage estimates of boost-phase kinetic-energy defenses as functions of launch parameters and defensive constellation size agree with integral predictions of near-exact calculations for constellation sizing. The calculations discussed here test more detailed aspects of the interaction. They indicate that SBIs can efficiently remove about 50% of the RVs from a heavy missile attack. The next 30% can removed with two-fold less effectiveness. The next 10% could double constellation sizes. 5 refs., 7 figs.

  7. Comprehensive time average digital holographic vibrometry

    NASA Astrophysics Data System (ADS)

    Psota, Pavel; Lédl, Vít; Doleček, Roman; Mokrý, Pavel; Vojtíšek, Petr; Václavík, Jan

    2016-12-01

    This paper presents a method that simultaneously deals with drawbacks of time-average digital holography: limited measurement range, limited spatial resolution, and quantitative analysis of the measured Bessel fringe patterns. When the frequency of the reference wave is shifted by an integer multiple of frequency at which the object oscillates, the measurement range of the method can be shifted either to smaller or to larger vibration amplitudes. In addition, phase modulation of the reference wave is used to obtain a sequence of phase-modulated fringe patterns. Such fringe patterns can be combined by means of phase-shifting algorithms, and amplitudes of vibrations can be straightforwardly computed. This approach independently calculates the amplitude values in every single pixel. The frequency shift and phase modulation are realized by proper control of Bragg cells and therefore no additional hardware is required.

  8. Simplified optical path-averaged rain gauge.

    PubMed

    Wang, T I; Earnshaw, K B; Lawrence, R S

    1978-02-01

    It has previously been shown that the scintillations produced by raindrops falling through a collimated laser beam can be used to measure the drop-size distribution and the rainfall rate, both averaged over the path. We now present a theoretical analysis, verified by observation, showing that the variance of the scintillations detected by a line-detector measured at frequencies near 1 kHz is closely related to rain rate and is nearly independent of drop-size distribution. If only rain rate is desired, the variance type of optical rain gauge has several advantages over the earlier model. It could use a diverging beam, thus eliminating the practical difficulties of maintaining adjustment and pointing of a collimated beam. Furthermore, it is less sensitive to the presence of updrafts and downdrafts along the beam and can thus be used over rough terrain.

  9. High average power linear induction accelerator development

    SciTech Connect

    Bayless, J.R.; Adler, R.J.

    1987-07-01

    There is increasing interest in linear induction accelerators (LIAs) for applications including free electron lasers, high power microwave generators and other types of radiation sources. Lawrence Livermore National Laboratory has developed LIA technology in combination with magnetic pulse compression techniques to achieve very impressive performance levels. In this paper we will briefly discuss the LIA concept and describe our development program. Our goals are to improve the reliability and reduce the cost of LIA systems. An accelerator is presently under construction to demonstrate these improvements at an energy of 1.6 MeV in 2 kA, 65 ns beam pulses at an average beam power of approximately 30 kW. The unique features of this system are a low cost accelerator design and an SCR-switched, magnetically compressed, pulse power system. 4 refs., 7 figs.

  10. Asymmetric network connectivity using weighted harmonic averages

    NASA Astrophysics Data System (ADS)

    Morrison, Greg; Mahadevan, L.

    2011-02-01

    We propose a non-metric measure of the "closeness" felt between two nodes in an undirected, weighted graph using a simple weighted harmonic average of connectivity, that is a real-valued Generalized Erdös Number (GEN). While our measure is developed with a collaborative network in mind, the approach can be of use in a variety of artificial and real-world networks. We are able to distinguish between network topologies that standard distance metrics view as identical, and use our measure to study some simple analytically tractable networks. We show how this might be used to look at asymmetry in authorship networks such as those that inspired the integer Erdös numbers in mathematical coauthorships. We also show the utility of our approach to devise a ratings scheme that we apply to the data from the NetFlix prize, and find a significant improvement using our method over a baseline.

  11. Average prime-pair counting formula

    NASA Astrophysics Data System (ADS)

    Korevaar, Jaap; Riele, Herman Te

    2010-04-01

    Taking r>0 , let π_{2r}(x) denote the number of prime pairs (p, p+2r) with p≤ x . The prime-pair conjecture of Hardy and Littlewood (1923) asserts that π_{2r}(x)˜ 2C_{2r} {li}_2(x) with an explicit constant C_{2r}>0 . There seems to be no good conjecture for the remainders ω_{2r}(x)=π_{2r}(x)- 2C_{2r} {li}_2(x) that corresponds to Riemann's formula for π(x)-{li}(x) . However, there is a heuristic approximate formula for averages of the remainders ω_{2r}(x) which is supported by numerical results.

  12. Angle-averaged Compton cross sections

    SciTech Connect

    Nickel, G.H.

    1983-01-01

    The scattering of a photon by an individual free electron is characterized by six quantities: ..cap alpha.. = initial photon energy in units of m/sub 0/c/sup 2/; ..cap alpha../sub s/ = scattered photon energy in units of m/sub 0/c/sup 2/; ..beta.. = initial electron velocity in units of c; phi = angle between photon direction and electron direction in the laboratory frame (LF); theta = polar angle change due to Compton scattering, measured in the electron rest frame (ERF); and tau = azimuthal angle change in the ERF. We present an analytic expression for the average of the Compton cross section over phi, theta, and tau. The lowest order approximation to this equation is reasonably accurate for photons and electrons with energies of many keV.

  13. Abnormal oral glucose tolerance and glucose malabsorption after vagotomy and pyloroplasty. A tracer method for measuring glucose absorption rates

    SciTech Connect

    Radziuk, J.; Bondy, D.C.

    1982-11-01

    The mechanisms underlying the abnormal glucose tolerance in patients who had undergone vagotomy and pyloroplasty were investigated by measuring the rates of absorption of ingested glucose and the clearance rate of glucose using tracer methods. These methods are based on labeling a 100-g oral glucose load with (1-/sup 14/C)glucose and measuring glucose clearance using plasma levels of infused (3-/sup 3/H)glucose. The rate of appearance of both ingested and total glucose is then calculated continuously using a two-compartment model of glucose kinetics. It was found that about 30% of the ingested glucose (100 g) failed to appear in the systemic circulation. That this was due to malabsorption was confirmed using breath-hydrogen analysis. The absorption period is short (101 +/- 11 min) compared with normal values but the clearance of glucose is identical to that in control subjects, and it peaks 132 +/- 7 min after glucose loading. The peak plasma insulin values were more than four times higher in patients than in normal subjects, and this may afford an explanation of rates of glucose clearance that are inappropriate for the short absorption period. The combination of glucose malabsorption and this clearance pattern could yield the hypoglycemia that may be observed in patients after gastric surgery.

  14. The balanced survivor average causal effect.

    PubMed

    Greene, Tom; Joffe, Marshall; Hu, Bo; Li, Liang; Boucher, Ken

    2013-05-07

    Statistical analysis of longitudinal outcomes is often complicated by the absence of observable values in patients who die prior to their scheduled measurement. In such cases, the longitudinal data are said to be "truncated by death" to emphasize that the longitudinal measurements are not simply missing, but are undefined after death. Recently, the truncation by death problem has been investigated using the framework of principal stratification to define the target estimand as the survivor average causal effect (SACE), which in the context of a two-group randomized clinical trial is the mean difference in the longitudinal outcome between the treatment and control groups for the principal stratum of always-survivors. The SACE is not identified without untestable assumptions. These assumptions have often been formulated in terms of a monotonicity constraint requiring that the treatment does not reduce survival in any patient, in conjunction with assumed values for mean differences in the longitudinal outcome between certain principal strata. In this paper, we introduce an alternative estimand, the balanced-SACE, which is defined as the average causal effect on the longitudinal outcome in a particular subset of the always-survivors that is balanced with respect to the potential survival times under the treatment and control. We propose a simple estimator of the balanced-SACE that compares the longitudinal outcomes between equivalent fractions of the longest surviving patients between the treatment and control groups and does not require a monotonicity assumption. We provide expressions for the large sample bias of the estimator, along with sensitivity analyses and strategies to minimize this bias. We consider statistical inference under a bootstrap resampling procedure.

  15. The research of differential reference electrode arrayed flexible IGZO glucose biosensor based on microfluidic framework

    NASA Astrophysics Data System (ADS)

    Chen, Jian-Syun; Chou, Jung-Chuan; Liao, Yi-Hung; Chen, Ruei-Ting; Huang, Min-Siang; Wu, Tong-Yu

    2017-03-01

    This study used a fast, simple, and low-cost method to fabricate arrayed flexible glucose biosensor, and the glucose biosensor was integrated with microfluidic framework for investigating sensing characteristics of glucose biosensor at the dynamic conditions. The indium gallium zinc oxide (IGZO) was adopted as sensing membrane and it was deposited on aluminum electrodes / polyethylene terephthalate (PET) substrate by the radio frequency sputtering system. Then, we utilized screen-printed technology to accomplish miniaturization of glucose biosensor. Finally, the glucose sensing membrane was composed of glucose oxidase (GOx) and nafion, which was dropped on IGZO sensing membrane to complete glucose biosensor. According to the experimental results, we found that optimal sensing characteristics of arrayed flexible IGZO glucose biosensor at the dynamic conditions were better than at the static conditions. The optimal average sensitivity and linearity of the arrayed flexible IGZO glucose biosensor were 7.255 mV/mM and 0.994 at 20 µL/min flow rate, respectively.

  16. Glucose, glycolysis and lymphocyte responses.

    PubMed

    Donnelly, Raymond P; Finlay, David K

    2015-12-01

    Activated lymphocytes engage in robust growth and rapid proliferation. To achieve this, they tend to adopt a form of glucose metabolism termed aerobic glycolysis. This type of metabolism allows for the use of large amounts of glucose to generate energy, but also to support biosynthetic processes. This review article will discuss how aerobic glycolysis supports the biosynthetic demands of activated T cells, B cells and Natural Killer cells, and the emerging concept that glycolysis is integrally linked to the differentiation and function of these lymphocyte populations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Glucose oxidation positively regulates glucose uptake and improves cardiac function recovery after myocardial reperfusion.

    PubMed

    Li, Tingting; Xu, Jie; Qin, Xinghua; Hou, Zuoxu; Guo, Yongzheng; Liu, Zhenhua; Wu, Jianjiang; Zheng, Hong; Zhang, Xing; Gao, Feng

    2017-03-21

    Myocardial reperfusion decreases glucose oxidation and uncouples glucose oxidation from glycolysis. Therapies that increase glucose oxidation lessen myocardial ischemia/reperfusion injury. However, the regulation of glucose uptake during reperfusion remains poorly understood. Here we found that glucose uptake was remarkably diminished in myocardium following reperfusion in Sprague-Dawley rats as detected by 18F-labeled and fluorescent-labeled glucose analogs, even though GLUT1 was upregulated by 3 folds and GLUT4 translocation remained unchanged compared with those of sham rats. The decreased glucose uptake was accompanied by suppressed glucose oxidation. Interestingly, stimulating glucose oxidation by inhibition of pyruvate dehydrogenase kinase 4 (PDK4), a rate-limiting enzyme for glucose oxidation, increased glucose uptake and alleviated ischemia/reperfusion injury. In vitro data in neonatal myocytes showed that PDK4 overexpression decreased glucose uptake, while its knockdown increased glucose uptake, suggesting a role of PDK4 in regulating glucose uptake. Moreover, inhibition of PDK4 increased myocardial glucose uptake with concomitant enhancement of cardiac insulin sensitivity following myocardial ischemia/reperfusion. These results showed that the suppressed glucose oxidation mediated by PDK4 contributes to the reduced glucose uptake in myocardium following reperfusion, and enhancement of glucose uptake exerts cardioprotection. The findings suggest that stimulating glucose oxidation via PDK4 could be an efficient approach to improve recovery from myocardial ischemia/reperfusion injury.

  18. Deterioration of insulin release rate response to glucose during oral glucose tolerance test is associated with an increased risk of incident diabetes in normal glucose tolerance subjects.

    PubMed

    Li, Yuanyuan; He, Shihui; Sun, Yao; Li, Guangwei; Xu, Qingsong; Wang, Chen; Jia, Weiping

    2017-09-01

    β-Cell dedifferentiation, characterized by loss of glucose sensitivity (β-cell glucose sensitivity [βCGS]), has been reported to play an important role in the development of type 2 diabetes (T2D). Traditionally, βCGS was derived from C-peptide-based method. However, C-peptide was not routinely examined in normal subjects and diabetes never treated with insulin. Thus, the aim of the study was to evaluate the use of insulin in oral glucose tolerance test (OGTT) in estimation of β-cell glucose response ability. A total of 1,599 subjects including normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and T2D were included in the study. A subgroup of NGT subjects (n = 591) were followed up for an average duration of 56.88 ± 20.76 months. Insulin release rate (IRRINS ) in the function of glucose (IRRINS response to glucose [IRRG]) during OGTT was compared with βCGS. Both βCGS derived from C-peptide by deconvolution approach and IRRG by insulin release progressively declined from NGT to IGT and T2D. Both βCGS and IRRG were associated with deposit of first-phase insulin secretion (DI1st ). After 56.88 ± 20.76 months, 32 (5.41%) NGT subjects had developed T2D. NGT subjects who progressed to diabetes after follow-up had lower IRRG and DI1st levels than those who did not (P < 0.01). Furthermore, multiple logistic regression analyses showed that decreased IRRG was a significant independent risk predictor for future diabetes after adjustment of age, body mass index (BMI), homeostasis model assessment (HOMA)-insulin resistance, DI1st and family history. NGT subjects with decreased IRRG during OGTT had defective early insulin secretion and were at higher risk of developing diabetes. IRRG could be a useful T2D predictor in NGT subjects. © 2017 IUBMB Life, 69(9):756-766, 2017. © 2017 International Union of Biochemistry and Molecular Biology.

  19. Glycolysis Controls Plasma Membrane Glucose Sensors To Promote Glucose Signaling in Yeasts

    PubMed Central

    Cairey-Remonnay, Amélie; Deffaud, Julien; Wésolowski-Louvel, Micheline; Lemaire, Marc

    2014-01-01

    Sensing of extracellular glucose is necessary for cells to adapt to glucose variation in their environment. In the respiratory yeast Kluyveromyces lactis, extracellular glucose controls the expression of major glucose permease gene RAG1 through a cascade similar to the Saccharomyces cerevisiae Snf3/Rgt2/Rgt1 glucose signaling pathway. This regulation depends also on intracellular glucose metabolism since we previously showed that glucose induction of the RAG1 gene is abolished in glycolytic mutants. Here we show that glycolysis regulates RAG1 expression through the K. lactis Rgt1 (KlRgt1) glucose signaling pathway by targeting the localization and probably the stability of Rag4, the single Snf3/Rgt2-type glucose sensor of K. lactis. Additionally, the control exerted by glycolysis on glucose signaling seems to be conserved in S. cerevisiae. This retrocontrol might prevent yeasts from unnecessary glucose transport and intracellular glucose accumulation. PMID:25512610

  20. Glucose Sensing Neurons in the Ventromedial Hypothalamus

    PubMed Central

    Routh, Vanessa H.

    2010-01-01

    Neurons whose activity is regulated by glucose are found in a number of brain regions. Glucose-excited (GE) neurons increase while glucose-inhibited (GI) neurons decrease their action potential frequency as interstitial brain glucose levels increase. We hypothesize that these neurons evolved to sense and respond to severe energy deficit (e.g., fasting) that threatens the brains glucose supply. During modern times, they are also important for the restoration of blood glucose levels following insulin-induced hypoglycemia. Our data suggest that impaired glucose sensing by hypothalamic glucose sensing neurons may contribute to the syndrome known as hypoglycemia-associated autonomic failure in which the mechanisms which restore euglycemia following hypoglycemia become impaired. On the other hand, increased responses of glucose sensing neurons to glucose deficit may play a role in the development of Type 2 Diabetes Mellitus and obesity. This review will discuss the mechanisms by which glucose sensing neurons sense changes in interstitial glucose and explore the roles of these specialized glucose sensors in glucose and energy homeostasis. PMID:22022208

  1. Breath ethanol and acetone as indicators of serum glucose levels: an initial report.

    PubMed

    Galassetti, Pietro R; Novak, Brian; Nemet, Dan; Rose-Gottron, Christie; Cooper, Dan M; Meinardi, Simone; Newcomb, Robert; Zaldivar, Frank; Blake, Donald R

    2005-02-01

    Many volatile organic compounds are present in exhaled breath and may represent by-products of endogenous biological processes. Ethanol is produced via alcoholic fermentation of glucose by gut bacteria and yeast, while acetone derives from oxidations of free fatty acids, influenced by glucose metabolism. We hypothesized that the integrated analysis of breath ethanol and acetone would provide a good approximation of the blood glucose profile during a glucose load. We collected simultaneous exhaled breath gas, ambient air, and serum glucose and insulin samples from 10 healthy volunteers at baseline and during an oral glucose tolerance test (OGTT) (ingestion of 75 g of glucose followed by 120 min of sampling). Gas samples were analyzed by gas chromatography/mass spectrometry. Mean glucose values displayed a typical OGTT pattern (rapid increase, peak values at 30-60 min, and gradual return to near baseline by 120 min). Breath ethanol displayed a similar pattern early in the test, with peak values at 30 min; this was followed by a fast return to basal levels by 60 min. Breath acetone decreased progressively below basal levels, with lowest readings obtained at 120 min. A multiple regression analysis of glucose, ethanol, and acetone was used to estimate glucose profiles that correlated with measured glucose values with an average individual correlation coefficient of 0.70, and not lower than 0.41 in any subject. The integrated analysis of multiple exhaled gases may serve as a marker of blood glucose levels. Further studies are needed to assess the usefulness of this method in different populations.

  2. An artificial pancreas provided a novel model of blood glucose level variability in beagles.

    PubMed

    Munekage, Masaya; Yatabe, Tomoaki; Kitagawa, Hiroyuki; Takezaki, Yuka; Tamura, Takahiko; Namikawa, Tsutomu; Hanazaki, Kazuhiro

    2015-12-01

    Although the effects on prognosis of blood glucose level variability have gained increasing attention, it is unclear whether blood glucose level variability itself or the manifestation of pathological conditions that worsen prognosis. Then, previous reports have not been published on variability models of perioperative blood glucose levels. The aim of this study is to establish a novel variability model of blood glucose concentration using an artificial pancreas. We maintained six healthy, male beagles. After anesthesia induction, a 20-G venous catheter was inserted in the right femoral vein and an artificial pancreas (STG-22, Nikkiso Co. Ltd., Tokyo, Japan) was connected for continuous blood glucose monitoring and glucose management. After achieving muscle relaxation, total pancreatectomy was performed. After 1 h of stabilization, automatic blood glucose control was initiated using the artificial pancreas. Blood glucose level varied for 8 h, alternating between the target blood glucose values of 170 and 70 mg/dL. Eight hours later, the experiment was concluded. Total pancreatectomy was performed for 62 ± 13 min. Blood glucose swings were achieved 9.8 ± 2.3 times. The average blood glucose level was 128.1 ± 5.1 mg/dL with an SD of 44.6 ± 3.9 mg/dL. The potassium levels after stabilization and at the end of the experiment were 3.5 ± 0.3 and 3.1 ± 0.5 mmol/L, respectively. In conclusion, the results of the present study demonstrated that an artificial pancreas contributed to the establishment of a novel variability model of blood glucose levels in beagles.

  3. Improved tolerance to sequential glucose loading (Staub-Traugott effect): size and mechanisms.

    PubMed

    Bonuccelli, Sandra; Muscelli, Elza; Gastaldelli, Amalia; Barsotti, Elisabetta; Astiarraga, Brenno D; Holst, Jens J; Mari, Andrea; Ferrannini, Ele

    2009-08-01

    Improved glucose tolerance to sequential glucose loading (Staub-Traugott effect) is an important determinant of day-to-day glycemic exposure. Its mechanisms have not been clearly established. We recruited 17 healthy volunteers to receive two sequential oral glucose tolerance tests (OGTTs), at time 0 min and 180 min (Study I). The protocol was repeated on a separate day (Study II) except that plasma glucose was clamped at 8.3 mmol/l between 60 and 180 min. beta-Cell function was analyzed by mathematical modeling of C-peptide concentrations. In a subgroup, glucose kinetics were measured by a triple-tracer technique (infusion of [6,6-(2)H(2)]glucose and labeling of the 2 glucose loads with [1-(2)H]glucose and [U-(13)C]glucose). In both Studies I and II, the plasma glucose response to the second OGTT equaled 84 +/- 2% (P = 0.003) of the response to the first OGTT. Absolute insulin secretion was lower (37.8 +/- 4.3 vs. 42.8 +/- 5.1 nmol/m(2), P = 0.02), but glucose potentiation (i.e., higher secretion at the same glycemia) was stronger (1.08 +/- 0.02- vs. 0.92 +/- 0.02-fold, P = 0.006), the increment being higher in Study II (+36 +/- 5%) than Study I (+19 +/- 6%, P < 0.05). In pooled data, a higher glucose area during the first OGTT was associated with a higher potentiation during the second OGTT (rho=0.60, P = 0.002). Neither insulin clearance nor glucose clearance differed between loads, and appearance of glucose over 3 h totalled 60 +/- 6 g for the first load and 52 +/- 5 g for the second load (P = not significant). Fasting endogenous glucose production [13.3 +/- 0.6 micromol x min(-1) x kg fat-free mass (FFM)(-1)] averaged 6.0 +/- 3.8 micromol x min(-1) x kg FFM(-1) between 0 and 180 min and 1.7 +/- 2.6 between 180 and 360 min (P < 0.03). Glucose potentiation and stronger suppression of endogenous glucose release are the main mechanisms underlying the Staub-Traugott effect.

  4. Average oxidation state of carbon in proteins.

    PubMed

    Dick, Jeffrey M

    2014-11-06

    The formal oxidation state of carbon atoms in organic molecules depends on the covalent structure. In proteins, the average oxidation state of carbon (Z(C)) can be calculated as an elemental ratio from the chemical formula. To investigate oxidation-reduction (redox) patterns, groups of proteins from different subcellular locations and phylogenetic groups were selected for comparison. Extracellular proteins of yeast have a relatively high oxidation state of carbon, corresponding with oxidizing conditions outside of the cell. However, an inverse relationship between Z(C) and redox potential occurs between the endoplasmic reticulum and cytoplasm. This trend provides support for the hypothesis that protein transport and turnover are ultimately coupled to the maintenance of different glutathione redox potentials in subcellular compartments. There are broad changes in Z(C) in whole-genome protein compositions in microbes from different environments, and in Rubisco homologues, lower Z(C) tends to occur in organisms with higher optimal growth temperature. Energetic costs calculated from thermodynamic models are consistent with the notion that thermophilic organisms exhibit molecular adaptation to not only high temperature but also the reducing nature of many hydrothermal fluids. Further characterization of the material requirements of protein metabolism in terms of the chemical conditions of cells and environments may help to reveal other linkages among biochemical processes with implications for changes on evolutionary time scales.

  5. Calculating Free Energies Using Average Force

    NASA Technical Reports Server (NTRS)

    Darve, Eric; Pohorille, Andrew; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    A new, general formula that connects the derivatives of the free energy along the selected, generalized coordinates of the system with the instantaneous force acting on these coordinates is derived. The instantaneous force is defined as the force acting on the coordinate of interest so that when it is subtracted from the equations of motion the acceleration along this coordinate is zero. The formula applies to simulations in which the selected coordinates are either unconstrained or constrained to fixed values. It is shown that in the latter case the formula reduces to the expression previously derived by den Otter and Briels. If simulations are carried out without constraining the coordinates of interest, the formula leads to a new method for calculating the free energy changes along these coordinates. This method is tested in two examples - rotation around the C-C bond of 1,2-dichloroethane immersed in water and transfer of fluoromethane across the water-hexane interface. The calculated free energies are compared with those obtained by two commonly used methods. One of them relies on determining the probability density function of finding the system at different values of the selected coordinate and the other requires calculating the average force at discrete locations along this coordinate in a series of constrained simulations. The free energies calculated by these three methods are in excellent agreement. The relative advantages of each method are discussed.

  6. Average oxidation state of carbon in proteins

    PubMed Central

    Dick, Jeffrey M.

    2014-01-01

    The formal oxidation state of carbon atoms in organic molecules depends on the covalent structure. In proteins, the average oxidation state of carbon (ZC) can be calculated as an elemental ratio from the chemical formula. To investigate oxidation–reduction (redox) patterns, groups of proteins from different subcellular locations and phylogenetic groups were selected for comparison. Extracellular proteins of yeast have a relatively high oxidation state of carbon, corresponding with oxidizing conditions outside of the cell. However, an inverse relationship between ZC and redox potential occurs between the endoplasmic reticulum and cytoplasm. This trend provides support for the hypothesis that protein transport and turnover are ultimately coupled to the maintenance of different glutathione redox potentials in subcellular compartments. There are broad changes in ZC in whole-genome protein compositions in microbes from different environments, and in Rubisco homologues, lower ZC tends to occur in organisms with higher optimal growth temperature. Energetic costs calculated from thermodynamic models are consistent with the notion that thermophilic organisms exhibit molecular adaptation to not only high temperature but also the reducing nature of many hydrothermal fluids. Further characterization of the material requirements of protein metabolism in terms of the chemical conditions of cells and environments may help to reveal other linkages among biochemical processes with implications for changes on evolutionary time scales. PMID:25165594

  7. Average sunrise time predicts depression prevalence.

    PubMed

    Olders, Henry

    2003-08-01

    Folk wisdom has it that early rising is associated with being "healthy, wealthy and wise." A physiologic explanation may be Wiegand's "Depressiogenic Theory of Sleep," which posits that excessive REM sleep causes depression. Sleeping late increases REM sleep, and thus may increase depression risk. Published depression prevalence research does not use arising time, but average sunrise time (AST) for cities might serve as an analogue for arising time. Two studies of depression prevalence in urban populations, the EURODEP Programme, which measured geriatric depression in nine European cities, and the Epidemiologic Catchment Area (ECA) study of five US centres, have so far lacked satisfactory explanations for the striking differences in depression prevalence between cities. It was hypothesized that differences in rising times between cities, as determined by AST, could explain the variability in depression prevalences. Correlations were calculated for published depression prevalences from the EURODEP and ECA studies, and AST for each site. For both studies, depression prevalences are significantly correlated with AST, with later sunrise (corresponding to earlier arising times in relation to sunrise) associated with lower depression prevalence. The hypothesis that later rising from sleep is associated with increased depression was supported. The findings also suggest that a city's depression prevalence could be reduced by simple public health measures to manipulate AST, such as going to Daylight Saving Time (DST) year-round or shifting time-zone boundaries. For individuals, getting up earlier from sleep may be helpful in depression.

  8. Global Average Brightness Temperature for April 2003

    NASA Image and Video Library

    2003-06-02

    This image shows average temperatures in April, 2003, observed by AIRS at an infrared wavelength that senses either the Earth's surface or any intervening cloud. Similar to a photograph of the planet taken with the camera shutter held open for a month, stationary features are captured while those obscured by moving clouds are blurred. Many continental features stand out boldly, such as our planet's vast deserts, and India, now at the end of its long, clear dry season. Also obvious are the high, cold Tibetan plateau to the north of India, and the mountains of North America. The band of yellow encircling the planet's equator is the Intertropical Convergence Zone (ITCZ), a region of persistent thunderstorms and associated high, cold clouds. The ITCZ merges with the monsoon systems of Africa and South America. Higher latitudes are increasingly obscured by clouds, though some features like the Great Lakes, the British Isles and Korea are apparent. The highest latitudes of Europe and Eurasia are completely obscured by clouds, while Antarctica stands out cold and clear at the bottom of the image. http://photojournal.jpl.nasa.gov/catalog/PIA00427

  9. Portal 5-hydroxytryptophan infusion enhances glucose disposal in conscious dogs

    PubMed Central

    Moore, Mary Courtney; Kimura, Kazuhiro; Shibata, Haruki; Honjoh, Tsutomu; Saito, Masayuki; Everett, Carrie A.; Smith, Marta S.; Cherrington, Alan D.

    2008-01-01

    Intraportal serotonin infusion enhances net hepatic glucose uptake (NHGU) during glucose infusion but blunts nonhepatic glucose uptake and can cause gastrointestinal discomfort and diarrhea at high doses. Whether the serotonin precursor 5-hydroxytryptophan (5-HTP) could enhance NHGU without gastrointestinal side effects during glucose infusion was examined in conscious 42-h-fasted dogs, using arteriovenous difference and tracer ([3-3H]glucose) techniques. Experiments consisted of equilibration (−120 to −30 min), basal (−30 to 0 min), and experimental (EXP; 0–270 min) periods. During EXP, somatostatin, fourfold basal intraportal insulin, basal intraportal glucagon, and peripheral glucose (to double the hepatic glucose load) were infused. In one group of dogs (HTP, n = 6), saline was infused intraportally from 0 to 90 min (P1), and 5-HTP was infused intraportally at 10, 20, and 40 μg·kg−1·min−1 from 90 to 150 (P2), 150 to 210 (P3), and 210 to 270 (P4) min, respectively. In the other group (SAL, n = 7), saline was infused intraportally from 0 to 270 min. NHGU in SAL was 14.8 ± 1.9, 18.5 ± 2.3, 16.3 ± 1.4, and 19.7 ± 1.6 μmol·kg−1·min−1 in P1–P4, whereas NHGU in 5-HTP averaged 16.4 ± 2.6, 18.5 ± 1.4, 20.8 ± 2.0, and 27.6 ± 2.6 μmol·kg−1·min−1 (P < 0.05 vs. SAL). Nonhepatic glucose uptake (μmol·kg−1·min−1) in SAL was 30.2 ± 4.3, 36.8 ± 5.8, 44.3 ± 5.8, and 54.6 ± 11.8 during P1–P4, respectively, whereas in HTP the corresponding values were 26.3 ± 6.8, 44.9 ± 10.1, 47.5 ± 11.7, and 51.4 ± 13.2 (not significant between groups). Intraportal 5-HTP enhances NHGU without significantly altering nonhepatic glucose uptake or causing gastrointestinal side effects, raising the possibility that a related agent might have a role in reducing postprandial hyperglycemia. PMID:15755767

  10. Effects of a sodium glucose co-transporter 2 selective inhibitor, ipragliflozin, on the diurnal profile of plasma glucose in patients with type 2 diabetes: A study using continuous glucose monitoring

    PubMed Central

    Yamada, Kentaro; Nakayama, Hitomi; Yoshinobu, Satoko; Kawano, Seiko; Tsuruta, Munehisa; Nohara, Masayuki; Hasuo, Rika; Akasu, Shoko; Tokubuchi, Ichiro; Wada, Nobuhiko; Hirao, Saori; Iwata, Shinpei; Kaku, Hiroo; Tajiri, Yuji

    2015-01-01

    Aims/Introduction To assess the effects of sodium glucose co-transporter 2 inhibitor therapy on the pathophysiology of type 2 diabetes. Materials and Methods We administered ipragliflozin to 21 inpatients with type 2 diabetes for 7 days, and analyzed the diurnal profiles of plasma glucose and 3-hydroxybutyrate. A total of 21 age-, sex- and body mass index-matched diabetic patients served as controls. Results Continuous glucose monitoring showed that the 24-h glucose curve was shifted downward without hypoglycemia by the administration of ipragliflozin. The average glucose level was reduced from 182 ± 54 mg/dL to 141 ± 33 mg/dL (P < 0.0001). The magnitude of the reduction was highly correlated with the baseline average glucose level. Homeostasis model assessment of insulin resistance was decreased, and homeostasis model assessment of β-cell function was increased during the treatment. Urinary glucose excretion was correlated with the average glucose level both on day 0 and on day 7, although the regression line was steeper and shifted leftward on day 7. The ipragliflozin-treated patients lost more weight than the control patients (1.4 ± 0.5 vs 0.5 ± 0.6 kg, P < 0.0001). Plasma levels of 3-hydroxybutyrate were significantly increased with peaks before breakfast and before dinner. Patient age and bodyweight loss were negatively and positively correlated with the peak levels of 3-hydroxybutyrate on day 7, respectively. Conclusions The ipragliflozin treatment improved the 24-h glucose curve without causing hypoglycemia. The close correlation between the magnitude of glucose reduction and the baseline plasma glucose concentration suggests that the risk of hypoglycemia is likely low. It might be prudent to monitor ketone body levels in younger patients and in patients with rapid weight loss. PMID:26543545

  11. Glucose-6-Phosphate Dehydrogenase Revisited

    PubMed Central

    O'Connell, Jerome T.; Henderson, Alfred R.

