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1

Liver kinetics of glucose analogs measured in pigs by PET: importance of dual-input blood sampling.  

DEFF Research Database (Denmark)

Metabolic processes studied by PET are quantified traditionally using compartmental models, which relate the time course of the tracer concentration in tissue to that in arterial blood. For liver studies, the use of arterial input may, however, cause systematic errors to the estimated kinetic parameters, because of ignorance of the dual blood supply from the hepatic artery and the portal vein to the liver. METHODS: Six pigs underwent PET after [15O]carbon monoxide inhalation, 3-O-[11C]methylglucose (MG) injection, and [18F]FDG injection. For the glucose scans, PET data were acquired for 90 min. Hepatic arterial and portal venous blood samples and flows were measured during the scan. The dual-input function was calculated as the flow-weighted input. RESULTS: For both MG and FDG, the compartmental analysis using arterial input led to systematic underestimation of the rate constants for rapid blood-tissue exchange. Furthermore, the arterial input led to absurdly low estimates for the extracellular volume compared with the independently measured hepatic blood volume of 0.25 +/- 0.01 mL/mL (milliliter blood per milliliter liver tissue). In contrast, the use of a dual-input function provided parameter estimates that were in agreement with liver physiology. Using the dual-input function, the clearances into the liver cells (K1 = 1.11 +/- 0.11 mL/min/mL for MG; K1 = 1.07 +/- 0.19 mL/min/mL for FDG) were comparable with the liver blood flow (F = 1.02 +/- 0.05 mL/min/mL). As required physiologically, the extracellular volumes estimated using the dual-input function were larger than the hepatic blood volume. The linear Gjedde-Patlak analysis produced parameter estimates that were unaffected by the choice of input function, because this analysis was confined to time scales for which the arterial-input and dual-input functions were very similar. CONCLUSION: Compartmental analysis of MG and FDG kinetics using dynamic PET data requires measurements of dual-input activity concentrations. Using the dual-input function, physiologically reasonable parameter estimates of K1, k2, and Vp were obtained, whereas the use of conventional arterial sampling underestimated these parameters compared with independent measurements of hepatic flow and hepatic blood volume. In contrast, the linear Gjedde-Patlak analysis, being less informative but more robust, gave similar parameter estimates (K, V) with both input functions. Udgivelsesdato: 2001-May

Munk, O L; Bass, L

2001-01-01

2

Raman spectroscopy for noninvasive glucose measurements  

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We report the first successful study of the use of Raman spectroscopy for quantitative, noninvasive (“transcutaneous”) measurement of blood analytes, using glucose as an example. As an initial evaluation of the ability of Raman spectroscopy to measure glucose transcutaneously, we studied 17 healthy human subjects whose blood glucose levels were elevated over a period of 2–3 h using a standard glucose tolerance test protocol. During the test, 461 Raman spectra were collected transcutaneo...

Enejder, Annika M. K.; Scecina, Thomas G.; Oh, Jeankun; Hunter, Martin; Shih, Wei-chuan; Sasic, Slobodan; Horowitz, Gary L.; Feld, Michael S.

2004-01-01

3

Identification of the D-glucose binding polypeptide of the renal Na+-D-glucose cotransporter with a covalently binding D-glucose analog.  

Science.gov (United States)

The covalently binding D-glucose analog 10-N-(bromoacetyl)amino-1-decyl-beta-D-glucopyranoside (BADG) was synthesised and shown to be a high-affinity inhibitor of the renal Na+-D-glucose contransporter. From renal brush-border membranes a protein fraction was isolated, in which the concentration of Na+-dependent phlorizin binding sites per mg protein was enriched 7-fold. In labeling experiments with this protein fraction a polypeptide of Mr approximately 79000 was identified as containing the D-glucose binding site of the renal Na+-D-glucose cotransporter. PMID:3838282

Neeb, M; Fasold, H; Koepsell, H

1985-03-11

4

Analog to Digital Conversion in Physical Measurements  

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There exist measuring devices where an analog input is converted into a digital output. Such converters can have a nonlinear internal dynamics. We show how measurements with such converting devices can be understood using concepts from symbolic dynamics. Our approach is based on a nonlinear one-to-one mapping between the analog input and the digital output of the device. We analyze the Bernoulli shift and the tent map which are realized in specific analog/digital converters....

Kapitaniak, T.; Zyczkowski, K.; Feudel, U.; Grebogi, C.

1999-01-01

5

Positron emission tomographic measurements of cerebral glucose utilization using [1-11C]D-glucose  

International Nuclear Information System (INIS)

Regional CMRglc was measured in seven healthy volunteers with positron emission tomography using [1-11C]D-glucose. Regional CBF was measured using [11C]fluoromethane. The arteriovenous differences of unlabeled glucose and oxygen together with 11C metabolites were also measured. In addition to the loss of [11C]CO2, a loss of acidic 11C metabolites was also detected. A three-compartment model was applied to the tracer data in the time interval 0-24 min. After correction for the loss of 11C metabolites, the tracer method gave an average CMRglc of 26.4 +/- 1.9 (SD) mumol/100 g/min, close to the value obtained with the Fick principle. After correction for the loss of [11C]CO2 only, the tracer method gave 23.6 +/- 2.1 mumol/100 g/min, compatible with (1/6) CMRO2, obtained with the Fick principle. These results and the time course of the loss of acidic 11C metabolites are consistent with the presence of nonoxidative metabolism of glucose that causes an early loss of mainly [11C]lacetate after a bolus injection of the tracer. This implies that [1-11C]D-glucose measures the rate of glucose oxidation rather than the total CMRglc. The experiments using [1-11C]D-glucose were compared to five analogous experiments using [U-11C]D-glucose together with [15O]H2O as a flow tracer. After correction for the loss of [11C]CO2, the two glucose tracers gave similar global values of CMRglc and other parameters associated with glucose utilization, but with labeling in the carbon-1 position, t with labeling in the carbon-1 position, the loss of [11C]CO2 was substantially delayed and the contrast between gray and white matter was improved

6

Non-Invasive Optical Blood Glucose Measurement  

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The method for noninvasively blood glucose monitoring system is discussed in this paper. Lot of research work has been done in developing the device which is completely noninvasive to avoid the pros & cons because of frequent pricking. In this paper we are trying to analyze the noninvasive blood glucose measurement study in the near infrared region which is the most suitable region for blood glucose measurement. For this purpose we use a technique which is similar to pulseoximetry based on ne...

Pande, Megha C.

2013-01-01

7

Glucose Measurement: Time for a Gold Standard  

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There is no internationally recognized reference method for the measurement of blood glucose. The Centers for Disease Control and Prevention (CDC) highlighted the need for standardization some years ago when a project was started. The project objectives were to (1) investigate whether there are significant differences in calibration levels among currently used glucose monitors for home use and (2) develop a reference method for glucose determination. A first study confirmed the assumption tha...

Hagvik, Joakim

2007-01-01

8

Comparability of venous and capillary glucose measurements in blood  

DEFF Research Database (Denmark)

Diabetes and glucose intolerance are diagnosed by measurement of glucose in blood. Glucose is usually measured as venous plasma or capillary whole blood and diagnostic criteria frequently provide equivalence estimates for these two methods. This study examined the relationship between glucose measured in capillary and venous samples collected at random, fasting and 2 h after oral glucose.

Colagiuri, S; Sandbaek, A

2003-01-01

9

Measurement of glucose and 2-deoxy-2-[18F]fluoro-D-glucose transport and phosphorylation rates in myocardium using dual-tracer kinetic experiments  

International Nuclear Information System (INIS)

To examine the use of 2-deoxy-2-[18F]fluoro-D-glucose (2-FDG) as a glucose analog for measuring glucose utilization rate in myocardium, dual-tracer kinetic experiments with 2-FDG and 2-[3H]glucose were performed in the perfused, isolated rabbit interventricular septum to measure simultaneously the transport and phosphorylation rates of glucose and 2-FDG. Results of the present study indicated that, in the septum, (i) the transport rate constants of 2-FDG and glucose were similar in magnitude, (ii) the phosphorylation rate constant for 2-FDG was about 60% of that of glucose, (iii) hypoxia caused an increase in phosphorylation rates of glucose and 2-FDG without affecting transport. 9 refs.; 1 figure; 3 tabs

10

Antitumor activity of creatine analogs produced by alterations in pancreatic hormones and glucose metabolism.  

Science.gov (United States)

When rats bearing the 13,762 mammary carcinoma were treated with intravenously administered creatine analogs, cyclocreatine, beta-guanidinopropionic acid or creatine phosphate on days 4 through 8 and 14 through 18 post tumor implantation, the tumor growth delay produced varied with whether the animals were drinking water or sugar water over the course of the study. The tumor growth delays increased when the animals drank sugar water from 9.3, 1.6 and 7.6 days for cyclocreatine, beta-guanidinopropionic acid and creatine phosphate, respectively, to 15.0, 6.3 and 12.6 days. Blood glucose was decreased over the course of the creatine analog treatment regimen and the skeletal muscle transport protein GLUT-4 increased 1.5 to 2-fold with the creatine analog treatments. Plasma insulin was profoundly decreased to 20-25% of normal by the creatine analog treatment while plasma glucagon levels were increased. Plasma somatostatin increased 3- to 4-fold during the administration of the creatine analogs. These results implicate alterations in pancreatic hormone balance in the antitumor activity of these creatine analogs. PMID:9627806

Ara, G; Gravelin, L M; Kaddurah-Daouk, R; Teicher, B A

1998-01-01

11

A review of metabolism of labeled glucoses for use in measuring glucose recycling  

Energy Technology Data Exchange (ETDEWEB)

The fate of tritium from each carbon of D-glucose and the metabolism of L-glucose and 2-deoxy-D-glucose are known. Differences in metabolism of labeled glucoses can be used to quantify physical and chemical recycling of glucose. Only physical recycling is measured by (1-{sup 3}H)-L-glucose, whereas (U-{sup 14}C)-D-glucose measures total recycling. The difference between (1-{sup 3}H)-L-glucose and (U-{sup 14}C)-D-glucose, therefore, is chemical recycling. Recycling from extracellular binding sites and hepatic glucose 6-phosphate can be measured by difference between (1,2-{sup 3}H)-2-deoxy-D-glucose and (1-{sup 3}H)-L-glucose, and the difference in irreversible loss of the two will measure extrahepatic uptake of D-glucose. Recycling via Cori-alanine cycle plus CO{sub 2} is the difference in irreversible loss measured by using (6-{sup 3}H)-glucose and (U-{sup 14}C)-D-glucose. Recycling via the hexose monophosphate pathway can be determined by difference in irreversible loss between (1-{sup 3}H)-D-glucose and (6-{sup 3}H)-D-glucose. Recycling via CO{sub 2} and glycerol must be measured directly with (U-{sup 14}C)glucose, bicarbonate, and glycerol. Recycling via hepatic glycogen can be estimated by subtracting all other measured chemical recycling from total chemical recycling. This review describes means to quantify glucose recycling in vivo, enabling studies of mechanisms for conservation and utilization of glucose. 54 references.

Russell, R.W.; Young, J.W. (Iowa State Univ., Ames (USA))

1990-04-01

12

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

International Nuclear Information System (INIS)

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 [1-14C]glucose and measuring glucose clearance using plasma levels of infused [3-3H]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

13

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

Energy Technology Data Exchange (ETDEWEB)

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.

Radziuk, J.; Bondy, D.C.

1982-11-01

14

Glucose-l-13C as a tracer for the measurement of systemic glucose production  

International Nuclear Information System (INIS)

Glucose-1-13C was used as a tracer for the quantitative measurement of systemic glucose production in 4 dogs and one human subject. The C-1 carbon atom of glucose was extracted as CO2 by enzymatic decarboxylation of glucose with coupled hexokinase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities. The 13C/12C ratio of the CO2 was measured using a magnetic deflection, double collector, mass spectrometer. The methods were checked in three normal and one diabetic dog by infusing glucose-1-14C and glucose-1-13C simultaneously according to the prime-constant-infusion technique. The systemic glucose production rates measured by the two methods were similar. Systemic glucose production rate was also measured in one normal adult man by infusing glucose-1-13C at the rate of 5.4 ?g/kg min following a prime injection of 22.8 mg. The calculated glucose production rate was 2.1 mg/kg min which is similar to results from previous radioisotope dilution studies in man

15

Clinical Experience of an Iontophoresis Based Glucose Measuring System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Currently finger pricking is the common method of blood glucose measurement in patients with diabetes mellitus. However, diabetes patients have proven to be reluctant to check their glucose profiles regularly because of the discomfort associated with this technique. Recently, a non-invasive and continuous Reverse Iontophoresis based Glucose Monitoring Device (RIGMD) was developed in Korea. The study was conducted during the period November 2003-January 2004 on 19 in-patients. Glucose measurem...

Rhee, Sang Youl; Chon, Suk; Koh, Gwanpyo; Paeng, Jeong Ryung; Oh, Seungjoon; Woo, Jeong-taek; Kim, Sung Woon; Kim, Jin-woo; Kim, Young Seol

2007-01-01

16

Activity of P536, a UDP-glucose analog, against Trypanosoma cruzi  

International Nuclear Information System (INIS)

P536, a UDP-glucose analog which was previously described as an antiviral agent, has a potent and selective activity against the intracellular and extracellular stages of Trypanosoma cruzi in vitro. It had a 50% inhibitory concentration of less than 5 micrograms/ml for T. cruzi extracellular cultured forms (epimastigote) and of 25 micrograms/ml for T. cruzi intracellular forms (amastigote) growing inside J774G8 macrophage-like cells. In contrast, the 50% inhibitory concentration was 100 micrograms/ml or greater for cultured mammalian cells and 180 micrograms/ml for the proliferation of mouse spleen lymphocytes. Furthermore, the addition of P536 (50 micrograms/ml) to T. cruzi-infected J774G8 cells cured the infected macrophages, making them able to grow and function normally. Studies on the mechanism of action of this drug indicated that it inhibited incorporation of [35S]methionine, [3H]thymidine, [3H]mannose, [14C]-N-acetylglucosamine, and [3H]uridine into macromolecules by T. cruzi epimastigotes, the last being the most sensitive

17

Effects of fasting on plasma glucose and prolonged tracer measurement of hepatic glucose output in NIDDM  

International Nuclear Information System (INIS)

We studied the measurement of hepatic glucose output (HGO) with prolonged [3-3H]glucose infusion in 14 patients with non-insulin-dependent diabetes mellitus (NIDDM). Over the course of 10.5 h, plasma glucose concentration fell with fasting by one-third, from 234 +/- 21 to 152 +/- 12 mg/dl, and HGO fell from 2.35 +/- 0.18 to 1.36 +/- 0.07 mg . kg-1 . min-1 (P less than .001). In the basal state, HGO and glucose were significantly correlated (r = 0.68, P = .03), and in individual patients, HGO and glucose were closely correlated as both fell with fasting (mean r = 0.79, P less than .01). Plasma [3-3H]glucose radioactivity approached a steady state only 5-6 h after initiation of the primed continuous infusion, and a 20% overestimate of HGO was demonstrated by not allowing sufficient time for tracer labeling of the glucose pool. Assumption of steady-state instead of non-steady-state kinetics in using Steele's equations to calculate glucose turnover resulted in a 9-24% overestimate of HGO. Stimulation of glycogenolysis by glucagon injection demonstrated no incorporation of [3-3H]glucose in hepatic glycogen during the prolonged tracer infusion. In a separate study, plasma glucose was maintained at fasting levels (207 +/- 17 mg/dl) for 8 h with the glucose-clamp technique. Total glucose turnover rates remained constant during this prolonged tracer infusion. However, HGO fell to 30% of the basal value simply by maintaining fasting hyperglycemisimply by maintaining fasting hyperglycemia in the presence of basal insulin levels

18

The sweet spot: FDG and other 2-carbon glucose analogs for multi-modal metabolic imaging of tumor metabolism.  

Science.gov (United States)

Multi-modal imaging approaches of tumor metabolism that provide improved specificity, physiological relevance and spatial resolution would improve diagnosing of tumors and evaluation of tumor progression. Currently, the molecular probe FDG, glucose fluorinated with (18)F at the 2-carbon, is the primary metabolic approach for clinical diagnostics with PET imaging. However, PET lacks the resolution necessary to yield intratumoral distributions of deoxyglucose, on the cellular level. Multi-modal imaging could elucidate this problem, but requires the development of new glucose analogs that are better suited for other imaging modalities. Several such analogs have been created and are reviewed here. Also reviewed are several multi-modal imaging studies that have been performed that attempt to shed light on the cellular distribution of glucose analogs within tumors. Some of these studies are performed in vitro, while others are performed in vivo, in an animal model. The results from these studies introduce a visualization gap between the in vitro and in vivo studies that, if solved, could enable the early detection of tumors, the high resolution monitoring of tumors during treatment, and the greater accuracy in assessment of different imaging agents. PMID:25625022

Cox, Benjamin L; Mackie, Thomas R; Eliceiri, Kevin W

2015-01-01

19

The sweet spot: FDG and other 2-carbon glucose analogs for multi-modal metabolic imaging of tumor metabolism  

Science.gov (United States)

Multi-modal imaging approaches of tumor metabolism that provide improved specificity, physiological relevance and spatial resolution would improve diagnosing of tumors and evaluation of tumor progression. Currently, the molecular probe FDG, glucose fluorinated with 18F at the 2-carbon, is the primary metabolic approach for clinical diagnostics with PET imaging. However, PET lacks the resolution necessary to yield intratumoral distributions of deoxyglucose, on the cellular level. Multi-modal imaging could elucidate this problem, but requires the development of new glucose analogs that are better suited for other imaging modalities. Several such analogs have been created and are reviewed here. Also reviewed are several multi-modal imaging studies that have been performed that attempt to shed light on the cellular distribution of glucose analogs within tumors. Some of these studies are performed in vitro, while others are performed in vivo, in an animal model. The results from these studies introduce a visualization gap between the in vitro and in vivo studies that, if solved, could enable the early detection of tumors, the high resolution monitoring of tumors during treatment, and the greater accuracy in assessment of different imaging agents. PMID:25625022

Cox, Benjamin L; Mackie, Thomas R; Eliceiri, Kevin W

2015-01-01

20

Double-label autoradiographic deoxyglucose method for sequential measurement of regional cerebral glucose utilization  

International Nuclear Information System (INIS)

A new double-label autoradiographic glucose analog method for the sequential measurement of altered regional cerebral metabolic rates for glucose in the same animal is presented. This method is based on the sequential injection of two boluses of glucose tracer labeled with two different isotopes (short-lived 18F and long-lived 3H, respectively). An operational equation is derived which allows the determination of glucose utilization for the time period before the injection of the second tracer; this equation corrects for accumulation and loss of the first tracer from the metabolic pool occurring after the injection of the second tracer. An error analysis of this operational equation is performed. The double-label deoxyglucose method is validated in the primary somatosensory (''barrel'') cortex of the anesthetized rat. Two different rows of whiskers were stimulated sequentially in each rat; the two periods of stimulation were each preceded by an injection of glucose tracer. After decapitation, dried brain slices were first exposed, in direct contact, to standard X-ray film and then to uncoated, ''tritium-sensitive'' film. Results show that the double-label deoxyglucose method proposed in this paper allows the quantification and complete separation of glucose utilization patterns elicited by two different stimulations sequentially applied in the same animal. (author)

 
 
 
 
21

[The research status and development of noninvasive glucose optical measurements].  

Science.gov (United States)

Diabetes threatens the health of human beings. Because of the disadvantages of invasive glucose detection, Noninvasive glucose measurement which diabetics press for becomes the hotspot in both domestic and overseas academic circles. But up to now none of the available devices offers enough precision to clinical application. The principle, method, characteristics of optical spectrum measurements and current development at home and abroad are reviewed in the present paper, such as photoacoustic spectroscopy method, Raman spectrometry, fluorescence method, polarimetry, optical coherence tomography and near infrared spectroscopy. Then the problems and technical analysis of noninvasive glucose measurements as well as the development direction are discussed, and the dynamic spectrum is pointed out to be one of the most application prospect methods for noninvasive glucose measurement. PMID:21137412

Li, Gang; Zhou, Mei; Wu, Hong-jie; Lin, Ling

2010-10-01

22

Temperature influence on non-invasive blood glucose measurement  

Science.gov (United States)

Regular monitoring of blood sugar level is important for the management of diabetes. The Near-Infra-Red (NIR) spectroscopy method is a promising approach and this involves some form of contact with the body skin. It is noted that the skin temperature does fluctuate with the environment and physiological conditions and the temperature has an influence on the glucose measurement. In this paper, in-vitro and in-vivo investigations on the temperature influence on blood glucose measurement were studied. The in-vitro results from FTIR spectrometer show that sample temperature has significant influence on water absorption, which significantly affects the glucose absorption measurement. The in-vivo results show that when skin temperature around the measurement site is taken into consideration, the prediction of blood glucose level greatly improves.

Zhang, Xiqin; Yeo, Joon Hock

2009-02-01

23

Blood Sugar Measurement in Zebrafish Reveals Dynamics of Glucose Homeostasis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The adult zebrafish has the potential to become an important model for diabetes-related research. To realize this potential, small-scale methods for analyzing pancreas function are required. The measurement of blood glucose level is a commonly used method for assessing ?-cell function, but the small size of the zebrafish presents challenges both for collecting blood samples and for measuring glucose. We have developed methods for collecting microsamples of whole blood and plasma for the meas...

Eames, Stefani C.; Philipson, Louis H.; Prince, Victoria E.; Kinkel, Mary D.

2010-01-01

24

Synthesis and characterization of 1-deoxy-?-D-glucopyranosyl-methanephosphonyl-5'-uridine monophosphate: a phosphono analog of UDP-glucose  

International Nuclear Information System (INIS)

The phosphono analog of UDP-glucose (UDPG) has been synthesized as a first entry into potential dead-end inhibitors of glycosyltransferases using UDP-sugars such as UDP-glucuronyltransferase and possible alternative substrates for UDPG dehydrogenase and epimerase. 1-Deoxy-?-D-glucopyranosylmethanephosphonate (G-1-CH2P) was synthesized by modifications of literature procedures and characterized by 1H, 31P and 13C NMR. Condensation of G-1-CH2P with UMP morpholidate gave the expected phosphono analog of UDPG (UDPCH2G) in low yield. G-1-CH2P was found to be a substrate for UTP: glucose-1-phosphate pyrophosphoyrlase. Thus, UDPCH2G can be prepared enzymatically from G-1-CH2P and UTP by the coupled action of the pyrophosphoyrlase and inorganic pyrophosphatase. Preliminary evidence suggests UDPCH2G is a very poor substrate for UDPG dehydrogenase. Thus, efficient enzymatic synthesis of the phosphono analog (UDPCH2GA) of UDP-glucuronate appears unlikely

25

Portal glucose infusion-glucose clamp measures hepatic influence on postprandial systemic glucose appearance as well as whole body glucose disposal  

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The full impact of the liver, through both glucose production and uptake, on systemic glucose appearance cannot be readily studied in a classical glucose clamp because hepatic glucose metabolism is regulated not only by portal insulin and glucose levels but also portal glucose delivery (the portal signal). In the present study, we modified the classical glucose clamp by giving exogenous glucose through portal vein, the “portal glucose infusion (PoG)-glucose clamp”, to determine the net he...

Zheng, Dan; Ionut, Viorica; Mooradian, Vahe; Stefanovski, Darko; Bergman, Richard N.

2009-01-01

26

Contribution to a decision making model for analogical measurement validation  

International Nuclear Information System (INIS)

In limits of studies taken on validity of analogic measures in nuclear power plant's operation, the present thesis takes aim at establishment of a model to reaching a decision on the indice of probability on measures obtained by preliminary validation system. In a first step, it is proposed to retain a system made by redundant measures in which the calcul of measures is based on the coherence between measures themselves and logic vote. In the second step, one equation is proposed to compute the index of probability of measures taken in account, the characteristics of the system

27

BIOSENSORS AND GLUCOSE MEASURING IN BIOLOGICAL FLUIDS  

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Some laboratory tests may be conducted outside the laboratory. These are the so-called Point of care investigation (POCT). Of course, these investigations are not carried out in real laboratory measuring instruments, because they are too complex, fixed and due to its size inappropriate. Therefore, the departments and clinics make use of smaller, portable systems, usually using a different technology than laboratory measurements. One of those most widely used systems are biosensors that are us...

Slodej, Lana

2011-01-01

28

Measurement of glucose concentration in interstitial fluid by surface plasmon resonance with D-galactose/D-glucose binding protein  

Science.gov (United States)

A novel minimally invasive way to measure blood glucose concentration is proposed by combining interstitial fluid transdermal extraction and surface plasma resonance (SPR) detecting. 55K Hz low-frequency ultrasound pulse is applied for less than 30 seconds to enhance the skin permeability and then interstitial fluid is extracted out of skin by vacuum. The mathematical model to express the correlation between interstitial fluid glucose and blood glucose is also developed by considering the changes of the skin conductivity. The glucose concentration in the interstitial fluid is determined using an optical SPR biological sensor that measures the refractive index. A protein-glucose binding technology using Dgalactose/ D-glucose Binding Protein for specific absorption of glucose is employed to increase SPR measurement precision. By immobilizing GGBP onto the surface of the SPR sensor, the experimental result indicates the detecting resolution of glucose rises to 1mg/L, the system succeeds in distinguishing glucose from other components in mixture. The feasibility of this method is validated for clinical application with the requirements of bloodless, painless, continuous glucose monitoring and a prototype microfluidic diabetes-monitoring device is under development.

Li, D. C.; Zhang, J. X.; Wu, P.; Huang, F. X.; Song, B.; Xu, K. X.

2009-08-01

29

Simultaneous measurement of glucose transport and utilization in the human brain  

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Glucose is the primary fuel for brain function, and determining the kinetics of cerebral glucose transport and utilization is critical for quantifying cerebral energy metabolism. The kinetic parameters of cerebral glucose transport, KMt and Vmaxt, in humans have so far been obtained by measuring steady-state brain glucose levels by proton (1H) NMR as a function of plasma glucose levels and fitting steady-state models to these data. Extraction of the kinetic parameters for cerebral glucose tra...

Shestov, Aa; Emir, Ue; Kumar, A.; Henry, P-g; Seaquist, Er; Oz, G.

2011-01-01

30

Fluorescence lifetime measurements of boronate derivatives to determine glucose concentration  

Energy Technology Data Exchange (ETDEWEB)

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)-anthracene (MAMA), and N-benzyl-N-methyl-N-methyl anthracene (AB-B). Fluorescence lifetime measurements confirmed the two species of AB, with and without PET. Fluorescence lifetimes were approximately 11 nsec without PET and 3 nsec with PET. The degree of the interaction between the N and the B atoms was also determined by fluorescence lifetime measurements. Electron transfer rates of AB were measured to be on the order of 10{sup 8} sec{sup -1}. Analysis of AB as a glucose sensor shows it has the potential for measuring glucose concentrations in solution with less than 5% error. Two novel glucose sensing molecules, Chloro-oxazone boronate (COB) and Napthyl-imide boronate (NIB), were synthesized. Both molecules have a N{yields}B dative bond similar to AB, but with longer wavelength fluorophores. COB and NIB were found to be unacceptable for use as glucose sensor molecules due to the small changes in average fluorescence lifetime.

Gable, J H

2000-06-01

31

Noninvasive blood glucose measurement using multiple laser diodes  

Science.gov (United States)

In the event of diabetes clinicians have advocated that frequent monitoring of a diabetic's blood glucose level is the key to avoid future complications (kidney failure, blindness, amputations, premature death, etc.,) associated with the disease. While the test-strip glucose meters available in current consumer markets allow for frequent monitoring, a more convenient technique that is accurate, painless and sample-free is preferable in a diabetic's daily routine. This paper presents a non-invasive blood glucose measurement technique using diffuse reflectance near infrared (NIR) signals. This technique uses a set of laser diodes, each operating at fixed wavelengths in the first overtone region. The NIR signals from the laser diodes are channeled to the measurement site viz., the nail-bed by means of optical fibers. A series of in vivo experiments have been performed on eight normal human subjects using a standard Oral Glucose Tolerance Test (OGTT) protocol. The reflected NIR signals are inputs to a Partial Least Squares (PLS) algorithm for calibration and future predictions. The calibration models used are developed using in vivo datasets and are unique to a particular individual. The 1218 paired points collected from the eight test subjects plotted on the Clarke Error Grid, revealed that 87.3% of these points fall within the A zone while the remainder, within the B zone, both of which, are clinically accepted. The standard error of prediction was +/-13.14mg/dL for the best calibration model. A Bland-Altman analysis of the 1218 paired points yields a 76.3% confidence level for a measurement accuracy of +/-20mg/dL. These results demonstrate the initial potential of the technique for non-invasive blood glucose measurements in vivo.