    1984-01-01

    Hemolytic diseases associated with drugs have been recognized since antiquity. Many of these anemias have been associated with oxidizing agents and deficiencies in the intraerythrocytic enzyme glucose-6-phosphate dehydrogenase. This paper outlines the discovery, prevalence, and variants of this enzyme. Methods of diagnosis of associated anemias are offered. PMID:6502728

  12. Glucose polymer regimens and hypernatraemia.

    PubMed Central

    Verber, I G; Bain, M

    1990-01-01

    A 3 year old boy who had glutaric aciduria diagnosed at 22 months of age was admitted with a history of lethargy, vomiting, and fever. He had been receiving glucose polymers as part of his dietary management. He was severely hypernatraemic, but after resuscitation and rehydration made a good recovery. The possible aetiology of his hypernatraemia is discussed. PMID:2378522

  13. Hepatocytes: critical for glucose homeostasis.

    PubMed

    Klover, Peter J; Mooney, Robert A

    2004-05-01

    Maintaining blood glucose levels within a narrow range is a critical physiological function requiring multiple metabolic pathways and involving several cell types, including a prominent role for hepatocytes. Under hormonal control, hepatocytes can respond to either feeding or fasting conditions by storing or producing glucose as necessary. In the fasting state, the effects of glucagon avoid hypoglycemia by stimulating glucogenesis and glycogenolysis and initiating hepatic glucose release. Postprandially, insulin prevents hyperglycemia, in part, by suppressing hepatic gluconeogenesis and glycogenolysis and facilitating hepatic glycogen synthesis. Both transcriptional regulation of rate limiting enzymes and modulation of enzyme activity through phosphorylation and allosteric regulation are involved. Type 2 diabetes mellitus is the most common serious metabolic condition in the world, and results from a subnormal response of tissues to insulin (insulin resistance) and a failure of the insulin-secreting beta cells to compensate. In type 2 diabetes, glucose is overproduced by the hepatocyte and is ineffectively metabolized by other organs. Impairments in the insulin signal transduction pathway appear to be critical lesions contributing to insulin resistance and type 2 diabetes.

  14. Near patient blood glucose monitoring.

    PubMed

    Laposata, M; Lewandrowski, K B

    1995-10-01

    This report describes the quality control and quality assurance programs for bedside glucometry at our institution. From our 3-year experience, a regular schedule of inspections is necessary for maintenance of high-quality bedside glucose testing. The most common violation of quality control/quality assurance in bedside glucometry in our institution was the failure to perform regular proficiency testing, in which one random patient's bedside capillary blood glucose value during each inspection period was compared to his or her venous plasma or serum glucose value obtained from the central laboratory. Failure to perform instrument maintenance and document operator certification were the next most common violations of quality control/quality assurance in our bedside glucometry program. Regarding the cost analysis for bedside glucometry, we conclude that bedside glucose testing is not inherently more expensive than testing performed within the clinical laboratory. The increased cost of bedside glucometry over laboratory testing can be significantly minimized by involvement of a limited number of health care workers and performance of bedside glucometry only on clinical units where testing is required more than five times per day.

  15. Flux-Averaged and Volume-Averaged Concentrations in Continuum Approaches to Solute Transport

    NASA Astrophysics Data System (ADS)

    Parker, J. C.; van Genuchten, M. Th.

    1984-07-01

    Transformations between volume-averaged pore fluid concentrations and flux-averaged concentrations are presented which show that both modes of concentration obey convective-dispersive transport equations of identical mathematical form for nonreactive solutes. The pertinent boundary conditions for the two modes, however, do not transform identically. Solutions of the convection-dispersion equation for a semi-infinite system during steady flow subject to a first-type inlet boundary condition is shown to yield flux concentrations, while solutions subject to a third-type boundary condition yield volume-averaged concentrations. These solutions may be applied with reasonable impunity to finite as well as semi-infinite media if back mixing at the exit is precluded. Implications of the distinction between resident and flux concentrations to laboratory and field studies of solute transport are discussed. It is suggested that perceived limitations of the convection-dispersion model for media with large variations in pore water velocities may in certain cases be attributable to a failure to distinguish between volume-averaged and flux-averaged concentrations.

  16. Impact of repeated measures and sample selection on genome-wide association studies of fasting glucose

    PubMed Central

    Rasmussen-Torvik, Laura J.; Alonso, Alvaro; Li, Man; Kao, Wen; Köttgen, Anna; Yan, Yuer; Couper, David; Boerwinkle, Eric; Bielinski, Suzette J.; Pankow, James S.

    2010-01-01

    Although GWAS have been performed in longitudinal studies, most used only a single trait measure. GWAS of fasting glucose have generally included only normoglycemic individuals. We examined the impact of both repeated measures and sample selection on GWAS in ARIC, a study which obtained four longitudinal measures of fasting glucose and included both individuals with and without prevalent diabetes. The sample included Caucasians and the Affymetrix 6.0 chip was used for genotyping. Sample sizes for GWAS analyses ranged from 8372 (first study visit) to 5782 (average fasting glucose). Candidate SNP analyses with SNPs identified through fasting glucose or diabetes GWAS were conducted in 9133 individuals, including 761 with prevalent diabetes. For a constant sample size, smaller p-values were obtained for the average measure of fasting glucose compared to values at any single visit, and two additional significant GWAS signals were detected. For four candidate SNPs (rs780094, rs10830963, rs7903146, and rs4607517), the strength of association between genotype and glucose was significantly (p-interaction < .05) different in those with and without prevalent diabetes and for all five fasting glucose candidate SNPs (rs780094, rs10830963, rs560887, rs4607517, rs13266634) the association with measured fasting glucose was more significant in the smaller sample without prevalent diabetes than in the larger combined sample of those with and without diabetes. This analysis demonstrates the potential utility of averaging trait values in GWAS studies and explores the advantage of using only individuals without prevalent diabetes in GWAS of fasting glucose. PMID:20839289

  17. Increases in Whole Blood Glucose Measurements Using Optically Based Self-Monitoring of Blood Glucose Analyzers Due to Extreme Canadian Winters

    PubMed Central

    Cembrowski, George C.; Smith, Barbara; O'Malley, Ellen M.

    2009-01-01

    Background Temperature and humidity have been reported to influence the results of whole blood glucose (WBG) measurements. Methods To determine whether patient WBG values were affected by seasonal variation, we conducted a retrospective analysis of 3 years' worth of weekly averages of patient WBG in five Edmonton hospitals. Results In all five hospitals, the winter WBG averages were consistently higher than the summer WBG averages, with the differences varying between 5% and 9%. Whole blood glucose averages were negatively correlated with the outside temperature. This seasonal variation was not observed in weekly patient averages of specimens run in a central hospital laboratory. Interpretation It is probable that the seasonal variation of WBG arises from the very low indoor humidities that are associated with external subzero temperatures. These increases in WBG in cold weather may be due to limitations in the WBG measuring systems when operated in decreased humidities and/or increased evaporation of the blood sample during the blood glucose measurement process. The implications of this seasonal variation are significant in that it (1) introduces increased variability in patient WBG, (2) may result in increased glucose-lowering therapy during periods of external cold and low indoor humidity, and (3) confounds evaluations of WBG meter technology in geographic regions of subzero temperature and low indoor humidity. To mitigate the risk of diagnosing and treating factitious hyperglycemia, the humidity of patient care areas must be strictly controlled. PMID:20144309

  18. Modeling the glucose sensor error.

    PubMed

    Facchinetti, Andrea; Del Favero, Simone; Sparacino, Giovanni; Castle, Jessica R; Ward, W Kenneth; Cobelli, Claudio

    2014-03-01

    Continuous glucose monitoring (CGM) sensors are portable devices, employed in the treatment of diabetes, able to measure glucose concentration in the interstitium almost continuously for several days. However, CGM sensors are not as accurate as standard blood glucose (BG) meters. Studies comparing CGM versus BG demonstrated that CGM is affected by distortion due to diffusion processes and by time-varying systematic under/overestimations due to calibrations and sensor drifts. In addition, measurement noise is also present in CGM data. A reliable model of the different components of CGM inaccuracy with respect to BG (briefly, "sensor error") is important in several applications, e.g., design of optimal digital filters for denoising of CGM data, real-time glucose prediction, insulin dosing, and artificial pancreas control algorithms. The aim of this paper is to propose an approach to describe CGM sensor error by exploiting n multiple simultaneous CGM recordings. The model of sensor error description includes a model of blood-to-interstitial glucose diffusion process, a linear time-varying model to account for calibration and sensor drift-in-time, and an autoregressive model to describe the additive measurement noise. Model orders and parameters are identified from the n simultaneous CGM sensor recordings and BG references. While the model is applicable to any CGM sensor, here, it is used on a database of 36 datasets of type 1 diabetic adults in which n = 4 Dexcom SEVEN Plus CGM time series and frequent BG references were available simultaneously. Results demonstrates that multiple simultaneous sensor data and proper modeling allow dissecting the sensor error into its different components, distinguishing those related to physiology from those related to technology.

  19. Global Average Brightness Temperature for April 2003

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site] Figure 1

    This image shows average temperatures in April, 2003, observed by AIRS at an infrared wavelength that senses either the Earth's surface or any intervening cloud. Similar to a photograph of the planet taken with the camera shutter held open for a month, stationary features are captured while those obscured by moving clouds are blurred. Many continental features stand out boldly, such as our planet's vast deserts, and India, now at the end of its long, clear dry season. Also obvious are the high, cold Tibetan plateau to the north of India, and the mountains of North America. The band of yellow encircling the planet's equator is the Intertropical Convergence Zone (ITCZ), a region of persistent thunderstorms and associated high, cold clouds. The ITCZ merges with the monsoon systems of Africa and South America. Higher latitudes are increasingly obscured by clouds, though some features like the Great Lakes, the British Isles and Korea are apparent. The highest latitudes of Europe and Eurasia are completely obscured by clouds, while Antarctica stands out cold and clear at the bottom of the image.

    The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

  20. Development of the MOSFET hybrid biosensor for self-monitoring of blood glucose

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Kazuyoshi; Kuroda, Tatsuro; Hirai, Yasutomo; Iwamoto, Naoyuki; Nakanishi, Naoyuki; Uetsuji, Yasutomo; Nakamachi, Eiji

    2006-01-01

    We focus on the research to develop a compact Self Monitoring of Blood Glucose (SMBG). The SMBG consists of (1) a micro electrical pumping system for blood extraction, (2) a painless microneedle as same size as a female mosquito's labium and (3) a biosensor to detect and evaluate an amount of glucose in extracted blood, by using enzyme such as glucose oxidase (GOx). A gold (Au) plate immobilized GOx was used as a biosensor and attached to the gate electrode of MOSFET. GOx was immobilized on a self-assembled spacer combined with an Au electrode by the cross-link method using BSA (bovine serum albumin) as an additional bonding material. The electrode could detect electrons generated by the hydrolysis of hydrogen peroxide produced by the reaction between GOx and glucose using the constant electric current measurement system of the MOSFET type hybrid biosensor system. The system can measure the change of gate voltage. The extracting speed for whole blood using the micro electrical pumping system was about 2 μl/min. The extracted volume was sufficient to determine the glucose level in the blood; it was comparable to the volume extracted in a commercial glucose level monitor. In the functional evaluation of the biosensor system using hydrogen peroxide solution, it is shown that the averaged output voltage increases in alignment to hydrogen peroxide concentration. The linear value was shown with the averaged output voltage in corresponding hydrogen peroxide concentration with the averaged output voltage obtained from the biosensor system by glucose solution concentration. Furthermore, it is confirmed that the averaged output voltage from the biosensor system obtained by whole blood showed the same voltage in corresponding glucose solution concentration. The hybrid biosensor obtained the useful performance for the SMBG.

  1. Finger temperature controller for non-invasive blood glucose measurement

    NASA Astrophysics Data System (ADS)

    Zhang, Xiqin; Ting, Choon Meng; Yeo, Joon Hock

    2010-11-01

    Blood glucose level is an important parameter for doctors to diagnose and treat diabetes. The Near-Infra-Red (NIR) spectroscopy method is the most promising approach and this involves measurement on the body skin. However it is noted that the skin temperature does fluctuate with the environmental and physiological conditions and we found that temperature has important influences on the glucose measurement. In-vitro and in-vivo investigations on the temperature influence on blood glucose measurement have been carried out. The in-vitro results show that water temperature has significant influence on water absorption. Since 90% of blood components are water, skin temperature of measurement site has significant influence on blood glucose measurement. Also the skin temperature is related to the blood volume, blood volume inside capillary vessels changes with skin temperature. In this paper the relationship of skin temperature and signal from the skin and inside tissue was studied at different finger temperatures. Our OGTT (oral glucose tolerance test) trials results show the laser signals follow the skin temperature trend and the correlation of signal and skin temperature is much stronger than the correlation of signal and glucose concentration. A finger heater device is designed to heat and maintain the skin temperature of measurement site. The heater is controlled by an electronic circuit according to the skin temperature sensed by a thermocouple that is put close to the measurement site. In vivo trials were carried out and the results show that the skin temperature significantly influences the signal fluctuations caused by pulsate blood and the average signal value.

  2. A correction method using a support vector machine to minimize hematocrit interference in blood glucose measurements.

    PubMed

    Shin, Jaeyeon; Park, Hodong; Cho, Sungpil; Nam, Hakhyun; Lee, Kyoung-Joung

    2014-09-01

    Point-of-care testing glucose meters are widely used, important tools for determining the blood glucose levels of people with diabetes, patients in intensive care units, pregnant women, and newborn infants. However, a number of studies have concluded that a change in hematocrit (Hct) levels can seriously affect the accuracy of glucose measurements. The aim of this study was to develop an algorithm for glucose calculation with improved accuracy using the Hct compensation method that minimizes the effects of Hct on glucose measurements. The glucose concentrations in this study were calculated with an adaptive calibration curve using linear fitting prediction and a support vector machine, which minimized the bias in the glucose concentrations caused by the Hct interference. This was followed by an evaluation of performance according to the international organization for standardization (ISO) 15197:2013 based on bias with respect to the reference method, the coefficient of variation, and the valid blood samples/total blood samples within the ±20% and 15% error grids. Chronoamperometry was performed to verify the effect of Hct variation and to compare the proposed method. As a result, the average coefficients of variation for chronoamperometry and the Hct compensation method were 2.43% and 3.71%, respectively, while the average biases (%) for these methods were 12.08% and 5.69%, respectively. The results of chronoamperometry demonstrated that a decrease in Hct levels increases glucose concentrations, whereas an increase in Hct levels reduces glucose concentrations. Finally, the proposed method has improved the accuracy of glucose measurements compared to existing chronoamperometry methods.

  3. A case of perioperative glucose control by using an artificial pancreas in a patient with glycogen storage disease.

    PubMed

    Yatabe, Tomoaki; Nakamura, Ryu; Kitagawa, Hiroyuki; Munekage, Masaya; Hanazaki, Kazuhiro

    2016-03-01

    A 57-year-old woman was diagnosed with type I glycogen storage disease in her twenties. She had undergone hepatectomy under general anesthesia with epidural anesthesia. Fifty minutes after the induction of anesthesia, a 20-gauge venous catheter was inserted in the patient's right hand, and an artificial pancreas (STG-55, Nikkiso Co., Tokyo, Japan) was connected for continuous glucose monitoring and automatic glucose control. Insulin was infused when the blood glucose level reached 120 mg/dL or higher, and glucose was infused when the level fell to 100 mg/dL or lower. After the Pringle maneuver, the blood glucose level increased, and insulin was administered automatically via an artificial pancreas. Hypoglycemia did not occur during the operation. After total parenteral nutrition was started in the intensive care unit (ICU), the blood glucose level increased, and the artificial pancreas controlled the blood glucose level through automatic insulin administration. Thirty-four hours after admission to the ICU, the artificial pancreas was removed because the blood sampling failed. After the removal of the artificial pancreas, blood glucose level was measured every 2 h until extubation. During the ICU stay, hypoglycemia never occurred, with the average blood glucose level being 144 mg/dL. In conclusion, the use of an artificial pancreas for perioperative blood glucose management in a patient with glycogen storage disease had the beneficial effect of enabling the management of blood glucose levels without hypoglycemia.

  4. Natural history and physiological determinants of changes in glucose tolerance in a non-diabetic population: the RISC Study.

    PubMed

    Ferrannini, E; Natali, A; Muscelli, E; Nilsson, P M; Golay, A; Laakso, M; Beck-Nielsen, H; Mari, A

    2011-06-01

    The natural history and physiological determinants of glucose intolerance in subjects living in Europe have not been investigated. The aim of this study was to increase our understanding of this area. We analysed the data from a population-based cohort of 1,048 non-diabetic, normotensive men and women (aged 30-60 years) in whom insulin sensitivity was measured by the glucose clamp technique (M/I index; average glucose infusion rate/steady-state insulin concentration) and beta cell function was estimated by mathematical modelling of the oral glucose tolerance test at baseline and 3 years later. Seventy-seven per cent of the participants had normal glucose tolerance (NGT) and 5% were glucose intolerant both at baseline and follow up; glucose tolerance worsened in 13% (progressors) and improved in 6% (regressors). The metabolic phenotype of the latter three groups was similar (higher prevalence of familial diabetes, older age, higher waist-to-hip ratio, higher fasting and 2 h plasma glucose, higher fasting and 2 h plasma insulin, lower insulin sensitivity and reduced beta cell glucose sensitivity with increased absolute insulin secretion). Adjusting for these factors in a logistic model, progression was predicted by insulin resistance (bottom M/I quartile, OR 2.52 [95% CI 1.51-4.21]) and beta cell glucose insensitivity (bottom quartile, OR 2.39 [95% CI 1.6-3.93]) independently of waist-to-hip ratio (OR 1.44 [95% CI 1.13-1.84] for one SD). At follow up, insulin sensitivity and beta cell glucose sensitivity were unchanged in the stable NGT and stable non-NGT groups, worsened in progressors and improved in regressors. Glucose tolerance deteriorates over time in young, healthy Europids. Progressors, regressors and glucose-intolerant participants share a common baseline phenotype. Insulin sensitivity and beta cell glucose sensitivity predict and track changes in glucose tolerance independently of sex, age and obesity.

  5. Peritoneal transport characteristics with glucose polymer based dialysate.

    PubMed

    Ho-dac-Pannekeet, M M; Schouten, N; Langendijk, M J; Hiralall, J K; de Waart, D R; Struijk, D G; Krediet, R T

    1996-09-01

    it remained unchanged during the dwell. In contrast, D/PNa+ of 1.36% glucose increased during the dwell, whereas D/PNa+ decreased with 3.86% glucose until 60 minutes, followed by a subsequent increase. The ultrafiltration coefficient (UFC) of the total peritoneal membrane was assessed using 3.86% glucose (0.18 +/- 0.04 ml/min/mm Hg), and the UFC of the small pores was assessed using icodextrin (0.06 +/- 0.008 ml/min/mm Hg). The difference between these represented the UFC through the transcellular pores, which averaged 50.5% of the total UFC, but with a very wide range (0 to 85%). An inverse relation existed between the duration of CAPD treatment and the total ultrafiltration coefficient (r = -0.68, P < 0.04), which could be attributed to a lower UFC of the transcellular pores in long-term patients (r = -0.66, P < 0.05), but not to the UFC of the small pores (r = -0.48, NS). The TCUFRo-60 min through the transcellular pores correlated with the sodium gradient, corrected for diffusion, in the first hour of the dwell (r = 0.69, P < 0.04), indicating that both parameters indeed measure transcellular water transport. It can be concluded that the glucose polymer solution induced sustained ultrafiltration and had no effect on peritoneal membrane characteristics. In addition, the results of the present study support the hypothesis that the glucose polymer solutions exerts its osmotic pressure across intercellular pores with radii of about 40 A. This leads to increased clearances of low molecular weight proteins such as beta 2m that are transported through these pores without sieving of Na+. The latter, as found during 3.86% glucose dialysate, is probably caused by transcellular water transport. The transcellular water transport accounted for 50% of the total ultrafiltration with glucose based dialysis solutions. It was lower in long-term CAPD patients.

  6. Interpreting Sky-Averaged 21-cm Measurements

    NASA Astrophysics Data System (ADS)

    Mirocha, Jordan

    2015-01-01

    Within the first ~billion years after the Big Bang, the intergalactic medium (IGM) underwent a remarkable transformation, from a uniform sea of cold neutral hydrogen gas to a fully ionized, metal-enriched plasma. Three milestones during this epoch of reionization -- the emergence of the first stars, black holes (BHs), and full-fledged galaxies -- are expected to manifest themselves as extrema in sky-averaged ("global") measurements of the redshifted 21-cm background. However, interpreting these measurements will be complicated by the presence of strong foregrounds and non-trivialities in the radiative transfer (RT) modeling required to make robust predictions.I have developed numerical models that efficiently solve the frequency-dependent radiative transfer equation, which has led to two advances in studies of the global 21-cm signal. First, frequency-dependent solutions facilitate studies of how the global 21-cm signal may be used to constrain the detailed spectral properties of the first stars, BHs, and galaxies, rather than just the timing of their formation. And second, the speed of these calculations allows one to search vast expanses of a currently unconstrained parameter space, while simultaneously characterizing the degeneracies between parameters of interest. I find principally that (1) physical properties of the IGM, such as its temperature and ionization state, can be constrained robustly from observations of the global 21-cm signal without invoking models for the astrophysical sources themselves, (2) translating IGM properties to galaxy properties is challenging, in large part due to frequency-dependent effects. For instance, evolution in the characteristic spectrum of accreting BHs can modify the 21-cm absorption signal at levels accessible to first generation instruments, but could easily be confused with evolution in the X-ray luminosity star-formation rate relation. Finally, (3) the independent constraints most likely to aide in the interpretation

  7. Glucose sensing by means of silicon photonics

    NASA Astrophysics Data System (ADS)

    Bockstaele, Ronny; Ryckeboer, Eva; Hattasan, Nannicha; De Koninck, Yannick; Muneeb, Muhammad; Verstuyft, Steven; Delbeke, Danaë; Bogaerts, Wim; Roelkens, Gunther; Baets, Roel

    2014-03-01

    Diabetes is a fast growing metabolic disease, where the patients suffer from disordered glucose blood levels. Monitoring the blood glucose values in combination with extra insulin injection is currently the only therapy to keep the glucose concentration in diabetic patients under control, minimizing the long-term effects of elevated glucose concentrations and improving quality of life of the diabetic patients. Implantable sensors allow continuous glucose monitoring, offering the most reliable data to control the glucose levels. Infrared absorption spectrometers offer a non-chemical measurement method to determine the small glucose concentrations in blood serum. In this work, a spectrometer platform based on silicon photonics is presented, allowing the realization of very small glucose sensors suitable for building implantable sensors. A proof-of-concept of a spectrometer with integrated evanescent sample interface is presented, and the route towards a fully implantable spectrometer is discussed.

  8. Genetics Home Reference: glucose phosphate isomerase deficiency

    MedlinePlus

    ... Me Understand Genetics Home Health Conditions GPI deficiency glucose phosphate isomerase deficiency Enable Javascript to view the ... boxes. Download PDF Open All Close All Description Glucose phosphate isomerase (GPI) deficiency is an inherited disorder ...

  9. Glucose Sensing for Diabetes Monitoring: Recent Developments

    PubMed Central

    Bruen, Danielle; Delaney, Colm; Florea, Larisa

    2017-01-01

    This review highlights recent advances towards non-invasive and continuous glucose monitoring devices, with a particular focus placed on monitoring glucose concentrations in alternative physiological fluids to blood. PMID:28805693

  10. Glucose Effect in the Acute Porphyrias

    MedlinePlus

    ... You are here Home Diet and Nutrition The glucose effect in acute porphyrias The disorders Acute Intermittent ... are treated initially with the administration of carbohydrate/glucose. This therapy has its basis in the ability ...

  11. Cadmium stimulates glucose metabolism in rat adipocytes

    SciTech Connect

    Yamamoto, A.; Wada, O.; Ono, T.; Ono, H.

    1986-07-01

    Cd/sup 2 +/ caused an increase in CO/sub 2/ formation from glucose in rat adipocytes. The apparent Km value for glucose was 2.02 mM for control condition, with Cd/sup 2 +/, and with insulin. Cd/sup 2 +/ stimulates glucose metabolism even though specific diffusion of glucose is blocked. A possible site effected by Cd/sup 2 +/ is discussed.

  12. 21 CFR 168.120 - Glucose sirup.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Glucose sirup. 168.120 Section 168.120 Food and... § 168.120 Glucose sirup. (a) Glucose sirup is the purified, concentrated, aqueous solution of nutritive... equivalent), expressed as D-glucose, is not less than 20.0 percent m/m calculated on a dry basis. (2) The...

  13. Fluorescence lifetime measurements of boronate derivatives to determine glucose concentration

    SciTech Connect

    Gable, J H

    2000-06-01

    A novel investigation into the fluorescence lifetimes of molecules, both established and newly designed, was performed. These molecules are the basis of a continuous, minimally invasive, glucose sensor based on fluorescence lifetime measurements. This sensor, if coupled with an automated insulin delivery device, would effectively create an artificial pancreas allowing for the constant monitoring and control of glucose levels in a person with diabetes. The proposed sensor includes a fluorescent molecule that changes its' fluorescence properties upon binding selectively and reversibly to glucose. One possible sensor molecule is N-methyl-N-(9-methylene anthryl)-2-methylenephenylboronic acid (AB). The fluorescence intensity of AB was shown to change in response to changing glucose concentrations. (James, 1994) James proposed that when glucose binds to AB the fluorescence intensity increases due to an enhancement of the N{yields}B dative bond which prevents photoinduced electron transfer (PET). PET from the amine (N) to the fluorophore (anthracene) quenches the fluorescence. The dative bond between the boron and the amine can prevent PET by involving the lone pair of electrons on the amine in interactions with the boron rather than allowing them to be transferred to the fluorophore. Results of this research show the average fluorescence lifetime of AB also changes with glucose concentration. It is proposed that fluorescence is due to two components: (1) AB with an enhanced N{yields}B interaction, and no PET, and (2) AB with a weak N{yields}B interaction, resulting in fluorescence quenching by PET. Lifetime measurements of AB as a function of both the pH of the solvent and glucose concentration in the solution were made to characterize this two component system and investigate the nature of the N{yields}B bond. Measurements of molecules similar to AB were also performed in order to isolate behavior of specific AB constituents. These molecules are 9-(Methylaminomethyl

  14. Near-infrared spectral methods for noninvasively measuring blood glucose

    NASA Astrophysics Data System (ADS)

    Fei, Sun; Kong, Deyi; Mei, Tao; Tao, Yongchun

    2004-05-01

    Determination of blood glucose concentrations in diabetic patients is a frequently occurring procedure and an important tool for diabetes management. Use of noninvasive detection techniques can relieve patients from the pain of frequent finger pokes and avoid the infection of disease via blood. This thesis discusses current research and analyzes the advantages and shortages of different measurement methods, including: optical methods (Transmission, Polarimetry and scattering), then, we give emphasis to analyze the technology of near-infrared (NIR) spectra. NIR spectral range 700 nm ~2300 nm was used because of its good transparency for biological tissue and presence of glucose absorption band. In this work, we present an outline of noninvasive blood glucose measurement. A near-infrared light beam is passed through the finger, and the spectral components of the emergent beam are measured using spectroscopic techniques. The device includes light sources having the wavelengths of 600 nm - 1800 nm to illuminate the tissue. Receptors associated with the light sources for receiving light and generating a transmission signal representing the light transmitted are also provided. Once a transmission signal is received by receptors, and the high and low values from each of the signals are stored in the device. The averaged values are then analyzed to determine the glucose concentration, which is displayed on the device.

  15. Effects of ethanol ingestion on maternal and fetal glucose homeostasis

    SciTech Connect

    Singh, S.P.; Snyder, A.K.; Singh, S.K.

    1984-08-01

    Carbohydrate metabolism has been studied in the offspring of rats fed liqiud diet containing ethanol during gestation (EF group). Weight-matched control dams were given liquid diet either by the pair-fed technique (PF group) or ad libitum (AF group). EF and PF dams showed reduced food consumption and attenuated gain in body weight during the gestation period compared with the AF group. Blood glucose, liver glycogen, and plasma insulin levels were significantly reduced in EF and PF dams. Ethanol ingestion resulted in a significant decrease in litter survival and fetal body weight. At term, EF pups on average showed a 30% decrease in blood glucose levels and 40% decrease in plasma insulin levels compared with AF pups. One hour after birth, EF pups exhibited a marked increase in blood sugar level compared with either control group. Fetal hyperinsulinemia disappeared shortly after delivery in control pups, as expected; however, in EF pups, the fall in plasma insulin level was gradual. Fetal and neonatal plasma glucagon levels were not altered by ethanol exposure in utero. Blood glucose levels remained significantly low at 2 days of age in EF pups, but reached near control values at 4 days of age. Plasma insulin and glucagon were nearly equal in EF and control pups at 2 and 4 days of age. These results show aberrations in blood glucose, plasma insulin, and liver glycogen levels in offspring exposed to ethanol in utero.

  16. Meal Detection and Carbohydrate Estimation Using Continuous Glucose Sensor Data.

    PubMed

    Samadi, Sediqeh; Turksoy, Kamuran; Hajizadeh, Iman; Feng, Jianyuan; Sevil, Mert; Cinar, Ali

    2017-05-01

    A meal detection and meal-size estimation algorithm is developed for use in artificial pancreas (AP) control systems for people with type 1 diabetes. The algorithm detects the consumption of a meal and estimates its carbohydrate (CHO) amount to determine the appropriate dose of insulin bolus for a meal. It can be used in AP systems without manual meal announcements, or as a safety feature for people who may forget entering meal information manually. Using qualitative representation of the filtered continuous glucose monitor signal, a time period labeled as meal flag is identified. At every sampling time during this time period, a fuzzy system estimates the amount of CHO. Meal size estimator uses both glucose sensor and insulin data. Meal insulin bolus is based on estimated CHO. The algorithm does not change the basal insulin rate. Thirty in silico subjects of the UVa/Padova simulator are used to illustrate the performance of the algorithm. For the evaluation dataset, the sensitivity and false positives detection rates are 91.3% and 9.3%, respectively, the absolute error in CHO estimation is 23.1%, the mean blood glucose level is 142 mg/dl, and glucose concentration stays in target range (70-180 mg/dl) for 76.8% of simulation duration on average.

  17. Performance characteristics of the HemoCue B-Glucose analyzer using whole-blood samples.

    PubMed

    Voss, E M; Cembrowski, G S

    1993-07-01

    We evaluated the HemoCue B-Glucose (HemoCue Inc, Mission Viejo, Calif) analyzer for accuracy, precision, linearity, and recovery. One hundred eighteen capillary whole-blood samples were analyzed in duplicate on the HemoCue B-Glucose and the YSI 2300 STAT Glucose/L-Lactate (Yellow Springs [Ohio] Instruments) analyzers; corresponding plasma glucose levels were measured in duplicate on the Roche Cobas MIRA (Roche Diagnostic Systems, Nutley, NJ) analyzer. Plasma glucose levels were converted to whole-blood equivalent glucose levels by using a factor of 1.11. The following regression equations were obtained: HemoCue = 1.02 (YSI) + 0.19, Sy/x = 0.52, r2 = .984; and HemoCue = 0.98 (whole-blood equivalent glucose levels) + 0.26, Sy/x = 0.55, r2 = .982. Within-run coefficients of variation were 4.0%, 3.5%, 2.2%, and 1.0% at glucose concentrations of 3.9, 5.4, 8.7, and 17.1 mmol/L (71, 97, 156, and 308 mg/dL), respectively. Between-run imprecision and total imprecision using lyopholized materials with three lot numbers of cuvettes were 4.2% and 5.6% at 2.1 mmol/L (37 mg/dL) and 2.4% and 2.7% at 5.2 mmol/L (95 mg/dL), respectively. The HemoCue B-Glucose analyzer displayed linearity between 0 and 22.2 mmol/L (0 and 400 mg/dL), and the percent recovery averaged 98.7% +/- 4.5% (mean +/- SD). The HemoCue B-Glucose analyzer is a rapid, simple, and reliable method for determinations of whole-blood glucose levels.

  18. Effect of glucose on the stress-strain behavior of ex-vivo rabbit cornea.

    PubMed

    Ni, Shouxiang; Yu, Jiguo; Bao, Fangjun; Li, Jinyang; Elsheikh, Ahmed; Wang, Qinmei

    2011-05-01

    The biomechanical changes in rabbit cornea preserved in storage media with different glucose concentrations are experimentally assessed. Two groups of eight fresh rabbit corneas were preserved for 10 days in storage medium Optisol-GS with glucose concentrations of 14 and 28 mM, respectively. Eight additional corneas preserved, glucose-free, in the same medium served as the control group. All specimens were tested under inflation conditions up to 45 mmHg posterior pressure, and the pressure-deformation data obtained experimentally were analyzed using shell theory to derive the stress-strain behavior. Comparisons were held between the three specimen groups in order to determine the effect of glucose concentration on corneal biomechanical behavior and thickness. After storage, the mean central corneal thickness in the control, low-glucose and high-glucose groups underwent statistically significant increases of 38.7 ± 11.3%, 45.4 ± 7.6% and 50.6 ± 8.6%, respectively. The corneas also demonstrated consistent stiffness increases with higher glucose concentrations. The tangent modulus values determined at different pressure levels between 10 and 40 mmHg underwent statistically significant increases with glucose level (P < 0.05). Compared to the control group, other specimens had higher tangent modulus by 17-20% on average with low glucose and 30-37% with high-glucose concentration. The results of the study indicate that the influence of the high-glucose level commonly experienced in diabetes on the biomechanical stiffness of the cornea should be considered in clinical management and in understanding corneal ectasia, glaucoma and the response to refractive surgery. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Comparative study of different control techniques for the regulation of blood glucose level in diabetic patients.

    PubMed

    Ibbini, Mohammed S

    2009-01-01

    Blood glucose regulation is of a great concern for insulin-dependant patients with excessive glucose in blood (hyperglycaemia), or low glucose profile (hypoglycaemia) due to excess insulin delivery. Both conditions can cause dangerous complications for diabetic patients, and hence glucose regulation in blood is of prime importance. Insulin pumps are used to deliver insulin in small quantities, allowing the glucose level to remain as close as possible to that of non-diabetics (near 100 mg dl(-1)). Different control techniques are used to maintain the glucose level and most of them depend on an exact mathematical or empirical model of insulin-glucose interaction. Recently, we have proposed different controllers that are based on fuzzy logic and so do not use mathematical modelling, which in general is nonlinear, complex and suffers from uncertainties. PI fuzzy controllers are physically related to classical PI and PID controllers, which are extremely popular. The parameter settings of classical and fuzzy logic controllers are based on deep common physical background. In this manuscript, a comparative study is proposed to evaluate the use of fuzzy logic controllers over other conventional controllers such as PI and PID controllers to maintain the blood glucose level within a normoglycaemic average especially when a diabetic patient is subjected to different conditions.