Ooi, E. T.; Zhang, X. Q.; Chen, J. H.; Soh, P. H.; Ng, K.; Yeo, J. H.

2007-02-01

32

A noninvasive method to measure splanchnic glucose uptake after oral glucose administration.  

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We have developed a noninvasive method to estimate splanchnic glucose uptake (SGU) in humans (oral glucose clamp technique [OG-CLAMP]), which combines a hyperinsulinemic clamp with an oral glucose load (oral glucose tolerance test). We validated this method in 12 nondiabetic subjects using hepatic vein catheterization (HVC) during an oral glucose tolerance test. During HVC, splanchnic blood flow increased from 1,395 +/- 64 to 1,935 +/- 109 ml/min, returning to basal after 180 min and accounte...

Ludvik, B.; Nolan, J. J.; Roberts, A.; Baloga, J.; Joyce, M.; Bell, J. M.; Olefsky, J. M.

1995-01-01

33

Plausible measurement analogies to some psychometric models of test performance.  

Science.gov (United States)

Psychometricians hypothesize that cognitive abilities such as reading, writing and spelling are measurable. However, they prefer to model item response probabilities than to study the internal structure of cognitive attributes. The theory of conjoint measurement, via its unique capacity to detect the quantitative structure of non-extensive attributes, can be used for the latter purpose. It is shown that conjoint systems analogous to the numerical composition rules advanced by the Rasch, many facet Rasch and two-parameter logistic models can be formulated using well-established axioms, representation theorems and proofs. Examples using empirical and synthetic data are presented. It was concluded that the lack of descriptive, behavioural theory remains the biggest obstacle to the scientific measurement of cognitive abilities. PMID:21973097

Kyngdon, Andrew

2011-11-01

34

Effects of maternal ethanol ingestion on uptake of glucose alanine analogs in fetal rats  

International Nuclear Information System (INIS)

The distribution of maternally-derived glucose and alanine has been studied in selected tissues of fetuses from ethanol-fed (EF) rats (30% of caloric intake throughout gestation). Controls received diet without ethanol by pair-feeding (PF) or ad libitum (AF). On the 22nd day of gestation, 2 ?Ci 3H 2-deoxyglucose (DG) and 1 ?Ci 14C ?-aminoisobutyric acid (AIB) were administered i.v. to each rat. One hour later, maternal blood, placenta, and fetal blood, liver, lung and brain were sampled for 3H and 14C activities. When compared to either control group, the mean 14C AIB activities of tissues from EF animals were reduced from 19 to 46%, with the greatest effect seen in the brain (3.7 +/- 0.1, 7.2 +/- 0.3 and 6.9 +/- 1.3 dpm/mg in EF, PF and AF fetuses respectively). In addition, the ratios of tissue:plasma 14C were reduced (p 3H 2-DG content of placenta (p < 0.05) and of brain (38.6 + 1.2, 48.1 +/- 1.2 and 47.2 +/- 1.2 in EF, PF and AF, p < 0.001). Brain weight showed significant positive correlations with AIB content (r = 0.466, p < 0.001) and with 2-DG content (r = 0.267, p < 0.01). Impaired uptake of maternally-derived nutrients may play a significant role in the effects of ethanol in utero

35

Flap Salvage Following Postoperative Venous Thrombosis Diagnosed by Blood Glucose Measurement in the Flaps  

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Objective: This is the first paper to report the measurement of blood glucose in flaps to detect early flap congestion and flap salvage following immediate flap exploration. Methods: We performed blood glucose measurement in a superficial circumflex iliac artery perforator flap and an anterolateral thigh flap postoperatively using Medisafe-Mini (Terumo, Japan), a regular capillary blood glucose–monitoring device. Results: The blood glucose measurements were low when in early venous thrombos...

Hara, Hisako; Mihara, Makoto; Narushima, Mitsunaga; Yamamoto, Takumi; Todokoro, Takeshi; Araki, Jun; Iida, Takuya; Koshima, Isao; Shim, Timothy Weng Hoh

2011-01-01

36

Blood glucose measurement by using hollow optical fiber-based attenuated total reflection probe  

Science.gov (United States)

A noninvasive glucose monitoring system based on mid-infrared, attenuated total reflection spectroscopy using a hollow optical fiber probe is developed. Owing to the flexible fiber probe, measurement of oral mucosa, where blood capillaries are near the skin surface, is possible. Blood glucose levels are measured by detecting the peak intensity of glucose absorption bands, and the experimental results showed that the reproducibility of the measurement is high enough for monitoring blood glucose.

Kino, Saiko; Tanaka, Yuki; Matsuura, Yuji

2014-05-01

37

Effects of gamma-rays and glucose analogs on the energy metabolism of a cell line derived from human cerebral glioma  

International Nuclear Information System (INIS)

Effects of gamma-rays and glucose analogs, 2-deoxy-D-glucose (2-DG), 5-thio-D-glucose (5-TG) and 3-O-methyl glucose (3-O-MG) on cellular energy metabolism have been studied in a cell line, derived from a human cerebral glioma, by analysing intermediates of glycolysis and some important nucleotides (ATP, NAD etc.) using the technique of isotachophoresis. Gamma-irradiation induced a transient decrease in the nucleotide levels accompanied by an accumulation of sugar phosphates, the nucleotide levels recovering in a few hours post-irradiation. 2-DG inhibited glycolysis and reduced the nucleotide levels of irradiated as well as unirradiated cells in a concentration-dependent manner both in presence and absence of respiration, whereas 5-TG and 3-OMG did not show significant effects in the presence of respiration. Reduced energy status observed with 2-DG under respiratory proficient conditions was completely reversed in 2 hr following its removal, whereas such a recovery was not observed in the absence of respiration. These results have important implications in the energy-linked modifications of tumor radiation response using glucose analogs. (author). 36 refs., 6 figs., 4 tabs

38

Measurement of lactate formation from glucose using [6-3H]- and [6-14C]glucose in humans  

International Nuclear Information System (INIS)

To assess the validity of determining the origin of plasma lactate from the ratio of lactate and glucose specific activities (SA) during infusion of labeled glucose, normal subjects received infusions of [6-3H]- and [6-14C]glucose for 4 h after a 12 h fast, and, on another day, cold glucose labeled with both tracers during 4-6 h of hyperinsulinemia (approximately 650 microU/ml). Basally, less lactate was derived from plasma glucose when measured with [6-3H]glucose (27 +/- 2%) than with [6-14C]glucose (40 +/- 2%, P less than 0.001). Insulin did not increase the percent of lactate derived from plasma glucose when measured with [6-3H]glucose (29 +/- 2%) but did increase when measured with [6-14C]glucose (60 +/- 4%). The arterialized blood (A) [3H]lactate SA was 30-40% higher (P less than 0.01) than deep venous blood (V) [3H]lactate SA, whereas A and V [14C]lactate SA were similar. During conversion of alanine to lactate with glutamic-pyruvic transaminase (GPT) and lactate dehydrogenase (LDH) in vitro, 32 +/- 2% of 3H in [3-3H]alanine was found in water and 68 +/- 2% in lactate. During infusion of [6-3H]- and [6-14C]glucose, the ratio of [14C]alanine to lactate SA (0.88 +/- 0.05) was less than the ratio of [3H]alanine to lactate SA (0.31 +/- 0.03, P less than 0.001). In conclusion (1) loss of 3H relative to 14C from position 6 in glucose occurs during lactate formation in extrahepatic tissues possibly due to the GPT reaction (alanine conversion to pyruvate), and (2) even ine conversion to pyruvate), and (2) even under supraphysiologic hyperinsulinemic conditions not all of plasma lactate originates from plasma glucose

39

Direct measurement of brain glucose concentrations in humans by 13C NMR spectroscopy  

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Glucose is the main fuel for energy metabolism in the normal human brain. It is generally assumed that glucose transport into the brain is not rate-limiting for metabolism. Since brain glucose concentrations cannot be determined directly by radiotracer techniques, we used 13C NMR spectroscopy after infusing enriched D-[1-13C]glucose to measure brain glucose concentrations at euglycemia and at hyperglycemia (range, 4.5-12.1 mM) in six healthy children (13-16 years old). Brain glucose concentra...

Gruetter, R.; Novotny, E. J.; Boulware, S. D.; Rothman, D. L.; Mason, G. F.; Shulman, G. I.; Shulman, R. G.; Tamborlane, W. V.

1992-01-01

40

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

International Nuclear Information System (INIS)

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. (paper)

 
 
 
 
41

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

Science.gov (United States)

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.

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

2013-12-01

42

Hepatic glucose output in humans measured with labeled glucose to reduce negative errors  

International Nuclear Information System (INIS)

Steele and others have suggested that minimizing changes in glucose specific activity when estimating hepatic glucose output (HGO) during glucose infusions could reduce non-steady-state errors. This approach was assessed in nondiabetic and type II diabetic subjects during constant low dose [27 mumol.kg ideal body wt (IBW)-1.min-1] glucose infusion followed by a 12 mmol/l hyperglycemic clamp. Eight subjects had paired tests with and without labeled infusions. Labeled infusion was used to compare HGO in 11 nondiabetic and 15 diabetic subjects. Whereas unlabeled infusions produced negative values for endogenous glucose output, labeled infusions largely eliminated this error and reduced the dependence of the Steele model on the pool fraction in the paired tests. By use of labeled infusions, 11 nondiabetic subjects suppressed HGO from 10.2 +/- 0.6 (SE) fasting to 0.8 +/- 0.9 mumol.kg IBW-1.min-1 after 90 min of glucose infusion and to -1.9 +/- 0.5 mumol.kg IBW-1.min-1 after 90 min of a 12 mmol/l glucose clamp, but 15 diabetic subjects suppressed only partially from 13.0 +/- 0.9 fasting to 5.7 +/- 1.2 at the end of the glucose infusion and 5.6 +/- 1.0 mumol.kg IBW-1.min-1 in the clamp (P = 0.02, 0.002, and less than 0.001, respectively)

43

Glucose measurement in interstitial fluid by microdialysis for the calibration of minimally invasive blood glucose monitoring  

Science.gov (United States)

According to the requirement of the calibration in minimally invasive blood glucose monitoring, a method based on microdialysis was presented to monitor glucose level in interstitial fluid continuously. An experimental system simulating the continuous change of glucose concentration in vivo was built. The influences on recovery of microdialysis caused by flow rate, glucose concentration, and temperature etc. were studied. The results led to the conclusion that the recovery fell by 71.7% when perfusion rate increased from 0.3 ?L/min to 3.0 ?L/min, while the different concentrations of glucose solutions scarcely contribute to the recovery instead, and the temperatures from 25 to 58 °C caused the recovery to increase by 34.6%.

Li, Dachao; Wang, Ridong; Chong, Hao; Liu, Yu; Xu, Kexin

2013-03-01

44

Relationship between fluctuations in glucose levels measured by continuous glucose monitoring and vascular endothelial dysfunction in type 2 diabetes mellitus  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Fluctuations in blood glucose level cause endothelial dysfunction and play a critical role in onset and/or progression of atherosclerosis. We hypothesized that fluctuation in blood glucose levels correlate with vascular endothelial dysfunction and that this relationship can be assessed using common bedside medical devices. Methods Fluctuations in blood glucose levels were measured over 24?hours by continuous glucose monitoring (CGM on admission day 2 in 57 patients with type 2 diabetes mellitus. The reactive hyperemia index (RHI, an index of vascular endothelial function, was measured using peripheral arterial tonometry (EndoPAT on admission day 3. Results The natural logarithmic-scaled RHI (L_RHI correlated with SD (r=?0.504; PPP=0.001 and percentage of time ?200?mg/dl (r=?0.292; P=0.028. In 12 patients with hypoglycemia, L_RHI also correlated with the percentage of time at hypoglycemia (r=?0.589; P=0.044. L_RHI did not correlate with HbA1c or fasting plasma glucose levels. Furthermore, L_RHI did not correlate with LDL cholesterol, HDL cholesterol, and triglyceride levels or with systolic and diastolic blood pressures. Finally, multivariate analysis identified MAGE as the only significant determinant of L_RHI. Conclusions Fluctuations in blood glucose levels play a significant role in vascular endothelial dysfunction in type 2 diabetes. Trial registration UMIN000007581

Torimoto Keiichi

2013-01-01

45

Localized 1H NMR measurement of glucose consumption in the human brain during visual stimulation.  

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Spatially localized 1H NMR spectroscopy has been applied to measure changes in brain glucose concentration during 8-Hz photic stimulation. NMR spectroscopic measurements were made in a 12-cm3 volume centered on the calcarine fissure and encompassing the primary visual cortex. The average maximum change in glucose levels was 0.34 mumol.g-1 (n = 5) at 15 min; glucose level had turned toward resting level at 25 min. The glucose change was used to calculate the increase of glucose cerebral metabo...

Chen, W.; Novotny, E. J.; Zhu, X. H.; Rothman, D. L.; Shulman, R. G.

1993-01-01

46

Blood glucose measurement by glucometer in comparison with standard method in diagnosis of neonatal hypoglycemia.  