  20. Superior long-term stability of a glucose biosensor based on inserted barrel plating gold electrodes.

    PubMed

    Hsu, Cheng-Teng; Hsiao, Hung-Chan; Fang, Mei-Yen; Zen, Jyh-Myng

    2009-10-15

    Disposable one shot usage blood glucose strips are routinely used in the diagnosis and management of diabetes mellitus and their performance can vary greatly. In this paper we critically evaluated the long-term stability of glucose strips made of barrel plating gold electrodes. Compared to other glucose biosensing platforms of vapor deposited palladium and screen printed carbon electrodes, the proposed glucose biosensor was found to show the best stability among the three biosensing platforms in thermal acceleration experiments at 40 degrees C for 6 months with an average bias of 3.4% at glucose concentrations of 5-20 mM. The precision test of this barrel plating gold glucose biosensor also showed the best performance (coefficients of variation in the range of 1.4-2.4%) in thermal acceleration experiments at 40 degrees C, 50 degrees C and 70 degrees C for 27 days. Error grid analysis revealed that all measurements fell in zone A and zone B. Regression analysis showed no significant difference between the proposed biosensor and the reference method at 99% confidence level. The amperometric glucose biosensor fabricated by inserting two barrel plating gold electrodes onto an injection-molding plastic base followed by immobilizing with a bio-reagent layer and membrane was very impressive with a long-term stability up to 2.5 years at 25 degrees C. Overall, these results indicated that the glucose oxidase/barrel plating gold biosensing platform is ideal for long-term accurate glycemic control.

  1. Blood Glucose Levels and Problem Behavior

    ERIC Educational Resources Information Center

    Valdovinos, Maria G.; Weyand, David

    2006-01-01

    The relationship between varying blood glucose levels and problem behavior during daily scheduled activities was examined. The effects that varying blood glucose levels had on problem behavior during daily scheduled activities were examined. Prior research has shown that differing blood glucose levels can affect behavior and mood. Results of this…

  2. Glucose Transport Machinery Reconstituted in Cell Models

    PubMed Central

    Hansen, Jesper S.; Elbing, Karin; Thompson, James R.; Malmstadt, Noah

    2015-01-01

    Here we demonstrate the production of a functioning cell model by formation of giant vesicles reconstituted with the GLUT1 glucose transporter and a glucose oxidase and hydrogen peroxidase linked fluorescent reporter internally. Hence, a simplified artificial cell is formed that is able to take up glucose and process it. PMID:25562394

  3. Glucose transport machinery reconstituted in cell models.

    PubMed

    Hansen, Jesper S; Elbing, Karin; Thompson, James R; Malmstadt, Noah; Lindkvist-Petersson, Karin

    2015-02-11

    Here we demonstrate the production of a functioning cell model by formation of giant vesicles reconstituted with the GLUT1 glucose transporter and a glucose oxidase and hydrogen peroxidase linked fluorescent reporter internally. Hence, a simplified artificial cell is formed that is able to take up glucose and process it.

  4. Blood Glucose Levels and Problem Behavior

    ERIC Educational Resources Information Center

    Valdovinos, Maria G.; Weyand, David

    2006-01-01

    The relationship between varying blood glucose levels and problem behavior during daily scheduled activities was examined. The effects that varying blood glucose levels had on problem behavior during daily scheduled activities were examined. Prior research has shown that differing blood glucose levels can affect behavior and mood. Results of this…

  5. Non-invasive glucose monitor

    NASA Technical Reports Server (NTRS)

    Lambert, James L. (Inventor); Borchert, Mark S. (Inventor)

    2001-01-01

    A non-invasive method for determining blood level of an analyte of interest, such as glucose, comprises: generating an excitation laser beam (e.g., at a wavelength of 700 to 900 nanometers); focusing the excitation laser beam into the anterior chamber of an eye of the subject so that aqueous humor in the anterior chamber is illuminated; detecting (preferably confocally detecting) a Raman spectrum from the illuminated aqueous humor; and then determining the blood glucose level (or the level of another analyte of interest) for the subject from the Raman spectrum. Preferably, the detecting step is followed by the step of subtracting a confounding fluorescence spectrum from the Raman spectrum to produce a difference spectrum; and determining the blood level of the analyte of interest for the subject from that difference spectrum, preferably using linear or nonlinear multivariate analysis such as partial least squares analysis. Apparatus for carrying out the foregoing method is also disclosed.

  6. A distinct metabolic signature predicts development of fasting plasma glucose

    PubMed Central

    2012-01-01

    Background High blood glucose and diabetes are amongst the conditions causing the greatest losses in years of healthy life worldwide. Therefore, numerous studies aim to identify reliable risk markers for development of impaired glucose metabolism and type 2 diabetes. However, the molecular basis of impaired glucose metabolism is so far insufficiently understood. The development of so called 'omics' approaches in the recent years promises to identify molecular markers and to further understand the molecular basis of impaired glucose metabolism and type 2 diabetes. Although univariate statistical approaches are often applied, we demonstrate here that the application of multivariate statistical approaches is highly recommended to fully capture the complexity of data gained using high-throughput methods. Methods We took blood plasma samples from 172 subjects who participated in the prospective Metabolic Syndrome Berlin Potsdam follow-up study (MESY-BEPO Follow-up). We analysed these samples using Gas Chromatography coupled with Mass Spectrometry (GC-MS), and measured 286 metabolites. Furthermore, fasting glucose levels were measured using standard methods at baseline, and after an average of six years. We did correlation analysis and built linear regression models as well as Random Forest regression models to identify metabolites that predict the development of fasting glucose in our cohort. Results We found a metabolic pattern consisting of nine metabolites that predicted fasting glucose development with an accuracy of 0.47 in tenfold cross-validation using Random Forest regression. We also showed that adding established risk markers did not improve the model accuracy. However, external validation is eventually desirable. Although not all metabolites belonging to the final pattern are identified yet, the pattern directs attention to amino acid metabolism, energy metabolism and redox homeostasis. Conclusions We demonstrate that metabolites identified using a high

  7. A distinct metabolic signature predicts development of fasting plasma glucose.

    PubMed

    Hische, Manuela; Larhlimi, Abdelhalim; Schwarz, Franziska; Fischer-Rosinský, Antje; Bobbert, Thomas; Assmann, Anke; Catchpole, Gareth S; Pfeiffer, Andreas Fh; Willmitzer, Lothar; Selbig, Joachim; Spranger, Joachim

    2012-02-02

    High blood glucose and diabetes are amongst the conditions causing the greatest losses in years of healthy life worldwide. Therefore, numerous studies aim to identify reliable risk markers for development of impaired glucose metabolism and type 2 diabetes. However, the molecular basis of impaired glucose metabolism is so far insufficiently understood. The development of so called 'omics' approaches in the recent years promises to identify molecular markers and to further understand the molecular basis of impaired glucose metabolism and type 2 diabetes. Although univariate statistical approaches are often applied, we demonstrate here that the application of multivariate statistical approaches is highly recommended to fully capture the complexity of data gained using high-throughput methods. We took blood plasma samples from 172 subjects who participated in the prospective Metabolic Syndrome Berlin Potsdam follow-up study (MESY-BEPO Follow-up). We analysed these samples using Gas Chromatography coupled with Mass Spectrometry (GC-MS), and measured 286 metabolites. Furthermore, fasting glucose levels were measured using standard methods at baseline, and after an average of six years. We did correlation analysis and built linear regression models as well as Random Forest regression models to identify metabolites that predict the development of fasting glucose in our cohort. We found a metabolic pattern consisting of nine metabolites that predicted fasting glucose development with an accuracy of 0.47 in tenfold cross-validation using Random Forest regression. We also showed that adding established risk markers did not improve the model accuracy. However, external validation is eventually desirable. Although not all metabolites belonging to the final pattern are identified yet, the pattern directs attention to amino acid metabolism, energy metabolism and redox homeostasis. We demonstrate that metabolites identified using a high-throughput method (GC-MS) perform well in

  8. Dexamethasone increases glucose cycling, but not glucose production, in healthy subjects

    SciTech Connect

    Wajngot, A.; Khan, A.; Giacca, A.; Vranic, M.; Efendic, S. )

    1990-11-01

    We established that measurement of glucose fluxes through glucose-6-phosphatase (G-6-Pase; hepatic total glucose output, HTGO), glucose cycling (GC), and glucose production (HGP), reveals early diabetogenic changes in liver metabolism. To elucidate the mechanism of the diabetogenic effect of glucocorticoids, we treated eight healthy subjects with oral dexamethasone (DEX; 15 mg over 48 h) and measured HTGO with (2-3H)glucose and HGP with (6-3H)glucose postabsorptively and during a 2-h glucose infusion (11.1 mumol.kg-1.min-1). (2-3H)- minus (6-3H)glucose equals GC. DEX significantly increased plasma glucose, insulin, C peptide, and HTGO, while HGP was unchanged. In controls and DEX, glucose infusion suppressed HTGO (82 vs. 78%) and HGP (87 vs. 91%). DEX increased GC postabsorptively (three-fold) P less than 0.005 and during glucose infusion (P less than 0.05) but decreased metabolic clearance and glucose uptake (Rd), which eventually normalized, however. Because DEX increased HTGO (G-6-Pase) and not HGP (glycogenolysis + gluconeogenesis), we assume that DEX increases HTGO and GC in humans by activating G-6-Pase directly, rather than by expanding the glucose 6-phosphate pool. Hyperglycemia caused by peripheral effects of DEX can also contribute to an increase in GC by activating glucokinase. Therefore, measurement of glucose fluxes through G-6-Pase and GC revealed significant early effects of DEX on hepatic glucose metabolism, which are not yet reflected in HGP.

  9. Modeling of relationship between glucose concentration in blood and glucose concentration in interstitial fluid

    NASA Astrophysics Data System (ADS)

    Shi, Ting; Li, Dachao; Ji, Yongjie; Li, Guoqing; Xu, Kexin

    2012-03-01

    In recent years, using the detection of interstitial fluid glucose concentration to realize the real-time continuous monitoring of blood glucose concentration gets more and more attention, because for one person, the relationship between blood glucose concentration and interstitial fluid glucose concentration satisfies specific rules. However, the glucose concentration in interstitial fluid is not entirely equal to the glucose concentration in blood and has a physiological lag because of the physiological difference of cells in blood and interstitial fluid. Because the clinical diagnostic criteria of diabetes are still blood glucose concentration, the evaluation model of the physiological lag parameter between the glucose concentration in blood and the glucose concentration in interstitial fluid should be established. The physiological difference in glucose molecules uptake, utilization, and elimination by cells in blood and interstitial fluid and the diffusion velocity of glucose molecule from blood to interstitial fluid will be induced to the mass transfer model to express the physiological lag parameter. Based on the continuous monitoring of glucose concentration in interstitial fluid, the project had studied the mass transfer model to establish the evaluation model of the physiological lag parameter between the glucose concentration in blood and the glucose concentration in interstitial fluid. We have preliminary achieved to evaluate the physiological lag parameter exactly and predict the glucose concentration in blood through the glucose concentration in interstitial fluid accurately.

  10. Reimbursement for Continuous Glucose Monitoring

    PubMed Central

    DeVries, J. Hans

    2016-01-01

    Abstract Continuous glucose monitoring (CGM) systems have been available for more than 15 years by now. However, market uptake is relatively low in most countries; in other words, relatively few patients with diabetes use CGM systems regularly. One major reason for the reluctance of patients to use CGM systems is the costs associated (i.e., in most countries no reimbursement is provided by the health insurance companies). In case reimbursement is in place, like in the United States, only certain patient groups get reimbursement that fulfills strict indications. This situation is somewhat surprising in view of the mounting evidence for benefits of CGM usage from clinical trials: most meta-analyses of these trials consistently show a clinically relevant improvement of glucose control associated with a reduction in hypoglycemic events. More recent trials with CGM systems with an improved CGM technology showed even more impressive benefits, especially if CGM systems are used in different combinations with an insulin pump (e.g., with automated bolus calculators and low glucose suspend features). Nevertheless, sufficient evidence is not available for all patient groups, and more data on cost–efficacy are needed. In addition, good data from real-world studies/registers documenting the benefits of CGM usage under daily life conditions would be of help to convince healthcare systems to cover the costs of CGM systems. In view of the ongoing improvements in established needle-type CGM systems, the fact that new CGM technology will come to the market soon (e.g., implantable sensors), that CGM-like systems are quite successfully at least in certain markets (like the flash glucose monitoring systems), and that the first artificial pancreas systems will come to the market in the next few years, there is a need to make sure that this major improvement in diabetes therapy becomes more widely available for patients with diabetes, for which better reimbursement is essential. PMID

  11. Oxidative metabolism: glucose versus ketones.

    PubMed

    Prince, Allison; Zhang, Yifan; Croniger, Colleen; Puchowicz, Michelle

    2013-01-01

    The coupling of upstream oxidative processes (glycolysis, beta-oxidation, CAC turnover) to mitochondrial oxidative phosphorylation (OXPHOS) under the driving conditions of energy demand by the cell results in the liberation of free energy as ATP. Perturbations in glycolytic CAC or OXPHOS can result in pathology or cell death. To better understand whole body energy expenditure during chronic ketosis, we used a diet-induced rat model of ketosis to determine if high-fat-carbohydrate-restricted "ketogenic" diet results in changes in total energy expenditure (TEE). Consistent with previous reports of increased energy expenditure in mice, we hypothesized that rats fed ketogenic diet for 3 weeks would result in increased resting energy expenditure due to alterations in metabolism associated with a "switch" in energy substrate from glucose to ketone bodies. The rationale is ketone bodies are a more efficient fuel than glucose. Indirect calorimetric analysis revealed a moderate increase in VO2 and decreased VCO2 and heat with ketosis. These results suggest ketosis induces a moderate uncoupling state and less oxidative efficiency compared to glucose oxidation.

  12. Non-Invasive Glucose Measurement

    NASA Astrophysics Data System (ADS)

    Blakley, Daniel

    2010-10-01

    There are two little words, when taken together have great implications: ``What IF'' In the US alone, there are millions who are burdened with diabetes and who must maintain their glucose levels by taking blood samples and having it analyzed. Even though this procedure has improved over time, still it is very intrusive and is a burden to many that must live with it. What if it were not necessary? Although it is current practice to measure glucose levels invasively (using blood samples), it may be possible to measure glucose non-invasively. Although several companies around the world have invested millions of dollars to address this problem, none have been successful thus far. However, there are many methods that hold a potential and many approaches that have not yet been explored. We are working on a review of what has been approached thus far and are entertaining proposals for a combined interdisciplinary approach which combines expertise from bioengineering, physics, and biology. We hope to learn from the unsuccessful attempts of others whilst employing innovative new approaches to this problem.

  13. 40 CFR 80.205 - How is the annual refinery or importer average and corporate pool average sulfur level determined?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... average and corporate pool average sulfur level determined? 80.205 Section 80.205 Protection of... ADDITIVES Gasoline Sulfur Gasoline Sulfur Standards § 80.205 How is the annual refinery or importer average and corporate pool average sulfur level determined? (a) The annual refinery or importer average...

  14. 40 CFR 80.205 - How is the annual refinery or importer average and corporate pool average sulfur level determined?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... average and corporate pool average sulfur level determined? 80.205 Section 80.205 Protection of... ADDITIVES Gasoline Sulfur Gasoline Sulfur Standards § 80.205 How is the annual refinery or importer average and corporate pool average sulfur level determined? (a) The annual refinery or importer average...

  15. 40 CFR 80.205 - How is the annual refinery or importer average and corporate pool average sulfur level determined?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... average and corporate pool average sulfur level determined? 80.205 Section 80.205 Protection of... ADDITIVES Gasoline Sulfur Gasoline Sulfur Standards § 80.205 How is the annual refinery or importer average and corporate pool average sulfur level determined? (a) The annual refinery or importer average...

  16. 40 CFR 80.205 - How is the annual refinery or importer average and corporate pool average sulfur level determined?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... average and corporate pool average sulfur level determined? 80.205 Section 80.205 Protection of... ADDITIVES Gasoline Sulfur Gasoline Sulfur Standards § 80.205 How is the annual refinery or importer average and corporate pool average sulfur level determined? (a) The annual refinery or importer average...

  17. Instantaneous, phase-averaged, and time-averaged pressure from particle image velocimetry

    NASA Astrophysics Data System (ADS)

    de Kat, Roeland

    2015-11-01

    Recent work on pressure determination using velocity data from particle image velocimetry (PIV) resulted in approaches that allow for instantaneous and volumetric pressure determination. However, applying these approaches is not always feasible (e.g. due to resolution, access, or other constraints) or desired. In those cases pressure determination approaches using phase-averaged or time-averaged velocity provide an alternative. To assess the performance of these different pressure determination approaches against one another, they are applied to a single data set and their results are compared with each other and with surface pressure measurements. For this assessment, the data set of a flow around a square cylinder (de Kat & van Oudheusden, 2012, Exp. Fluids 52:1089-1106) is used. RdK is supported by a Leverhulme Trust Early Career Fellowship.

  18. Determining average path length and average trapping time on generalized dual dendrimer

    NASA Astrophysics Data System (ADS)

    Li, Ling; Guan, Jihong

    2015-03-01

    Dendrimer has wide number of important applications in various fields. In some cases during transport or diffusion process, it transforms into its dual structure named Husimi cactus. In this paper, we study the structure properties and trapping problem on a family of generalized dual dendrimer with arbitrary coordination numbers. We first calculate exactly the average path length (APL) of the networks. The APL increases logarithmically with the network size, indicating that the networks exhibit a small-world effect. Then we determine the average trapping time (ATT) of the trapping process in two cases, i.e., the trap placed on a central node and the trap is uniformly distributed in all the nodes of the network. In both case, we obtain explicit solutions of ATT and show how they vary with the networks size. Besides, we also discuss the influence of the coordination number on trapping efficiency.

  19. Lagrangian averages, averaged Lagrangians, and the mean effects of fluctuations in fluid dynamics.

    PubMed

    Holm, Darryl D.

    2002-06-01

    We begin by placing the generalized Lagrangian mean (GLM) equations for a compressible adiabatic fluid into the Euler-Poincare (EP) variational framework of fluid dynamics, for an averaged Lagrangian. This is the Lagrangian averaged Euler-Poincare (LAEP) theorem. Next, we derive a set of approximate small amplitude GLM equations (glm equations) at second order in the fluctuating displacement of a Lagrangian trajectory from its mean position. These equations express the linear and nonlinear back-reaction effects on the Eulerian mean fluid quantities by the fluctuating displacements of the Lagrangian trajectories in terms of their Eulerian second moments. The derivation of the glm equations uses the linearized relations between Eulerian and Lagrangian fluctuations, in the tradition of Lagrangian stability analysis for fluids. The glm derivation also uses the method of averaged Lagrangians, in the tradition of wave, mean flow interaction. Next, the new glm EP motion equations for incompressible ideal fluids are compared with the Euler-alpha turbulence closure equations. An alpha model is a GLM (or glm) fluid theory with a Taylor hypothesis closure. Such closures are based on the linearized fluctuation relations that determine the dynamics of the Lagrangian statistical quantities in the Euler-alpha equations. Thus, by using the LAEP theorem, we bridge between the GLM equations and the Euler-alpha closure equations, through the small-amplitude glm approximation in the EP variational framework. We conclude by highlighting a new application of the GLM, glm, and alpha-model results for Lagrangian averaged ideal magnetohydrodynamics. (c) 2002 American Institute of Physics.

  20. Challenges of inpatient blood glucose monitoring: standards, methods, and devices to measure blood glucose.

    PubMed

    Hermayer, Kathie L; Loftley, Aundrea S; Reddy, Sumana; Narla, Satya Nandana; Epps, Nina A; Zhu, Yusheng

    2015-03-01

    Glucose control in the hospital setting is very important. There is a high incidence of hyperglycemia, hypoglycemia, and glycemic variability in hospitalized patients. Safe insulin delivery and glucose control is dependent on reliable glucose meters and monitoring systems in the hospital. Different glucose monitoring systems use arterial, venous, central venous, and capillary blood samples. It is important for clinicians to be aware that there are limitations of specific point-of-care (POC) glucose meters and that situations exist whereby POC glucose meters as the sole measurement device should be avoided. POC meter devices are not approved by the Food and Drug Administration for use in critical care, although POC meter devices are commonly used in critical care settings and elsewhere. This review focuses on glucose assay principles, instrument technology, influences on glucose measurement, standards for glucose measurement, and an evaluation of different methods to measure blood glucose in the hospital setting.

  1. Sustained nonoxidative glucose utilization and depletion of glycogen in reperfused canine myocardium

    SciTech Connect

    Schwaiger, M.; Neese, R.A.; Araujo, L.; Wyns, W.; Wisneski, J.A.; Sochor, H.; Swank, S.; Kulber, D.; Selin, C.; Phelps, M.

    1989-03-01

    Ischemically injured reperfused myocardium is characterized by increased 18F-fluorodeoxyglucose uptake as demonstrated by positron emission tomography. To elucidate the metabolic fate of exogenous glucose entering reperfused myocardium, D-(6-14C) glucose and L-(U-13C) lactate were used to determine glucose uptake, glucose oxidation and the contribution of exogenous glucose to lactate production. The pathologic model under investigation consisted of a 3 h balloon occlusion of the left anterior descending coronary artery followed by 24 h of reperfusion in canine myocardium. The extent and severity of myocardial injury after the ischemia and reperfusion were assessed by histochemical evaluation (triphenyltetrazolium chloride and periodic acid-Schiff stains). Thirteen intervention and four control dogs were studied. The glucose uptake in the occluded/reperfused area was significantly enhanced compared with that in control dogs (0.40 +/- 0.14 versus 0.15 +/- 0.10 mumol/ml, respectively). In addition, a significantly greater portion of the glucose extracted immediately entered glycolysis in the intervention group (75%) than in the control dogs (33%). The activity of the nonoxidative glycolytic pathway was markedly increased in the ischemically injured reperfused area, as evidenced by the four times greater lactate release in this area compared with the control value. The dual carbon-labeled isotopes showed that 57% of the exogenous glucose entering glycolysis was being converted to lactate. Exogenous glucose contributed to greater than 90% of the observed lactate production. This finding was confirmed by the histochemical finding of sustained glycogen depletion in the occlusion/reperfusion area. The average area of glycogen depletion (37%) significantly exceeded the average area of necrosis (17%).

  2. Experimental evidence and isotopomer analysis of mixotrophic glucose metabolism in the marine diatom Phaeodactylum tricornutum.

    PubMed

    Zheng, Yuting; Quinn, Andrew H; Sriram, Ganesh

    2013-11-14

    Heterotrophic fermentation using simple sugars such as glucose is an established and cost-effective method for synthesizing bioproducts from bacteria, yeast and algae. Organisms incapable of metabolizing glucose have limited applications as cell factories, often despite many other advantageous characteristics. Therefore, there is a clear need to investigate glucose metabolism in potential cell factories. One such organism, with a unique metabolic network and a propensity to synthesize highly reduced compounds as a large fraction of its biomass, is the marine diatom Phaeodactylum tricornutum (Pt). Although Pt has been engineered to metabolize glucose, conflicting lines of evidence leave it unresolved whether Pt can natively consume glucose. Isotope labeling experiments in which Pt was mixotrophically grown under light on 100% U-(13)C glucose and naturally abundant (~99% (12)C) dissolved inorganic carbon resulted in proteinogenic amino acids with an average 13C-enrichment of 88%, thus providing convincing evidence of glucose uptake and metabolism. The dissolved inorganic carbon was largely incorporated through anaplerotic rather than photosynthetic fixation. Furthermore, an isotope labeling experiment utilizing 1-(13)C glucose and subsequent metabolic pathway analysis indicated that (i) the alternative Entner-Doudoroff and Phosphoketolase glycolytic pathways are active during glucose metabolism, and (ii) during mixotrophic growth, serine and glycine are largely synthesized from glyoxylate through photorespiratory reactions rather than from 3-phosphoglycerate. We validated the latter result for mixotrophic growth on glycerol by performing a 2-(13)C glycerol isotope labeling experiment. Additionally, gene expression assays showed that known, native glucose transporters in Pt are largely insensitive to glucose or light, whereas the gene encoding cytosolic fructose bisphosphate aldolase 3, an important glycolytic enzyme, is overexpressed in light but insensitive to

  3. Experimental evidence and isotopomer analysis of mixotrophic glucose metabolism in the marine diatom Phaeodactylum tricornutum

    PubMed Central

    2013-01-01

    Background Heterotrophic fermentation using simple sugars such as glucose is an established and cost-effective method for synthesizing bioproducts from bacteria, yeast and algae. Organisms incapable of metabolizing glucose have limited applications as cell factories, often despite many other advantageous characteristics. Therefore, there is a clear need to investigate glucose metabolism in potential cell factories. One such organism, with a unique metabolic network and a propensity to synthesize highly reduced compounds as a large fraction of its biomass, is the marine diatom Phaeodactylum tricornutum (Pt). Although Pt has been engineered to metabolize glucose, conflicting lines of evidence leave it unresolved whether Pt can natively consume glucose. Results Isotope labeling experiments in which Pt was mixotrophically grown under light on 100% U-13C glucose and naturally abundant (~99% 12C) dissolved inorganic carbon resulted in proteinogenic amino acids with an average 13C-enrichment of 88%, thus providing convincing evidence of glucose uptake and metabolism. The dissolved inorganic carbon was largely incorporated through anaplerotic rather than photosynthetic fixation. Furthermore, an isotope labeling experiment utilizing 1-13C glucose and subsequent metabolic pathway analysis indicated that (i) the alternative Entner-Doudoroff and Phosphoketolase glycolytic pathways are active during glucose metabolism, and (ii) during mixotrophic growth, serine and glycine are largely synthesized from glyoxylate through photorespiratory reactions rather than from 3-phosphoglycerate. We validated the latter result for mixotrophic growth on glycerol by performing a 2-13C glycerol isotope labeling experiment. Additionally, gene expression assays showed that known, native glucose transporters in Pt are largely insensitive to glucose or light, whereas the gene encoding cytosolic fructose bisphosphate aldolase 3, an important glycolytic enzyme, is overexpressed in light but

  4. Diet Treatment Glucose Transporter Type 1 Deficiency (G1D)

    ClinicalTrials.gov

    2017-06-06

    GLUT1DS1; Epilepsy; Glut1 Deficiency Syndrome 1, Autosomal Recessive; Glucose Metabolism Disorders; Glucose Transport Defect; Glucose Transporter Type 1 Deficiency Syndrome; Glucose Transporter Protein Type 1 Deficiency Syndrome

  5. The glucose signaling network in yeast.

    PubMed

    Kim, Jeong-Ho; Roy, Adhiraj; Jouandot, David; Cho, Kyu Hong

    2013-11-01

    Most cells possess a sophisticated mechanism for sensing glucose and responding to it appropriately. Glucose sensing and signaling in the budding yeast Saccharomyces cerevisiae represent an important paradigm for understanding how extracellular signals lead to changes in the gene expression program in eukaryotes. This review focuses on the yeast glucose sensing and signaling pathways that operate in a highly regulated and cooperative manner to bring about glucose-induction of HXT gene expression. The yeast cells possess a family of glucose transporters (HXTs), with different kinetic properties. They employ three major glucose signaling pathways-Rgt2/Snf3, AMPK, and cAMP-PKA-to express only those transporters best suited for the amounts of glucose available. We discuss the current understanding of how these pathways are integrated into a regulatory network to ensure efficient uptake and utilization of glucose. Elucidating the role of multiple glucose signals and pathways involved in glucose uptake and metabolism in yeast may reveal the molecular basis of glucose homeostasis in humans, especially under pathological conditions, such as hyperglycemia in diabetics and the elevated rate of glycolysis observed in many solid tumors. © 2013.

  6. Electrochemical non-enzymatic glucose sensors.

    PubMed

    Park, Sejin; Boo, Hankil; Chung, Taek Dong

    2006-01-18

    The electrochemical determination of glucose concentration without using enzyme is one of the dreams that many researchers have been trying to make come true. As new materials have been reported and more knowledge on detailed mechanism of glucose oxidation has been unveiled, the non-enzymatic glucose sensor keeps coming closer to practical applications. Recent reports strongly imply that this progress will be accelerated in 'nanoera'. This article reviews the history of unraveling the mechanism of direct electrochemical oxidation of glucose and making attempts to develop successful electrochemical glucose sensors. The electrochemical oxidation of glucose molecules involves complex processes of adsorption, electron transfer, and subsequent chemical rearrangement, which are combined with the surface reactions on the metal surfaces. The information about the direct oxidation of glucose on solid-state surfaces as well as new electrode materials will lead us to possible breakthroughs in designing the enzymeless glucose sensing devices that realize innovative and powerful detection. An example of those is to introduce nanoporous platinum as an electrode, on which glucose is oxidized electrochemically with remarkable sensitivity and selectivity. Better model of such glucose sensors is sought by summarizing and revisiting the previous reports on the electrochemistry of glucose itself and new electrode materials.

  7. The glucose signaling network in yeast

    PubMed Central

    Kim, Jeong-Ho; Roy, Adhiraj; Jouandot, David; Cho, Kyu Hong

    2013-01-01

    Background Most cells possess a sophisticated mechanism for sensing glucose and responsing to it appropriately. Glucose sensing and signaling in the budding yeast Saccharomyces cerevisiae represents an important paradigm for understanding how extracellular signals lead to changes in the gene expression program in eukaryotes. Scope of review This review focuses on the yeast glucose sensing and signaling pathways that operate in a highly regulated and cooperative manner to bring about glucose-induction of HXT gene expression. Major conclusions The yeast cells possess a family of glucose transporters (HXTs), with different kinetic properties. They employ three major glucose signaling pathways— Rgt2/Snf3, AMPK, and cAMP-PKA—to express only those transporters best suited for the amounts of glucose available. We discuss the current understanding of how these pathways are integrated into a regulatory network to ensure efficient uptake and utilization of glucose. General significance Elucidating the role of multiple glucose signals and pathways involved in glucose uptake and metabolism in yeast may reveal the molecular basis of glucose homeostasis in humans, especially under pathological conditions, such as hyperglycemia in diabetics and the elevated rate of glycolysis observed in many solid tumors. PMID:23911748

  8. Markers of glycemic control in the mouse: comparisons of 6-h- and overnight-fasted blood glucoses to Hb A1c.

    PubMed

    Han, Byoung Geun; Hao, Chuan-Ming; Tchekneva, Elena E; Wang, Ying-Ying; Lee, Chieh Allen; Ebrahim, Benyamin; Harris, Raymond C; Kern, Timothy S; Wasserman, David H; Breyer, Matthew D; Qi, Zhonghua

    2008-10-01

    The present studies examined the relationship between fasting blood glucose and Hb A(1c) in C57BL/6J, DBA/2J, and KK/HlJ mice with and without diabetes mellitus. Daily averaged blood glucose levels based on continuous glucose monitoring and effects of 6-h vs. overnight fasting on blood glucose were determined. Daily averaged blood glucose levels were highly correlated with Hb A(1c), as determined with a hand-held automated device using an immunodetection method. R(2) values were 0.90, 0.95, and 0.99 in KK/HIJ, C57BL/6J, and DBA/2J, respectively. Six-hour fasting blood glucose correlated more closely with the level of daily averaged blood glucose and with Hb A(1c) than did blood glucose following an overnight fast. To validate the immunoassay-determined Hb A(1c), we also measured total glycosylated hemoglobin using boronate HPLC. Hb A(1c) values correlated well with total glycosylated hemoglobin in all three strains but were relatively lower than total glycosylated hemoglobin in diabetic DBA/2J mice. These results show that 6-h fasting glucose provides a superior index of glycemic control and correlates more closely with Hb A(1c) than overnight-fasted blood glucose in these strains of mice.

  9. Prochlorococcus can use the Pro1404 transporter to take up glucose at nanomolar concentrations in the Atlantic Ocean

    PubMed Central

    Muñoz-Marín, María del Carmen; Luque, Ignacio; Zubkov, Mikhail V.; Hill, Polly G.; Diez, Jesús; García-Fernández, José Manuel

    2013-01-01

    Prochlorococcus is responsible for a significant part of CO2 fixation in the ocean. Although it was long considered an autotrophic cyanobacterium, the uptake of organic compounds has been reported, assuming they were sources of limited biogenic elements. We have shown in laboratory experiments that Prochlorococcus can take up glucose. However, the mechanisms of glucose uptake and its occurrence in the ocean have not been shown. Here, we report that the gene Pro1404 confers capability for glucose uptake in Prochlorococcus marinus SS120. We used a cyanobacterium unable to take up glucose to engineer strains that express the Pro1404 gene. These recombinant strains were capable of specific glucose uptake over a wide range of glucose concentrations, showing multiphasic transport kinetics. The Ks constant of the high affinity phase was in the nanomolar range, consistent with the average concentration of glucose in the ocean. Furthermore, we were able to observe glucose uptake by Prochlorococcus in the central Atlantic Ocean, where glucose concentrations were 0.5–2.7 nM. Our results suggest that Prochlorococcus are primary producers capable of tuning their metabolism to energetically benefit from environmental conditions, taking up not only organic compounds with key limiting elements in the ocean, but also molecules devoid of such elements, like glucose. PMID:23569224

  10. Prochlorococcus can use the Pro1404 transporter to take up glucose at nanomolar concentrations in the Atlantic Ocean.