Science.gov (United States)

Hypoglycemia is considered as a serious risk factor in neonates. In the majority of cases, it occurs with no clinical symptoms. Accordingly, early diagnosis is extremely imperative, which can also lead to less morbidity and mortality. The aim of this study was to assess the importance of screening blood glucose using glucometer (known as a quick and cost-effective diagnostic test) in comparison with laboratory method. A total of 219 neonates at risk of hypoglycemia were included in this study. Blood glucose was measured by glucometer and laboratory. In addition glucose level of capillary blood was measured by glucometer at the same time. Sensitivity and specificity of capillary blood glucose measurement by glucometer were 83.5%, 97.5% respectively (ppv=80%), (npv=98%). Capillary blood glucose measured by glucometer has an acceptable sensitivity and specificity in measurement of neonatal blood glucose. Therefore measurement by glucometer is recommended as a proper diagnostic test. PMID:25149886

Nayeri, Fatemeh; Shariat, Mamak; Mousavi Behbahani, Hamid Modarres; Dehghan, Padideh; Ebrahim, Bita

2014-01-01

47

Noninvasive diagnostic devices for diabetes through measuring tear glucose.  

Science.gov (United States)

This article reviews the development of a noninvasive diagnostic for diabetes by detecting ocular glucose. Early diagnosis and daily management are very important to diabetes patients to ensure a healthy life. Commercial blood glucose sensors have been used since the 1970s. Millions of diabetes patients have to prick their finger for a drop of blood 4-5 times a day to check blood glucose levels--almost 1800 times annually. There is a strong need to have a noninvasive device to help patients to manage the disease easily and painlessly. Instead of detecting the glucose in blood, monitoring the glucose level in other body fluids may provide a feasible approach for noninvasive diagnosis and diabetes control. Tear glucose has been studied for several decades. This article reviews studies on ocular glucose and its monitoring methods. Attempts to continuously monitor the concentration of tear glucose by using contact lens-based sensors are discussed as well as our current development of a nanostructured lens-based sensor for diabetes. This disposable biosensor for the detection of tear glucose may provide an alternative method to help patients manage the disease conveniently. PMID:21303640

Zhang, Jin; Hodge, William; Hutnick, Cindy; Wang, Xianbin

2011-01-01

48

Measurement of the absorption coefficient of a glucose solution through transmission of light and polarymetry techniques  

Science.gov (United States)

Diabetes is a disease with no cure, but can be controlled to improve the quality of life of sufferers. Currently there are means to control, but this means they have the disadvantage that in order to measure the amount of glucose is necessary to take blood samples that are painful. This paper presents a system for measuring glucose using non-invasive optical techniques: using absorption spectroscopy and polarimetry technique. It shows the results obtained from experiments done on samples containing distilled water and different amounts of glucose to study the absorption coefficient of glucose with both techniques. Water is used because it is one of the main elements in the blood and interferes with glucose measurement. This experiment will develop a prototype to measure glucose through a non-invasive technique.

Yáñez M., J.

2011-10-01

49

Non-invasive Glucose Measurements Using Wavelength Modulated Differential Photothermal Radiometry (WM-DPTR)  

Science.gov (United States)

Wavelength-modulated differential laser photothermal radiometry (WM-DPTR) is introduced for potential development of clinically viable non-invasive glucose biosensors. WM-DPTR features unprecedented glucose-specificity and sensitivity by combining laser excitation by two out-of-phase modulated beams at wavelengths near the peak and the baseline of a prominent and isolated mid-IR glucose absorption band. Measurements on water-glucose phantoms (0 to 300 mg/dl glucose concentration) demonstrate high sensitivity to meet wide clinical detection requirements ranging from hypoglycemia to hyperglycemia. The measurement results have been validated by simulations based on fully developed WM-DPTR theory. For sensitive and accurate glucose measurements, the key is the selection and tight control of the intensity ratio and the phase shift of the two laser beams.

Guo, X.; Mandelis, A.; Zinman, B.

2012-11-01

50

Glycolysis-induced discordance between glucose metabolic rates measured with radiolabeled fluorodeoxyglucose and glucose  

International Nuclear Information System (INIS)

We have developed an autoradiographic method for estimating the oxidative and glycolytic components of local CMRglc (LCMRglc), using sequentially administered [18F]fluorodeoxyglucose (FDG) and [14C]-6-glucose (GLC). FDG-6-phosphate accumulation is proportional to the rate of glucose phosphorylation, which occurs before the divergence of glycolytic (GMg) and oxidative (GMo) glucose metabolism and is therefore related to total cerebral glucose metabolism GMt: GMg + GMo = GMt. With oxidative metabolism, the 14C label of GLC is temporarily retained in Krebs cycle-related substrate pools. We hypothesize that with glycolytic metabolism, however, a significant fraction of the 14C label is lost from the brain via lactate production and efflux from the brain. Thus, cerebral GLC metabolite concentration may be more closely related to GMo than to GMt. If true, the glycolytic metabolic rate will be related to the difference between FDG- and GLC-derived LCMRglc. Thus far, we have studied normal awake rats, rats with limbic activation induced by kainic acid (KA), and rats visually stimulated with 16-Hz flashes. In KA-treated rats, significant discordance between FDG and GLC accumulation, which we attribute to glycolysis, occurred only in activated limbic structures. In visually stimulated rats, significant discordance occurred only in the optic tectum

51

The use of /sup 11/C-glucose and positron emission tomography to measure brain glucose metabolism  

International Nuclear Information System (INIS)

To measure regional cerebral metabolism of glucose (CMRGlu) with positron emission tomography (PET), but avoid the potential problems inherent in the use of /sup 18/F-fluoro-deoxyglucose, (e.g. regional variation in regional rate constants and instability of the ''lumped constant''), the authors have developed a method using uniformly labeled /sup 11/C-glucose. The method employs a 4-compartment model that accounts for vascular tracer, transport of tracer in and out of the extravascular space, metabolism of tracer, and the production of labeled carbon dioxide, which is free to leave the tissue with blood flow. The differential equations for this model, when solved for CMRGlu, yield CMRGlu=k/sub 1/ . k/sub 3/ . CBF . C/sub B//[k/sub 1/ . k/sub 3/+CBF/CBV . (k/sub 2/+k/sub 3/)] where CBF and CBV are cerebral blood flow and volume, C/sub B/ is unlabeled blood glucose content, k/sub 1/ and k/sub 2/ are transport rate constants and k/sub 3/ is the metabolism rate constant. The authors have begun implementing this technique in baboons and human subjects by first measuring regional CBV and CBF with extant PET methods, then after injection of 20-40mCi of U-/sup 11/C-glucose, estimating the rate constants from 40 sequential PET scans taken over 20 minutes. Resulting white-to-gray matter range in CMRGlu for one typical human subject was 2.9 to 6.3 mg/(min . 100 mg). Oxygen metabolism (CMRO/sub 2/) was also measured at the same sitting with PET and the molar ratio of CMRO/sub 2//CMRGlu ranged from 5.8 to 6.4 as would be expected. These results demonstrate that it may be feasible to avoid the difficulties of an analogue tracer in the measurement of CMRGlu by using /sup 11/C-glucose

52

Noninvasive Diagnostic Devices for Diabetes through Measuring Tear Glucose  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This article reviews the development of a noninvasive diagnostic for diabetes by detecting ocular glucose. Early diagnosis and daily management are very important to diabetes patients to ensure a healthy life. Commercial blood glucose sensors have been used since the 1970s. Millions of diabetes patients have to prick their finger for a drop of blood 4–5 times a day to check blood glucose levels—almost 1800 times annually. There is a strong need to have a noninvasive device to help patient...

Zhang, Jin; Hodge, William; Hutnick, Cindy; Wang, Xianbin

2011-01-01

53

Investigation of the specificity of Raman spectroscopy in non-invasive blood glucose measurements  

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Although several in vivo blood glucose measurement studies have been performed by different research groups using near-infrared (NIR) absorption and Raman spectroscopic techniques, prospective prediction has proven to be a challenging problem. An important issue in this case is the demonstration of causality of glucose concentration to the spectral information, especially as the intrinsic glucose signal is smaller compared to that of the other analytes in the blood-tissue matrix. Furthermore,...

Dingari, Narahara Chari; Barman, Ishan; Singh, Gajendra P.; Kang, Jeon Woong; Dasari, Ramachandra R.; Feld, Michael S.

2011-01-01

54

Blood glucose measurements in the critically ill: more than just a blood draw  

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A crucial determinant for the success of intensive insulin therapy in critically ill patients is the frequent and accurate measurement of blood glucose values with immediate feedback of results. In general, therefore, this is achieved by point-of-care testing, raising the question of the best way of monitoring blood glucose. Corstjens and coworkers, in the previous issue of Critical Care, demonstrate that, in spite of good correlation to "conventional" laboratory glucose assessment, absolute ...

Brunkhorst, Frank M.; Wahl, Hans G.

2006-01-01

55

New optical method for noninvasive blood glucose measurement by optical ultrasonic modulation  

Science.gov (United States)

A new optical technique for continuous, noninvasive monitoring of blood glucose levels based on ultrasonic modulation of scattering light is proposed. The ultrasound-modulated scattered light has an accurate separation of scattering and absorption changes in tissue. And the optical scattering and absorbing coefficient of tissue depend on the concentration of glucose in the extracellular fluid. As the glucose induced to scattering and absorption changes, the ultrasoundmodulated light also changes. In this paper, a correlation is observed between ultrasound-modulated light intensity as well as its modulation depth and blood glucose concentration in phantom experiments. In addition, some researches about ultrasound-modulated signal affected by the temperature of glucose aqueous solution are done. Preliminary experiments find that this method is a promising noninvasive blood glucose measurement.

Zhu, Lili; Lin, Jieqing; Xie, Wenming; Li, Hui

2010-11-01

56

Measuring Glucose Concentrations: Daily Practice, Current and Future Developments  

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Self-monitoring of blood glucose (SMBG) by means of modern glucose meters is of relevance for all patients with diabetes. It not only provides important information about the effect of therapeutic interventions on metabolic control, but about the effect of exercise and meals as well. Therefore, it is an essential part of diabetes therapy. However, it has received little interest from academia in the last 10 years. This is in sharp contrast to the massive increase in SMBG use in the last decad...

Heinemann, Lutz

2008-01-01

57

Clinically Important Factors Influencing the Diagnostic Measurement of Pleural Fluid pH and Glucose  

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RATIONALE: Accurate pleural fluid pH and glucose measurement is a key component in the diagnosis and management of patients with pleural effusion. Standardized methods of pleural fluid collection have not been defined. OBJECTIVES: To assess the effect of common clinical factors that may distort measurement accuracy of pleural fluid pH and glucose. METHODS: Ninety-two exudative pleural aspirates were collected in commercially available blood gas syringes. MEASUREMENTS AND MAIN RESULTS: Samples...

Rahman, Nm; Mishra, Ek; Davies, He; Davies, Rj; Lee, Yc

2008-01-01

58

Non-Invasive Glucose Measurement by Use of Metabolic Heat Conformation Method  

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A non-invasive glucose measurement system based on the method of metabolic heat conformation (MHC) is presented in this paper. This system consists of three temperature sensors, two humidity sensors, an infrared sensor and an optical measurement device. The glucose level can be deduced from the quantity of heat dissipation, blood flow rate of local tissue and degree of blood oxygen saturation. The methodology of the data process and the measurement error are also analyzed. The system is appli...

Junfeng Li; Dongsheng Wang; Xiaohao Wang; Fei Tang

2008-01-01

59

Analog voltmeter for measuring oxygen concentration in fast reactor sodium circuits  

International Nuclear Information System (INIS)

An analog voltmeter designed for oxygen concentration measurement in the sodium coolant of fast reactors and thus the determination of oxygen corrosion action on the reactor core materials was tested in a sodium loop. The oxygen concentration is determined from the measurements of voltage across a solid electrolyte galvanic cell and of ambient temperature measured by a thermocouple. Thermocouple voltage ranges within 10 and 21 mV while the input from the galvanic cell within 0.2 and 0.45 V. The measured values of both quantities are combined at the analog voltmeter output according to a certain relation shown and give oxygen concentration. (Z.M.)

60

Factors Affecting Blood Glucose Monitoring: Sources of Errors in Measurement  

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Glucose monitoring has become an integral part of diabetes care but has some limitations in accuracy. Accuracy may be limited due to strip manufacturing variances, strip storage, and aging. They may also be due to limitations on the environment such as temperature or altitude or to patient factors such as improper coding, incorrect hand washing, altered hematocrit, or naturally occurring interfering substances. Finally, exogenous interfering substances may contribute errors to the system eval...

Ginsberg, Barry H.

2009-01-01

 
 
 
 
61

A high sensitivity MEA probe for measuring real time rat brain glucose flux.  

Science.gov (United States)

The mammalian central nervous system (CNS) relies on a constant supply of external glucose for its undisturbed operation. This article presents an implantable Multi-Electrode Array (MEA) probe for brain glucose measurement. The MEA was implemented on Silicon-On-Insulator (SOI) wafer using Micro-Electro-Mechanical-Systems (MEMS) methods. There were 16 platinum recording sites on the probe and enzyme glucose oxidase (GOx) was immobilized on them. The glucose sensitivity of the MEA probe was as high as 489 µA mM(-1) cm(-2). 1,3-Phenylenediamine (mPD) was electropolymerized onto the Pt recording surfaces to prevent larger molecules such as ascorbic acid (AA), 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), and dopamine (DA) from reaching the recording sites surface. The MEA probe was implanted in the anesthetized rat striatum and responded to glucose levels which were altered by intraperitoneal injection of glucose and insulin. After the in vivo experiment, the MEA probe still kept sensitivity to glucose, these suggested that the MEA probe was reliable for glucose monitoring in brain extracellular fluid (ECF). PMID:24362080

Wei, Wenjing; Song, Yilin; Shi, Wentao; Lin, Nansen; Jiang, Tingjun; Cai, Xinxia

2014-05-15

62

The measurement of the nigrostriatal dopaminergic function and glucose metabolism in patients with movement disorders  

International Nuclear Information System (INIS)

The nigrostriatal dopaminergic function and glucose metabolism were evaluated in 34 patients with various movement disorders by using positron emission tomography with 18F-Dopa and 18F-FDG respectively. The 18F-Dopa uptake in the striatum (the caudate head and the putamen) decreased in patients with Parkinson's disease but was relatively unaffected in the caudate. The cerebral glucose metabolism was normal in patients with Parkinson's disease. The 18F-Dopa uptake in the striatum also decreased in cases of atypical parkinsonism and in cases of progressive supranuclear palsy, but there was no difference in the uptake between the caudate and the putamen. The glucose metabolism decreased in the cerebral hemisphere including the striatum; this finding was also different from those of Parkinson's disease. A normal 18F-Dopa uptake in the striatum with a markedly decreased striatal glucose metabolism and a mildly decreased cortical glucose metabolism was observed in cases of Huntington's disease and Wilson's disease. The 18F-Dopa uptake in the striatum increased and the glucose metabolism was normal in cases of idiopathic dystonia. Various patterns of 18F-Dopa uptake and glucose metabolism were thus observed in the various movement disorders. These results suggest that the measurements of the 18F-Dopa uptake and the cerebral glucose metabolism would be useful for the evaluation of the strid be useful for the evaluation of the striatal function in various movement disorders. (author)

63

Picosecond time measurement using ultra fast analog memories  

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The currently existing electronics dedicated to precise time measurement is mainly based on the use of constant fraction discriminators (CFD) associated with Time to Digital Converters (TDC). The constant fraction technique minimizes the time walk effect (dependency of timing on the pulse amplitude). Several attempts have been made to integrate CFD in multi-channel ASICs. But the time resolution measured on the most advanced one is of the order of 30 ps rms. Two main techniques are used for t...