    PubMed

    Muñoz-Marín, María del Carmen; Luque, Ignacio; Zubkov, Mikhail V; Hill, Polly G; Diez, Jesús; García-Fernández, José Manuel

    2013-05-21

    Prochlorococcus is responsible for a significant part of CO2 fixation in the ocean. Although it was long considered an autotrophic cyanobacterium, the uptake of organic compounds has been reported, assuming they were sources of limited biogenic elements. We have shown in laboratory experiments that Prochlorococcus can take up glucose. However, the mechanisms of glucose uptake and its occurrence in the ocean have not been shown. Here, we report that the gene Pro1404 confers capability for glucose uptake in Prochlorococcus marinus SS120. We used a cyanobacterium unable to take up glucose to engineer strains that express the Pro1404 gene. These recombinant strains were capable of specific glucose uptake over a wide range of glucose concentrations, showing multiphasic transport kinetics. The Ks constant of the high affinity phase was in the nanomolar range, consistent with the average concentration of glucose in the ocean. Furthermore, we were able to observe glucose uptake by Prochlorococcus in the central Atlantic Ocean, where glucose concentrations were 0.5-2.7 nM. Our results suggest that Prochlorococcus are primary producers capable of tuning their metabolism to energetically benefit from environmental conditions, taking up not only organic compounds with key limiting elements in the ocean, but also molecules devoid of such elements, like glucose.

  11. Correspondence of continuous interstitial glucose measurement against arterialised and capillary glucose following an oral glucose tolerance test in healthy volunteers.

    PubMed

    Dye, Louise; Mansfield, Michael; Lasikiewicz, Nicola; Mahawish, Lena; Schnell, Rainer; Talbot, Duncan; Chauhan, Hitesh; Croden, Fiona; Lawton, Clare

    2010-01-01

    The aim of the present study was to validate the Glucoday continuous interstitial ambulatory glucose-monitoring device (AGD) against plasma glucose measured from arterialised venous (AV) and glucose from capillary whole blood (finger prick, FP) in non-diabetic subjects in response to an oral glucose tolerance test. Fifteen healthy overweight men (age 30-49 years, BMI 26-31 kg/m2) participated. Glucose levels were measured before, during and after consumption of an oral 75 g glucose load using twelve FP samples and forty-four 1 ml AV blood samples during 180 min. Interstitial glucose was measured via the AGD. Three venous samples for fasting insulin were taken to estimate insulin resistance. Profiles of AGD, AV and FP glucose were generated for each participant. Glucose values for each minute of the measurement period were interpolated using a locally weighted scatterplot smoother. Data were compared using Bland-Altman plots that showed good correspondence between all pairs of measurements. Concordance between the three methods was 0.8771 (Kendall's W, n 15, P < 0.001). Concordance was greater between AV and FP (W = 0.9696) than AGD and AV (W = 0.8770) or AGD and FP (W = 0.8764). Analysis of time to peak glucose indicated that AGD measures lagged approximately 15 min behind FP and AV measures. Percent body fat was significantly correlated with time to peak glucose levels for each measure, while BMI and estimated insulin resistance (homeostatic model assessment, HOMA) were not. In conclusion, AGD shows good correspondence with FP and AV glucose measures in response to a glucose load with a 15 min time lag. Taking this into account, AGD has potential application in nutrition and behaviour studies.

  12. A comparative effectiveness analysis of three continuous glucose monitors.

    PubMed

    Damiano, Edward R; El-Khatib, Firas H; Zheng, Hui; Nathan, David M; Russell, Steven J

    2013-02-01

    To compare three continuous glucose monitoring (CGM) devices in subjects with type 1 diabetes under closed-loop blood glucose (BG) control. Six subjects with type 1 diabetes (age 52 ± 14 years, diabetes duration 32 ± 14 years) each participated in two 51-h closed-loop BG control experiments in the hospital. Venous plasma glucose (PG) measurements (GlucoScout, International Biomedical) obtained every 15 min (2,360 values) were paired in time with corresponding CGM glucose (CGMG) measurements obtained from three CGM devices, the Navigator (Abbott Diabetes Care), the Seven Plus (DexCom), and the Guardian (Medtronic), worn simultaneously by each subject. Errors in paired PG-CGMG measurements and data reporting percentages were obtained for each CGM device. The Navigator had the best overall accuracy, with an aggregate mean absolute relative difference (MARD) of all paired points of 11.8 ± 11.1% and an average MARD across all 12 experiments of 11.8 ± 3.8%. The Seven Plus and Guardian produced aggregate MARDs of all paired points of 16.5 ± 17.8% and 20.3 ± 18.0%, respectively, and average MARDs across all 12 experiments of 16.5 ± 6.7% and 20.2 ± 6.8%, respectively. Data reporting percentages, a measure of reliability, were 76% for the Seven Plus and nearly 100% for the Navigator and Guardian. A comprehensive head-to-head-to-head comparison of three CGM devices for BG values from 36 to 563 mg/dL revealed marked differences in performance characteristics that include accuracy, precision, and reliability. The Navigator outperformed the other two in these areas.

  13. Personalized glucose forecasting for type 2 diabetes using data assimilation

    PubMed Central

    Albers, David J.; Gluckman, Bruce; Ginsberg, Henry; Hripcsak, George; Mamykina, Lena

    2017-01-01

    Type 2 diabetes leads to premature death and reduced quality of life for 8% of Americans. Nutrition management is critical to maintaining glycemic control, yet it is difficult to achieve due to the high individual differences in glycemic response to nutrition. Anticipating glycemic impact of different meals can be challenging not only for individuals with diabetes, but also for expert diabetes educators. Personalized computational models that can accurately forecast an impact of a given meal on an individual’s blood glucose levels can serve as the engine for a new generation of decision support tools for individuals with diabetes. However, to be useful in practice, these computational engines need to generate accurate forecasts based on limited datasets consistent with typical self-monitoring practices of individuals with type 2 diabetes. This paper uses three forecasting machines: (i) data assimilation, a technique borrowed from atmospheric physics and engineering that uses Bayesian modeling to infuse data with human knowledge represented in a mechanistic model, to generate real-time, personalized, adaptable glucose forecasts; (ii) model averaging of data assimilation output; and (iii) dynamical Gaussian process model regression. The proposed data assimilation machine, the primary focus of the paper, uses a modified dual unscented Kalman filter to estimate states and parameters, personalizing the mechanistic models. Model selection is used to make a personalized model selection for the individual and their measurement characteristics. The data assimilation forecasts are empirically evaluated against actual postprandial glucose measurements captured by individuals with type 2 diabetes, and against predictions generated by experienced diabetes educators after reviewing a set of historical nutritional records and glucose measurements for the same individual. The evaluation suggests that the data assimilation forecasts compare well with specific glucose measurements

  14. Fluorescent nano-PEBBLE sensors designed for intracellular glucose imaging.

    PubMed

    Xu, Hao; Aylott, Jonathan W; Kopelman, Raoul

    2002-11-01

    Polyacrylamide-based, ratiometric, spherical, optical nanosensors, or polyacrylamide PEBBLEs (Probes Encapsulated By Biologically Localized Embedding), have been fabricated, aimed at real-time glucose imaging in intact biological systems, i.e. living cells. These nanosensors are prepared using a microemulsion polymerization process, and their average size is about 45 nm in diameter. The sensors incorporate glucose oxidase (GOx), an oxygen sensitive fluorescent indicator (Ru[dpp(SO3Na)2]3)Cl2, and an oxygen insensitive fluorescent dye, Oregon Green 488-dextran or Texas Red-dextran, as a reference for the purpose of ratiometric intensity measurements. The enzymatic oxidation of glucose to gluconic acid results in the local depletion of oxygen, which is measured by the oxygen sensitive ruthenium dye. The small size and inert matrix of these sensors allows them to be inserted into living cells with minimal physical and chemical perturbations to their biological functions. The PEBBLE matrix protects the enzyme and fluorescent dyes from interference by proteins in cells, enabling reliable in vivo chemical analysis. Conversely, the matrix also significantly reduces the toxicity of the indicator and reference dyes to the cells, so that a larger variety of dyes can be used in optimal fashion. Furthermore, the PEBBLE matrix enables the synergistic approach in which there is a steady state of local oxygen consumption, and this cannot be achieved by separately introducing free enzyme and dyes into a cell. The work presented here describes the production and characterization of glucose sensitive PEBBLEs, and their potential for intracellular glucose measurements. The sensor response is determined in terms of the linear range, ratiometric operation, response time, sensor stability, reversibility and immunity to interferences.

  15. Reconstitution of the glucose transport activity of rat adipocytes.

    PubMed

    Malchoff, D M; Parker, V G; Langdon, R G

    1985-07-25

    Rat epididymal fat cell membrane proteins were extracted from adipocyte ghosts with octylglucoside and incorporated by detergent dialysis into unilamellar phosphatidylcholine vesicles approx. 200 nm in diameter. The rate of glucose transport into the vesicles under zero-trans conditions was substrate dependent, saturable and inhibited by phloretin and cytochalasin B. Their maximum specific transport activity was 35.6 mumol/min per mg protein, and their half saturation constant for glucose was 15 mM. Glucose transport into the reconstituted vesicles was inhibited by only those sugars which competitively inhibited glucose transport into intact adipocytes. A major protein component of the vesicles was a 100 kDa protein which we had previously found to react with the affinity label maltosyl isothiocyanate (Malchoff, D.M., Olansky, L., Pohl, S. and Langdon, R.G. (1981) Fed. Proc. 40, 1893). Removal of adipocyte ghost membrane extrinsic proteins with dimethylmaleic anhydride followed by extraction of the resulting membrane pellet with octylglucoside yielded a solution which contained two major proteins, of Mr 100 000 and 85 000, with very small quantities of lower Mr proteins. Vesicles into which these proteins were incorporated had average specific transport activities of 624 mumol/min per mg protein and half saturation constants of 22 mM. Our results strongly indicate that the native glucose transporter of the rat adipocyte, like that of the human erythrocyte (Shelton, R.L. and Langdon, R.G. (1983) Biochim. Biophys. Acta 733, 25-33), is a 100 kDa protein.

  16. Statistical transformation and the interpretation of inpatient glucose control data.

    PubMed

    Saulnier, George E; Castro, Janna C; Cook, Curtiss B

    2014-03-01

    To introduce a statistical method of assessing hospital-based non-intensive care unit (non-ICU) inpatient glucose control. Point-of-care blood glucose (POC-BG) data from hospital non-ICUs were extracted for January 1 through December 31, 2011. Glucose data distribution was examined before and after Box-Cox transformations and compared to normality. Different subsets of data were used to establish upper and lower control limits, and exponentially weighted moving average (EWMA) control charts were constructed from June, July, and October data as examples to determine if out-of-control events were identified differently in nontransformed versus transformed data. A total of 36,381 POC-BG values were analyzed. In all 3 monthly test samples, glucose distributions in nontransformed data were skewed but approached a normal distribution once transformed. Interpretation of out-of-control events from EWMA control chart analyses also revealed differences. In the June test data, an out-of-control process was identified at sample 53 with nontransformed data, whereas the transformed data remained in control for the duration of the observed period. Analysis of July data demonstrated an out-of-control process sooner in the transformed (sample 55) than nontransformed (sample 111) data, whereas for October, transformed data remained in control longer than nontransformed data. Statistical transformations increase the normal behavior of inpatient non-ICU glycemic data sets. The decision to transform glucose data could influence the interpretation and conclusions about the status of inpatient glycemic control. Further study is required to determine whether transformed versus nontransformed data influence clinical decisions or evaluation of interventions.

  17. 20 CFR 404.221 - Computing your average monthly wage.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 2 2013-04-01 2013-04-01 false Computing your average monthly wage. 404.221... DISABILITY INSURANCE (1950- ) Computing Primary Insurance Amounts Average-Monthly-Wage Method of Computing Primary Insurance Amounts § 404.221 Computing your average monthly wage. (a) General. Under the average...

  18. 20 CFR 226.62 - Computing average monthly compensation.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true Computing average monthly compensation. 226.62... COMPUTING EMPLOYEE, SPOUSE, AND DIVORCED SPOUSE ANNUITIES Years of Service and Average Monthly Compensation § 226.62 Computing average monthly compensation. The employee's average monthly compensation is...

  19. 20 CFR 226.62 - Computing average monthly compensation.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Computing average monthly compensation. 226... RETIREMENT ACT COMPUTING EMPLOYEE, SPOUSE, AND DIVORCED SPOUSE ANNUITIES Years of Service and Average Monthly Compensation § 226.62 Computing average monthly compensation. The employee's average monthly compensation...

  20. 40 CFR 1033.710 - Averaging emission credits.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Averaging emission credits. 1033.710... Averaging emission credits. (a) Averaging is the exchange of emission credits among your engine families. You may average emission credits only as allowed by § 1033.740. (b) You may certify one or more engine...

  1. Hepatic glucose sensing is impaired, but can be normalized, in people with impaired fasting glucose.

    PubMed

    Perreault, Leigh; Færch, Kristine; Kerege, Anna A; Bacon, Samantha D; Bergman, Bryan C

    2014-07-01

    Abnormal endogenous glucose production (EGP) is a characteristic feature in people with impaired fasting glucose (IFG). We sought to determine whether impaired hepatic glucose sensing contributes to abnormal EGP in IFG and whether it could be experimentally restored. Glucose production (rate of appearance; Ra) and flux (glucose cycling) were assessed during a hyperglycemic-euinsulinemic somatostatin clamp with an infusion of [6,6-(2)H2-]glucose and [2-(2)H]glucose before and after enhanced hepatic glucokinase activity via an infusion of low-dose fructose in people with IFG and normal glucose tolerance (NGT). During euglycemia, neither endogenous glucose production [(6,6-(2)H2)-glucose Ra; P = 0.53] or total glucose output (TGO; [2-(2)H]-glucose Ra; P = .12) was different between groups, but glucose cycling ([2-(2)H]glucose Ra to [6,6-(2)H2-]glucose Ra; a surrogate measure of hepatic glucokinase activity in the postabsorptive state) was lower in IFG than NGT (P = .04). Hyperglycemia suppressed EGP more in NGT than IFG (P < .01 for absolute or relative suppression, NGT vs IFG), whereas TGO decreased similarly in both groups (P = .77). The addition of fructose completely suppressed EGP in IFG (P < .01) and tended to do the same to TGO (P = .01; no such changes in NGT, P = .39-.55). Glucose cycling (which reflects glucose-6-phosphatase activity during glucose infusion) was similar in IFG and NGT (P = .51) during hyperglycemia and was unchanged and comparable between groups with the addition of fructose (P = .24). In summary, glucose sensing is impaired in IFG but can be experimentally restored with low-dose fructose. Glucokinase activation may prove to be a novel strategy for the prevention of diabetes in this high-risk group.

  2. Evidence of extensive plasma glucose recycling following a glucose load in seabass.

    PubMed

    Rito, João; Viegas, Ivan; Pardal, Miguel A; Jones, John G

    2017-09-01

    Seabass and other carnivorous fish are highly dependent on gluconeogenesis from dietary amino acids to maintain glycemia. Glucose recycling (glucose→C3-intermediate→glucose) may potentiate the effects of glucose administration in sparing amino acid gluconeogenesis. To date, very few measurements of glucose recycling have been reported in fish. Thus, to determine the extent of glucose recycling following a glycemic challenge, juvenile seabass were given an intraperitoneal glucose load (2gkg(-1)) enriched with [U-(13)C]glucose. (13)C NMR analysis of plasma glucose (13)C-isotopomers was used to determine the fractional contributions of glucose derived directly from the load versus that from glucose recycling at 48h after the load. Both fed and 21-day fasted fish (20 per condition) were studied. In fasted fish, 18±4% of plasma glucose was directly derived from the load while 13±2% was derived from glucose recycling. In fed fish, the load accounted for 6±1% of plasma glucose levels while glucose recycling contributed 16±4%. (13)C NMR analysis of plasma lactate revealed (13)C-isotopomers corresponding to the expected C3-intermediates of peripheral [U-(13)C]glucose catabolism indicating that circulating lactate was a key intermediate in glucose carbon recycling under these conditions. In conclusion, glucose recycling was shown to contribute a significant portion of plasma glucose levels in both fed and fasted seabass 48h after an intraperitoneal glucose challenge and circulating lactate was shown to be an intermediate of this pathway. Copyright © 2017. Published by Elsevier Inc.

  3. Changes in average length of stay and average charges generated following institution of PSRO review.

    PubMed

    Westphal, M; Frazier, E; Miller, M C

    1979-01-01

    A five-year review of accounting data at a university hospital shows that immediately following institution of concurrent PSRO admission and length of stay review of Medicare-Medicaid patients, there was a significant decrease in length of stay and a fall in average charges generated per patient against the inflationary trend. Similar changes did not occur for the non-Medicare-Medicaid patients who were not reviewed. The observed changes occurred even though the review procedure rarely resulted in the denial of services to patients, suggesting an indirect effect of review.

  4. Ultrafiltration Characteristics of Glucose Polymers with Low Polydispersity

    PubMed Central

    Leypoldt, John K.; Hoff, Catherine M.; Piscopo, Dean; Carr, Seraya N.; Svatek, Jessica M.; Holmes, Clifford J.

    2013-01-01

    ♦ Background: Icodextrin, a glucose polymer with a polydispersity [ratio of weight-average molecular weight (Mw) to number-average molecular weight] of approximately 2.6, has been shown, compared with glucose, to provide superior ultrafiltration (UF) efficiency [ratio of UF to carbohydrate (CHO) absorbed] when used as an osmotic agent during a long-dwell peritoneal dialysis exchange. In an experimental rabbit model, we evaluated the effect of Mw on the UF and UF efficiency of glucose polymers with low polydispersity. ♦ Methods: A crossover trial in female New Zealand White rabbits (2.20 - 2.65 kg) with surgically implanted peritoneal catheters evaluated two glucose polymers at nominal concentrations of 7.5 g/dL: a 6K polymer (Mw: 6.4 kDa; polydispersity: 2.3) and a 19K polymer (Mw: 18.8 kDa; polydispersity: 2.0). Rabbits were randomized to receive either the 6K (n = 11) or the 19K (n = 12) solution during the first exchange (40 mL/kg body weight). The alternative solution was evaluated in a second exchange 3 days later. During each 4-hour dwell, the UF and total glucose polymer CHO absorbed were determined. ♦ Results: The UF was higher for the 6K (p < 0.0001) than for the 19K polymer (mean ± standard deviation: 73.6 ± 30.8 mL vs. 43.0 ± 20.2 mL), as was the amount of CHO absorbed (42.5% ± 9.8% vs. 35.7% ± 11.0%, p = 0.021). In spite of higher CHO absorption, an approximately 50% higher (p = 0.029) UF efficiency was achieved with the 6K polymer (28.3 ± 18.8 mL/g) than with the 19K polymer (19.0 ± 11.3 mL/g). The results were independent of the order of the experimental exchanges. ♦ Conclusions: Glucose polymers with low polydispersity are effective osmotic agents in a rabbit model. The low-Mw polymer was more effective at generating UF and had a higher UF efficiency, but those results came at the expense of the polymer being more readily absorbed from the peritoneal cavity. PMID:23123667

  5. Achieving direct electrochemistry of glucose oxidase by one step electrochemical reduction of graphene oxide and its use in glucose sensing.

    PubMed

    Shamsipur, Mojtaba; Tabrizi, Mahmoud Amouzadeh

    2014-12-01

    In this paper, the direct electrochemistry of glucose oxidase (GOD) was accomplished at a glassy carbon electrode modified with electrochemically reduced graphene oxide/sodium dodecyl sulfate (GCE/ERGO/SDS). A pair of reversible peaks is exhibited on GCE/ERGO/SDS/GOD by cyclic voltammetry. The peak-to-peak potential separation of immobilized GOD is 28 mV in 0.1 M phosphate buffer solution (pH7.0) with a scan rate of 50 mV/s. The average surface coverage is 2.62×10(-10) mol cm(-2). The resulting biosensor exhibited a good response to glucose with linear range from 1 to 8 mM (R(2)=0.9878), good reproducibility and detection limit of 40.8 μM. The results from the biosensor were similar (±5%) to those obtained from the clinical analyzer.

  6. Kinetic energy equations for the average-passage equation system

    NASA Technical Reports Server (NTRS)

    Johnson, Richard W.; Adamczyk, John J.

    1989-01-01

    Important kinetic energy equations derived from the average-passage equation sets are documented, with a view to their interrelationships. These kinetic equations may be used for closing the average-passage equations. The turbulent kinetic energy transport equation used is formed by subtracting the mean kinetic energy equation from the averaged total instantaneous kinetic energy equation. The aperiodic kinetic energy equation, averaged steady kinetic energy equation, averaged unsteady kinetic energy equation, and periodic kinetic energy equation, are also treated.

  7. A MEMS differential viscometric sensor for affinity glucose detection in continuous glucose monitoring

    NASA Astrophysics Data System (ADS)

    Huang, Xian; Li, Siqi; Davis, Erin; Leduc, Charles; Ravussin, Yann; Cai, Haogang; Song, Bing; Li, Dachao; Accili, Domenico; Leibel, Rudolph; Wang, Qian; Lin, Qiao

    2013-05-01

    Micromachined viscometric affinity glucose sensors have been previously demonstrated using vibrational cantilever and diaphragm. These devices featured a single glucose detection module that determines glucose concentrations through viscosity changes of glucose-sensitive polymer solutions. However, fluctuations in temperature and other environmental parameters might potentially affect the stability and reliability of these devices, creating complexity in their applications in subcutaneously implanted continuous glucose monitoring (CGM). To address these issues, we present a MEMS differential sensor that can effectively reject environmental disturbances while allowing accurate glucose detection. The sensor consists of two magnetically driven vibrating diaphragms situated inside microchambers filled with a boronic-acid based glucose-sensing solution and a reference solution insensitive to glucose. Glucose concentrations can be accurately determined by characteristics of the diaphragm vibration through differential capacitive detection. Our in vitro and preliminary in vivo experimental data demonstrate the potential of this sensor for highly stable subcutaneous CGM applications.

  8. Sourdough-leavened bread improves postprandial glucose and insulin plasma levels in subjects with impaired glucose tolerance.

    PubMed

    Maioli, Mario; Pes, Giovanni Mario; Sanna, Manuela; Cherchi, Sara; Dettori, Mariella; Manca, Elena; Farris, Giovanni Antonio

    2008-06-01

    Sourdough bread has been reported to improve glucose metabolism in healthy subjects. In this study postprandial glycaemic and insulinaemic responses were evaluated in subjects with impaired glucose tolerance (IGT) who had a meal containing sourdough bread leavened with lactobacilli, in comparison to a reference meal containing bread leavened with baker yeast. Sixteen IGT subjects (age range 52-75, average BMI 29.9 +/- 4.2 kg/ m2) were randomly given a meal containing sourdough bread (A) and a meal containing the reference bread (B) in two separate occasions at the beginning of the study and after 7 days. Sourdough bread was leavened for 8 h using a starter containing autochthonous Saccharomyces cerevisiae and several bacilli able to produce a significant amount of D-and L-lactic acid, whereas the reference bread was leavened for 2 h with commercial baker yeast containing Saccharomyces cerevisiae. Plasma glucose and insulin levels were measured at time 0, 30, 60, 120, and 180 min. In IGT subjects sourdough bread induced a significantly lower plasma glucose response at 30 minutes (p = 0.048) and a smaller incremental area under curve (AUC) delta 0-30 and delta 0-60 min (p = 0.020 and 0.018 respectively) in comparison to the bread leavened with baker yeast. Plasma insulin response to this type of bread showed lower values at 30 min (p = 0.045) and a smaller AUC delta 0-30 min (p = 0.018). This study shows that in subjects with IGT glycaemic and insulinaemic responses after the consumption of sourdough bread are lower than after the bread leavened with baker yeast. This effect is likely due to the lactic acid produced during dough leavening as well as the reduced availability of simple carbohydrates. Thus, sour-dough bread may potentially be of benefit in subjects with impaired glucose metabolism.

  9. Analytical Performance Evaluation of Infopia Element™ Auto-coding Blood Glucose Monitoring System for Self-Monitoring of Blood Glucose.

    PubMed

    Park, Hae-Il; Lee, Seong-Su; Son, Jang-Won; Kwon, Hee-Sun; Kim, Sung Rae; Chae, Hyojin; Kim, Myungshin; Kim, Yonggoo; Yoo, Soonjib

    2016-11-01

    Element™ Auto-coding Blood Glucose Monitoring System (BGMS; Infopia Co., Ltd., Anyang-si, Korea) was developed for self-monitoring of blood glucose (SMBG). Precision, linearity, and interference were tested. Eighty-four capillary blood samples measured by Element™ BGMS were compared with central laboratory method (CLM) results in venous serum. Accuracy was evaluated using ISO 15197:2013 criteria. Coefficients of variation (CVs; mean) were 2.4% (44.2 mg/dl), 3.7% (100.6 mg/dl), and 2.1% (259.8 mg/dl). Linearity was shown at concentrations 39.25-456.25 mg/l (y = 0.989 + 0.984x, SE = 17.63). Up to 15 mg/dl of galactose, ascorbic acid, and acetaminophen, interference > 10.4% was not observed. Element™ BGMS glucose was higher than CLM levels by 3.2 mg/dl (at 200 mg/dl) to 8.2 mg/dl (at 100 mg/dl). The minimum specification for bias (3.3%) was met at 140 and 200 mg/l glucose. In the Clarke and consensus error grids, 100% of specimens were within zone A and B. For Element™ BGMS values, 92.9% (78/84) to 94.0% (79/84) were within a 15 mg/dl (< 100 mg/dl) or 15% (> 100 mg/dl) of the average CLM value. Element™ BGMS was considered an appropriate SMBG for home use; however, the positive bias at low-to-mid glucose levels requires further improvement. © 2016 Wiley Periodicals, Inc.

  10. FRET-based glucose monitoring for bioprocessing

    NASA Astrophysics Data System (ADS)

    Bartolome, Amelita; Smalls-Mantey, Lauren; Lin, Debora; Rao, Govind; Tolosa, Leah

    2006-02-01

    The glucose-mediated conformational changes in the glucose binding protein (GBP) have been exploited in the development of fluorescence based glucose sensors. The fluorescence response is generated by a polarity sensitive dye attached to a specific site. Such fluorescent sensors respond to submicromolar glucose at diffusion-controlled rates mimicking the wild type. However, such sensors have been limited to in vitro glucose sensing because of the preliminary dye-labeling step. In the study described here, the dye-labeling step is omitted by genetically encoding the GBP with two green fluorescent mutants namely, the green fluorescent protein (GFP) and the yellow fluorescent protein (YFP) in the N- and C-terminal ends, respectively. These two GFP mutants comprise a fluorescence resonance energy transfer (FRET) donor and acceptor pair. Thus, when glucose binds with GBP, the conformational changes affect the FRET efficiency yielding a dose-dependent response. A potential application for this FRET-based glucose biosensor is online glucose sensing in bioprocessing and cell culture. This was demonstrated by the measurement of glucose consumption in yeast fermentation. Further development of this system should yield in vivo measurement of glucose in bioprocesses.

  11. Coping with an exogenous glucose overload: glucose kinetics of rainbow trout during graded swimming.

    PubMed

    Choi, Kevin; Weber, Jean-Michel

    2016-03-15

    This study examines how chronically hyperglycemic rainbow trout modulate glucose kinetics in response to graded exercise up to critical swimming speed (Ucrit), with or without exogenous glucose supply. Our goals were 1) to quantify the rates of hepatic glucose production (Ra glucose) and disposal (Rd glucose) during graded swimming, 2) to determine how exogenous glucose affects the changes in glucose fluxes caused by exercise, and 3) to establish whether exogenous glucose modifies Ucrit or the cost of transport. Results show that graded swimming causes no change in Ra and Rd glucose at speeds below 2.5 body lengths per second (BL/s), but that glucose fluxes may be stimulated at the highest speeds. Excellent glucoregulation is also achieved at all exercise intensities. When exogenous glucose is supplied during exercise, trout suppress hepatic production from 16.4 ± 1.6 to 4.1 ± 1.7 μmol·kg(-1)·min(-1) and boost glucose disposal to 40.1 ± 13 μmol·kg(-1)·min(-1). These responses limit the effects of exogenous glucose to a 2.5-fold increase in glycemia, whereas fish showing no modulation of fluxes would reach dangerous levels of 114 mM of blood glucose. Exogenous glucose reduces metabolic rate by 16% and, therefore, causes total cost of transport to decrease accordingly. High glucose availability does not improve Ucrit because the fish are unable to take advantage of this extra fuel during maximal exercise and rely on tissue glycogen instead. In conclusion, trout have a remarkable ability to adjust glucose fluxes that allows them to cope with the cumulative stresses of a glucose overload and graded exercise.

  12. Coping with an exogenous glucose overload: glucose kinetics of rainbow trout during graded swimming

    PubMed Central

    Choi, Kevin

    2015-01-01

    This study examines how chronically hyperglycemic rainbow trout modulate glucose kinetics in response to graded exercise up to critical swimming speed (Ucrit), with or without exogenous glucose supply. Our goals were 1) to quantify the rates of hepatic glucose production (Ra glucose) and disposal (Rd glucose) during graded swimming, 2) to determine how exogenous glucose affects the changes in glucose fluxes caused by exercise, and 3) to establish whether exogenous glucose modifies Ucrit or the cost of transport. Results show that graded swimming causes no change in Ra and Rd glucose at speeds below 2.5 body lengths per second (BL/s), but that glucose fluxes may be stimulated at the highest speeds. Excellent glucoregulation is also achieved at all exercise intensities. When exogenous glucose is supplied during exercise, trout suppress hepatic production from 16.4 ± 1.6 to 4.1 ± 1.7 μmol·kg−1·min−1 and boost glucose disposal to 40.1 ± 13 μmol·kg−1·min−1. These responses limit the effects of exogenous glucose to a 2.5-fold increase in glycemia, whereas fish showing no modulation of fluxes would reach dangerous levels of 114 mM of blood glucose. Exogenous glucose reduces metabolic rate by 16% and, therefore, causes total cost of transport to decrease accordingly. High glucose availability does not improve Ucrit because the fish are unable to take advantage of this extra fuel during maximal exercise and rely on tissue glycogen instead. In conclusion, trout have a remarkable ability to adjust glucose fluxes that allows them to cope with the cumulative stresses of a glucose overload and graded exercise. PMID:26719305

  13. Noninvasive Ultrasonic Glucose Sensing with Large Pigs (∼200 Pounds) Using a Lightweight Cymbal Transducer Array and Biosensors

    PubMed Central

    Park, Eun-Joo; Werner, Jacob; Beebe, Joshua; Chan, Samantha; Barrie Smith, Nadine

    2009-01-01

    Background To prevent complications in diabetes, the proper management of blood glucose levels is essential. Since conventional glucose meters require pricking fingers or other areas of the skin, a noninvasive method for monitoring blood glucose levels is desired. Using a lightweight cymbal transducer array, this study was conducted to noninvasively determine the glucose levels of pigs having a similar size to humans. Method In vivo experiments using eight pigs (∼200 pounds) were performed in five groups. A cymbal array with four biosensors was attached to the axillary area of the pig. The array was operated at 20 kHz at special peak–temporal peak intensity (Isptp) equal to 50 or 100 mW/cm2 for 5, 10, or 20 minutes. After the ultrasound exposure, glucose concentrations of the interstitial fluid were determined using biosensors. For comparison, glucose levels of blood samples collected from the ear vein were measured by a commercial glucose meter. Result In comparison, glucose levels determined by a cymbal array and biosensor system were close to those measured by a glucose meter. After a 20-minute ultrasound exposure at Isptp = 100 mW/cm2, the average glucose level determined by the ultrasound system was 175 ± 7 mg/dl, which is close to 166 ± 5 mg/dl measured by the glucose meter. Conclusion Results indicate the feasibility of using a cymbal array for noninvasive glucose sensing on pigs having a similar size to humans. Further studies on the ultrasound conditions, such as frequency, intensity, and exposure time, will be continued for effective glucose sensing. PMID:20144290

  14. 40 CFR 60.1755 - How do I convert my 1-hour arithmetic averages into appropriate averaging times and units?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... part, section 4.3, to calculate the daily geometric average concentrations of sulfur dioxide emissions... appendix A of this part, section 5.4, to determine the daily geometric average percent reduction of... averages into appropriate averaging times and units? 60.1755 Section 60.1755 Protection of...

  15. 40 CFR 62.15210 - How do I convert my 1-hour arithmetic averages into appropriate averaging times and units?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... of 40 CFR part 60, section 4.3, to calculate the daily geometric average concentrations of sulfur... 19, section 5.4, to determine the daily geometric average percent reduction of potential sulfur... averages into appropriate averaging times and units? 62.15210 Section 62.15210 Protection of...