Breton, D.; Delagnes, E.; Maalmi, J.

2009-01-01

64

Chance correlation in non-invasive glucose measurement using near-infrared spectroscopy  

International Nuclear Information System (INIS)

Although the non-invasive glucose measurement technique based on near-infrared (NIR) spectroscopy has been an active research area for over twenty years, a reliable monitoring method has not been established yet. The key problem is that the spectral variations due to glucose concentration are extremely small compared to that from other biological components. In addition, there are also some ambiguous time-dependent physiological processes, which make the explanation of the model more difficult, especially in the universal calibration. Therefore, in order to produce a model that is related to the actual spectral variation of glucose, reproducible measurements and clinical validation experiments that improve the selectivity and signal to noise ratio of glucose measurement are needed. In this paper, chance correlation in spectroscopy analysis is investigated, which is one of the obstacles to achieving successful NIR spectroscopy analysis, especially in in vivo measurement. The reasons for chance correlation in the in vitro and in vivo experiments are analysed. Methods to avoid it are suggested accordingly and verified with the in vitro experiments. We also investigate the chance correlation for the in vivo NIR diffuse reflectance spectroscopy monitoring blood. Results show that there is significant signal variation after glucose is taken, and the potential chance correlation factors including the instrument-related and physiology-related variations during the in vivo exp-related variations during the in vivo experiments do not contribute to the multivariate model for glucose concentration

65

Integrated catheter system for continuous glucose measurement and simultaneous insulin infusion.  

Science.gov (United States)

A new measurement system enables combination of continuous glucose monitoring (CGM) and insulin infusion. A sensor system comprising an optical glucose biosensor and an optical oxygen sensor is integrated into the insulin infusion catheter of an insulin pump. Both sensors rely on near infrared (NIR) phosphorescent porphyrin dyes, wherefore the signals can be read out transcutaneous and non-invasively with a custom-built phase fluorometer measurement module. The spectral properties of the indicator dyes and the optical setup of the measurement module were optimized to enable independent read-out in two channels. Dynamic ranges from 0 mmHg to 160 mmHg oxygen and 0mg/dL to 360 mg/dL glucose (LOD 2mg/dL) are covered by the oxygen and the glucose sensor, respectively. In-vivo measurements in pigs demonstrate good correlation of reference blood glucose levels and glucose values obtained with the presented sensor system. The evaluation of the clinical accuracy of the system with Clarke Error Grid Analysis showed similar results to CGM-devices currently on the market. PMID:25194803

Nacht, Barbara; Larndorfer, Christoph; Sax, Stefan; Borisov, Sergey M; Hajnsek, Martin; Sinner, Frank; List-Kratochvil, Emil J W; Klimant, Ingo

2015-02-15

66

A Weak Signal Extraction Method for Human Blood Glucose Noninvasive Measurement using Near Infrared Spectroscopy  

Science.gov (United States)

Background interference from optical absorption of matrix components, low spectral selectivity and low spectral sensitivity are the main interference factors for human blood glucose noninvasive measurement using near infrared (NIR) spectroscopy. In order to extract the weak glucose concentration information, a modified uninformative variable elimination (mUVE) method combined with successive projections algorithm (SPA) named as mUVE-SPA, is proposed. mUVE is used to eliminate matrix background and high-frequency noise by wavelet multi-resolution technology. SPA is followed to select variables with minimum colinearity by projection algorithm in a vector space. The proposed method was applied in two NIR spectra data sets (plasma samples experiment in vitro and human blood glucose noninvasive measurement experiment in vivo) respectively. The performance and adaptability of the proposed strategy were discussed. The results indicate that the proposed hybrid method can give an alternative path to extract weak glucose information and yield more parsimonious models with higher precision.

Li, Li-Na; Li, Qing-Bo; Zhang, Guang-Jun

2009-11-01

67

Non Invasive Blood Glucose Measurement using NIR technique based on occlusion spectroscopy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Diabetes is considered to be one of the major health care epidemics of modern era. The determination of blood glucose concentration using the self monitoring blood glucose devices involves the chemical analysis of blood samples taken by pricking the finger or extracting blood from forearm. The pain, discomfort and inconvenience in the current invasive method has led to the feasibility study of noninvasive measurement techniques. In this paper, an optical method using NIR technique based on oc...

Shinde, Prof A. A.; Prasad, Dr R. K.

2011-01-01

68

Accuracy in Blood Glucose Measurement: What Will a Tightening of Requirements Yield?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nowadays, almost all persons with diabetes—at least those using antidiabetic drug therapy—use one of a plethora of meters commercially available for self-monitoring of blood glucose. The accuracy of blood glucose (BG) measurement using these meters has been presumed to be adequate; that is, the accuracy of these devices was not usually questioned until recently. Health authorities in the United States (Food and Drug Administration) and in other countries are currently endeavoring to tight...

Heinemann, Lutz; Lodwig, Volker; Freckmann, Guido

2012-01-01

69

Wavelength-modulated differential laser photothermal radiometry for blood glucose measurements  

Science.gov (United States)

A Wavelength-Modulated Differential Laser Photothermal Radiometer (WM-DPTR) technique was used for non-invasive blood glucose monitoring in the mid-IR range, where the prominent absorption peak is glucose specific and isolated from other interfering peaks in human blood. The WM-DPTR method consists of the out-of-phase modulated excitation at two discrete wavelengths 9.5 ?m and 10.4 ?m (near the peak and the baseline of glucose absorption), generated from two quantum cascade lasers (QCL) and the differential emission detection through a thermal-wave upconversion process via a HgCdZnTe (MCZT) detector (2-5 ?m). The differential method suppresses the background signal and reduces source-detection interference, thus enhancing glucose detection sensitivity. The results from aqueous glucose phantom (0-440 mg/dl) measurements demonstrate that both amplitude and phase of the WM-DPTR signal can be used for glucose detection. The dynamic range and the sensitivity of the glucose detection are influenced greatly by the laser intensity ratio and modulation frequency. The optimal intensity ratio for high sensitivity is ~1. Other laser intensity ratios increase dynamic range but reduce sensitivity. Sensitivity increases with frequency.

Guo, X.; Mandelis, A.; Matvienko, A.; Sivagurunathan, K.; Zinman, B.

2010-03-01

70

Wavelength-modulated differential laser photothermal radiometry for blood glucose measurements  

Energy Technology Data Exchange (ETDEWEB)

A Wavelength-Modulated Differential Laser Photothermal Radiometer (WM-DPTR) technique was used for non-invasive blood glucose monitoring in the mid-IR range, where the prominent absorption peak is glucose specific and isolated from other interfering peaks in human blood. The WM-DPTR method consists of the out-of-phase modulated excitation at two discrete wavelengths 9.5 {mu}m and 10.4 {mu}m (near the peak and the baseline of glucose absorption), generated from two quantum cascade lasers (QCL) and the differential emission detection through a thermal-wave upconversion process via a HgCdZnTe (MCZT) detector (2-5 {mu}m). The differential method suppresses the background signal and reduces source-detection interference, thus enhancing glucose detection sensitivity. The results from aqueous glucose phantom (0-440 mg/dl) measurements demonstrate that both amplitude and phase of the WM-DPTR signal can be used for glucose detection. The dynamic range and the sensitivity of the glucose detection are influenced greatly by the laser intensity ratio and modulation frequency. The optimal intensity ratio for high sensitivity is {approx}1. Other laser intensity ratios increase dynamic range but reduce sensitivity. Sensitivity increases with frequency.

Guo, X; Mandelis, A; Matvienko, A; Sivagurunathan, K [Department of MIE, University Toronto, 5 King' s College Road, Toronto, ON M5S 3G8 (Canada); Zinman, B, E-mail: guox@mie.utoronto.c [Samuel Luenfeld Research Institute, Mount Sinai Hospital, University of Toronto, 60 Murray Street, Toronto, ON M5T 3L9 (Canada)

2010-03-01

71

Wavelength-modulated differential laser photothermal radiometry for blood glucose measurements  

International Nuclear Information System (INIS)

A Wavelength-Modulated Differential Laser Photothermal Radiometer (WM-DPTR) technique was used for non-invasive blood glucose monitoring in the mid-IR range, where the prominent absorption peak is glucose specific and isolated from other interfering peaks in human blood. The WM-DPTR method consists of the out-of-phase modulated excitation at two discrete wavelengths 9.5 ?m and 10.4 ?m (near the peak and the baseline of glucose absorption), generated from two quantum cascade lasers (QCL) and the differential emission detection through a thermal-wave upconversion process via a HgCdZnTe (MCZT) detector (2-5 ?m). The differential method suppresses the background signal and reduces source-detection interference, thus enhancing glucose detection sensitivity. The results from aqueous glucose phantom (0-440 mg/dl) measurements demonstrate that both amplitude and phase of the WM-DPTR signal can be used for glucose detection. The dynamic range and the sensitivity of the glucose detection are influenced greatly by the laser intensity ratio and modulation frequency. The optimal intensity ratio for high sensitivity is ?1. Other laser intensity ratios increase dynamic range but reduce sensitivity. Sensitivity increases with frequency.

72

The analogy between optical beam shifts and quantum weak measurements  

CERN Document Server

We describe how the notion of optical beam shifts (including the spatial and angular Goos-H\\"anchen shift and Imbert-Federov shift) can be understood as a classical analogue of a quantum measurement of the polarization state of a paraxial beam by its transverse amplitude distribution. Under this scheme, complex quantum weak values are interpreted as spatial and angular shifts of polarized scalar components of the reflected beam. This connection leads us to predict an extra spatial shift for beams with a radially-varying phase dependence.

Dennis, Mark R

2012-01-01

73

Monte Carlo simulation of non-invasive glucose measurement based on FMCW LIDAR  

Science.gov (United States)

Continuous non-invasive glucose monitoring is a powerful tool for the treatment and management of diabetes. A glucose measurement method, with the potential advantage of miniaturizability with no moving parts, based on the frequency modulated continuous wave (FMCW) LIDAR technology is proposed and investigated. The system mainly consists of an integrated near-infrared tunable semiconductor laser and a detector, using heterodyne technology to convert the signal from time-domain to frequency-domain. To investigate the feasibility of the method, Monte Carlo simulations have been performed on tissue phantoms with optical parameters similar to those of human interstitial fluid. The simulation showed that the sensitivity of the FMCW LIDAR system to glucose concentration can reach 0.2mM. Our analysis suggests that the FMCW LIDAR technique has good potential for noninvasive blood glucose monitoring.

Xiong, Bing; Wei, Wenxiong; Liu, Nan; He, Jian-Jun

2010-11-01

74

Shape information from glucose curves: Functional data analysis compared with traditional summary measures  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Plasma glucose levels are important measures in medical care and research, and are often obtained from oral glucose tolerance tests (OGTT with repeated measurements over 2–3?hours. It is common practice to use simple summary measures of OGTT curves. However, different OGTT curves can yield similar summary measures, and information of physiological or clinical interest may be lost. Our mean aim was to extract information inherent in the shape of OGTT glucose curves, compare it with the information from simple summary measures, and explore the clinical usefulness of such information. Methods OGTTs with five glucose measurements over two hours were recorded for 974 healthy pregnant women in their first trimester. For each woman, the five measurements were transformed into smooth OGTT glucose curves by functional data analysis (FDA, a collection of statistical methods developed specifically to analyse curve data. The essential modes of temporal variation between OGTT glucose curves were extracted by functional principal component analysis. The resultant functional principal component (FPC scores were compared with commonly used simple summary measures: fasting and two-hour (2-h values, area under the curve (AUC and simple shape index (2-h minus 90-min values, or 90-min minus 60-min values. Clinical usefulness of FDA was explored by regression analyses of glucose tolerance later in pregnancy. Results Over 99% of the variation between individually fitted curves was expressed in the first three FPCs, interpreted physiologically as “general level” (FPC1, “time to peak” (FPC2 and “oscillations” (FPC3. FPC1 scores correlated strongly with AUC (r=0.999, but less with the other simple summary measures (?0.42?r?0.79. FPC2 scores gave shape information not captured by simple summary measures (?0.12?r?0.40. FPC2 scores, but not FPC1 nor the simple summary measures, discriminated between women who did and did not develop gestational diabetes later in pregnancy. Conclusions FDA of OGTT glucose curves in early pregnancy extracted shape information that was not identified by commonly used simple summary measures. This information discriminated between women with and without gestational diabetes later in pregnancy.