  16. The Effect of an Instant Hand Sanitizer on Blood Glucose Monitoring Results

    PubMed Central

    Mahoney, John J; Ellison, John M; Glaeser, Danielle; Price, David

    2011-01-01

    Background People with diabetes mellitus are instructed to clean their skin prior to self-monitoring of blood glucose to remove any dirt or food residue that might affect the reading. Alcohol-based hand sanitizers have become popular when soap and water are not available. The aim of this study was to determine whether a hand sanitizer is compatible with glucose meter testing and effective for the removal of exogenous glucose. Methods We enrolled 34 nonfasting subjects [14 male/20 female, mean ages 45 (standard deviation, 9.4)] years, 2 with diagnosed diabetes/32 without known diabetes]. Laboratory personnel prepared four separate fingers on one hand of each subject by (1) cleaning the second finger with soap and water and towel drying (i.e., control finger), (2) cleaning the third finger with an alcohol-based hand sanitizer, (3) coating the fourth finger with cola and allowing it to air dry, and (4) coating the fifth finger with cola and then cleaning it with the instant hand sanitizer after the cola had dried. Finger sticks were performed on each prepared finger and blood glucose was measured. Several in vitro studies were also performed to investigate the effectiveness of the hand sanitizer for removal of exogenous glucose.z Results Mean blood glucose values from fingers cleaned with instant hand sanitizer did not differ significantly from the control finger (p = .07 and .08, respectively) and resulted in 100% accurate results. Blood glucose data from the fourth (cola-coated) finger were substantially higher on average compared with the other finger conditions, but glucose data from the fifth finger (cola-coated then cleaned with hand sanitizer) was similar to the control finger. The data from in vitro experiments showed that the hand sanitizer did not adversely affect glucose meter results, but when an exogenous glucose interference was present, the effectiveness of the hand sanitizer on glucose bias (range: 6% to 212%) depended on the surface area and degree of

  17. Value of continuous glucose monitoring for minimizing severe hypoglycemia during tight glycemic control.

    PubMed

    Steil, Garry M; Langer, Monica; Jaeger, Karen; Alexander, Jamin; Gaies, Michael; Agus, Michael S D

    2011-11-01

    Tight glycemic control can potentially reduce morbidity and mortality in the intensive care unit but increases the risk of hypoglycemia. The most effective means to avoid hypoglycemia is to obtain frequent blood glucose samples, but this increases the burden to nursing staff. The objective of this study was to assess the ability of a real-time continuous glucose monitor to reduce hypoglycemia (blood glucose <60 mg/dL [3.3 mmol/L]) during standard care or tight glycemic control effected with a proportional integral derivative insulin titration algorithm. Real-time continuous glucose monitor profiles obtained from an ongoing prospective randomized trial of tight glycemic control were retrospectively analyzed to determine whether the continuous glucose measure had prevented instances of hypoglycemia. Cardiac intensive care unit. Children 3 yrs of age or younger undergoing cardiac surgery were studied. Intravenous insulin infusion and rescue glucose guided by the real-time continuous glucose monitor and the proportional integral derivative algorithm in the tight glycemic control arm (n = 155; target glucose 80-110 mg/dL [4.4-6.1 mmol/L]) and the real-time continuous glucose monitor in the standard care arm (n = 156). No reduction in hypoglycemia was observed with real-time continuous glucose monitor alarms set at 60 mg/dL (3.3 mmol/L) (zero of 19 occurrences of blood glucose <60 mg/dL [3.3 mmol/L] detected); 18 of 40 subsequent incidences of hypoglycemia were detected after the alarm threshold was increased to 70 mg/dL (3.9 mmol/L). In the tight glycemic control arm, eight incidences were reduced in duration and an additional eight events were prevented with intravenous glucose. In the standard care arm, three of nine occurrences of hypoglycemia were detected with the duration reduced in all cases. On average, one to two false hypoglycemia alarms were observed in each patient. The real-time continuous glucose monitor in combination with proportional integral derivative

  18. The effect of an instant hand sanitizer on blood glucose monitoring results.

    PubMed

    Mahoney, John J; Ellison, John M; Glaeser, Danielle; Price, David

    2011-11-01

    People with diabetes mellitus are instructed to clean their skin prior to self-monitoring of blood glucose to remove any dirt or food residue that might affect the reading. Alcohol-based hand sanitizers have become popular when soap and water are not available. The aim of this study was to determine whether a hand sanitizer is compatible with glucose meter testing and effective for the removal of exogenous glucose. We enrolled 34 nonfasting subjects [14 male/20 female, mean ages 45 (standard deviation, 9.4)] years, 2 with diagnosed diabetes/32 without known diabetes]. Laboratory personnel prepared four separate fingers on one hand of each subject by (1) cleaning the second finger with soap and water and towel drying (i.e., control finger), (2) cleaning the third finger with an alcohol-based hand sanitizer, (3) coating the fourth finger with cola and allowing it to air dry, and (4) coating the fifth finger with cola and then cleaning it with the instant hand sanitizer after the cola had dried. Finger sticks were performed on each prepared finger and blood glucose was measured. Several in vitro studies were also performed to investigate the effectiveness of the hand sanitizer for removal of exogenous glucose.z Mean blood glucose values from fingers cleaned with instant hand sanitizer did not differ significantly from the control finger (p = .07 and .08, respectively) and resulted in 100% accurate results. Blood glucose data from the fourth (cola-coated) finger were substantially higher on average compared with the other finger conditions, but glucose data from the fifth finger (cola-coated then cleaned with hand sanitizer) was similar to the control finger. The data from in vitro experiments showed that the hand sanitizer did not adversely affect glucose meter results, but when an exogenous glucose interference was present, the effectiveness of the hand sanitizer on glucose bias (range: 6% to 212%) depended on the surface area and degree of dilution. In our study

  19. The lack of long-range negative correlations in glucose dynamics is associated with worse glucose control in patients with diabetes mellitus.

    PubMed

    Ogata, Hitomi; Tokuyama, Kumpei; Nagasaka, Shoichiro; Tsuchita, Takeshi; Kusaka, Ikuyo; Ishibashi, Shun; Suzuki, Hiroaki; Yamada, Nobuhiro; Hamano, Kumiko; Kiyono, Ken; Struzik, Zbigniew R; Yamamoto, Yoshiharu

    2012-07-01

    Glucose dynamics measured in ambulatory settings are fluid in nature and exhibit substantial complexity. We recently showed that a long-range negative correlation of glucose dynamics, which is considered to reflect blood glucose controllability over a substantial period, is absent in patients with diabetes mellitus. This was demonstrated using detrended fluctuation analysis (DFA), a modified random-walk analysis method for the detection of long-range correlations. In the present study, we further assessed the relationships between the established clinical indices of glycemic or insulinogenic control of hemoglobin A(1c) (HbA(1c)), glycated albumin (GA), 1,5-anhydroglucitol, and urine C-peptide immunoreactivity and the recently proposed DFA-based indices obtained from continuous glucose monitoring in 104 Japanese diabetic patients. Significant correlations between the following parameters were observed: (1) HbA(1c) and the long-range scaling exponent α(2) (r = 0.236, P < .05), (2) GA and α(2) (r = 0.254, P < .05), (3) GA and the short-range scaling exponent α(1) (r = 0.233, P < .05), and (4) urine C-peptide immunoreactivity and the mean glucose fluctuations (r = -0.294, P < .01). Therefore, we concluded that increases in the long-range DFA scaling exponent, which are indicative of the lack of a long-range negative correlation in glucose dynamics, reflected abnormalities in average glycemic control as clinically determined using HbA(1c) and GA parameters.

  20. Increased blood glucose is related to disturbed cerebrovascular pressure reactivity after traumatic brain injury.

    PubMed

    Donnelly, Joseph; Czosnyka, Marek; Sudhan, Nazneen; Varsos, Georgios V; Nasr, Nathalie; Jalloh, Ibrahim; Liu, Xiuyun; Dias, Celeste; Sekhon, Mypinder S; Carpenter, Keri L H; Menon, David K; Hutchinson, Peter J; Smielewski, Peter

    2015-02-01

    Increased blood glucose and impaired pressure reactivity (PRx) after traumatic brain injury (TBI) are both known to correlate with unfavorable patient outcome. However, the relationship between these two variables is unknown. To test the hypothesis that increased blood glucose leads to increased PRx, we retrospectively analyzed data from 86 traumatic brain injured patients admitted to the Neurocritical Care Unit. Data analyzed included arterial glucose concentration, intracranial pressure (ICP), cerebral perfusion pressure (CPP) and end-tidal CO2. PRx was calculated as the moving correlation coefficient between averaged (10 seconds) arterial blood pressure and ICP. One arterial glucose concentration and one time-aligned PRx value were obtained for each patient, during each day until the fifth day after ictus. Mean arterial glucose concentrations during the first 5 days since ictus were positively correlated with mean PRx (Pearson correlation coefficient = 0.25, p = 0.02). The correlation was strongest on the first day after injury (Pearson correlation coefficient = 0.47, p = 0.008). Our preliminary findings indicate that increased blood glucose may impair cerebrovascular reactivity, potentially contributing to a mechanistic link between increased blood glucose and poorer outcome after TBI.

  1. The role of symmetry in attraction to average faces.

    PubMed

    Jones, Benedict C; DeBruine, Lisa M; Little, Anthony C

    2007-11-01

    Although many studies have demonstrated that average faces tend to be attractive, few studies have examined the extent to which symmetry contributes to the attractiveness of average faces. Such studies are potentially important, however, because average faces are highly symmetric and increasing the symmetry of face images increases their attractiveness. Here we demonstrate that increasing averageness of 2-D face shape independently of symmetry is sufficient to increase attractiveness, indicating that preferences for symmetry cannot solely explain the attractiveness of average faces. Additionally, we show that averageness preferences are significantly weaker when the effects of symmetry are controlled for using computer graphic methods than when the effects of symmetry are not controlled for, suggesting that symmetry contributes to the attractiveness of average faces. Importantly, this latter finding was not explained by the greater perceived similarity between versions offaces that varied in averageness, but not symmetry, than between versions of faces that varied in both averageness and symmetry.

  2. Pancreatic perfusion and subsequent response to glucose in healthy individuals and patients with type 1 diabetes.

    PubMed

    Carlbom, Lina; Espes, Daniel; Lubberink, Mark; Eriksson, Olof; Johansson, Lars; Jansson, Leif; Korsgren, Olle; Ahlström, Håkan; Carlsson, Per-Ola

    2016-09-01

    The aim of this study was to investigate pancreatic perfusion and its response to a glucose load in patients with type 1 diabetes mellitus compared with non-diabetic ('healthy') individuals. Eight individuals with longstanding type 1 diabetes and ten sex-, age- and BMI-matched healthy controls underwent dynamic positron emission tomography scanning with (15)O-labelled water before and after intravenous administration of glucose. Perfusion in the pancreas was measured. Portal and arterial hepatic perfusion were recorded as references. Under fasting conditions, total pancreatic perfusion was on average 23% lower in the individuals with diabetes compared with healthy individuals. Glucose increased total pancreatic and portal hepatic blood perfusion in healthy individuals by 48% and 38%, respectively. In individuals with diabetes there was no significant increase in either total pancreatic or portal hepatic perfusion. Individuals with type 1 diabetes have reduced basal pancreatic perfusion and a severely impaired pancreatic and splanchnic perfusion response to intravenous glucose stimulation.

  3. Pancreatic regulation of glucose homeostasis

    PubMed Central

    Röder, Pia V; Wu, Bingbing; Liu, Yixian; Han, Weiping

    2016-01-01

    In order to ensure normal body function, the human body is dependent on a tight control of its blood glucose levels. This is accomplished by a highly sophisticated network of various hormones and neuropeptides released mainly from the brain, pancreas, liver, intestine as well as adipose and muscle tissue. Within this network, the pancreas represents a key player by secreting the blood sugar-lowering hormone insulin and its opponent glucagon. However, disturbances in the interplay of the hormones and peptides involved may lead to metabolic disorders such as type 2 diabetes mellitus (T2DM) whose prevalence, comorbidities and medical costs take on a dramatic scale. Therefore, it is of utmost importance to uncover and understand the mechanisms underlying the various interactions to improve existing anti-diabetic therapies and drugs on the one hand and to develop new therapeutic approaches on the other. This review summarizes the interplay of the pancreas with various other organs and tissues that maintain glucose homeostasis. Furthermore, anti-diabetic drugs and their impact on signaling pathways underlying the network will be discussed. PMID:26964835

  4. Sex steroids and glucose metabolism.

    PubMed

    Allan, Carolyn A

    2014-01-01

    Testosterone levels are lower in men with metabolic syndrome and type 2 diabetes mellitus (T2DM) and also predict the onset of these adverse metabolic states. Body composition (body mass index, waist circumference) is an important mediator of this relationship. Sex hormone binding globulin is also inversely associated with insulin resistance and T2DM but the data regarding estrogen are inconsistent. Clinical models of androgen deficiency including Klinefelter's syndrome and androgen deprivation therapy in the treatment of advanced prostate cancer confirm the association between androgens and glucose status. Experimental manipulation of the insulin/glucose milieu and suppression of endogenous testicular function suggests the relationship between androgens and insulin sensitivity is bidirectional. Androgen therapy in men without diabetes is not able to differentiate the effect on insulin resistance from that on fat mass, in particular visceral adiposity. Similarly, several small clinical studies have examined the efficacy of exogenous testosterone in men with T2DM, however, the role of androgens, independent of body composition, in modifying insulin resistance is uncertain.

  5. Why control blood glucose levels?

    PubMed

    Rossini, A A

    1976-03-01

    The controversy as to the relationship between the degree of control of diabetes and the progression of the complications of the disease has not been solved. However, in this review, various studies suggesting a relationship between the metabolic abnormality and the diabetic complications are examined. The disadvantages of the uncontrolled diabetes mellitus can be divided into two major categories-short-term and long-term. The short-term disadvantages of controlled diabetes mellitus include the following: (1) ketoacidosis and hyperosmolar coma; (2) intracellular dehydration; (3) electrolyte imbalance; (4) decreased phagocytosis; (5) immunologic and lymphocyte activity; (6) impairment of wound healing; and (7) abnormality of lipids. The long-term disadvantages of uncontrolled diabetes melitus include the following: (1) nephropathy; (2) neuropathy; (3) retinopathy; (4) cataract formation; (5) effect on perinatal mortality; (6) complications of vascular disease; and (7) the evaluation of various clinical studies suggesting the relationship of elevated blood glucose levels and complications of diabetes mellitus. It is suggested that until the question of control can absolutely be resolved, the recommendation is that the blood glucose levels should be controlled as close to the normal as possible.

  6. Circadian control of glucose metabolism.

    PubMed

    Kalsbeek, Andries; la Fleur, Susanne; Fliers, Eric

    2014-07-01

    The incidence of obesity and type 2 diabetes mellitus (T2DM) has risen to epidemic proportions. The pathophysiology of T2DM is complex and involves insulin resistance, pancreatic β-cell dysfunction and visceral adiposity. It has been known for decades that a disruption of biological rhythms (which happens the most profoundly with shift work) increases the risk of developing obesity and T2DM. Recent evidence from basal studies has further sparked interest in the involvement of daily rhythms (and their disruption) in the development of obesity and T2DM. Most living organisms have molecular clocks in almost every tissue, which govern rhythmicity in many domains of physiology, such as rest/activity rhythms, feeding/fasting rhythms, and hormonal secretion. Here we present the latest research describing the specific role played by the molecular clock mechanism in the control of glucose metabolism and speculate on how disruption of these tissue clocks may lead to the disturbances in glucose homeostasis.

  7. Circadian control of glucose metabolism

    PubMed Central

    Kalsbeek, Andries; la Fleur, Susanne; Fliers, Eric

    2014-01-01

    The incidence of obesity and type 2 diabetes mellitus (T2DM) has risen to epidemic proportions. The pathophysiology of T2DM is complex and involves insulin resistance, pancreatic β-cell dysfunction and visceral adiposity. It has been known for decades that a disruption of biological rhythms (which happens the most profoundly with shift work) increases the risk of developing obesity and T2DM. Recent evidence from basal studies has further sparked interest in the involvement of daily rhythms (and their disruption) in the development of obesity and T2DM. Most living organisms have molecular clocks in almost every tissue, which govern rhythmicity in many domains of physiology, such as rest/activity rhythms, feeding/fasting rhythms, and hormonal secretion. Here we present the latest research describing the specific role played by the molecular clock mechanism in the control of glucose metabolism and speculate on how disruption of these tissue clocks may lead to the disturbances in glucose homeostasis. PMID:24944897

  8. Regulation of Blood Glucose by Hypothalamic Pyruvate Metabolism

    NASA Astrophysics Data System (ADS)

    Lam, Tony K. T.; Gutierrez-Juarez, Roger; Pocai, Alessandro; Rossetti, Luciano

    2005-08-01

    The brain keenly depends on glucose for energy, and mammalians have redundant systems to control glucose production. An increase in circulating glucose inhibits glucose production in the liver, but this negative feedback is impaired in type 2 diabetes. Here we report that a primary increase in hypothalamic glucose levels lowers blood glucose through inhibition of glucose production in rats. The effect of glucose requires its conversion to lactate followed by stimulation of pyruvate metabolism, which leads to activation of adenosine triphosphate (ATP)-sensitive potassium channels. Thus, interventions designed to enhance the hypothalamic sensing of glucose may improve glucose homeostasis in diabetes.

  9. Application of Semipermeable Membranes in Glucose Biosensing

    PubMed Central

    Kulkarni, Tanmay; Slaughter, Gymama

    2016-01-01

    Glucose biosensors have received significant attention in recent years due to the escalating mortality rate of diabetes mellitus. Although there is currently no cure for diabetes mellitus, individuals living with diabetes can lead a normal life by maintaining tight control of their blood glucose levels using glucose biosensors (e.g., glucometers). Current research in the field is focused on the optimization and improvement in the performance of glucose biosensors by employing a variety of glucose selective enzymes, mediators and semipermeable membranes to improve the electron transfer between the active center of the enzyme and the electrode substrate. Herein, we summarize the different semipermeable membranes used in the fabrication of the glucose biosensor, that result in improved biosensor sensitivity, selectivity, dynamic range, response time and stability. PMID:27983630

  10. Gut-brain mechanisms controlling glucose homeostasis

    PubMed Central

    Scarlett, Jarrad M.

    2015-01-01

    Our current understanding of glucose homeostasis is centered on glucose-induced secretion of insulin from pancreatic islets and insulin action on glucose metabolism in peripheral tissues. In addition, however, recent evidence suggests that neurocircuits located within a brain-centered glucoregulatory system work cooperatively with pancreatic islets to promote glucose homeostasis. Among key observations is evidence that, in addition to insulin-dependent mechanisms, the brain has the capacity to potently lower blood glucose levels via mechanisms that are insulin-independent, some of which are activated by signals emanating from the gastrointestinal tract. This review highlights evidence supporting a key role for a “gut-brain-liver axis” in control of glucose homeostasis by the brain-centered glucoregulatory system and the implications of this regulatory system for diabetes pathogenesis and treatment. PMID:25705395

  11. Continuous Glucose Monitoring Systems: A Review

    PubMed Central

    Vashist, Sandeep Kumar

    2013-01-01

    There have been continuous advances in the field of glucose monitoring during the last four decades, which have led to the development of highly evolved blood glucose meters, non-invasive glucose monitoring (NGM) devices and continuous glucose monitoring systems (CGMS). Glucose monitoring is an integral part of diabetes management, and the maintenance of physiological blood glucose concentration is the only way for a diabetic to avoid life-threatening diabetic complications. CGMS have led to tremendous improvements in diabetic management, as shown by the significant lowering of glycated hemoglobin (HbA1c) in adults with type I diabetes. Most of the CGMS have been minimally-invasive, although the more recent ones are based on NGM techniques. This manuscript reviews the advances in CGMS for diabetes management along with the future prospects and the challenges involved. PMID:26824930

  12. Blood glucose prediction using neural network

    NASA Astrophysics Data System (ADS)

    Soh, Chit Siang; Zhang, Xiqin; Chen, Jianhong; Raveendran, P.; Soh, Phey Hong; Yeo, Joon Hock

    2008-02-01

    We used neural network for blood glucose level determination in this study. The data set used in this study was collected using a non-invasive blood glucose monitoring system with six laser diodes, each laser diode operating at distinct near infrared wavelength between 1500nm and 1800nm. The neural network is specifically used to determine blood glucose level of one individual who participated in an oral glucose tolerance test (OGTT) session. Partial least squares regression is also used for blood glucose level determination for the purpose of comparison with the neural network model. The neural network model performs better in the prediction of blood glucose level as compared with the partial least squares model.

  13. Postprandial glucose response to selected tropical fruits in normal glucose-tolerant Nigerians.

    PubMed

    Edo, A; Eregie, A; Adediran, O; Ohwovoriole, A; Ebengho, S

    2011-01-01

    The glycemic response to commonly eaten fruits in Nigeria has not been reported. Therefore, this study assessed the plasma glucose response to selected fruits in Nigeria. Ten normal glucose-tolerant subjects randomly consumed 50 g carbohydrate portions of three fruits: banana (Musa paradisiaca), pineapple (Ananus comosus), and pawpaw (Carica papaya), and a 50-g glucose load at 1-week intervals. Blood samples were collected in the fasting state and half-hourly over a 2-h period post-ingestion of the fruits or glucose. The samples were analyzed for plasma glucose concentrations. Plasma glucose responses were assessed by the peak plasma glucose concentration, maximum increase in plasma glucose, 2-h postprandial plasma glucose level, and incremental area under the glucose curve and glycemic index (GI). The results showed that the blood glucose response to these three fruits was similar in terms of their incremental areas under the glucose curve, maximum increase in plasma glucose, and glycemic indices (GIs). The 2-h postprandial plasma glucose level of banana was significantly higher than that of pineapple, P < 0.025. The mean ± SEM GI values were as follows: pawpaw; 86 ± 26.8%; banana, 75.1 ± 21.8%; pineapple, 64.5 ± 11.3%. The GI of glucose is taken as 100. The GI of pineapple was significantly lower than that of glucose (P < 0.05). Banana, pawpaw, and pineapple produced a similar postprandial glucose response. Measured portions of these fruits may be used as fruit exchanges with pineapple having the most favorable glycemic response.

  14. Bioluminescence Imaging of Glucose in Tissue Surrounding Polyurethane and Glucose Sensor Implants

    PubMed Central

    Prichard, Heather L; Schroeder, Thies; Reichert, William M; Klitzman, Bruce

    2010-01-01

    Background The bioluminescence technique was used to quantify the local glucose concentration in the tissue surrounding subcutaneously implanted polyurethane material and surrounding glucose sensors. In addition, some implants were coated with a single layer of adipose-derived stromal cells (ASCs) because these cells improve the wound-healing response around biomaterials. Methods Control and ASC-coated implants were implanted subcutaneously in rats for 1 or 8 weeks (polyurethane) or for 1 week only (glucose sensors). Tissue biopsies adjacent to the implant were immediately frozen at the time of explant. Cryosections were assayed for glucose concentration profile using the bioluminescence technique. Results For the polyurethane samples, no significant differences in glucose concentration within 100 μm of the implant surface were found between bare and ASC-coated implants at 1 or 8 weeks. A glucose concentration gradient was demonstrated around the glucose sensors. For all sensors, the minimum glucose concentration of approximately 4 mM was found at the implant surface and increased with distance from the sensor surface until the glucose concentration peaked at approximately 7 mM at 100 μm. Then the glucose concentration decreased to 5.5–6.5 mM more than 100 μmm from the surface. Conclusions The ASC attachment to polyurethane and to glucose sensors did not change the glucose profiles in the tissue surrounding the implants. Although most glucose sensors incorporate a diffusion barrier to reduce the gradient of glucose and oxygen in the tissue, it is typically assumed that there is no steep glucose gradient around the sensors. However, a glucose gradient was observed around the sensors. A more complete understanding of glucose transport and concentration gradients around sensors is critical. PMID:20920425

  15. Is fructose sweeter than glucose for rats?

    PubMed

    Ramirez, I

    1996-11-01

    Because it is generally thought that the intensity of the taste of fructose is greater than that of glucose for rats, it seemed surprising when sham-fed rats drank substantially less of a mixture of 6% fructose plus saccharin than of a mixture of 6% glucose plus saccharin. At least 3 different factors contribute to this effect. First, the taste of fructose is less attractive to rats than is the taste of glucose; sham-fed rats strongly preferred glucose over fructose (no saccharin was used in this experiment). The second factor is experience. Rats having substantial previous experience with glucose, but not with fructose, consistently preferred glucose over fructose. Conversely, rats having substantial previous experience with fructose, but not with glucose, initially showed no consistent preference but subsequently tended to prefer glucose. The third factor is an interaction between saccharin and the type of sugar. Rats given only one solution at a time drink approximately as much fructose as glucose when the solutions contain no saccharin. The addition of 0.25% saccharin to 6% glucose stimulated intake, whereas the addition of the same amount of saccharin to 6% fructose did not stimulate intake. As a result, rats ingested substantially more of a mixture of 0.25% saccharin plus 6% glucose than they did of a comparable mixture of saccharin and fructose, even though rats ingest similar amounts of fructose and glucose without saccharin in single-bottle tests. Because the differential effect of saccharin on intake appeared within 2 h in naive rats, and did not greatly change over a 3-day period, it is probably not attributable to conditioning. These results suggest that these sugars have qualitatively different tastes.

  16. A self-powered glucose biosensing system.

    PubMed

    Slaughter, Gymama; Kulkarni, Tanmay

    2016-04-15

    A self-powered glucose biosensor (SPGS) system is fabricated and in vitro characterization of the power generation and charging frequency characteristics in glucose analyte are described. The bioelectrodes consist of compressed network of three-dimensional multi-walled carbon nanotubes with redox enzymes, pyroquinoline quinone glucose dehydrogenase (PQQ-GDH) and laccase functioning as the anodic and cathodic catalyst, respectively. When operated in 45 mM glucose, the biofuel cell exhibited an open circuit voltage and power density of 681.8 mV and 67.86 µW/cm(2) at 335 mV, respectively, with a current density of 202.2 µA/cm(2). Moreover, at physiological glucose concentration (5mM), the biofuel cell exhibits open circuit voltage and power density of 302.1 mV and 15.98 µW/cm(2) at 166.3 mV, respectively, with a current density of 100 µA/cm(2). The biofuel cell assembly produced a linear dynamic range of 0.5-45 mM glucose. These findings show that glucose biofuel cells can be further investigated in the development of a self-powered glucose biosensor by using a capacitor as the transducer element. By monitoring the capacitor charging frequencies, which are influenced by the concentration of the glucose analyte, a linear dynamic range of 0.5-35 mM glucose is observed. The operational stability of SPGS is monitored over a period of 63 days and is found to be stable with 15.38% and 11.76% drop in power density under continuous discharge in 10mM and 20mM glucose, respectively. These results demonstrate that SPGSs can simultaneously generate bioelectricity to power ultra-low powered devices and sense glucose.

  17. Glucose starvation-induced turnover of the yeast glucose transporter Hxt1.

    PubMed

    Roy, Adhiraj; Kim, Yong-Bae; Cho, Kyu Hong; Kim, Jeong-Ho

    2014-09-01

    The budding yeast Saccharomyces cerevisiae possesses multiple glucose transporters with different affinities for glucose that enable it to respond to a wide range of glucose concentrations. The steady-state levels of glucose transporters are regulated in response to changes in the availability of glucose. This study investigates the glucose regulation of the low affinity, high capacity glucose transporter Hxt1. Western blotting and confocal microscopy were performed to evaluate glucose regulation of the stability of Hxt1. Our results show that glucose starvation induces endocytosis and degradation of Hxt1 and that this event requires End3, a protein required for endocytosis, and the Doa4 deubiquitination enzyme. Mutational analysis of the lysine residues in the Hxt1 N-terminal domain demonstrates that the two lysine residues, K12 and K39, serve as the putative ubiquitin-acceptor sites by the Rsp5 ubiquitin ligase. We also demonstrate that inactivation of PKA (cAMP-dependent protein kinase A) is needed for Hxt1 turnover, implicating the role of the Ras/cAMP-PKA glucose signaling pathway in the stability of Hxt1. Hxt1, most useful when glucose is abundant, is internalized and degraded when glucose becomes depleted. Of note, the stability of Hxt1 is regulated by PKA, known as a positive regulator for glucose induction of HXT1 gene expression, demonstrating a dual role of PKA in regulation of Hxt1. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Glucose sensing and signaling by two glucose receptors in the yeast Saccharomyces cerevisiae.

    PubMed

    Ozcan, S; Dover, J; Johnston, M

    1998-05-01

    How eukaryotic cells sense availability of glucose, their preferred carbon and energy source, is an important, unsolved problem. Bakers' yeast (Saccharomyces cerevisiae) uses two glucose transporter homologs, Snf3 and Rgt2, as glucose sensors that generate a signal for induction of expression of genes encoding hexose transporters (HXT genes). We present evidence that these proteins generate an intracellular glucose signal without transporting glucose. The Snf3 and Rgt2 glucose sensors contain unusually long C-terminal tails that are predicted to be in the cytoplasm. These tails appear to be the signaling domains of Snf3 and Rgt2 because they are necessary for glucose signaling by Snf3 and Rgt2, and transplantation of the C-terminal tail of Snf3 onto the Hxt1 and Hxt2 glucose transporters converts them into glucose sensors that can generate a signal for glucose-induced HXT gene expression. These results support the idea that yeast senses glucose using two modified glucose transporters that serve as glucose receptors.

  19. Elucidation of the glucose transport pathway in glucose transporter 4 via steered molecular dynamics simulations.

    PubMed

    Sheena, Aswathy; Mohan, Suma S; Haridas, Nidhina Pachakkil A; Anilkumar, Gopalakrishnapillai

    2011-01-01

    GLUT4 is a predominant insulin regulated glucose transporter expressed in major glucose disposal tissues such as adipocytes and muscles. Under the unstimulated state, GLUT4 resides within intracellular vesicles. Various stimuli such as insulin translocate this protein to the plasma membrane for glucose transport. In the absence of a crystal structure for GLUT4, very little is known about the mechanism of glucose transport by this protein. Earlier we proposed a homology model for GLUT4 and performed a conventional molecular dynamics study revealing the conformational rearrangements during glucose and ATP binding. However, this study could not explain the transport of glucose through the permeation tunnel. To elucidate the molecular mechanism of glucose transport and its energetic, a steered molecular dynamics study (SMD) was used. Glucose was pulled from the extracellular end of GLUT4 to the cytoplasm along the pathway using constant velocity pulling method. We identified several key residues within the tunnel that interact directly with either the backbone ring or the hydroxyl groups of glucose. A rotation of glucose molecule was seen near the sugar binding site facilitating the sugar recognition process at the QLS binding site. This study proposes a possible glucose transport pathway and aids the identification of several residues that make direct interactions with glucose during glucose transport. Mutational studies are required to further validate the observation made in this study.

  20. Hemoglobin A1c and mean glucose in patients with type 1 diabetes: analysis of data from the Juvenile Diabetes Research Foundation continuous glucose monitoring randomized trial.

    PubMed

    Wilson, Darrell M; Xing, Dongyuan; Beck, Roy W; Block, Jennifer; Bode, Bruce; Fox, Larry A; Hirsch, Irl; Kollman, Craig; Laffel, Lori; Ruedy, Katrina J; Steffes, Michael; Tamborlane, William V

    2011-03-01

    To determine the relationship between mean sensor glucose concentrations and hemoglobin A(1c) (HbA(1c)) values measured in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications laboratory at the University of Minnesota in a cohort of subjects with type 1 diabetes from the Juvenile Diabetes Research Foundation continuous glucose monitoring randomized trial. Near-continuous glucose sensor data (≥ 4 days/week) were collected for 3 months before a central laboratory-measured HbA(1c) was performed for 252 subjects aged 8-74 years, the majority of whom had stable HbA(1c) values (77% within ± 0.4% of the patient mean). The slope (95% CI) for mean sensor glucose concentration (area under the curve) versus a centrally measured HbA(1c) was 24.4 mg/dL (22.0-26.7) for each 1% change in HbA(1c), with an intercept of -16.2 mg/dL (-32.9 to 0.6). Although the slope did not vary with age or sex, there was substantial individual variability, with mean sensor glucose concentrations ranging from 128 to 187 mg/dL for an HbA(1c) of 6.9-7.1%. The root mean square of the errors between the actual mean sensor glucose concentration versus the value calculated using the regression equation was 14.3 mg/dL, whereas the median absolute difference was 10.1 mg/dL. There is substantial individual variability between the measured versus calculated mean glucose concentrations. Consequently, estimated average glucose concentrations calculated from measured HbA(1c) values should be used with caution.

  1. General aspects of muscle glucose uptake.

    PubMed

    Alvim, Rafael O; Cheuhen, Marcel R; Machado, Silmara R; Sousa, André Gustavo P; Santos, Paulo C J L

    2015-03-01

    Glucose uptake in peripheral tissues is dependent on the translocation of GLUT4 glucose transporters to the plasma membrane. Studies have shown the existence of two major signaling pathways that lead to the translocation of GLUT4. The first, and widely investigated, is the insulin activated signaling pathway through insulin receptor substrate-1 and phosphatidylinositol 3-kinase. The second is the insulin-independent signaling pathway, which is activated by contractions. Individuals with type 2 diabetes mellitus have reduced insulin-stimulated glucose uptake in skeletal muscle due to the phenomenon of insulin resistance. However, those individuals have normal glucose uptake during exercise. In this context, physical exercise is one of the most important interventions that stimulates glucose uptake by insulin-independent pathways, and the main molecules involved are adenosine monophosphate-activated protein kinase, nitric oxide, bradykinin, AKT, reactive oxygen species and calcium. In this review, our main aims were to highlight the different glucose uptake pathways and to report the effects of physical exercise, diet and drugs on their functioning. Lastly, with the better understanding of these pathways, it would be possible to assess, exactly and molecularly, the importance of physical exercise and diet on glucose homeostasis. Furthermore, it would be possible to assess the action of drugs that might optimize glucose uptake and consequently be an important step in controlling the blood glucose levels in diabetic patients, in addition to being important to clarify some pathways that justify the development of drugs capable of mimicking the contraction pathway.