Frøslie Kathrine Frey

2013-01-01

75

Comparison between (1-11C)-D-glucose, (U-11C)-D-glucose, and (18F)2-fluoro-2-deoxy-D-glucose as tracers for PET measurement of cerebral glucose utilization  

International Nuclear Information System (INIS)

(1-11C)-D-glucose(1-G) is evaluated as a tracer for cerebral glucose utilization and compared to uniformly labelled glucose, (U-11C)-D-glucose, to (18F)2-fluoro-2-deoxy-D-glucose (FDG), and to results obtained by the Fick principle. (author). 14 refs.; 3 figs.; 1 tab

76

Photoacoustic measurement for glucose solution concentration based on tunable pulsed laser induced ultrasound  

Science.gov (United States)

Noninvasive measurement of blood glucose concentration (BGC) has become a research hotspot. BGC measurement based on photoacoustic spectroscopy (PAS) was employed to detect the photoacoustic (PA) signal of blood glucose due to the advantages of avoiding the disturbance of optical scattering. In this paper, a set of custom-built BGC measurement system based on tunable optical parametric oscillator (OPO) pulsed laser and ultrasonic transducer was established to test the PA response effect of the glucose solution. In the experiments, we successfully acquired the time resolved PA signals of distilled water and glucose aqueous solution, and the PA peak-to-peak values(PPV) were gotten under the condition of excitated pulsed laser with changed wavelength from 1340nm to 2200nm by increasing interval of 10nm, the optimal characteristic wavelengths of distilled water and glucose solution were determined. Finally, to get the concentration prediction error, we used the linear fitting of ordinary least square (OLS) algorithm to fit the PPV of 1510nm, and we got the predicted concentration error was about 0.69mmol/L via the fitted linear equation. So, this system and scheme have some values in the research of noninvasive BGC measurement.

Ren, Zhong; Liu, Guodong; Huang, Zhen; Zhao, Dengji

2012-12-01

77

A dielectric inverse problem applied to human skin measurements during glucose excursions.  

Science.gov (United States)

A fringing field capacitive sensor has been used to measure the dielectric properties of human skin and underlying tissue in the MHz frequency range. It has recently been shown in clinical experimental studies that these dielectric properties can be related to the effects of in vivo glucose variations of the test subject. Previously, the relationship between electrical impedance and the glucose level has been established via statistical methods, such as the regression method. In this work, we explored a different approach, namely the resolution of the so-called inverse problem. First we applied the method on an artificial two-layer lossy system in order to test the sensitivity of the solution to forced changes in the layer properties and its stability to a constant setting. After validation of this method on artificial systems, a similar inverse problem was set and solved for dielectric measurements on human skin during an induced glucose excursion, where the skin is also modelled as a double-layer system. The changes of the measured permittivity and conductivity of the second layer versus the glucose changes are calculated for 22 study days. The statistical distribution shows that the median slopes of both dielectric properties are negative. These results can be used to test our hypothesis and to continue building potential explanations for the phenomena induced by the glucose changes on the skin layer dielectric parameters. PMID:21743123

Dewarrat, F; Falco, L; Mueller, M; Reinhard, S; Caduff, A; Talary, M S

2011-08-01

78

Measurement of the Incretin Hormones: Glucagon-Like Peptide-1 and Glucose-Dependent Insulinotropic Peptide  

DEFF Research Database (Denmark)

The two incretin hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), are secreted from the gastrointestinal tract in response to meals and contribute to the regulation of glucose homeostasis by increasing insulin secretion. Assessment of plasma concentrations of GLP-1 and GIP is often an important endpoint in both clinical and preclinical studies and, therefore, accurate measurement of these hormones is important. Here, we provide an overview of current approaches for the measurement of the incretin hormones, with particular focus on immunological methods.

Kuhre, Rune Ehrenreich; Wewer Albrechtsen, Nicolai Jacob

2014-01-01

79

Evaluating the blood glucose measured via glucometry in diagnosis of hypoglycemia in neonates  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: Hypoglycemia is one of the most prevalent problems seen in neonates and can lead toirreversible brain damage if not to be diagnosed in time. Today, the blood glucose is mostly checked bylaboratory methods that have a significant delay and can result in many adverse effects such as vesselrupture. The goal of this study was to evaluate the value of the glucometry device in diagnosis ofhypoglycemia in neonates.Materials and Methods: This study has been conducted over 156 hospitalized neonates in Amir almomenin Hospital, Semnan, Iran. The blood glucose in all cases has been simultaneously measured by bothlaboratory methods (glucose oxidase as the golden standard and glucometer. These measurements alongwith the relevant data for neonatal risk factors were recorded in the checklist. The blood glucosemeasurements of less than or equal 35 mg/dL in first two hours after birth, less than or equal 40mg/dL in 3to 24 hours after birth, less than or equal 45 mg/dL in more than 24 hours after birth are considered ashypoglycemic.Results: 58 neonates (37.2% were hypoglycemic.The measurement of blood glucose levels viaglucometer for hypoglycemia detection had a high precision (Area under curve = 0.941, Standard error=0.018, P= 0.0001. The optimum cut-off point yielded to equivalent of 51mg/dL. So that for fasting bloodglucose of less than or equal 51mg/dL, sensitivity, specificity, positive, and negative predictive values were,respectively, 94.7%, 81.6%, 75.3%, and 96.4%.Conclusion: Findings show that, blood glucose levels measured by glucometry have goodaccuracy for diagnosis of hypoglycemia in newborns. Thus, it is recommended that in case ofscreening and frequent need of monitoring neonatal blood glucose, this device be used as asuitable replacement of laboratory methods

Shamsollah Nooripoor

2012-06-01

80

Optical measurement of osmotic water transport in cultured cells. Role of glucose transporters  

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Methodology was developed to measure osmotic water permeability in monolayer cultured cells and applied to examine the proposed role of glucose transporters in the water pathway (1989. Proc. Natl. Acad. Sci. USA. 86:8397-8401). J774 macrophages were grown on glass coverslips and mounted in a channel-type perfusion chamber for rapid fluid exchange without cell detachment. Relative cell volume was measured by 45 degrees light scattering using an inverted microscope; measurement accuracy was val...

1992-01-01

 
 
 
 
81

Classification of diabetes and measurement of blood glucose concentration noninvasively using near infrared spectroscopy  

Science.gov (United States)

Developing noninvasive blood glucose monitoring method is an to immense need to alleviate the pain and suffering of diabetics associated with the frequent pricking of skin for taking blood sample. A hybrid algorithm for multivariate calibration is proposed to improve the prediction performance of classification of diabetes and measurement of blood glucose concentration by near infrared (NIR) spectroscopy noninvasively. The algorithm is based on wavelet prism modified uninformative variable elimination approach (WP-mUVE) combined with least squares support vector machine (LSSVM), named as WP-mUVE-LSSVM. The method is successfully applied to diabetic classification experiment (in vivo) and blood glucose concentration measurement experiment (in vivo) respectively. Human tongue is selected as the measuring site in this study. To evaluate effectiveness of pretreatment method and quality of calibration models, several usually used pretreatment methods and kernel functions of LSSVM are introduced comparing with our method. Higher quality data is obtained by our pretreatment method owing to the elimination of varying background and noise of spectra data simultaneously. Better prediction accuracy and adaptability are obtained by LSSVM model with radial basis kernel function. The results indicate that WP-mUVE-LSSVM holds promise for the classification of diabetes and measurement of blood glucose concentration noninvasively based on human tongue using NIR spectroscopy.

Li, Zhe; Li, Gang; Yan, Wen-Juan; Lin, Ling

2014-11-01

82

The effect of borate polymer layers on glucose measurement by surface plasmon resonance  

Science.gov (United States)

A new borate polymer PAA-ran-PAAPBA that can adsorb glucose specifically is introduced into the glucose measurement based on surface plasmon resonance. Six and twelve layers of borate polymer are bound onto the SPR sensors respectively through the layer-by-layer self-assembly binding method, and then the effect of different layers on the glucose concentration measurement is studied. The experiment is conducted in three concentration ranges, 1~10mg/dL, 10~100mg/dL and 100~1000mg/dL. The Results show that the performance of 12-layer-polymer sensor is better than that of the 6-layer-polymer sensor in the first two ranges, and the measuring result has no big difference in the range of 100~1000mg/d. It indicates that the enhancement of polymer layer on the surface of SPR sensor can dramatically improve the glucose measurement in the low concentration range.

Li, Dachao; Yang, Jia; Wu, Peng; Yang, Di; Wang, Bo; Lin, Yuan; Xu, Kexin

2013-03-01

83

Measurement of glucose concentration in turbid media by the polarization state of backscattered laser light  

Science.gov (United States)

Biological tissues, including human skin, are complex objects for optical measurements. Because of its multi-component structure, they are characterized by a combined response to various dynamic changes, both inside and outside of the biological object. Change of glucose concentration in the blood leads to a number of processes, which affect the light scattering properties of the skin and subcutaneous layers, herewith scattering coefficient and the polarization of the scattered light vary. The possibility of non-invasive blood glucose detection by parameters of backscattered laser light was experimentally demonstrated. Degree of polarization of light scattered by human skin and model objects was registered and dependence of the polarization state of backscattered radiation on the glucose concentration in the human blood was shown. A laboratory model of a differential polarimeter, which allows registering the parameters of the polarized radiation scattered by human skin and glucose containing models was developed. Using the developed model, model and full-scale experiments were conducted. In the model experiments, the light scattered in the forward and backwards direction by the following model objects: a 20% solution of milk and a 50% solution of whole human blood was investigated. The ability of the developed sensor to noninvasively detect the concentration of glucose in the blood was demonstrated.

Kafidova, Galina A.; Aksenov, Evgenii T.; Petrov, Victor M.

2013-06-01

84

Glucose concentration measured by the hybrid coherent anti-Stokes Raman-scattering technique  

Science.gov (United States)

We investigate the possibility of using a hybrid coherent anti-Stokes Raman scattering technique for noninvasive monitoring of blood glucose levels. Our technique combines instantaneous coherent excitation of several characteristic molecular vibrations with subsequent probing of these vibrations by an optimally shaped, time-delayed, narrowband laser pulse. This pulse configuration mitigates the nonresonant four-wave mixing background while maximizing the Raman-resonant signal and allows rapid and highly specific detection even in the presence of multiple scattering. Under certain conditions we find that the measured signal is linearly proportional to the glucose concentration due to optical interference with the residual background light, which allows reliable detection of spectral signatures down to medically relevant glucose levels.

Wang, Xi; Zhang, Aihua; Zhi, Miaochan; Sokolov, Alexei V.; Welch, George R.

2010-01-01

85

Glucose concentration measured by the hybrid coherent anti-Stokes Raman-scattering technique  

International Nuclear Information System (INIS)

We investigate the possibility of using a hybrid coherent anti-Stokes Raman scattering technique for noninvasive monitoring of blood glucose levels. Our technique combines instantaneous coherent excitation of several characteristic molecular vibrations with subsequent probing of these vibrations by an optimally shaped, time-delayed, narrowband laser pulse. This pulse configuration mitigates the nonresonant four-wave mixing background while maximizing the Raman-resonant signal and allows rapid and highly specific detection even in the presence of multiple scattering. Under certain conditions we find that the measured signal is linearly proportional to the glucose concentration due to optical interference with the residual background light, which allows reliable detection of spectral signatures down to medically relevant glucose levels.

86

An investigation of the effect of in vivo interferences on Raman glucose measurements  

Science.gov (United States)

Raman spectroscopy is a promising technology for noninvasive blood glucose monitoring because of its good selectivity for the glucose molecule. The low sensitivity of the Raman signal however, makes it difficult to quantify the concentration of glucose directly from the Raman spectra. To solve this, statistical methods such as PCA (principle component analysis) and PLS (partial least square) are traditionally used. These statistical methods general work very well and give highly accurate results, provided there is no interference. In the in-vivo case however, there are many interferences such as the inhomogeneity of tissue, physiological changes, and denaturation of the tissue by the light source. This study investigates the affect of in-vivo interferences on Raman glucose measurements. In this study, a high throughput dispersive Raman system was constructed with an 830nm multimode laser, a multiple conductor optical fiber bundle, and a back-illuminated CCD spectrometer. A simply phantom was devised, which was comprised of a plastic cuvette fitted with a human fingernail window and glucose doped human serum used as the sample. To test the inhomogeneity of tissue samples, different sites of the phantom were exposed to the laser. In the case of denaturation, tests were conducted under two laser power densities: low (3.7mW/mm2) and high density (110mW/mm2). To simulate the physiological change, gelatin phantoms of varied concentration were investigated. The results of the study indicate that the dominant interferers for Raman in-vivo glucose measurements are the inhomogeneity of the tissue and the denaturation by the laser power density. The next phase for this study will be the design of a high SNR Raman system which affords a low power density laser sample illumination as well as larger volumetric illumination to mitigate the effects of tissue inhomogeneity.

Shim, Bongchu; Oh, Hyunho; Oh, Jeankun; Yang, Yongju; Ku, Yunhee; Kim, Moosub; Kim, Dami; Eum, Hyejin; Cho, Seongmoon; Miller, David R.

2011-03-01

87

Selection circuits to evaluate analog signals in multi-channel measurement and control systems  

International Nuclear Information System (INIS)

The analog signals of neighbouring channels in multichannel measuring and central systems must be surveyed for impermissible deviations and used to generate representative signals. The principles of the selection circuits registering the generation and its behaviour in the case of defects or drop-out of the input signals are described. A realized circuit is presented which largely eliminates the effects of defects of input signals on representative signals. (orig.)

88

H-2g, a glucose analog of blood group H antigen, mediates monocyte recruitment in vitro and in vivo via IL-8/CXCL8  

Directory of Open Access Journals (Sweden)

Full Text Available Bradley J Rabquer,1,2 Yong Hou,1 Jeffrey H Ruth,1 Wei Luo,1 Daniel T Eitzman,1 Alisa E Koch,3,1 Mohammad A Amin11University of Michigan Medical School, Department of Internal Medicine, Ann Arbor, MI, USA; 2Albion College, Biology Department, Albion, MI, USA; 3VA Medical Service, Department of Veterans Affairs, Ann Arbor, MI, USAObjective: Monocyte (MN recruitment is an essential inflammatory component of many autoimmune diseases, including rheumatoid arthritis (RA. In this study we investigated the ability of 2-fucosyllactose (H-2g, a glucose analog of blood group H antigen to induce MN migration in vivo and determined if H-2g-induced interleukin-8 (IL-8/CXCL8 plays a role in MN ingress in RA.Methods: Sponge granuloma and intravital microscopy assays were performed to examine H-2g-induced in vivo MN migration and rolling, respectively. MNs were stimulated with H-2g, and the production of IL-8/CXCL8 was assessed by enzyme-linked immunosorbent assay and quantitative polymerase chain reaction. Lastly, in vitro MN migration assays and an in vivo RA synovial tissue severe combined immunodeficiency mouse model were used to determine the role of IL-8/CXCL8 in H-2g-induced MN migration.Results: In vivo, H-2g induced significantly greater MN migration compared to phosphate buffered saline. Intravital microscopy revealed that H-2g mediates MN migration in vivo by inducing MN rolling. In addition, H-2g induced MN production of IL-8/CXCL8, a process that was dependent on Src kinase. Moreover, we found that H-2g mediated MN migration in vitro, and in vivo migration was inhibited by a neutralizing anti-IL-8/CXCL8 antibody.Conclusion: These findings suggest that H-2g mediates MN recruitment in vitro and in vivo (in part via IL-8/CXCL8.Keywords: inflammation, rheumatoid arthritis, chemokine, migration

Rabquer BJ

2012-09-01

89

Clinical review: Consensus recommendations on measurement of blood glucose and reporting glycemic control in critically ill adults.  