  2. Enzyme Analysis to Determine Glucose Content

    NASA Astrophysics Data System (ADS)

    Carpenter, Charles; Ward, Robert E.

    Enzyme analysis is used for many purposes in food science and technology. Enzyme activity is used to indicate adequate processing, to assess enzyme preparations, and to measure constituents of foods that are enzyme substrates. In this experiment, the glucose content of corn syrup solids is determined using the enzymes, glucose oxidase and peroxidase. Glucose oxidase catalyzes the oxidation of glucose to form hydrogen peroxide (H2O2), which then reacts with a dye in the presence of peroxidase to give a stable colored product.

  3. Maternal glucose response to betamethasone administration.

    PubMed

    Langen, Elizabeth S; Kuperstock, Jessica L; Sung, Joyce F; Taslimi, Mark; Byrne, James; El-Sayed, Yasser Y

    2015-02-01

    This study aims to describe the pattern of maternal glucose response to betamethasone administration using a continuous glucose monitoring system. A prospective observational trial was conducted among women receiving clinically indicated betamethasone between 24 and 34 weeks gestation. At the time of initial betamethasone administration, a continuous glucose monitoring device was inserted which measured interstitial fluid glucose levels every 5 minutes. Glucose levels were monitored for 7 days, until delivery, or until hospital discharge, whichever came first. We recorded the percentage of time women spent above three glucose thresholds: 110, 144, and 180 mg/dL, respectively. A total of 17 women were enrolled at the time of betamethasone administration and data were available for 15 patients. There were 11 nondiabetic and 4 diabetic women. Both diabetic and nondiabetic women had the highest recorded blood glucose readings between 24 and 48 hours after the first injection of betamethasone. In that period, nondiabetic women spent 73, 40, and 17% of the time with blood glucose levels above the 110, 144, and 180 mg/dL thresholds, respectively. Nondiabetic women receiving betamethasone manifest significant hyperglycemia after betamethasone administration. If delivery is imminent, maternal glucose response to betamethasone may need to be monitored to prevent possible neonatal hypoglycemia. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  4. Glucose metabolism in rat retinal pigment epithelium.

    PubMed

    Coffe, Víctor; Carbajal, Raymundo C; Salceda, Rocío

    2006-01-01

    The retinal pigment epithelium (RPE) is the major transport pathway for exchange of metabolites and ions between choroidal blood supply and the neural retina. To gain insight into the mechanisms controlling glucose metabolism in RPE and its possible relationship to retinopathy, we studied the influence of different glucose concentrations on glycogen and lactate levels and CO(2) production in RPE from normal and streptozotocin-treated diabetic rats. Incubation of normal RPE in the absence of glucose caused a decrease in lactate production and glycogen content. In normal RPE, increasing glucose concentrations from 5.6 mM to 30 mM caused a four-fold increase in glucose accumulation and CO(2) yield, as well as reduction in lactate and glycogen production. In RPE from diabetic rats glucose accumulation did not increase in the presence of high glucose substrate, but it showed a four- and a seven-fold increase in CO(2) production through the mitochondrial and pentose phosphate pathways, respectively. We found high glycogen levels in RPE which can be used as an energy reserve for RPE itself and/or neural retina. Findings further show that the RPE possesses a high oxidative capacity. The large increase in glucose shunting to the pentose phosphate pathway in diabetic retina exposed to high glucose suggests a need for reducing capacity, consistent with increased oxidative stress.

  5. Glucose Transporters in Cardiac Metabolism and Hypertrophy

    PubMed Central

    Shao, Dan; Tian, Rong

    2016-01-01

    The heart is adapted to utilize all classes of substrates to meet the high-energy demand, and it tightly regulates its substrate utilization in response to environmental changes. Although fatty acids are known as the predominant fuel for the adult heart at resting stage, the heart switches its substrate preference toward glucose during stress conditions such as ischemia and pathological hypertrophy. Notably, increasing evidence suggests that the loss of metabolic flexibility associated with increased reliance on glucose utilization contribute to the development of cardiac dysfunction. The changes in glucose metabolism in hypertrophied hearts include altered glucose transport and increased glycolysis. Despite the role of glucose as an energy source, changes in other nonenergy producing pathways related to glucose metabolism, such as hexosamine biosynthetic pathway and pentose phosphate pathway, are also observed in the diseased hearts. This article summarizes the current knowledge regarding the regulation of glucose transporter expression and translocation in the heart during physiological and pathological conditions. It also discusses the signaling mechanisms governing glucose uptake in cardiomyocytes, as well as the changes of cardiac glucose metabolism under disease conditions. PMID:26756635

  6. Cost averaging techniques for robust control of flexible structural systems

    NASA Technical Reports Server (NTRS)

    Hagood, Nesbitt W.; Crawley, Edward F.

    1991-01-01

    Viewgraphs on cost averaging techniques for robust control of flexible structural systems are presented. Topics covered include: modeling of parameterized systems; average cost analysis; reduction of parameterized systems; and static and dynamic controller synthesis.

  7. Patient and hospital characteristics associated with average length of stay.

    PubMed

    Shi, L

    1996-01-01

    This article examines the relationship between patient, hospital characteristics, and hospital average length of stay controlling for major disease categories. A constellation of patient and physician factors were found to be significantly associated with average hospital length of stay.

  8. Real-time instrument averages 100 data sets

    NASA Technical Reports Server (NTRS)

    Birchenough, A. G.; Rice, W. J.; Toma, G. B.

    1979-01-01

    Instrument generates average curve of 100 consecutive cycles of any function that occurs as time varying electrical signal. Device has been used to average parameters on 1975 Chevrolet V-8 engine, and on Continental six cylinder aircraft engine.

  9. Effect of a Prolonged Altitude Expedition on Glucose Tolerance and Abdominal Fatness

    ERIC Educational Resources Information Center

    Chen, Mu-Tsung; Lee, Wen-Chih; Chen, Shih-Chang; Chen, Chiu-Chou; Chen, Chung-Yu; Lee, Shin-Da; Jensen, Jorgen; Kuo, Chia-Hua

    2010-01-01

    In the present study, we investigated the effect of a long-term mountain expedition on glucose tolerance and insulin action. Twelve registered mountaineers ages 31 years (SD = 1.1) participated in a 25-day expedition at a 2,200-3,800-m altitude with an average duration of 8 hr per day. Arterial oxygen saturation (SaO[subscript 2]) was…

  10. Effect of a Prolonged Altitude Expedition on Glucose Tolerance and Abdominal Fatness

    ERIC Educational Resources Information Center

    Chen, Mu-Tsung; Lee, Wen-Chih; Chen, Shih-Chang; Chen, Chiu-Chou; Chen, Chung-Yu; Lee, Shin-Da; Jensen, Jorgen; Kuo, Chia-Hua

    2010-01-01

    In the present study, we investigated the effect of a long-term mountain expedition on glucose tolerance and insulin action. Twelve registered mountaineers ages 31 years (SD = 1.1) participated in a 25-day expedition at a 2,200-3,800-m altitude with an average duration of 8 hr per day. Arterial oxygen saturation (SaO[subscript 2]) was…

  11. Naked eye detection of glucose in urine using glucose oxidase immobilized gold nanoparticles.

    PubMed

    Radhakumary, Changerath; Sreenivasan, Kunnatheeri

    2011-04-01

    Colloidal gold is extensively used for molecular sensing because of the flexibilities it offers in terms of modification of the gold nanoparticle surface with a variety of functional groups using thiol chemistry. We describe a simple assay that allows the visual detection of glucose in aqueous samples and demonstrates its applicability by estimating glucose in urine. To enable the glucose detection, we functionalized the thiol capped gold nanoparticles with glucose oxidase, the enzyme specific to β-D glucose, using carbodiimide chemistry. The visible color change of the GOD-functionalized gold nanoparticles from red to blue on interaction with glucose is the principle applied here for the sensing of urine glucose level. The solution turns blue when the glucose concentration exceeds 100 μg/mL. The approach depicted here seems to be important, particularly in third world countries where high tech diagnostics aids are inaccessible to the bulk of the population.

  12. Diauxic Growth of Azotobacter vinelandii on Galactose and Glucose: Regulation of Glucose Transport by Another Hexose.

    PubMed

    Wong, T Y; Pei, H; Bancroft, K; Childers, G W

    1995-02-01

    The growth curve of Azotobacter vinelandii was biphasic when the organism was grown in a medium containing a mixture of galactose and glucose. Galactose was the primary carbon source; glucose was also consumed, but the rate at which it was consumed was lower than the rate at which galactose was consumed during the first phase of growth. Metabolic pathways for both sugars were induced. Cell cultures exhibited a second lag period as galactose was depleted. The length of this lag phase varied from 2 to 10 h depending on the pregrowth history of the cells. The second log growth phase occurred at the expense of the remaining glucose in the medium and was accompanied by induction of the high-maximum rate of metabolism glucose-induced glucose permease and increases in the levels of glucose metabolic enzymes. The second lag phase of diauxie may have been due to the time required for induction of the glucose-induced glucose permease.

  13. A tale of two compartments: interstitial versus blood glucose monitoring.

    PubMed

    Cengiz, Eda; Tamborlane, William V

    2009-06-01

    Self-monitoring of blood glucose was described as one of the most important advancements in diabetes management since the invention of insulin in 1920. Recent advances in glucose sensor technology for measuring interstitial glucose concentrations have challenged the dominance of glucose meters in diabetes management, while raising questions about the relationships between interstitial and blood glucose levels. This article will review the differences between interstitial and blood glucose and some of the challenges in measuring interstitial glucose levels accurately.

  14. Synthesis of Averaged Circuit Models for Switched Power Converters

    DTIC Science & Technology

    1989-11-01

    November 1989 LIDS-P-1930 Synthesis of Averaged Circuit Models for Switched Power Converters * Seth R. Sanders George C. Verghese Abstract Averaged... circuit models for switching power converters are useful for purposes of analysis and obtaining engineering intuition into the operation of these...switched circuits . This paper develops averaged circuit models for switching converters using an in-place averaging method. The method proceeds in a

  15. Stokes-Mueller matrix polarimetry system for glucose sensing

    NASA Astrophysics Data System (ADS)

    Phan, Quoc-Hung; Lo, Yu-Lung

    2017-05-01

    A Stokes-Mueller matrix polarimetry system consisting of a polarization scanning generator (PSG) and a high-accuracy Stokes polarimeter is used to sense the glucose concentration in aqueous solutions with and without scattering effects, respectively. In the proposed system, an electro-optic (EO) modulator driven by a saw-tooth waveform voltage is used to perform full state of polarization (linear/circular) scanning, while a self-built Stokes polarimeter is used to obtain dynamic measurements of the output polarized light intensity. It is shown that the measured output Stokes vectors have an accuracy of 10-4, i.e., one order higher than that of existing commercial Stokes polarimeters. The experimental results show that the optical rotation angle varies linearly with the glucose concentration over the range of 0-0.5 g/dl. Moreover, glucose sensing is successfully achieved at concentrations as low as 0.02 g/dl with a resolution of 10-6 deg/mm and an average deviation of 10-4 deg. In general, the polarimetry system proposed in this study provides a fast and reliable method for measuring the Stokes vectors, and thus has significant potential for biological sensing applications.

  16. Seasonal Temperature Changes Do Not Affect Cardiac Glucose Metabolism

    PubMed Central

    Schildt, Jukka; Loimaala, Antti; Hippeläinen, Eero; Nikkinen, Päivi; Ahonen, Aapo

    2015-01-01

    FDG-PET/CT is widely used to diagnose cardiac inflammation such as cardiac sarcoidosis. Physiological myocardial FDG uptake often creates a problem when assessing the possible pathological glucose metabolism of the heart. Several factors, such as fasting, blood glucose, and hormone levels, influence normal myocardial glucose metabolism. The effect of outdoor temperature on myocardial FDG uptake has not been reported before. We retrospectively reviewed 29 cancer patients who underwent PET scans in warm summer months and again in cold winter months. We obtained myocardial, liver, and mediastinal standardized uptake values (SUVs) as well as quantitative cardiac heterogeneity and the myocardial FDG uptake pattern. We also compared age and body mass index to other variables. The mean myocardial FDG uptake showed no significant difference between summer and winter months. Average outdoor temperature did not correlate significantly with myocardial SUVmax in either summer or winter. The heterogeneity of myocardial FDG uptake did not differ significantly between seasons. Outdoor temperature seems to have no significant effect on myocardial FDG uptake or heterogeneity. Therefore, warming the patients prior to attending cardiac PET studies in order to reduce physiological myocardial FDG uptake seems to be unnecessary. PMID:26858844

  17. Sample Size Bias in Judgments of Perceptual Averages

    ERIC Educational Resources Information Center

    Price, Paul C.; Kimura, Nicole M.; Smith, Andrew R.; Marshall, Lindsay D.

    2014-01-01

    Previous research has shown that people exhibit a sample size bias when judging the average of a set of stimuli on a single dimension. The more stimuli there are in the set, the greater people judge the average to be. This effect has been demonstrated reliably for judgments of the average likelihood that groups of people will experience negative,…

  18. 7 CFR 760.640 - National average market price.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false National average market price. 760.640 Section 760.640....640 National average market price. (a) The Deputy Administrator will establish the National Average Market Price (NAMP) using the best sources available, as determined by the Deputy Administrator, which...

  19. 7 CFR 760.640 - National average market price.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 7 2011-01-01 2011-01-01 false National average market price. 760.640 Section 760.640....640 National average market price. (a) The Deputy Administrator will establish the National Average Market Price (NAMP) using the best sources available, as determined by the Deputy Administrator, which...

  20. 7 CFR 51.2561 - Average moisture content.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Average moisture content. 51.2561 Section 51.2561... STANDARDS) United States Standards for Grades of Shelled Pistachio Nuts § 51.2561 Average moisture content. (a) Determining average moisture content of the lot is not a requirement of the grades, except when...

  1. 7 CFR 51.577 - Average midrib length.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Average midrib length. 51.577 Section 51.577... STANDARDS) United States Standards for Celery Definitions § 51.577 Average midrib length. Average midrib... attachment at the base to the first node....

  2. 7 CFR 51.577 - Average midrib length.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Average midrib length. 51.577 Section 51.577... STANDARDS) United States Standards for Celery Definitions § 51.577 Average midrib length. Average midrib... attachment at the base to the first node....

  3. Perturbation resilience and superiorization methodology of averaged mappings

    NASA Astrophysics Data System (ADS)

    He, Hongjin; Xu, Hong-Kun

    2017-04-01

    We first prove the bounded perturbation resilience for the successive fixed point algorithm of averaged mappings, which extends the string-averaging projection and block-iterative projection methods. We then apply the superiorization methodology to a constrained convex minimization problem where the constraint set is the intersection of fixed point sets of a finite family of averaged mappings.

  4. Averaging and Globalising Quotients of Informetric and Scientometric Data.

    ERIC Educational Resources Information Center

    Egghe, Leo; Rousseau, Ronald

    1996-01-01

    Discussion of impact factors for "Journal Citation Reports" subject categories focuses on the difference between an average of quotients and a global average, obtained as a quotient of averages. Applications in the context of informetrics and scientometrics are given, including journal prices and subject discipline influence scores.…

  5. 40 CFR 1033.710 - Averaging emission credits.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Averaging emission credits. 1033.710 Section 1033.710 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION... Averaging emission credits. (a) Averaging is the exchange of emission credits among your engine families...

  6. 7 CFR 51.2561 - Average moisture content.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Average moisture content. 51.2561 Section 51.2561 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards....2561 Average moisture content. (a) Determining average moisture content of the lot is not a...

  7. 7 CFR 51.2561 - Average moisture content.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Average moisture content. 51.2561 Section 51.2561... STANDARDS) United States Standards for Grades of Shelled Pistachio Nuts § 51.2561 Average moisture content. (a) Determining average moisture content of the lot is not a requirement of the grades, except...

  8. 7 CFR 51.2561 - Average moisture content.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Average moisture content. 51.2561 Section 51.2561 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards....2561 Average moisture content. (a) Determining average moisture content of the lot is not a...

  9. 7 CFR 51.2548 - Average moisture content determination.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Average moisture content determination. 51.2548 Section 51.2548 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE... Nuts in the Shell § 51.2548 Average moisture content determination. (a) Determining average...

  10. 7 CFR 51.2561 - Average moisture content.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Average moisture content. 51.2561 Section 51.2561... STANDARDS) United States Standards for Grades of Shelled Pistachio Nuts § 51.2561 Average moisture content. (a) Determining average moisture content of the lot is not a requirement of the grades, except...

  11. 7 CFR 51.2548 - Average moisture content determination.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Average moisture content determination. 51.2548 Section 51.2548 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE... Nuts in the Shell § 51.2548 Average moisture content determination. (a) Determining average...

  12. 78 FR 16711 - Annual Determination of Average Cost of Incarceration

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-18

    ... of Prisons Annual Determination of Average Cost of Incarceration AGENCY: Bureau of Prisons, Justice. ACTION: Notice. SUMMARY: The fee to cover the average cost of incarceration for Federal inmates in Fiscal Year 2011 was $28,893.40. The average annual cost to confine an inmate in a Community...

  13. Averaging and Globalising Quotients of Informetric and Scientometric Data.

    ERIC Educational Resources Information Center

    Egghe, Leo; Rousseau, Ronald

    1996-01-01

    Discussion of impact factors for "Journal Citation Reports" subject categories focuses on the difference between an average of quotients and a global average, obtained as a quotient of averages. Applications in the context of informetrics and scientometrics are given, including journal prices and subject discipline influence scores.…

  14. Sample Size Bias in Judgments of Perceptual Averages

    ERIC Educational Resources Information Center

    Price, Paul C.; Kimura, Nicole M.; Smith, Andrew R.; Marshall, Lindsay D.

    2014-01-01

    Previous research has shown that people exhibit a sample size bias when judging the average of a set of stimuli on a single dimension. The more stimuli there are in the set, the greater people judge the average to be. This effect has been demonstrated reliably for judgments of the average likelihood that groups of people will experience negative,…

  15. 20 CFR 404.221 - Computing your average monthly wage.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Computing your average monthly wage. 404.221... DISABILITY INSURANCE (1950- ) Computing Primary Insurance Amounts Average-Monthly-Wage Method of Computing Primary Insurance Amounts § 404.221 Computing your average monthly wage. (a) General. Under the...

  16. 20 CFR 404.220 - Average-monthly-wage method.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Average-monthly-wage method. 404.220 Section... INSURANCE (1950- ) Computing Primary Insurance Amounts Average-Monthly-Wage Method of Computing Primary Insurance Amounts § 404.220 Average-monthly-wage method. (a) Who is eligible for this method. You must...

  17. 40 CFR 1042.710 - Averaging emission credits.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Averaging emission credits. 1042.710..., Banking, and Trading for Certification § 1042.710 Averaging emission credits. (a) Averaging is the exchange of emission credits among your engine families. (b) You may certify one or more engine families to...

  18. Impact of Glucose Tolerance Status, Sex, and Body Size on Glucose Absorption Patterns During OGTTs

    PubMed Central

    Færch, Kristine; Pacini, Giovanni; Nolan, John J.; Hansen, Torben; Tura, Andrea; Vistisen, Dorte

    2013-01-01

    OBJECTIVE We studied whether patterns of glucose absorption during oral glucose tolerance tests (OGTTs) were abnormal in individuals with impaired glucose regulation and whether they were related to sex and body size (height and fat-free mass). We also examined how well differences in insulin sensitivity and β-cell function measured by gold-standard tests were reflected in the corresponding OGTT-derived estimates. RESEARCH DESIGN AND METHODS With validated methods, various aspects of glucose absorption were estimated from 12-point, 3-h, 75-g OGTTs in 66 individuals with normal glucose tolerance (NGT), isolated impaired fasting glucose (i-IFG), or isolated impaired glucose tolerance (i-IGT). Insulin sensitivity and β-cell function were measured with the euglycemic-hyperinsulinemic clamp and intravenous glucose tolerance tests, respectively. Surrogate markers of both conditions were calculated from OGTTs. RESULTS More rapid glucose absorption (P ≤ 0.036) and reduced late glucose absorption (P ≤ 0.039) were observed in the i-IFG group relative to NGT and i-IGT groups. Women with i-IGT had a lower early glucose absorption than did men with i-IGT (P = 0.041); however, this difference did not persist when differences in body size were taken into account (P > 0.28). Faster glucose absorption was related to higher fasting (P = 0.001) and lower 2-h (P = 0.001) glucose levels and to greater height and fat-free mass (P < 0.001). All OGTT-derived measures of insulin sensitivity, but only one of three measures of β-cell function, reflected the differences for these parameters between those with normal and impaired glucose regulation as measured by gold-standard tests. CONCLUSIONS Glucose absorption patterns during an OGTT are significantly related to plasma glucose levels and body size, which should be taken into account when estimating β-cell function from OGTTs in epidemiological studies. PMID:24062321

  19. Mechanical stress and glucose concentration modulate glucose transport in cultured rat podocytes.

    PubMed

    Lewko, Barbara; Bryl, Ewa; Witkowski, Jacek M; Latawiec, Elzbieta; Angielski, Stefan; Stepinski, Jan

    2005-02-01

    Recent studies show that mechanical stress modifies both morphology and protein expression in podocytes. Ambient glucose is another factor modulating protein synthesis in these cells. In diabetes, podocytes experience elevated glucose concentrations as well as mechanical strain generated by high intracapillary pressures. Both these factors are responsible for podocyte injury, leading to impairment of kidney glomerular function. In the present study, we examined the effects of glucose concentration and mechanical stress on glucose uptake in podocytes. Following a 24 h pre-incubation in low (2.5 mM, LG), normal (5.6 mM, NG) or high (30 mM, HG) glucose media, cultured rat podocytes were exposed to 4 h mechanical stress. We used the labelled glucose analogue, [3H]2-deoxy-D-glucose, to measure glucose uptake. The distribution of facilitative glucose transporters GLUT2 and GLUT4 was assessed by flow cytometry. In the control (static) cells, glucose uptake was similar in the three glucose groups. In mechanically stressed podocytes, glucose uptake increased 2-fold in the LG and NG groups but increased 3-fold in the HG group. In the NG cells, mechanical load increased the membrane expression of GLUT2 and reduced the membrane-bound GLUT4. In stretched HG cells, the membrane expression of both GLUT2 and GLUT4 was decreased. High glucose decreased the plasma membrane GLUT2 content in the stretched cells, whereas both static and stretched podocytes showed an elevation in GLUT4. Mechanical stress potentiated glucose uptake in podocytes and this effect was enhanced by high ambient glucose. The decreased expression of GLUT2 and GLUT4 on the surface of stretched cells suggests that the activity of other glucose transporters may be regulated by mechanical stress in podocytes.

  20. CMOS image sensor-based implantable glucose sensor using glucose-responsive fluorescent hydrogel

    PubMed Central

    Tokuda, Takashi; Takahashi, Masayuki; Uejima, Kazuhiro; Masuda, Keita; Kawamura, Toshikazu; Ohta, Yasumi; Motoyama, Mayumi; Noda, Toshihiko; Sasagawa, Kiyotaka; Okitsu, Teru; Takeuchi, Shoji; Ohta, Jun

    2014-01-01

    A CMOS image sensor-based implantable glucose sensor based on an optical-sensing scheme is proposed and experimentally verified. A glucose-responsive fluorescent hydrogel is used as the mediator in the measurement scheme. The wired implantable glucose sensor was realized by integrating a CMOS image sensor, hydrogel, UV light emitting diodes, and an optical filter on a flexible polyimide substrate. Feasibility of the glucose sensor was verified by both in vitro and in vivo experiments. PMID:25426316

  1. Glucose-6-Phosphate Dehydrogenase Deficiency.

    PubMed

    Luzzatto, Lucio; Nannelli, Caterina; Notaro, Rosario

    2016-04-01

    G6PD is a housekeeping gene expressed in all cells. Glucose-6-phosphate dehydrogenase (G6PD) is part of the pentose phosphate pathway, and its main physiologic role is to provide NADPH. G6PD deficiency, one of the commonest inherited enzyme abnormalities in humans, arises through one of many possible mutations, most of which reduce the stability of the enzyme and its level as red cells age. G6PD-deficient persons are mostly asymptomatic, but they can develop severe jaundice during the neonatal period and acute hemolytic anemia when they ingest fava beans or when they are exposed to certain infections or drugs. G6PD deficiency is a global health issue.

  2. Analytic characteristics of three Bayer contour blood glucose monitoring systems in neonates.

    PubMed

    Dietzen, Dennis J; Nenninger, Denise A; Simmons, David A; Pardo, Scott; Pandya, Mauli; Fullam, Jeanellen

    2015-03-01

    Hypoglycemia in infants is common, is difficult to recognize, and may lead to permanent neurologic impairment. Low glucose concentrations and high hematocrits in newborns pose significant analytic challenges for whole blood glucose meters. Three Bayer glucose monitoring systems were evaluated using 211 blood samples from 162 neonates (age range 5 hours to 29 days, median age 3 days). Hematocrit and whole blood glucose were determined in heparinized whole blood, and plasma glucose was determined using the Roche Cobas 6000. Accuracy was evaluated against plasma concentrations using ISO 15197:2013 and CLSI POCT 12-A3 criteria. Glucose imprecision on the Cobas system was 1.8-2.6% (CV) from 26-610 mg/dL. Imprecision across all meter systems was 2.8% (CV) at 130 mg/dL. Glucose concentrations, hematocrit, and total bilirubin ranged from 20-150 mg/dL, 18 -75%, and 0.5-19.6 mg/dL, respectively. Linear regression analysis of whole blood versus plasma for the 3 combined systems yielded an average slope of 1.06 and correlation coefficient greater than 0.980. Bias between the Contour and Cobas was not significantly correlated with hematocrit. Greater than 99% of meter results were within 15 mg/dL and 20% of plasma results at glucose concentrations ≤ 75 and > 75 mg/dL, respectively. Of meter results, 97% were within 12.5 mg/dL of plasma results at concentrations ≤ 100 mg/dL, while 96% of meter results were within 12.5% of plasma at concentrations > 100 mg/dL. The Bayer CONTOUR Blood Glucose Monitoring Systems exceed ISO 15197:2013 and CLSI criteria in neonatal blood samples.

  3. Effects of exenatide and liraglutide on 24-hour glucose fluctuations in type 2 diabetes.

    PubMed

    Nagakura, Jo; Yamakawa, Tadashi; Taguri, Masataka; Tsuchiya, Hirohisa; Shigematsu, Erina; Suzuki, Jun; Morita, Satoshi; Kadonosono, Kazuaki; Terauchi, Yasuo

    2016-01-01

    We evaluated the influence of short-term treatment with exenatide twice daily or liraglutide once daily on daily blood glucose fluctuations in 40 patients with type 2 diabetes inadequately controlled by sulfonylureas. The patients in a multicenter, open-label trial were randomly assigned to receive add-on exenatide (10 μg/day, n = 21) or add-on liraglutide (0.3-0.9 mg/day, n = 19), and underwent 24-hour continuous subcutaneous glucose monitoring. There was no significant between-group difference in glucose fluctuations during the day, as assessed by calculating mean amplitude of glycemic excursion (MAGE) and standard deviation (SD). However, the mean blood glucose levels at 3 hours after breakfast and dinner were significantly lower in the exenatide group than the liraglutide group (breakfast: 127.3 ± 24.1 vs. 153.4 ± 28.7 mg/dL; p = 0.006, dinner: 108.7 ± 17.3 vs. 141.9 ± 24.2 mg/dL; p < 0.001). In contrast, mean blood glucose levels and their SD were significantly lower between 0000 h and 0600 h in the liraglutide group than the exenatide group (average glucose: 126.9 ± 27.1 vs. 107.1 ± 24.0 mg/dL; p = 0.029, SD: 15.2 ± 10.5 vs. 8.7 ± 3.8; p = 0.020). Both groups had similar glucose fluctuations despite differences in 24-hour blood glucose profiles. Therefore, each of these agents may have advantages or disadvantages and should be selected according to the blood glucose profile of the patient.

  4. The effectiveness of glucose, sucrose, and fructose in treating hypoglycemia in children with type 1 diabetes.

    PubMed

    Husband, Allison C; Crawford, Susan; McCoy, Lesley A; Pacaud, Danièle

    2010-05-01

    There is a lack of evidence regarding the most effective treatment option for managing naturally occurring hypoglycemia in children with type 1 diabetes. The objectives of this study were (i) to determine if sucrose and fructose are equally effective as glucose in the treatment of spontaneous hypoglycemia in children with type 1 diabetes; and (ii) to determine prestudy and poststudy hypoglycemia treatment preferences. Thirty-three subjects [aged 5.4-15.5 yr and average duration of type 1 diabetes of 3.1 yr (SD = 2.3)] participated in a randomized, crossover design. The main outcome was the effectiveness of treatment as defined by a blood glucose meter reading that was > or = 4.0 mmol/L 15 min after treatment. Each subject treated five hypoglycemic events with each treatment type: glucose (BD Glucose Tablets), sucrose (Skittles), and fructose (Fruit to Go). There was a significant difference between the effectiveness of the three treatments [Wilk's Lambda F(2,28) = 8.64, p = 0.001]. No significant difference between treatment with glucose and treatment with sucrose was noted, but the treatment effectiveness for fructose was significantly lower than sucrose [F (1,29) = 16.09, p < 0.001] and glucose [F (1,29) = 15.64, p < 0.001]. The preferred treatment choices before the study were as follows: 36% glucose, 18% sucrose, and 33% fructose sources. Poststudy, 52% of children preferred the same treatment, which was effective (glucose or sucrose), followed by 35% who changed their preference to an effective treatment. Skittles are as effective in treating hypoglycemia as more expensive BD Glucose Tablets in children with type 1 diabetes.

  5. Thermoinactivation Mechanism of Glucose Isomerase

    NASA Astrophysics Data System (ADS)

    Lim, Leng Hong; Saville, Bradley A.

    In this article, the mechanisms of thermoinactivation of glucose isomerase (GI) from Streptomyces rubiginosus (in soluble and immobilized forms) were investigated, particularly the contributions of thiol oxidation of the enzyme's cysteine residue and a "Maillard-like" reaction between the enzyme and sugars in high fructose corn syrup (HFCS). Soluble GI (SGI) was successfully immobilized on silica gel (13.5 μm particle size), with an activity yield between 20 and 40%. The immobilized GI (IGI) has high enzyme retention on the support during the glucose isomerization process. In batch reactors, SGI (half-life =145 h) was more stable than IGI (half-life=27 h) at 60°C in HFCS, whereas at 80°C, IGI (half-life=12 h) was more stable than SGI (half-life=5.2 h). IGI was subject to thiol oxidation at 60°C, which contributed to the enzyme's deactivation. IGI was subject to thiol oxidation at 80°C, but this did not contribute to the deactivation of the enzyme. SGI did not undergo thiol oxidation at 60°C, but at 80°C SGI underwent severe precipitation and thiol oxidation, which caused the enzyme to deactivate. Experimental results show that immobilization suppresses the destablizing effect of thiol oxidation on GI. A "Maillard-like" reaction between SGI and the sugars also caused SGI thermoinactivation at 60, 70, and 80°C, but had minimal effect on IGI. At 60 and 80°C, IGI had higher thermostability in continuous reactors than in batch reactors, possibily because of reduced contact with deleterious compounds in HFCS.

  6. Evidence that humans can taste glucose polymers.

    PubMed

    Lapis, Trina J; Penner, Michael H; Lim, Juyun

    2014-11-01

    The sense of taste is essential for identifying potential nutrients and poisons. Accordingly, specialized taste receptor cells are activated by food-derived chemicals. Because of its importance in the human diet, oral detection of starch, or its degradation products, would presumably be highly beneficial. Yet, it has long been assumed that simple sugars are the only class of carbohydrates that humans can taste. There is, however, considerable evidence that rodents can taste starch degradation products (i.e., glucose polymers composed of maltooligosaccharides with 3-10 glucose units and maltopolysaccharides with >10 glucose units) and that their detection is independent of the sweet taste receptor, T1R2/T1R3. The present study was designed 1) to measure individual differences in human taste perception of glucose polymers, 2) to understand individual differences in the activity of salivary α-amylase, and 3) to investigate the role that salivary α-amylase may play in the taste perception of glucose polymers. In the first experiment, subjects rated taste intensity of glucose, sucrose, NaCl, and glucose polymers of various chain lengths, while their noses were clamped. Saliva samples from the subjects were also collected and their salivary α-amylase activity was assayed. Results showed that the perceived intensities of glucose, sucrose, and NaCl were significantly correlated (r = 0.75-0.85, P < 0.001), but not with the longer chain glucose polymers, whereas intensity ratings of all glucose polymers were highly correlated with one another (r = 0.69-0.82, P < 0.001). Importantly, despite large individual differences in α-amylase activity among subjects, responsiveness to glucose polymers did not significantly differ between individuals with high and low α-amylase activity. A follow up experiment was conducted to quantify the concentrations of glucose and maltose that were inherently present in the glucose polymer stimuli and to determine whether the amounts were

  7. Hypothalamic glucose sensing: making ends meet

    PubMed Central

    Routh, Vanessa H.; Hao, Lihong; Santiago, Ammy M.; Sheng, Zhenyu; Zhou, Chunxue

    2014-01-01

    The neuroendocrine system governs essential survival and homeostatic functions. For example, growth is needed for development, thermoregulation maintains optimal core temperature in a changing environment, and reproduction ensures species survival. Stress and immune responses enable an organism to overcome external and internal threats while the circadian system regulates arousal and sleep such that vegetative and active functions do not overlap. All of these functions require a significant portion of the body's energy. As the integrator of the neuroendocrine system, the hypothalamus carefully assesses the energy status of the body in order to appropriately partition resources to provide for each system without compromising the others. While doing so the hypothalamus must ensure that adequate glucose levels are preserved for brain function since glucose is the primary fuel of the brain. To this end, the hypothalamus contains specialized glucose sensing neurons which are scattered throughout the nuclei controlling distinct neuroendocrine functions. We hypothesize that these neurons play a key role in enabling the hypothalamus to partition energy to meet these peripheral survival needs without endangering the brain's glucose supply. This review will first describe the varied mechanisms underlying glucose sensing in neurons within discrete hypothalamic nuclei. We will then evaluate the way in which peripheral energy status regulates glucose sensitivity. For example, during energy deficit such as fasting specific hypothalamic glucose sensing neurons become sensitized to decreased glucose. This increases the gain of the information relay when glucose availability is a greater concern for the brain. Finally, changes in glucose sensitivity under pathological conditions (e.g., recurrent insulin-hypoglycemia, diabetes) will be addressed. The overall goal of this review is to place glucose sensing neurons within the context of hypothalamic control of neuroendocrine function

  8. Development of a Robust Optical Glucose Sensor

    NASA Astrophysics Data System (ADS)

    Cote, Gerard Laurence

    1990-01-01

    The long term objective of this research was the development of a noninvasive, optically-based, polarimetric sensor to monitor in vivo glucose concentrations. The goal of diabetes therapy is to approximate the 24-hour blood glucose profile of a normal individual. There have been major advances in the development of reliable, versatile, and accurate pumps for the delivery of insulin to diabetic patients and in the development of control algorithms for closed-loop insulin delivery, however, there remain major obstacles to the development of clinically useful, continuous glucose sensors. The development of an accurate noninvasive glucose sensor would have significant application in the diagnosis and management of diabetes mellitis both in conjunction with, and independent of, the glucose pump controller applications. The linear polarization vector of light routes when it interacts with an optically active material such as glucose. The amount of rotation of polarization is directly proportional to the glucose concentration and to the path length. The ability to quantitate blood glucose levels for the limited available path length in our primary sensing site, namely, the anterior chamber of the eye, therefore depends on the signal-to-noise ratio of the polarization detector. Our primary research focused on the development and testing of a prototype optical polarimetry system using D + glucose solution in a test cell, as well as using an enucleated human eye to assess the sensitivity of the system to measure physiologic glucose levels for the approximate one centimeter path length present in the anterior chamber of the eye. Our research has led to the development of a true phase technique in which helium neon laser light was coupled through a rotating linear polarizer along with two stationary linear polarizers and two detectors to produce reference and signal outputs whose amplitudes varied sinusoidally and whose phase was proportional to the rotation of light caused by

  9. Pseudo-bi-enzyme glucose sensor: ZnS hollow spheres and glucose oxidase concerted catalysis glucose.

    PubMed

    Shuai, Ying; Liu, Changhua; Wang, Jia; Cui, Xiaoyan; Nie, Ling

    2013-06-07

    This work creatively uses peroxidase-like ZnS hollow spheres (ZnS HSs) to cooperate with glucose oxidase (GOx) for glucose determinations. This approach is that the ZnS HSs electrocatalytically oxidate the enzymatically generated H2O2 to O2, and then the O2 circularly participates in the previous glucose oxidation by glucose oxidase. Au nanoparticles (AuNPs) and carbon nanotubes (CNTs) are used as electron transfer and enzyme immobilization matrices, respectively. The biosensor of glucose oxidase-carbon nanotubes-Au nanoparticles-ZnS hollow spheres-gold electrode (GOx-CNT-AuNPs-ZnS HSs-GE) exhibits a rapid response, a low detection limit (10 μM), a wide linear range (20 μM to 7 mM) as well as good anti-interference, long-term longevity and reproducibility.

  10. Two glucose sensing/signaling pathways stimulate glucose-induced inactivation of maltose permease in Saccharomyces.

    PubMed Central

    Jiang, H; Medintz, I; Michels, C A

    1997-01-01

    Glucose is a global metabolic regulator in Saccharomyces. It controls the expression of many genes involved in carbohydrate utilization at the level of transcription, and it induces the inactivation of several enzymes by a posttranslational mechanism. SNF3, RGT2, GRR1 and RGT1 are known to be involved in glucose regulation of transcription. We tested the roles of these genes in glucose-induced inactivation of maltose permease. Our results suggest that at least two signaling pathways are used to monitor glucose levels. One pathway requires glucose sensor transcript and the second pathway is independent of glucose transport. Rgt2p, which along with Snf3p monitors extracellular glucose levels, appears to be the glucose sensor for the glucose-transport-independent pathway. Transmission of the Rgt2p-dependent signal requires Grr1p. RGT2 and GRR1 also play a role in regulating the expression of the HXT genes, which appear to be the upstream components of the glucose-transport-dependent pathway regulating maltose permease inactivation. RGT2-1, which was identified as a dominant mutation causing constitutive expression of several HXT genes, causes constitutive proteolysis of maltose permease, that is, in the absence of glucose. A model of these glucose sensing/signaling pathways is presented. Images PMID:9243508

  11. Glucose effectiveness is the major determinant of intravenous glucose tolerance in the rat.

    PubMed

    McArthur, M D; You, D; Klapstein, K; Finegood, D T

    1999-04-01

    To determine the importance of insulin for glucose disposal during an intravenous glucose tolerance test in rats, experiments were performed in four cohorts of conscious unrestrained rats fasted overnight. In cohorts 1-3, a bolus of tracer ([3-3H]glucose, 50 microCi) was given alone, with glucose (0.3 g/kg) to induce an endogenous insulin response (approximately 1,100 pmol/l), or with exogenous insulin to give physiological (1,700 pmol/l) or supraphysiological (12,000 pmol/l) plasma levels. Raising plasma insulin within the physiological range had no effect (P > 0.05), but supraphysiological levels induced hypoglycemia (7.3 +/- 0.2 to 3.6 +/- 0.2 mmol/l) and increased [3H]glucose disappearance rate (P < 0.001). In cohort 4, a primed, continuous tracer infusion was started 120 min before saline or glucose bolus injection. [3H]glucose levels fell 15-20%, and the disappearance rate rose 36% (P < 0.05) after glucose injection. These results indicate that in fasted rats a tracer bolus injection protocol is not sufficiently sensitive to measure the physiological effect of insulin released in response to a bolus of glucose because this effect of insulin is small. Glucose itself is the predominant mediator of glucose disposal after a bolus of glucose in the fasted rat.

  12. Feedback Regulation of Glucose Transporter Gene Transcription in Kluyveromyces lactis by Glucose Uptake

    PubMed Central

    Milkowski, C.; Krampe, S.; Weirich, J.; Hasse, V.; Boles, E.; Breunig, K. D.

    2001-01-01

    In the respirofermentative yeast Kluyveromyces lactis, only a single genetic locus encodes glucose transporters that can support fermentative growth. This locus is polymorphic in wild-type isolates carrying either KHT1 and KHT2, two tandemly arranged HXT-like genes, or RAG1, a low-affinity transporter gene that arose by recombination between KHT1 and KHT2. Here we show that KHT1 is a glucose-induced gene encoding a low-affinity transporter very similar to Rag1p. Kht2p has a lower Km (3.7 mM) and a more complex regulation. Transcription is high in the absence of glucose, further induced by low glucose concentrations, and repressed at higher glucose concentrations. The response of KHT1 and KHT2 gene regulation to high but not to low concentrations of glucose depends on glucose transport. The function of either Kht1p or Kht2p is sufficient to mediate the characteristic response to high glucose, which is impaired in a kht1 kht2 deletion mutant. Thus, the KHT genes are subject to mutual feedback regulation. Moreover, glucose repression of the endogenous β-galactosidase (LAC4) promoter and glucose induction of pyruvate decarboxylase were abolished in the kht1 kht2 mutant. These phenotypes could be partially restored by HXT gene family members from Saccharomyces cerevisiae. The results indicate that the specific responses to high but not to low glucose concentrations require a high rate of glucose uptake. PMID:11514503

  13. Nonfermentable, glucose-containing products formed from glucose under cellulose acid hydrolysis conditions

    Treesearch

    J. L. Minor

    1983-01-01

    Solutions of D-glucose in dilute sulfuric acid were allowed to react under time and temperature conditions which simulated the production of glucose from cellulose. Under these conditions, glucose undergoes a number of reactions including isomerization, dehydration, transglycosidation, polymerization, and anhydride formation. The specific interest in this report was to...

  14. Improved Oxygen-Beam Texturing of Glucose-Monitoring Optics

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.

    2006-01-01

    An improved method has been devised for using directed, hyperthermal beams of oxygen atoms and ions to impart desired textures to the tips of polymethylmethacrylate [PMMA] optical fibers to be used in monitoring the glucose content of blood. The improved method incorporates, but goes beyond, the method described in Texturing Blood-Glucose- Monitoring Optics Using Oxygen Beams (LEW-17642-1), NASA Tech Briefs, Vol. 29, No. 4 (April 2005), page 11a. The basic principle of operation of such a glucose-monitoring sensor is as follows: The textured surface of the optical fiber is coated with chemicals that interact with glucose in such a manner as to change the reflectance of the surface. Light is sent down the optical fiber and is reflected from, the textured surface. The resulting change in reflectance of the light is measured as an indication of the concentration of glucose. The required texture on the ends of the optical fibers is a landscape of microscopic cones or pillars having high aspect ratios (microscopic structures being taller than they are wide). The average distance between hills must be no more than about 5 mso that blood cells (which are wider) cannot enter the valleys between the hills, where they would interfere with optical sensing of glucose in the blood plasma. On the other hand, the plasma is required to enter the valleys, and high aspect ratio structures are needed to maximize the surface area in contact with the plasma, thereby making it possible to obtain a given level of optical glucose-measurement sensitivity with a relatively small volume of blood. There is an additional requirement that the hills be wide enough that a sufficient amount of light can propagate into them and, after reflection, can propagate out of them. The method described in the cited prior article produces a texture comprising cones and pillars that conform to the average-distance and aspect-ratio requirements. However, a significant fraction of the cones and pillars are so

  15. Robust Morphological Averages in Three Dimensions for Anatomical Atlas Construction

    NASA Astrophysics Data System (ADS)

    Márquez, Jorge; Bloch, Isabelle; Schmitt, Francis

    2004-09-01

    We present original methods for obtaining robust, anatomical shape-based averages of features of the human head anatomy from a normal population. Our goals are computerized atlas construction with representative anatomical features and morphopometry for specific populations. A method for true-morphological averaging is proposed, consisting of a suitable blend of shape-related information for N objects to obtain a progressive average. It is made robust by penalizing, in a morphological sense, the contributions of features less similar to the current average. Morphological error and similarity, as well as penalization, are based on the same paradigm as the morphological averaging.

  16. Noninvasive blood glucose monitoring during oral intake of different sugars with optical coherence tomography in human subjects.

    PubMed

    Zhang, Yuqing; Wei, Huajiang; Yang, Hongqin; He, Yonghong; Wu, Guoyong; Xie, Shusen; Zhu, Zhenguo; He, Ruoyu

    2013-09-01

    The potential of OCT applied to noninvasive blood glucose monitoring has attracted significant efforts. In this work we investigated the feasibility of OCT in monitoring blood glucose during oral intake of different sugars in humans. Five groups of experiments were performed, in which different sugars were used. The OCT signal slope (OCTSS) changed with variation of blood glucose concentration (BGC). A good correlation between OCTSS and BGC was observed in these experiments. The averaged correlation coefficients R between OCTSS and BGC are 0.900, 0.836, 0.895 and 0.884, corresponding to oral administration of glucose, fructose, sucrose and mixed sugar, respectively. Our studies demonstrated the capability and accuracy of the OCT system in monitoring BGC noninvasively and it could become a powerful tool in daily blood glucose monitoring for patients. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Carbon nanotube mat as mediator-less glucose sensor electrode.

    PubMed

    Ryu, Jongeun; Kim, Hansang; Lee, Sangeui; Hahn, H Thomas; Lashmore, David

    2010-02-01

    In this paper, the direct electron transfer of glucose oxidase (GOx) on carbon nanotube (CNT) mat electrode is demonstrated. Because of the electrical conductivity and mechanical strength of CNT mat, it can be used as an electrode as well as a catalyst support. Therefore, the preparation process for the CNT mat based sensor electrode is simpler than that of the conventional CNT dispersed sensor electrodes. GOx was covalently immobilized on the oxidized CNT mat, which is connected to a wire by using silver paste and epoxy glue. Attenuated Total Reflectance Fourier Transform-Infrared (ATR-FTIR) result shows transmittance peaks at 1637 cm(-1) and 1525 cm(-1) which are corresponding to the band I and II of amide. Cyclic voltammetric shows a pair of well-defined redox peaks with the average formal potential of -0.425 V (vs. Ag/AgCl reference electrode) in the phosphate buffered saline solution (1 x PBS, pH 7.4). Calculated electron transfer rate constant and the surface density of GOx were 1.71 s(-1) and (3.27 +/- 0.20) x 10(-13) mol/cm2, respectively. Cyclic voltammograms of GOx-CNT mat in glucose solution show that the immobilized GOx retains its catalytic activity to glucose. The amperometric sensor response showed a linear dependence on the glucose concentration in the range of 0.2 mM to 2.18 mM with a detection sensitivity of 4.05 microA mM(-1) cm(-2). The Michaelis-Menten constant of the immobilized GOx was calculated to be 2.18 mM.

  18. Glucose Disappearance in Biological Treatment Systems

    PubMed Central

    Jeris, John S.; Cardenas, Raul R.

    1966-01-01

    Laboratory scale anaerobic and aerobic treatment units were conditioned with a daily slug-feed of glucose. After a period of acclimation and stabilization, glucose disappearance was monitored continuously after the slug feed. A continuous sampling apparatus is described. Mathematical analysis of the data indicate zero-order reactions for both biological treatment systems. PMID:16349685

  19. Glucose-Induced Acidification in Yeast Cultures

    ERIC Educational Resources Information Center

    Myers, Alan; Bourn, Julia; Pool, Brynne

    2005-01-01

    We present an investigation (for A-level biology students and equivalent) into the mechanism of glucose-induced extracellular acidification in unbuffered yeast suspensions. The investigation is designed to enhance understanding of aspects of the A-level curriculum that relate to the phenomenon (notably glucose catabolism) and to develop key skills…

  20. Molecular pathophysiology of hepatic glucose production.

    PubMed

    Sharabi, Kfir; Tavares, Clint D J; Rines, Amy K; Puigserver, Pere

    2015-12-01

    Maintaining blood glucose concentration within a relatively narrow range through periods of fasting or excess nutrient availability is essential to the survival of the organism. This is achieved through an intricate balance between glucose uptake and endogenous glucose production to maintain constant glucose concentrations. The liver plays a major role in maintaining normal whole body glucose levels by regulating the processes of de novo glucose production (gluconeogenesis) and glycogen breakdown (glycogenolysis), thus controlling the levels of hepatic glucose release. Aberrant regulation of hepatic glucose production (HGP) can result in deleterious clinical outcomes, and excessive HGP is a major contributor to the hyperglycemia observed in Type 2 diabetes mellitus (T2DM). Indeed, adjusting glycemia as close as possible to a non-diabetic range is the foremost objective in the medical treatment of patients with T2DM and is currently achieved in the clinic primarily through suppression of HGP. Here, we review the molecular mechanisms controlling HGP in response to nutritional and hormonal signals and discuss how these signals are altered in T2DM.

  1. [Intracellular signals involved in glucose control].

    PubMed

    Cruz, M; Velasco, E; Kumate, J

    2001-01-01

    Many proteins are involved in glucose control. The first step for glucose uptake is insulin receptor-binding. Stimulation of the insulin receptor results in rapid autophosphorylation and conformational changes in the beta chain and the subsequent phosphorylation of the insulin receptor substrate. This results in the docking of several SH2 domain proteins, including PI 3-kinase and other adapters. The final event is glucose transporter (GLUT) translocation to the cell surface. GLUT is in the cytosol but after insulin stimulation, several proteins are activated either in the GLUT vesicles or in the inner membrane. The role of the cytoskeleton is not well known, but it apparently participates in membrane fusion and vesicle mobilization. After glucose uptake, several hexokines metabolize the glucose to generate energy, convert the glucose in glycogen and store it. Type 2 diabetes is characterized by high glucose levels and insulin resistance. The insulin receptor is diminished on the cell surface membrane, tyrosine phosphorylation is decreased, serine and threonine phosphorylation is augmented. Apparently, the main problem with GLUT protein is in its translocation to the cell surface. At present, we know the role of many proteins involved in glucose control. However, we do not understand the significance of insulin resistance at the molecular level with type 2 diabetes.

  2. Glucose-Induced Acidification in Yeast Cultures

    ERIC Educational Resources Information Center

    Myers, Alan; Bourn, Julia; Pool, Brynne

    2005-01-01

    We present an investigation (for A-level biology students and equivalent) into the mechanism of glucose-induced extracellular acidification in unbuffered yeast suspensions. The investigation is designed to enhance understanding of aspects of the A-level curriculum that relate to the phenomenon (notably glucose catabolism) and to develop key skills…

  3. Molecular Pathophysiology of Hepatic Glucose Production

    PubMed Central

    Sharabi, Kfir; Tavares, Clint D. J.; Rines, Amy K.; Puigserver, Pere

    2015-01-01

    Maintaining blood glucose concentration within a relatively narrow range through periods of fasting or excess nutrient availability is essential to the survival of the organism. This is achieved through an intricate balance between glucose uptake and endogenous glucose production to maintain constant glucose concentrations. The liver plays a major role in maintaining normal whole body glucose levels by regulating the processes of de novo glucose production (gluconeogenesis) and glycogen breakdown (glycogenolysis), thus controlling the levels of hepatic glucose release. Aberrant regulation of hepatic glucose production (HGP) can result in deleterious clinical outcomes, and excessive HGP is a major contributor to the hyperglycemia observed in Type 2 diabetes mellitus (T2DM). Indeed, adjusting glycaemia as close as possible to a non-diabetic range is the foremost objective in the medical treatment of patients with T2DM and is currently achieved in the clinic primarily through suppression of HGP. Here, we review the molecular mechanisms controlling HGP in response to nutritional and hormonal signals and discuss how these signals are altered in T2DM. PMID:26549348

  4. 40 CFR 60.1755 - How do I convert my 1-hour arithmetic averages into appropriate averaging times and units?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 7 2013-07-01 2013-07-01 false How do I convert my 1-hour arithmetic...-hour arithmetic averages into appropriate averaging times and units? (a) Use the equation in § 60.1935... Reference Method 19 in appendix A of this part, section 4.1, to calculate the daily arithmetic average for...

  5. 40 CFR 60.1755 - How do I convert my 1-hour arithmetic averages into appropriate averaging times and units?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 7 2014-07-01 2014-07-01 false How do I convert my 1-hour arithmetic...-hour arithmetic averages into appropriate averaging times and units? (a) Use the equation in § 60.1935... Reference Method 19 in appendix A of this part, section 4.1, to calculate the daily arithmetic average for...

  6. 40 CFR 62.15210 - How do I convert my 1-hour arithmetic averages into appropriate averaging times and units?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 9 2013-07-01 2013-07-01 false How do I convert my 1-hour arithmetic... convert my 1-hour arithmetic averages into appropriate averaging times and units? (a) Use the equation in... 19, section 4.1, to calculate the daily arithmetic average for concentrations of nitrogen oxides. (d...

  7. Icodextrin improves metabolic and fluid management in high and high-average transport diabetic patients.

    PubMed

    Paniagua, Ramón; Ventura, María-de-Jesús; Avila-Díaz, Marcela; Cisneros, Alejandra; Vicenté-Martínez, Marlén; Furlong, María-Del-Carmen; García-González, Zuzel; Villanueva, Diana; Orihuela, Oscar; Prado-Uribe, María-Del-Carmen; Alcántara, Guadalupe; Amato, Dante

    2009-01-01

    Icodextrin-based solutions (ICO) have clinical and theoretical advantages over glucose-based solutions (GLU) in fluid and metabolic management of diabetic peritoneal dialysis (PD) patients; however, these advantages have not yet been tested in a randomized fashion. To analyze the effects of ICO on metabolic and fluid control in high and high-average transport diabetic patients on continuous ambulatory PD (CAPD). A 12-month, multicenter, open-label, randomized controlled trial was conducted to compare ICO (n = 30) versus GLU (n = 29) in diabetic CAPD patients with high-average and high peritoneal transport characteristics. The basic daily schedule was 3 x 2 L GLU (1.5%) and either 1 x 2 L ICO (7.5%) or 1 x 2 L GLU (2.5%) for the long-dwell exchange, with substitution of 2.5% or 4.25% for 1.5% GLU being allowed when clinically necessary. Variables related to metabolic and fluid control were measured each month. Groups were similar at baseline in all measured variables. More than 66% of the patients using GLU, but only 9% using ICO, needed prescriptions of higher glucose concentration solutions. Ultrafiltration (UF) was higher (198 +/- 101 mL/day, p < 0.05) in the ICO group than in the GLU group over time. Changes from baseline were more pronounced in the ICO group than in the GLU group for extracellular fluid volume (0.23 +/- 1.38 vs -1.0 +/- 1.48 L, p < 0.01) and blood pressure (systolic 1.5 +/- 24.0 vs -10.4 +/- 30.0 mmHg, p < 0.01; diastolic 1.5 +/- 13.5 vs -6.2 +/- 14.2 mmHg, p < 0.01). Compared to baseline, patients in the ICO group had better metabolic control than those in the GLU group: glucose absorption was more reduced (-17 +/- 44 vs -64 +/- 35 g/day) as were insulin needs (3.6 +/- 3.4 vs - 9.1 +/- 4.7 U/day, p < 0.01), fasting serum glucose (8.3 +/- 36.5 vs -37 +/- 25.8 mg/dL, p < 0.01), triglycerides (54.5 +/- 31.9 vs -54.7 +/- 39.9 mg/dL, p < 0.01), and glycated hemoglobin (0.79% +/- 0.79% vs -0.98% +/- 0.51%, p < 0.01). Patients in the ICO group had

  8. Glucose kinetics during prolonged exercise in highly trained human subjects: effect of glucose ingestion

    PubMed Central

    Jeukendrup, Asker E; Raben, Anne; Gijsen, Annemie; Stegen, Jos H C H; Brouns, Fred; Saris, Wim H M; Wagenmakers, Anton J M

    1999-01-01

    The objectives of this study were (1) to investigate whether glucose ingestion during prolonged exercise reduces whole body muscle glycogen oxidation, (2) to determine the extent to which glucose disappearing from the plasma is oxidized during exercise with and without carbohydrate ingestion and (3) to obtain an estimate of gluconeogenesis. After an overnight fast, six well-trained cyclists exercised on three occasions for 120 min on a bicycle ergometer at 50% maximum velocity of O2 uptake and ingested either water (Fast), or a 4% glucose solution (Lo-Glu) or a 22% glucose solution (Hi-Glu) during exercise. Dual tracer infusion of [U-13C]-glucose and [6,6-2H2]-glucose was given to measure the rate of appearance (Ra) of glucose, muscle glycogen oxidation, glucose carbon recycling, metabolic clearance rate (MCR) and non-oxidative disposal of glucose. Glucose ingestion markedly increased total Ra especially with Hi-Glu. After 120 min Ra and rate of disappearance (Rd) of glucose were 51-52 μmol kg−1 min−1 during Fast, 73-74 μmol kg−1 min−1 during Lo-Glu and 117–119 μmol kg−1 min−1 during Hi-Glu. The percentage of Rd oxidized was between 96 and 100% in all trials. Glycogen oxidation during exercise was not reduced by glucose ingestion. The vast majority of glucose disappearing from the plasma is oxidized and MCR increased markedly with glucose ingestion. Glucose carbon recycling was minimal suggesting that gluconeogenesis in these conditions is negligible. PMID:10050023

  9. Effect of Portal Glucose Sensing on Systemic Glucose Levels in SD and ZDF Rats

    PubMed Central

    Pal, Atanu; Rhoads, David B.; Tavakkoli, Ali

    2016-01-01

    Background The global epidemic of Type-2-Diabetes (T2D) highlights the need for novel therapeutic targets and agents. Roux-en-Y-Gastric-Bypass (RYGB) is the most effective treatment. Studies investigating the mechanisms of RYGB suggest a role for post-operative changes in portal glucose levels. We investigate the impact of stimulating portal glucose sensors on systemic glucose levels in health and T2D, and evaluated the role of sodium-glucose-cotransporter-3 (SGLT3) as the possible sensor. Methods Systemic glucose and hormone responses to portal stimulation were measured. In Sprague-Dawley (SD) rats, post-prandial state was simulated by infusing glucose into the portal vein. The SGLT3 agonist, alpha-methyl-glucopyranoside (αMG), was then added to further stimulate the portal sensor. To elucidate the neural pathway, vagotomy or portal denervation was followed by αMG+glucose co-infusion. The therapeutic potential of portal glucose sensor stimulation was investigated by αMG-only infusion (vs. saline) in SD and Zucker-Diabetic-Fatty (ZDF) rats. Hepatic mRNA expression was also measured. Results αMG+glucose co-infusion reduced peak systemic glucose (vs. glucose alone), and lowered hepatic G6Pase expression. Portal denervation, but not vagotomy, abolished this effect. αMG-only infusion lowered systemic glucose levels. This glucose-lowering effect was more pronounced in ZDF rats, where portal αMG infusion increased insulin, C-peptide and GIP levels compared to saline infusions. Conclusions The portal vein is capable of sensing its glucose levels, and responds by altering hepatic glucose handling. The enhanced effect in T2D, mediated through increased GIP and insulin, highlights a therapeutic target that could be amenable to pharmacological modulation or minimally-invasive surgery. PMID:27806092

  10. Canagliflozin Lowers Postprandial Glucose and Insulin by Delaying Intestinal Glucose Absorption in Addition to Increasing Urinary Glucose Excretion

    PubMed Central

    Polidori, David; Sha, Sue; Mudaliar, Sunder; Ciaraldi, Theodore P.; Ghosh, Atalanta; Vaccaro, Nicole; Farrell, Kristin; Rothenberg, Paul; Henry, Robert R.

    2013-01-01

    OBJECTIVE Canagliflozin, a sodium glucose cotransporter (SGLT) 2 inhibitor, is also a low-potency SGLT1 inhibitor. This study tested the hypothesis that intestinal canagliflozin levels postdose are sufficiently high to transiently inhibit intestinal SGLT1, thereby delaying intestinal glucose absorption. RESEARCH DESIGN AND METHODS This two-period, crossover study evaluated effects of canagliflozin on intestinal glucose absorption in 20 healthy subjects using a dual-tracer method. Placebo or canagliflozin 300 mg was given 20 min before a 600-kcal mixed-meal tolerance test. Plasma glucose, 3H-glucose, 14C-glucose, and insulin were measured frequently for 6 h to calculate rates of appearance of oral glucose (RaO) in plasma, endogenous glucose production, and glucose disposal. RESULTS Compared with placebo, canagliflozin treatment reduced postprandial plasma glucose and insulin excursions (incremental 0- to 2-h area under the curve [AUC0–2h] reductions of 35% and 43%, respectively; P < 0.001 for both), increased 0- to 6-h urinary glucose excretion (UGE0–6h, 18.2 ± 5.6 vs. <0.2 g; P < 0.001), and delayed RaO. Canagliflozin reduced AUC RaO by 31% over 0 to 1 h (geometric means, 264 vs. 381 mg/kg; P < 0.001) and by 20% over 0 to 2 h (576 vs. 723 mg/kg; P = 0.002). Over 2 to 6 h, canagliflozin increased RaO such that total AUC RaO over 0 to 6 h was <6% lower versus placebo (960 vs. 1,018 mg/kg; P = 0.003). A modest (∼10%) reduction in acetaminophen absorption was observed over the first 2 h, but this difference was not sufficient to explain the reduction in RaO. Total glucose disposal over 0 to 6 h was similar across groups. CONCLUSIONS Canagliflozin reduces postprandial plasma glucose and insulin by increasing UGE (via renal SGLT2 inhibition) and delaying RaO, likely due to intestinal SGLT1 inhibition. PMID:23412078

  11. A Formula for the Conversion of 5-Minute Average, 10 Minute Average Rain Rate into 1-Minute Average Rain Rate for Prediction of Rain Induced Attenuation

    NASA Astrophysics Data System (ADS)

    Sharma, Parshotam; Hudiara, I. S.; Singh, M. L.

    2009-09-01

    The attenuation of microwave signal due to rain is a well established fact now. Localized models based on the rain rate and attenuation statistics is the basic necessity for a RF communication system designer. For development of any such model, we need long term statistics. These days most of the metrological data that is available is in the form of either 5-min or 10-min average rain rate and if we want to utilize this data, we need to convert this into 1-min equivalent average rain fall. In this paper, a formula has been purposed for the conversion of 5 min and 10 min average rain rate into 1 min equivalent average rain rate.

  12. 21 CFR 862.1345 - Glucose test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Glucose test system. 862.1345 Section 862.1345....1345 Glucose test system. (a) Identification. A glucose test system is a device intended to measure glucose quantitatively in blood and other body fluids. Glucose measurements are used in the diagnosis and...

  13. Glucose Recognition in Vitro Using Fluorescent Spectroscopy

    SciTech Connect

    Noronha, G; Heiss, A M; Reilly, J R; Vachon, Jr, D J; Cary, D R; Zaitseva, N P; Reibold, R A; Lane, S M; Peyser, T A; Satcher, J H

    2001-04-25

    Diabetes is a disease that affects over 16 million people in the USA at a cost of 100 billion dollars annually. The ability to regulate insulin delivery in people with Type 1 diabetes is imperative as is the need to manage glucose levels in all people with this disease. Our current method for monitoring glucose is a (FDA approved) minimally invasive enzymatic sensor that can measure glucose levels in vivo for three days. We are focused on developing a noninvasive implantable glucose sensor that will be interrogated by an external device. The material must be robust, easy to process, biocompatible and resistant to biofouling. In this Presentation we will discuss the development of a new polymeric matrix that can recognize physiological levels of glucose in vitro using fluorescent spectroscopy.

  14. Diurnal Variation in Response to Intravenous Glucose*

    PubMed Central

    Whichelow, Margaret J.; Sturge, R. A.; Keen, H.; Jarrett, R. J.; Stimmler, L.; Grainger, Susan

    1974-01-01

    Intravenous glucose tolerance tests (25 g) were performed in the morning and afternoon on 13 apparently normal persons. The individual K values (rate of decline of blood sugar) were all higher in the morning tests, and the mean values were significantly higher in the morning. Fasting blood sugar levels were slightly lower in the afternoon. There was no difference between the fasting morning and afternoon plasma insulin levels, but the levels after glucose were lower in the afternoon. Growth hormone levels were low at all times in non-apprehensive subjects and unaffected by glucose. The results suggest that the impaired afternoon intravenous glucose tolerance, like oral glucose tolerance, is associated with impaired insulin release and insulin resistance. PMID:4817160

  15. Contribution of glucose kinase to glucose repression of xylose utilization in Bacillus megaterium.

    PubMed Central

    Späth, C; Kraus, A; Hillen, W

    1997-01-01

    The glk gene from Bacillus megaterium, which encodes glucose kinase, was isolated and analyzed. Disruption by a transcriptional glk-luxAB fusion indicated that glk is the only glucose kinase gene in that strain but did not affect growth of that mutant on glucose. Determination of luciferase activity under various growth conditions revealed constitutive transcription of glk. Expression of a xylA-lacZ fusion was repressed by glucose in the strain with the glk disruption about twofold less efficiently than in the wild type. The potential contribution of glk expression to glucose repression is discussed. PMID:9393732

  16. Glucose Biosensor Based on Immobilization of Glucose Oxidase in Platinum Nanoparticles/Graphene/Chitosan Nanocomposite Film

    SciTech Connect

    Wu, Hong; Wang, Jun; Kang, Xinhuang; Wang, Chong M.; Wang, Donghai; Liu, Jun; Aksay, Ilhan A.; Lin, Yuehe

    2009-09-01

    The bionanocomposite film consisting of glucose oxidase/Pt/functional graphene sheets/chitosan (GOD/Pt/FGS/chitosan) for glucose sensing was described. With the electrocatalytic synergy of FGS and Pt nanoparticles to hydrogen peroxide, a sensitive biosensor with detection limit of 0.6 µM glucose was achieved. The biosensor also had good reproducibility, long term stability and negligible interfering signals from ascorbic acid and uric acid comparing to the response to glucose. The large surface area and good conductivity of graphene suggests that graphene is a potential candidate for sensor material. The hybrid nanocomposite glucose sensor provides new opportunity for clinical diagnosis and point-of-care applications.