Science.gov (United States)

The management reporting and assessment of glycemic control lacks standardization. The use of different methods to measure the blood glucose concentration and to report the performance of insulin treatment yields major disparities and complicates the interpretation and comparison of clinical trials. We convened a meeting of 16 experts plus invited observers from industry to discuss and where possible reach consensus on the most appropriate methods to measure and monitor blood glucose in critically ill patients and on how glycemic control should be assessed and reported. Where consensus could not be reached, recommendations on further research and data needed to reach consensus in the future were suggested. Recognizing their clear conflict of interest, industry observers played no role in developing the consensus or recommendations from the meeting. Consensus recommendations were agreed for the measurement and reporting of glycemic control in clinical trials and for the measurement of blood glucose in clinical practice. Recommendations covered the following areas: How should we measure and report glucose control when intermittent blood glucose measurements are used? What are the appropriate performance standards for intermittent blood glucose monitors in the ICU? Continuous or automated intermittent glucose monitoring - methods and technology: can we use the same measures for assessment of glucose control with continuous and intermittent monitoring? What is acceptable performance for continuous glucose monitoring systems? If implemented, these recommendations have the potential to minimize the discrepancies in the conduct and reporting of clinical trials and to improve glucose control in clinical practice. Furthermore, to be fit for use, glucose meters and continuous monitoring systems must match their performance to fit the needs of patients and clinicians in the intensive care setting. PMID:23767816

Finfer, Simon; Wernerman, Jan; Preiser, Jean-Charles; Cass, Tony; Desaive, Thomas; Hovorka, Roman; Joseph, Jeffrey I; Kosiborod, Mikhail; Krinsley, James; Mackenzie, Iain; Mesotten, Dieter; Schultz, Marcus J; Scott, Mitchell G; Slingerland, Robbert; Van den Berghe, Greet; Van Herpe, Tom

2013-01-01

90

Brain glucose concentrations in poorly controlled diabetes mellitus as measured by high-field magnetic resonance spectroscopy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hyperglycemia and diabetes alter the function and metabolism of many tissues. The effect on the brain remains poorly defined, but some animal data suggest that chronic hyperglycemia reduces rates of brain glucose transport and/or metabolism. To address this question in human beings, we measured glucose in the occipital cortex of patients with poorly controlled diabetes and healthy volunteers at the same levels of plasma glucose using proton magnetic resonance spectroscopy. Fourteen patients w...

Seaquist, Elizabeth R.; Tkac, Ivan; Damberg, Greg; Thomas, William; Gruetter, Rolf

2005-01-01

91

The Unscented Kalman Filter estimates the plasma insulin from glucose measurement.  

Science.gov (United States)

Understanding the simultaneous interaction within the glucose and insulin homeostasis in real-time is very important for clinical treatment as well as for research issues. Until now only plasma glucose concentrations can be measured in real-time. To support a secure, effective and rapid treatment e.g. of diabetes a real-time estimation of plasma insulin would be of great value. A novel approach using an Unscented Kalman Filter that provides an estimate of the current plasma insulin concentration is presented, which operates on the measurement of the plasma glucose and Bergman's Minimal Model of the glucose insulin homeostasis. We can prove that process observability is obtained in this case. Hence, a successful estimator design is possible. Since the process is nonlinear we have to consider estimates that are not normally distributed. The symmetric Unscented Kalman Filter (UKF) will perform best compared to other estimator approaches as the Extended Kalman Filter (EKF), the simplex Unscented Kalman Filter (UKF), and the Particle Filter (PF). The symmetric UKF algorithm is applied to the plasma insulin estimation. It shows better results compared to the direct (open loop) estimation that uses a model of the insulin subsystem. PMID:20934485

Eberle, Claudia; Ament, Christoph

2011-01-01

92

Double-injection FDG method to measure cerebral glucose metabolism twice in a single procedure  

International Nuclear Information System (INIS)

[18F]fluorodeoxyglucose (FDG) and positron emission tomography (PET) may be used to examine changes in cerebral glucose metabolism in two physiological conditions. We proposed and evaluated a double injection-single session FDG method with biological constraints for this purpose. Simulated brain time-radioactivity curves (TACs) generated by using a plasma TAC from an actual study and physiological combinations of input values in a kinetic model were analyzed to evaluate the accuracy of the proposed method. The reproducibility of the estimated values obtained by this method was tested in five normal volunteers who were studied with a dynamic PET scan and two injections of FDG in a single session while fasting. The simulation study showed that the estimated values obtained by the proposed method agreed well with the input values. In the human study, plasma glucose levels were 5.3±0.2 and 5.0±0.2 mM in the first and second measurements, respectively. The difference between the plasma glucose measurements was small but statistically significant (p*1 or rCMRglc, there were small deviations in K* (less than 10%) and LC (less than 5%) with a statistical significance (p* and LC seemed to relate to the difference in the plasma glucose level. The double-injection FDG method with biological constrains can be used to th biological constrains can be used to estimate rCMRglc and LC sequentially in a single PET scanning session. (author)

93

Advancement in polarimetric glucose sensing: simulation and measurement of birefringence properties of cornea  

Science.gov (United States)

Clinical guidelines dictate that frequent blood glucose monitoring in diabetic patients is critical towards proper management of the disease. Although, several different types of glucose monitors are now commercially available, most of these devices are invasive, thereby adversely affecting patient compliance. To this end, optical polarimetric glucose sensing through the eye has been proposed as a potential noninvasive means to aid in the control of diabetes. Arguably, the most critical and limiting factor towards successful application of such a technique is the time varying corneal birefringence due to eye motion artifact. We present a spatially variant uniaxial eye model to serve as a tool towards better understanding of the cornea's birefringence properties. The simulations show that index-unmatched coupling of light is spatially limited to a smaller range when compared to the index-matched situation. Polarimetric measurements on rabbits' eyes indicate relative agreement between the modeled and experimental values of corneal birefringence. In addition, the observed rotation in the plane of polarized light for multiple wavelengths demonstrates the potential for using a dual-wavelength polarimetric approach to overcome the noise due to timevarying corneal birefringence. These results will ultimately aid us in the development of an appropriate eye coupling mechanism for in vivo polarimetric glucose measurements.

Malik, Bilal H.; Coté, Gerard L.

2011-03-01

94

Measurement of glucose utilization by Pseudomonas fluorescens that are free-living and that are attached to surfaces  

International Nuclear Information System (INIS)

The assimilation and respiration of glucose by attached and free-living Pseudomonas fluorescens were compared. The attachment surfaces were polyvinylidene fluoride, polyethylene, and glass. Specific uptake of [1C]glucose was determined after bacterial biomass was measured by (1) microscopic counts or (2) prelabelling of cells by providing [3H]leucine as substrate, followed by dual-labelling scintillation counting. The glucose concentration was 1.4, 3.5, 5.5, 7.6, or 9.7 ?M. Glucose assimilation by cells which became detached from the surfaces during incubation with glucose was also measured after the detached cells were collected by filtration. The composition of the substratum had no effect on the amount of glucose assimilated by attached cells. Glucose assimilation by attached cells exceeded that by free-living cells by a factor of between 2 and 5 or more, and respiration of glucose by surface-associated cells was greater than that by free-living bacteria. Glucose assimilation by detached cells was greater than that by attached bacteria. Measurements of biomass by microscopic counts gave more consistent results than those obtained with dual-labelling, but in general, results obtained by both methods were corroborative

95

Investigation of 18F-2-deoxyglucose for the measure of myocardial glucose metabolism  

International Nuclear Information System (INIS)

18F labeled 2-deoxyglucose (18FDG) was studied as a glucose analog. Myocardial uptake and retention, blood clearance, species (dog, monkey, man) dependence and effect of diet on uptake were investigated. Normal myocardial uptake of 18FDG was 3 to 4% in dog and monkey and 1 to 4% of injected dose in man compared to brain uptake of 2% in dog, 5 to 6% in monkey and 4 to 8% in man. The metabolic rate (MR) for glucose in non-fasting (glycolytic state) was 2.8 times greater than in fasting (ketogenic state). Human subjects showed higher myocardial uptake after a normal meal than after meal containing mostly free fatty acids (FFA). Blood clearance was rapid with initial clearance t1/2 of 0.2 to 0.3 min followed by a t1/2 of 8.4 +- 1.2 min in dog and 11.6 +- 1.1 min in man. A small third component had a t1/2 of 59 +- 10 min and 88 +- 4 min in dog and man, respectively. High image contrast ratios between heart and blood (dog 3.5/1; man 14/1), heart and lung (dog 9/1; man 20/1), heart and liver (dog 15/1; man 10/1) were found with the ECAT positron tomograph. 18FDG was found to be rapidly taken up by the myocardium without any significant tissue clearance over a 4 hour period. 18FDG is transported, phosphorylated to 18FDG-6-PO4 and trapped in myocardial cells in the same manner as has been found for brain and exhibits excellent imaging properties. Determination of glucose and FFA MR in vivo with ECT provides a method for investigation and assessment of changing aerobic and anaerobic metabolic rates in ischemic heart disease in man

96

ANALOG FRONT-END ELECTRONICS FOR BEAM POSITION MEASUREMENT ON THE BEAM HALO MEASUREMENT  

International Nuclear Information System (INIS)

Enhancements have been made to the log-ratio analog front-end electronics based on the Analog Devices 8307 logarithmic amplifier as used on the LEDA accelerator. The dynamic range of greater than 85 dB, has been extended to nearly the full capability of the AD8307 from the previous design of approximately 65 dB through the addition of a 350 MHz band-pass filter, careful use of ground and power plane placement, signal routing, and power supply bypassing. Additionally, selection of high-isolation RF switches (55dB) has been an integral part of a new calibration technique, which is fully described in another paper submitted to this conference. Provision has also been made for insertion of a first-stage low-noise amplifier for using the circuit under low-signal conditions

97

ANALOG FRONT-END ELECTRONICS FOR BEAM POSITION MEASUREMENT ON THE BEAM HALO MEASUREMENT  

Energy Technology Data Exchange (ETDEWEB)

Enhancements have been made to the log-ratio analog front-end electronics based on the Analog Devices 8307 logarithmic amplifier as used on the LEDA accelerator. The dynamic range of greater than 85 dB, has been extended to nearly the full capability of the AD8307 from the previous design of approximately 65 dB through the addition of a 350 MHz band-pass filter, careful use of ground and power plane placement, signal routing, and power supply bypassing. Additionally, selection of high-isolation RF switches (55dB) has been an integral part of a new calibration technique, which is fully described in another paper submitted to this conference. Provision has also been made for insertion of a first-stage low-noise amplifier for using the circuit under low-signal conditions.

Shurter, R. B. (Robert B.); Cote, T. J. (Thomas J.); Gilpatrick, J. D. (John Douglas)

2001-01-01

98

ANALOG FRONT-END ELECTRONICS FOR BEAM POSITION MEASUREMENT ON THE BEAM HALO MEASUREMENT  

Energy Technology Data Exchange (ETDEWEB)

Enhancements have been made to the log-ratio analog front-end electronics based on the Analog Devices 8307 logarithmic amplifier as used on the LEDA accelerator. The dynamic range of greater than 85 dB, has been extended to nearly the full capability of the AD8307 from the previous design of approximately 65 dB through the addition of a 350 MHz band-pass filter, careful use of ground and power plane placement, signal routing, and power supply bypassing. Additionally, selection of high-isolation RF switches (55dB) has been an integral part of a new calibration technique, which is fully described in another paper submitted to this conference. Provision has also been made for insertion of a first-stage low-noise amplifier for using the circuit under low-signal conditions.

R.B. SHURTER; T.J. COTE; J.D. GILPATRICK

2001-06-01

99

Detection accuracy of three glucose meters estimated by capillary blood glucose measurements compared with venous blood evaluated by the diabetes unit of the Hospital Evangélico de Curitiba, Brazil  

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Mirnaluci Paulino Ribeiro Gama, Camile Fiorese Cruzeta, Ana Carolina Ossowski, Marina Rech Bay, Mariella Muller Michaelis, Stênio Lujan CamachoEndocrinology and Diabetes Service, Hospital Universitário Evangélico de Curitiba, BrazilObjective: To compare capillary blood glucose measurements between three different glucose meters and with the serum glucose values of inpatients at the diabetes unit of Hospital Universitário Evangélico de Curi...

Sl, Camacho; Mm, Michaelis; Bay MR; Ac, Ossowski; Cf, Cruzeta; Mp, Gama

2012-01-01

100

Study of specificity for noninvasive glucose measurements based on two-dimensional correlation mid-infrared spectroscopy  

Science.gov (United States)

Glucose specificity is the premise of spectroscopic measurements for blood glucose concentration, and it is also paramount for feasibility study of a spectral measurement method. Two-dimensional correlation spectroscopy technology is widely used in many fields such as inter-/intra-molecular reaction, material phase transition and information extraction because of its high resolution and the effective "sequential order" rules (Noda's rule). By using 2D correlation spectroscopy analysis, we aim at exploring glucose specificity for noninvasive glucose measurements from mid-infrared spectra collected from human beings. The study is mainly divided into two parts. The first part is to prove the realizability of the method by 2D correlation analysis of in vitro solutions which all contain glucose. And the second part is validating characteristic information of glucose from mid-infrared ATR spectra of human fingers by use of the 2D correlation spectroscopy technology. The conclusion is that glucose specific spectral information is really present in noninvasive mid-infrared in vivo spectra. So the feasibility of mid-infrared spectroscopy in noninvasive measurements of blood glucose concentration is demonstrated fundamentally.