  17. A novel noninvasive blood glucose monitor.

    PubMed

    Malchoff, Carl D; Shoukri, Kamal; Landau, Julian I; Buchert, Janusz M

    2002-12-01

    To evaluate the precision and accuracy of a new advanced prototype of a noninvasive blood glucose monitor across a wide range of serum glucose concentrations. An advanced handheld noninvasive glucose monitor prototype was calibrated and tested using patients recruited by the General Research Center of the University of Connecticut Health Center. The monitor, developed by Infratec, uses principles of thermal emission spectroscopy. The noninvasive measurement of tympanic membrane glucose concentration was calibrated to the serum glucose concentration using 432 paired measurements from 20 subjects with insulin-requiring diabetes. This calibration was subsequently tested (results of power analyses) in a blind fashion with 126 paired measurements from six diabetic subjects who require insulin. In vivo measurements demonstrated the reproducibility of the methodology of the noninvasive glucose monitor. Based on the calibration model, predicted glucose concentrations for six subjects were as follows (for 126 data points): SD = 32 mg/dl, mean absolute relative error (%MARE) = 11.6, with a correlation coefficient of r = 0.87. Noninvasive glucose results were also compared with laboratory reference measurements using an error-in-variables method. Clark error grid analysis showed that 100% of the measurements fell within zones A and B (90% in zone A and 10% in zone B). The SD for all noninvasive measured concentrations was 27 mg/dl, %MARE was 8.6, and the correlation coefficient was r = 0.94. This first independent clinical study of an advanced noninvasive blood glucose prototype based on thermal emission in the mid-infrared spectral region has demonstrated glucose measurements with clinically acceptable accuracy but without the necessity of individual daily calibration.

  18. Identification of Glucose Transporters in Aspergillus nidulans

    PubMed Central

    dos Reis, Thaila Fernanda; Menino, João Filipe; Bom, Vinícius Leite Pedro; Brown, Neil Andrew; Colabardini, Ana Cristina; Savoldi, Marcela; Goldman, Maria Helena S.; Rodrigues, Fernando; Goldman, Gustavo Henrique

    2013-01-01

    To characterize the mechanisms involved in glucose transport, in the filamentous fungus Aspergillus nidulans, we have identified four glucose transporter encoding genes hxtB-E. We evaluated the ability of hxtB-E to functionally complement the Saccharomyces cerevisiae EBY.VW4000 strain that is unable to grow on glucose, fructose, mannose or galactose as single carbon source. In S. cerevisiae HxtB-E were targeted to the plasma membrane. The expression of HxtB, HxtC and HxtE was able to restore growth on glucose, fructose, mannose or galactose, indicating that these transporters accept multiple sugars as a substrate through an energy dependent process. A tenfold excess of unlabeled maltose, galactose, fructose, and mannose were able to inhibit glucose uptake to different levels (50 to 80 %) in these s. cerevisiae complemented strains. Moreover, experiments with cyanide-m-chlorophenylhydrazone (CCCP), strongly suggest that hxtB, -C, and –E mediate glucose transport via active proton symport. The A. nidulans ΔhxtB, ΔhxtC or ΔhxtE null mutants showed ~2.5-fold reduction in the affinity for glucose, while ΔhxtB and -C also showed a 2-fold reduction in the capacity for glucose uptake. The ΔhxtD mutant had a 7.8-fold reduction in affinity, but a 3-fold increase in the capacity for glucose uptake. However, only the ΔhxtB mutant strain showed a detectable decreased rate of glucose consumption at low concentrations and an increased resistance to 2-deoxyglucose. PMID:24282591

  19. Demonstration of a critical role for free fatty acids in mediating counterregulatory stimulation of gluconeogenesis and suppression of glucose utilization in humans.

    PubMed Central

    Fanelli, C; Calderone, S; Epifano, L; De Vincenzo, A; Modarelli, F; Pampanelli, S; Perriello, G; De Feo, P; Brunetti, P; Gerich, J E

    1993-01-01

    In vitro studies indicate that FFA compete with glucose as an oxidative fuel in muscle and, in addition, stimulate gluconeogenesis in liver. During counterregulation of hypoglycemia, plasma FFA increase and this is associated with an increase in glucose production and a suppression of glucose utilization. To test the hypothesis that FFA mediate changes in glucose metabolism that occur during counterregulation, we examined the effects of acipimox, an inhibitor of lipolysis, on glucose production and utilization ([3-3H]glucose), and incorporation of [U-14C]-alanine into glucose during insulin-induced hypoglycemia. Eight normal volunteers were infused with insulin for 8 h to produce modest hypoglycemia (approximately 3 mM) on two occasions, first without acipimox (control) and then with acipimox administration (250 mg per os at 60 and 240 min). Despite identical plasma insulin concentrations, glucose had to be infused in the acipimox experiments (glucose-clamp technique) to maintain plasma glucose concentrations identical to those in control experiments. Acipimox completely prevented counterregulatory increases in lipolysis so that during the last 4 h plasma FFA were below baseline values and averaged 67 +/- 13 vs. 725 +/- 65 microM in control experiments, P < 0.001. Concomitantly, overall glucose production was reduced by 40% (5.5 +/- 11 vs. 9.3 +/- 0.7 mumol/kg per min, P < 0.001), and gluconeogenesis from alanine was reduced by nearly 70% (0.32 +/- 0.09 vs. 1.00 +/- 0.18 mumol/kg per min, P < 0.001), while glucose utilization increased by 15% (10.8 +/- 1.4 vs. 9.3 +/- 0.7 mumol/kg per min). We conclude that FFA play a critical role in mediating changes in glucose metabolism during counterregulation, and that under these conditions, FFA exert a much more profound effect on hepatic glucose production than on glucose utilization. PMID:8408616

  20. Self-Monitoring of Blood Glucose

    PubMed Central

    Elgart, Jorge F.; González, Lorena; Rucci, Enzo

    2014-01-01

    Although test strips for self-monitoring of blood glucose (SMBG) represent around 50% of diabetes treatment cost in Argentina, little is known about their current use and relationship with different types of treatment. We therefore aimed to estimate the current use of test strips and identify the major use drivers and the percentage they represent of total prescription costs in 2 entities of the social security system (SSS) of Argentina. Observational retrospective study measuring test strip prescriptions delivered by pharmacies from the province of Buenos Aires (8115 records collected during 3 months provided by the Colegio de Farmacéuticos de la Provincia de Buenos Aires) of affiliates with type 2 diabetes (T2DM) from 2 large entities of the SSS system. The average monthly test strips/patient used for SMBG was 97.5 ± 70.1. This number varied according to treatment: monotherapy with oral antidiabetic drugs (OAD) < combined OAD therapy < insulin treatment. Test strips represented a higher percentage of the total prescription cost in people under OAD monotherapy (84.6%) and lower in those with insulin analogs (46.9%). In our population, the type of hyperglycemia treatment was the main driver of test strip use for SMBG and its impact on the total prescription cost depends on the kind of such treatment. Since it has been shown that patients’ education and prescription audit can optimize test strip use and treatment outcomes, implementation of such strategies could appropriately support, optimize, and reduce ineffective test strip use in people with T2DM. PMID:25208965

  1. Cell Based Metabolic Barriers to Glucose Diffusion: Macrophages and Continuous Glucose Monitoring

    PubMed Central

    Klueh, Ulrike; Frailey, Jackman; Qiao, Yi; Antar, Omar; Kreutzer, Donald L.

    2014-01-01

    It is assumed that MQ are central to glucose sensor bio-fouling and therefore have a major negative impact on continuous glucose monitoring (CGM) performance in vivo. However to our knowledge there is no data in the literature to directly support or refute this assumption. Since glucose and oxygen (O2) are key to glucose sensor function in vivo, understanding and controlling glucose and O2 metabolic activity of MQ is likely key to successful glucose sensor performance. We hypothesized that the accumulation of MQ at the glucose sensor-tissue interface will act as “Cell Based Metabolic Barriers” (CBMB) to glucose diffusing from the interstitial tissue compartment to the implanted glucose sensor and as such creating an artificially low sensor output, thereby compromising sensor function and CGM. Our studies demonstrated that 1) direct injections of MQ at in vivo sensor implantation sites dramatically decreased sensor output (measured in nA), 2) addition of MQ to glucose sensors in vitro resulted in a rapid and dramatic fall in sensor output and 3) lymphocytes did not affect sensor function in vitro or in vivo. These data support our hypothesis that MQ can act as metabolic barriers to glucose and O2 diffusion in vivo and in vitro. PMID:24461328

  2. Glucose-dependent insulinotropic polypeptide directly induces glucose transport in rat skeletal muscle.

    PubMed

    Snook, Laelie A; Nelson, Emery M; Dyck, David J; Wright, David C; Holloway, Graham P

    2015-08-01

    Several gastrointestinal proteins have been identified to have insulinotropic effects, including glucose-dependent insulinotropic polypeptide (GIP); however, the direct effects of incretins on skeletal muscle glucose transport remain largely unknown. Therefore, the purpose of the current study was to examine the role of GIP on skeletal muscle glucose transport and insulin signaling in rats. Relative to a glucose challenge, a mixed glucose+lipid oral challenge increased circulating GIP concentrations, skeletal muscle Akt phosphorylation, and improved glucose clearance by ∼35% (P < 0.05). These responses occurred without alterations in serum insulin concentrations. In an incubated soleus muscle preparation, GIP directly stimulated glucose transport and increased GLUT4 accumulation on the plasma membrane in the absence of insulin. Moreover, the ability of GIP to stimulate glucose transport was mitigated by the addition of the PI 3-kinase (PI3K) inhibitor wortmannin, suggesting that signaling through PI3K is required for these responses. We also provide evidence that the combined stimulatory effects of GIP and insulin on soleus muscle glucose transport are additive. However, the specific GIP receptor antagonist (Pro(3))GIP did not attenuate GIP-stimulated glucose transport, suggesting that GIP is not signaling through its classical receptor. Together, the current data provide evidence that GIP regulates skeletal muscle glucose transport; however, the exact signaling mechanism(s) remain unknown.

  3. Cell based metabolic barriers to glucose diffusion: macrophages and continuous glucose monitoring.

    PubMed

    Klueh, Ulrike; Frailey, Jackman T; Qiao, Yi; Antar, Omar; Kreutzer, Donald L

    2014-03-01

    It is assumed that MQ are central to glucose sensor bio-fouling and therefore have a major negative impact on continuous glucose monitoring (CGM) performance in vivo. However to our knowledge there is no data in the literature to directly support or refute this assumption. Since glucose and oxygen (O2) are key to glucose sensor function in vivo, understanding and controlling glucose and O2 metabolic activity of MQ is likely key to successful glucose sensor performance. We hypothesized that the accumulation of MQ at the glucose sensor-tissue interface will act as "Cell Based Metabolic Barriers" (CBMB) to glucose diffusing from the interstitial tissue compartment to the implanted glucose sensor and as such creating an artificially low sensor output, thereby compromising sensor function and CGM. Our studies demonstrated that 1) direct injections of MQ at in vivo sensor implantation sites dramatically decreased sensor output (measured in nA), 2) addition of MQ to glucose sensors in vitro resulted in a rapid and dramatic fall in sensor output and 3) lymphocytes did not affect sensor function in vitro or in vivo. These data support our hypothesis that MQ can act as metabolic barriers to glucose and O2 diffusion in vivo and in vitro.

  4. Glucose sensing mechanisms in hypothalamic cell models: glucose inhibition of AgRP synthesis and secretion.

    PubMed

    Chalmers, Jennifer A; Jang, Janet J; Belsham, Denise D

    2014-01-25

    Glucose-sensing neurons play a role in energy homeostasis, yet how orexigenic neurons sense glucose remains unclear. As models of glucose-inhibited (GI) neurons, mHypoE-29/1 and mHypoA-NPY/GFP cells express the essential orexigenic neuropeptide AgRP and glucose sensing machinery. Exposure to increasing concentrations of glucose or the glucose analog 2-deoxyglucose (2-DG) results in a decrease in AgRP mRNA levels. Taste receptor, Tas1R2 mRNA expression was reduced by glucose, whereas 2-DG reduced Tas1R3 mRNA levels. Increasing glucose concentrations elicited a rise in Akt and neuronal nitric oxide synthase (nNOS) phosphorylation, CaMKKβ levels, and a reduction of AMP-kinase alpha phosphorylation. Inhibitors of NOS and the cystic fibrosis transmembrane conductance regulator (CFTR) prevented a decrease in AgRP secretion with glucose, suggesting a pivotal role for nNOS and the CFTR in glucose-sensing. These models possess the hallmark characteristics of GI neurons, and can be used to disentangle the mechanisms by which orexigenic neurons sense glucose.

  5. Glucose biosensor based on nanocomposite films of CdTe quantum dots and glucose oxidase.

    PubMed

    Li, Xinyu; Zhou, Yunlong; Zheng, Zhaozhu; Yue, Xiuli; Dai, Zhifei; Liu, Shaoqin; Tang, Zhiyong

    2009-06-02

    A blood glucose sensor has been developed based on the multilayer films of CdTe semiconductor quantum dots (QDs) and glucose oxidase (GOD) by using the layer-by-layer assembly technique. When the composite films were contacted with glucose solution, the photoluminescence of QDs in the films was quickly quenched because the enzyme-catalyzed reaction product (H2O2) of GOD and glucose gave rise to the formation of surface defects on QDs. The quenching rate was a function of the concentration of glucose. The linear range and sensitivity for glucose determination could be adjusted by controlling the layers of QDs and GOD. The biosensor was used to successfully determine the concentration of blood glucose in real serum samples without sample pretreatment and exhibited satisfactory reproducibility and accuracy.

  6. Icodextrin:a major problem for glucose dehydrogenase-based glucose point of care testing systems.

    PubMed

    Floré, K; Delanghe, J

    2006-01-01

    Recently a number of glucose dehydrogenase-based point of care (POCT) systems for glucose monitoring were successfully introduced on the market. Icodextrin, a glucose polymer is widely used as an osmotic agent in continuous ambulatory peritoneal dialysis (CAPD). Its metabolites are substrates for glucose dehydrogenase, inducing an analytical error which is gaining importance in the determination of glucose in a hospital environment. Since icodextrin is hydrolysed by amylase in the extracellular fluids, the analytical error in vivo is aggravated by the presence of the smaller oligosaccharides which originate from amylase activity. Clinicians should be warned about the spurious high glucose results which might occur in icodextrin-treated patients. In particular in in conditions associated with increased amylase activities, analytical errors are to be expected in icodextrin-treated patients. Alternative glucose determination methods should be recommended in the latter group of patients.

  7. Enzymatic deposition of Au nanoparticles on the designed electrode surface and its application in glucose detection.

    PubMed

    Zhang, Hongfang; Liu, Ruixiao; Sheng, Qinglin; Zheng, Jianbin

    2011-02-01

    This paper reported the enzymatic deposition of Au nanoparticles (AuNPs) on the designed 3-mercapto-propionic acid/glucose oxidase/chitosan (MPA/GOD/Chit) modified glassy carbon electrode and its application in glucose detection. Chit served as GOD immobilization matrix and interacted with MPA through electrostatic attraction. AuNPs, without nano-seeds presented on the electrode surface, was produced through the glucose oxidase catalyzed oxidation of glucose. The mechanism of production of AuNPs was confirmed to be that enzymatic reaction products H(2)O(2) in the solution reduce gold complex to AuNPs. The characterizations of the electrode modified after each assembly step was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy showed the average particle size of the AuNPs is 40nm with a narrow particle size distribution. The content of AuNPs on the electrode surfaces was measured by differential pulse stripping voltammetry. The electrochemical signals on voltammogram showed a linear increase with the glucose concentration in the range of 0.010-0.12mM with a detection limit of 4μM. This provided a method to the determination of glucose. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Immune system and glucose metabolism interaction in schizophrenia: a chicken-egg dilemma.

    PubMed

    Steiner, Johann; Bernstein, Hans-Gert; Schiltz, Kolja; Müller, Ulf J; Westphal, Sabine; Drexhage, Hemmo A; Bogerts, Bernhard

    2014-01-03

    Impaired glucose metabolism and the development of metabolic syndrome contribute to a reduction in the average life expectancy of individuals with schizophrenia. It is unclear whether this association simply reflects an unhealthy lifestyle or whether weight gain and impaired glucose tolerance in patients with schizophrenia are directly attributable to the side effects of atypical antipsychotic medications or disease-inherent derangements. In addition, numerous previous studies have highlighted alterations in the immune system of patients with schizophrenia. Increased concentrations of interleukin (IL)-1, IL-6, and transforming growth factor-beta (TGF-β) appear to be state markers, whereas IL-12, interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and soluble IL-2 receptor (sIL-2R) appear to be trait markers of schizophrenia. Moreover, the mononuclear phagocyte system (MPS) and microglial activation are involved in the early course of the disease. This review illustrates a "chicken-egg dilemma", as it is currently unclear whether impaired cerebral glucose utilization leads to secondary disturbances in peripheral glucose metabolism, an increased risk of cardiovascular complications, and accompanying pro-inflammatory changes in patients with schizophrenia or whether immune mechanisms may be involved in the initial pathogenesis of schizophrenia, which leads to disturbances in glucose metabolism such as metabolic syndrome. Alternatively, shared underlying factors may be responsible for the co-occurrence of immune system and glucose metabolism disturbances in schizophrenia.

  9. Impact of blood sample collection and processing methods on glucose levels in community outreach studies.

    PubMed

    Turchiano, Michael; Nguyen, Cuong; Fierman, Arthur; Lifshitz, Mark; Convit, Antonio

    2013-01-01

    Glucose obtained from unprocessed blood samples can decrease by 5%-7% per hour due to glycolysis. This study compared the impact of glucose degradation on measured glucose values by examining two different collection methods. For the first method, blood samples were collected in tubes containing sodium fluoride (NaF), a glycolysis inhibitor. For the second method, blood samples were collected in tubes containing a clot activator and serum gel separator and were centrifuged to separate the serum and plasma 20 minutes after sample collection. The samples used in the two methods were collected during the same blood draw and were assayed by the clinical laboratory 2-4 hours after the samples were obtained. A total of 256 pairs of samples were analyzed. The average glucose reading for the centrifuged tubes was significantly higher than the NaF tubes by 0.196 ± 0.159 mmol/L (P < 0.01) or 4.2%. This study demonstrates the important role collection methods play in accurately assessing glucose levels of blood samples collected in the field, where working environment may be suboptimal. Therefore, blood samples collected in the field should be promptly centrifuged before being transported to clinical labs to ensure accurate glucose level measurements.

  10. Jump neural network for real-time prediction of glucose concentration.

    PubMed

    Zecchin, Chiara; Facchinetti, Andrea; Sparacino, Giovanni; Cobelli, Claudio

    2015-01-01

    Prediction of the future value of a variable is of central importance in a wide variety of fields, including economy and finance, meteorology, informatics, and, last but not least important, medicine. For example, in the therapy of Type 1 Diabetes (T1D), in which, for patient safety, glucose concentration in the blood should be maintained in a defined normoglycemic range, the ability to forecast glucose concentration in the short-term (with a prediction horizon of around 30 min) might be sufficient to reduce the incidence of hypoglycemic and hyperglycemic events. Neural Network (NN) approaches are suitable for prediction purposes because of their ability to model nonlinear dynamics and handle in their inputs signals coming from different domains. In this chapter we illustrate the design of a jump NN glucose prediction algorithm that exploits past glucose concentration data, measured in real-time by a minimally invasive continuous glucose monitoring (CGM) sensor, and information on ingested carbohydrates, supplied by the patient himself or herself. The methodology is assessed by tuning the NN on data of ten T1D individuals and then testing it on a dataset of ten different subjects. Results with a prediction horizon of 30 min show that prediction of glucose concentration in T1D via NN is feasible and sufficiently accurate. The average time anticipation obtained is compatible with the generation of preventive hypoglycemic and hyperglycemic alerts and the improvement of artificial pancreas performance.

  11. Glucose transporters in the human placenta.

    PubMed

    Illsley, N P

    2000-01-01

    The availability of antibodies and cDNA probes specific for the various members of the facilitated-diffusion glucose transporter (GLUT) family has enabled researchers to obtain a much clearer picture of the mechanisms for placental uptake and transplacental transport of glucose. This review examines studies of human placental glucose transport with the aim of providing a model which describes the transporter isoforms present in the placenta, their cellular localization and functional significance. The GLUT1 glucose transporter, present on both the microvillous and basal membranes of the syncytial barrier, is the primary isoform involved in the transplacental movement of glucose. Although GLUT3 mRNA is widely distributed, GLUT3 protein is localized to the arterial component of the vascular endothelium, where it may play a role in enhancing transplacental glucose transport. This data is in contrast to the situation in other mammalian species, such as the mouse, rat and sheep, where GLUT3 protein is not only present in those epithelial cells which carry out transplacental transport but becomes an increasingly prominent isoform as gestation progresses. The asymmetric distribution of GLUT1 in the human syncytiotrophoblast (microvillous>basal) means that basal GLUT1 acts as the rate limiting step in transplacental transfer. Changes in basal GLUT1 therefore have the potential to cause alterations in transplacental transport of glucose. Although there appear to be no changes in syncytial GLUT1 expression in intrauterine growth retardation, in diabetic pregnancies increases in basal GLUT1 expression and activity have been observed, with significant consequences for the maternal-fetal flux of glucose. Little is known of glucose transporter regulation in the placenta save for the effects of hyper- and hypoglycemia. GLUT1 expression and activity appear to be inversely related to extracellular glucose concentration, however within the physiological range, GLUT1 expression is

  12. Adaptive face coding and discrimination around the average face.

    PubMed

    Rhodes, Gillian; Maloney, Laurence T; Turner, Jenny; Ewing, Louise

    2007-03-01

    Adaptation paradigms highlight the dynamic nature of face coding and suggest that identity is coded relative to an average face that is tuned by experience. In low-level vision, adaptive coding can enhance sensitivity to differences around the adapted level. We investigated whether sensitivity to differences around the average face is similarly enhanced. Converging evidence from three paradigms showed no enhancement. Discrimination of small interocular spacing differences was not better for faces close to the average (Study 1). Nor was perceived similarity reduced for face pairs close to (spanning) the average (Study 2). On the contrary, these pairs were judged most similar. Maximum likelihood perceptual difference scaling (Studies 3 and 4) confirmed that sensitivity to differences was reduced, not enhanced, around the average. We conclude that adaptive face coding does not enhance discrimination around the average face.

  13. Subdiffusion in time-averaged, confined random walks

    NASA Astrophysics Data System (ADS)

    Neusius, Thomas; Sokolov, Igor M.; Smith, Jeremy C.

    2009-07-01

    Certain techniques characterizing diffusive processes, such as single-particle tracking or molecular dynamics simulation, provide time averages rather than ensemble averages. Whereas the ensemble-averaged mean-squared displacement (MSD) of an unbounded continuous time random walk (CTRW) with a broad distribution of waiting times exhibits subdiffusion, the time-averaged MSD, δ2¯ , does not. We demonstrate that, in contrast to the unbounded CTRW, in which δ2¯ is linear in the lag time Δ , the time-averaged MSD of the CTRW of a walker confined to a finite volume is sublinear in Δ , i.e., for long lag times δ2¯˜Δ1-α . The present results permit the application of CTRW to interpret time-averaged experimental quantities.

  14. Random time averaged diffusivities for Lévy walks

    NASA Astrophysics Data System (ADS)

    Froemberg, D.; Barkai, E.

    2013-07-01

    We investigate a Lévy walk alternating between velocities ±v0 with opposite sign. The sojourn time probability distribution at large times is a power law lacking its mean or second moment. The first case corresponds to a ballistic regime where the ensemble averaged mean squared displacement (MSD) at large times is ⟨x2⟩ ∝ t2, the latter to enhanced diffusion with ⟨x2⟩ ∝ tν, 1 < ν < 2. The correlation function and the time averaged MSD are calculated. In the ballistic case, the deviations of the time averaged MSD from a purely ballistic behavior are shown to be distributed according to a Mittag-Leffler density function. In the enhanced diffusion regime, the fluctuations of the time averages MSD vanish at large times, yet very slowly. In both cases we quantify the discrepancy between the time averaged and ensemble averaged MSDs.

  15. Lognormal Distributions and Geometric Averages of Symmetric Positive Definite Matrices.

    PubMed

    Schwartzman, Armin

    2016-12-01

    This article gives a formal definition of a lognormal family of probability distributions on the set of symmetric positive definite (SPD) matrices, seen as a matrix-variate extension of the univariate lognormal family of distributions. Two forms of this distribution are obtained as the large sample limiting distribution via the central limit theorem of two types of geometric averages of i.i.d. SPD matrices: the log-Euclidean average and the canonical geometric average. These averages correspond to two different geometries imposed on the set of SPD matrices. The limiting distributions of these averages are used to provide large-sample confidence regions and two-sample tests for the corresponding population means. The methods are illustrated on a voxelwise analysis of diffusion tensor imaging data, permitting a comparison between the various average types from the point of view of their sampling variability.

  16. Facile fabrication of network film electrodes with ultrathin Au nanowires for nonenzymatic glucose sensing and glucose/O2 fuel cell.

    PubMed

    Yang, Lu; Zhang, Yijia; Chu, Mi; Deng, Wenfang; Tan, Yueming; Ma, Ming; Su, Xiaoli; Xie, Qingji; Yao, Shuozhuo

    2014-02-15

    We report here on the facile fabrication of network film electrodes with ultrathin Au nanowires (AuNWs) and their electrochemical applications for high-performance nonenzymatic glucose sensing and glucose/O2 fuel cell under physiological conditions (pH 7.4, containing 0.15M Cl(-)). AuNWs with an average diameter of ~7 or 2 nm were prepared and can self-assemble into robust network films on common electrodes. The network film electrode fabricated with 2-nm AuNWs exhibits high sensitivity (56.0 μA cm(-2)mM(-1)), low detection limit (20 μM), short response time (within 10s), excellent selectivity, and good storage stability for nonenzymatic glucose sensing. Glucose/O2 fuel cells were constructed using network film electrodes as the anode and commercial Pt/C catalyst modified glassy carbon electrode as cathode. The glucose/O2 fuel cell using 2-nm AuNWs as anode catalyst output a maximum power density of is 126 μW cm(-2), an open-circuit cell voltage of 0.425 V, and a short-circuit current density of 1.34 mA cm(-2), respectively. Due to the higher specific electroactive surface area of 2-nm AuNWs, the network film electrode fabricated with 2-nm AuNWs exhibited higher electrocatalytic activity toward glucose oxidation than the network film electrode fabricated with 7-nm AuNWs. The network film electrode exhibits high electrocatalytic activity toward glucose oxidation under physiological conditions, which is helpful for constructing implantable electronic devices.

  17. Accelerated intestinal glucose absorption in morbidly obese humans: relationship to glucose transporters, incretin hormones, and glycemia.

    PubMed

    Nguyen, Nam Q; Debreceni, Tamara L; Bambrick, Jenna E; Chia, Bridgette; Wishart, Judith; Deane, Adam M; Rayner, Chris K; Horowitz, Michael; Young, Richard L

    2015-03-01

    Intestinal glucose absorption is mediated by sodium-dependent glucose transporter 1 (SGLT-1) and glucose transporter 2 (GLUT2), which are linked to sweet taste receptor (STR) signaling and incretin responses. This study aimed to examine intestinal glucose absorption in morbidly obese humans and its relationship to the expression of STR and glucose transporters, glycemia, and incretin responses. Seventeen nondiabetic, morbidly obese subjects (body mass index [BMI], 48 ± 4 kg/m(2)) and 11 lean controls (BMI, 25 ± 1 kg/m(2)) underwent endoscopic duodenal biopsies before and after a 30-minute intraduodenal glucose infusion (30 g glucose and 3 g 3-O-methylglucose [3-OMG]). Blood glucose and plasma concentrations of 3-OMG, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1), insulin, and glucagon were measured over 270 minutes. Expression of duodenal SGLT-1, GLUT2, and STR (T1R2) was quantified by PCR. The increase in plasma 3-OMG (P < .001) and blood glucose (P < .0001) were greater in obese than lean subjects. Plasma 3-OMG correlated directly with blood glucose (r = 0.78, P < .01). In response to intraduodenal glucose, plasma GIP (P < .001), glucagon (P < .001), and insulin (P < .001) were higher, but GLP-1 (P < .001) was less in the obese compared with lean. Expression of SGLT-1 (P = .035), but not GLUT2 or T1R2, was higher in the obese, and related to peak plasma 3-OMG (r = 0.60, P = .01), GIP (r = 0.67, P = .003), and insulin (r = 0.58, P = .02). In morbid obesity, proximal intestine glucose absorption is accelerated and related to increased SGLT-1 expression, leading to an incretin-glucagon profile promoting hyperinsulinemia and hyperglycemia. These findings are consistent with the concept that accelerated glucose absorption in the proximal gut underlies the foregut theory of obesity and type 2 diabetes.

  18. Yeast AMP-activated protein kinase monitors glucose concentration changes and absolute glucose levels.

    PubMed

    Bendrioua, Loubna; Smedh, Maria; Almquist, Joachim; Cvijovic, Marija; Jirstrand, Mats; Goksör, Mattias; Adiels, Caroline B; Hohmann, Stefan

    2014-05-02

    Analysis of the time-dependent behavior of a signaling system can provide insight into its dynamic properties. We employed the nucleocytoplasmic shuttling of the transcriptional repressor Mig1 as readout to characterize Snf1-Mig1 dynamics in single yeast cells. Mig1 binds to promoters of target genes and mediates glucose repression. Mig1 is predominantly located in the nucleus when glucose is abundant. Upon glucose depletion, Mig1 is phosphorylated by the yeast AMP-activated kinase Snf1 and exported into the cytoplasm. We used a three-channel microfluidic device to establish a high degree of control over the glucose concentration exposed to cells. Following regimes of glucose up- and downshifts, we observed a very rapid response reaching a new steady state within less than 1 min, different glucose threshold concentrations depending on glucose up- or downshifts, a graded profile with increased cell-to-cell variation at threshold glucose concentrations, and biphasic behavior with a transient translocation of Mig1 upon the shift from high to intermediate glucose concentrations. Fluorescence loss in photobleaching and fluorescence recovery after photobleaching data demonstrate that Mig1 shuttles constantly between the nucleus and cytoplasm, although with different rates, depending on the presence of glucose. Taken together, our data suggest that the Snf1-Mig1 system has the ability to monitor glucose concentration changes as well as absolute glucose levels. The sensitivity over a wide range of glucose levels and different glucose concentration-dependent response profiles are likely determined by the close integration of signaling with the metabolism and may provide for a highly flexible and fast adaptation to an altered nutritional status.

  19. A glucose oxidase-coupled DNAzyme sensor for glucose detection in tears and saliva.

    PubMed

    Liu, Chengcheng; Sheng, Yongjie; Sun, Yanhong; Feng, Junkui; Wang, Shijin; Zhang, Jin; Xu, Jiacui; Jiang, Dazhi

    2015-08-15

    Biosensors have been widely investigated and utilized in a variety of fields ranging from environmental monitoring to clinical diagnostics. Glucose biosensors have triggered great interest and have been widely exploited since glucose determination is essential for diabetes diagnosis. In here, we designed a novel dual-enzyme biosensor composed of glucose oxidase (GOx) and pistol-like DNAzyme (PLDz) to detect glucose levels in tears and saliva. First, GOx, as a molecular recognition element, catalyzes the oxidation of glucose forming H2O2; then PLDz recognizes the produced H2O2 as a secondary signal and performs a self-cleavage reaction promoted by Mn(2+), Co(2+) and Cu(2+). Thus, detection of glucose could be realized by monitoring the cleavage rate of PLDz. The slope of the cleavage rate of PLDz versus glucose concentration curve was fitted with a Double Boltzmann equation, with a range of glucose from 100 nM to 10mM and a detection limit of 5 μM. We further applied the GOx-PLDz 1.0 biosensor for glucose detection in tears and saliva, glucose levels in which are 720±81 μM and 405±56 μM respectively. Therefore, the GOx-PLDz 1.0 biosensor is able to determine glucose levels in tears and saliva as a noninvasive glucose biosensor, which is important for diabetic patients with frequent/continuous glucose monitoring requirements. In addition, induction of DNAzyme provides a new approach in the development of glucose biosensors. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Fasting enhances the response of arcuate neuropeptide Y-glucose-inhibited neurons to decreased extracellular glucose

    PubMed Central

    Murphy, Beth Ann; Fioramonti, Xavier; Jochnowitz, Nina; Fakira, Kurt; Gagen, Karen; Contie, Sylvain; Lorsignol, Anne; Penicaud, Luc; Martin, William J.; Routh, Vanessa H.

    2009-01-01

    Fasting increases neuropeptide Y (NPY) expression, peptide levels, and the excitability of NPY-expressing neurons in the hypothalamic arcuate (ARC) nucleus. A subpopulation of ARC-NPY neurons (∼40%) are glucose-inhibited (GI)-type glucose-sensing neurons. Hence, they depolarize in response to decreased glucose. Because fasting enhances NPY neurotransmission, we propose that during fasting, GI neurons depolarize in response to smaller decreases in glucose. This increased excitation in response to glucose decreases would increase NPY-GI neuronal excitability and enhance NPY neurotransmission. Using an in vitro hypothalamic explant system, we show that fasting enhances NPY release in response to decreased glucose concentration. By measuring relative changes in membrane potential using a membrane potential-sensitive dye, we demonstrate that during fasting, a smaller decrease in glucose depolarizes NPY-GI neurons. Furthermore, incubation in low (0.7 mM) glucose enhanced while leptin (10 nM) blocked depolarization of GI neurons in response to decreased glucose. Fasting, leptin, and glucose-induced changes in NPY-GI neuron glucose sensing were mediated by 5′-AMP-activated protein kinase (AMPK). We conclude that during energy sufficiency, leptin reduces the ability of NPY-GI neurons to sense decreased glucose. However, after a fast, decreased leptin and glucose activate AMPK in NPY-GI neurons. As a result, NPY-GI neurons become depolarized in response to smaller glucose fluctuations. Increased excitation of NPY-GI neurons enhances NPY release. NPY, in turn, shifts energy homeostasis toward increased food intake and decreased energy expenditure to restore energy balance. PMID:19211911