Cao, Yuzhen; Zhang, Wen; Liu, Rong; Zhang, Wanjie; Xu, Kexin

2012-03-01

 
 
 
 
101

Noninvasive measurement of regional myocardial glucose metabolism by positron emission computed tomography. [Dogs  

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While the results of regional myocardial glucose metabolism measurements using positron emission computed tomography (/sup 13/N-ammonia) are promising, their utility and value remains to be determined in man. If this technique can be applied to patients with acute myocardial ischemia or infarction it may permit delineation of regional myocardial segments with altered, yet still active metabolism. Further, it may become possible to evaluate the effects of interventions designed to salvage reversibly injured myocardium by this technique.

Schelbert, H.R.; Phelps, M.E.

1980-06-01

102

Angular measurements of light scattered by the glucose containing biological tissues and their phantoms  

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Method of optical polarimetry is well known, but earlier it was mainly used to low scattering media. In this paper we consider the possibility of measuring the glucose concentration by detecting polarization of the backscattered laser light. Dependencies of the degree of polarization and of the optical rotation on the registration angle were received. Furthermore, the significant impact of the wavelength and the power of probing beam on the degree of polarization was shown.

Domnin, K. G.; Cherevatenko, G. A.; Aksenov, E. T.

2014-10-01

103

Noninvasive measurement of regional myocardial glucose metabolism by positron emission computed tomography  

International Nuclear Information System (INIS)

While the results of regional myocardial glucose metabolism measurements using positron emission computed tomography (13N-ammonia) are promising, their utility and value remains to be determined in man. If this technique can be applied to patients with acute myocardial ischemia or infarction it may permit delineation of regional myocardial segments with altered, yet still active metabolism. Further, it may become possible to evaluate the effects of interventions designed to salvage reversibly injured myocardium by this technique

104

Reproducibility of cerebral glucose utilization measured by positron emission tomography and the [18F]-2-fluoro-2-deoxy-d-glucose method in resting, healthy human subjects  

International Nuclear Information System (INIS)

The stability of cerebral glucose utilization was examined in nine right-handed, healthy men (age, 24.88±2.93 years) using positron emission tomography (PET) and the [18F]-fluorodeoxyglucose (FDG) method. Each study was run twice at intervals of 1-12 weeks with the subject at rest. The average cerebral metabolic rate for glucose (CMRGlu) was 5.40±0.71 mg/100 g per min (coefficient of variance, 13.08). The average intraindividual variation of CMRGlu was 7.91%±15.46% (P=0.13). Metabolic indices (MI: Regional/mean cortical CMRGlu) were used to determine the regional cerebral metabolic distribution. The interindividual (coefficient of variance, 7.13) and intraindividual variabilities (average variation, -0.12%±8.76%) of MI were smaller than those of metabolic rates. No reproducible significant asymmetry was observed. The FDG method used with subjects at rest thus yields low intraindividual variability of both cerebral glucose consumption and regional metabolic distribution, even at an interval of several weeks. Cerebral glucose utilization measured under such conditions may act as a reliable reference for determination of the influences of physiological (activation), pharmacological or pathological processes on cerebral glucose metabolism. (orig.)

105

Low power analog readout front-end electronics for time and energy measurements  

Science.gov (United States)

We report on the design and measurements of an analog front-end readout electronics dedicated for silicon microstrip detectors with relatively large capacitance of the order of tens pF for time and energy measurements of incoming pulses. The front-end readout electronics is required to process input pulses with an average rate of 150 kHz/channel with low both power consumption and noise at the same time. In the presented solution the single channel is built of two different parallel processing paths: fast and slow. The fast path includes the fast CR-RC shaper with the peaking time tp=40 ns and is optimized to determine the input charge arrival time. The slow path, which consists of the slow CR-(RC)2 shaper with the peaking time tp=80 ns, is dedicated for low noise accurate energy measurement. The analog front-end electronics was implemented in UMC 180 nm CMOS technology as a prototype ASIC AFE. The AFE chip contains 8 channels with the size of 58 ?m×1150 ?m each. It has low power dissipation Pdiss=3.1 mW per single channel. The article presents the details of the front-end architecture and the measurement results.

Kleczek, R.; Grybos, P.; Szczygiel, R.

2014-06-01

106

Precision analog signal processor for beam position measurements in electron storage rings  

International Nuclear Information System (INIS)

Beam position monitors (BPM) in electron and positron storage rings have evolved from simple systems composed of beam pickups, coaxial cables, multiplexing relays, and a single receiver (usually a analyzer) into very complex and costly systems of multiple receivers and processors. The older may have taken minutes to measure the circulating beam closed orbit. Today instrumentation designers are required to provide high-speed measurements of the beam orbit, often at the ring revolution frequency. In addition the instruments must have very high accuracy and resolution. A BPM has been developed for the Advanced Light Source (ALS) in Berkeley which features high resolution and relatively low cost. The instrument has a single purpose; to measure position of a stable stored beam. Because the pickup signals are multiplexed into a single receiver, and due to its narrow bandwidth, the receiver is not intended for single-turn studies. The receiver delivers normalized measurements of X and Y position entirely by analog means at nominally 1 V/mm. No computers are involved. No software is required. Bergoz, a French company specializing in precision beam instrumentation, integrated the ALS design m their new BPM analog signal processor module. Performance comparisons were made on the ALS. In this paper we report on the architecture and performance of the ALS prototype BPM

107

Evaluation of the Efficacy and Correlation between Blood Glucose Measured Using Glucometers and Enzymatic Laboratory Methods  

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Background and Objectives: Diabetes Mellitus (DM is the most common chronic metabolic disease, with many complications including renal failure, blindness and non-traumatic amputation, so it is important to monitor and regulate blood glucose. Considering how easy home blood glucose monitoring is, we decided to evaluate the performance of two available glucometers for detection of blood glucose compared with standard laboratory methods.

 

Methods: In this analytical study, we compared the capillary blood glucose levels of 60 volunteers with mean age of 32.8±9.6 years in Tabriz Mehr Laboratory as determined by test strips (two different Glucometers with venous blood glucose levels’ measurements by the enzymatic method (the standard laboratory kit. Data were analyzed using one way-ANOVA test, T-test, Pearson correlation and Bland and Altman plot.

 

Results: The mean differences of No: 1 and No: 2 Glucometers with enzymatic laboratory method were 20.78±11.61 and 4.5±3.76mg/dl respectively. The one way ANOVA test indicated significant differences between three methods (p<0.05. Further Duncan's test revealed significant differences between two devices (p=0.001 and device No.1 and laboratory method (p=0.001; however, the differences between device No.2 and laboratory method were not statistically significant (p=0.83.

 

Conclusion: According to the results, calibrating the devices with laboratory instruments in order to make major clinical decisions is recommended.

R Rasouli

2012-05-01

108

The characteristic time of glucose diffusion measured for muscle tissue at optical clearing  

International Nuclear Information System (INIS)

The study of agent diffusion in biological tissues is very important to understand and characterize the optical clearing effects and mechanisms involved: tissue dehydration and refractive index matching. From measurements made to study the optical clearing, it is obvious that light scattering is reduced and that the optical properties of the tissue are controlled in the process. On the other hand, optical measurements do not allow direct determination of the diffusion properties of the agent in the tissue and some calculations are necessary to estimate those properties. This fact is imposed by the occurrence of two fluxes at optical clearing: water typically directed out of and agent directed into the tissue. When the water content in the immersion solution is approximately the same as the free water content of the tissue, a balance is established for water and the agent flux dominates. To prove this concept experimentally, we have measured the collimated transmittance of skeletal muscle samples under treatment with aqueous solutions containing different concentrations of glucose. After estimating the mean diffusion time values for each of the treatments we have represented those values as a function of glucose concentration in solution. Such a representation presents a maximum diffusion time for a water content in solution equal to the tissue free water content. Such a maximum represents the real diffusion time of glucose in the muscle and with this value we could calculate the corresponding diffusion coefficient. (paper)

109

Measurement of glucose concentration in a thin turbid medium by a transmitted Gaussian beam  

Science.gov (United States)

We show that it is possible to measure glucose concentration in a thin sample containing a turbid medium that simulates optical properties of biological tissue by recording the profile of a sinusoidal reflective grating by means of a laser Gaussian beam. We have described a similar approach for the case of transparent samples in a previous report. Although due to the turbidity of the sample the laser beam is scattered, we show that the probe beam is still sensitive enough to allow the detection of the grating profile. We describe how the changes recorded by the system, when profiling a region of the grating, allow us to determine the concentration of glucose in the turbid medium. We include experimental results.

Cervantes-L, Joel; Cywiak, Moisés; Olvera-R, Octavio; Cywiak, David

2014-11-01

110

[Biochemical measurements of glucose metabolism in relation to cause of death and postmortem effects].  

Science.gov (United States)

This study was performed to examine the relationship between postmortem biochemical values and cause of death. The follow samples were taken from 399 corpses: cerebrospinal fluid (CSF; n = 376, suboccipital), blood (n = 158, femoral vein), and urine (n = 101, at autopsy). (See Table 1 for causes of death) All samples were stored at -80 degrees C. A further 100 samples of blood were later taken and stored at +4 degrees C before testing. Biochemical determinations made were: glucose in CSF, blood, and urine (hexokinase method); lactate (LDH/GPT) and free acetone (HS-gas chromatography) in CSF; hemoglobin A1 in blood (microcolumn technique). In 34 cases fatal diabetic coma was considered verified by morphological and chemical findings. One hundred cases of sudden cardiac death were chosen as the main control group. In 32 of the 34 cases defined above, the value of the formula of Traub (glucose + lactate in CSF) exceeded 415 mg/dl. It is not influenced significantly by hyperglycemia or hyperlactatemia due to factors other than diabetes (i.e., carbon monoxide, asphyxia). After death the value rose till the 30th hpm, then remained stable for at least 1 week. Fatal coma was defined as the ketoacidotic form if free acetone in CSF ranged above 21 mg/l. In these cases, CSF glucose and free acetone correlated positively. Hemoglobin A1 remained stable after death. Its amount was independent from postmortem blood glucose, postmortem interval and total hemoglobin. Furthermore, the manner of storage (-80 degrees or +4 degrees C) had no significant influence on its values. In 29 of 34 cases of fatal coma, Hb A1 exceeded 12.1%. Analysis of urine glucose showed elevated levels (over 500 mg/dl) in diabetic comas. On conclusion, fatal diabetic coma seems indicated as the cause of death if measured values of postmortem biochemistry exceed the following limits: CSF-Traub 415 mg/dl, free acetone (CSF) 21 mg/l; Hb A1 12.1%; urine glucose 500 mg/dl. Most important are the Traub formula and hemoglobin A1. Usually, in fatal coma both values are elevated. If both of them are normal, diabetic coma can nearly be excluded. Combined evaluation of all values is absolutely necessary. Morphology must also always be taken into account. Consequently, a diagnosis of fatal coma can be obtained by a process of elimination. PMID:3765899

Kernbach, G; Püschel, K; Brinkmann, B

1986-01-01

111

Feasibility of Overnight Closed-Loop Control Based on Hourly Blood Glucose Measurements  

Science.gov (United States)

Introduction Safe and effective closed-loop control (artificial pancreas) is the ultimate goal of insulin delivery. In this study, we examined the performance of a closed-loop control algorithm used for the overnight time period to safely achieve a narrow target range of blood glucose (BG) concentrations prior to breakfast. The primary goal was to compare the quality of algorithm control during repeated overnight experiments. Materials and Methods Twenty-three subjects with type 1 diabetes performed 2 overnight experiments on each of three visits at the study site, resulting in 138 overnight experiments. On the first evening, the subject’s insulin therapy was applied; on the second, the insulin was delivered by an algorithm based on subcutaneous continuous glucose measurements (including meal control) until midnight. Overnight closed-loop control was applied between midnight and 6 a.m. based on hourly venous BG measurements during the first and second nights. Results The number of BG values within the target range (90–150 mg/dl) increased from 52.9% (219 out of 414 measure-ments) during the first nights to 72.2% (299 out of 414 measurements) during the second nights (p < .001, ?2-test). The occurrence of hypoglycemia interventions was reduced from 14 oral glucose interventions, the latest occurring at 2:36 a.m. during the first nights, to 1 intervention occurring at 1:02 a.m. during the second nights (p < .001, ?2-test). Conclusions Overnight controller performance improved when optimized initial control was given; this was suggested by the better metabolic control during the second night. Adequate controller run-in time seems to be important for achieving good overnight control. In addition, the findings demonstrate that hourly BG data are sufficient for the closed-loop control algorithm tested to achieve appropriate glycemic control. PMID:22920817

Patte, Caroline; Pleus, Stefan; Galley, Paul; Weinert, Stefan; Haug, Cornelia; Freckmann, Guido

2012-01-01

112

Measurement and modeling of solubilities of D-glucose in water/alcohol and alcohol/alcohol systems  

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In this work, the solubilities of D-glucose in water/methanol and ethanol/methanol mixtures are measured at 40 and 60 C, using a simple and accurate analytical method. A modified UNIQUAC model is used for the correlation of the experimental solubility data. New UNIQUAC interaction parameters for the pairs D-glucose/alcohol, water/alcohol, and alcohol/alcohol are estimated based on the ternary solubility data presented in this work together with those available in the literature for D-glucose in water/ethanol. The solubility calculations were performed using an equation based on enthalpy of fusion data for D-glucose. The model describes satisfactorily the experimental solubility data of D-glucose in water/ethanol, water/methanol, and ethanol/methanol mixtures at both temperatures.

Peres, A.M.; Macedo, E.A.

1997-07-01

113

Iris as a reflector for differential absorption low-coherence interferometry to measure glucose level in the anterior chamber  

Science.gov (United States)

We present a method of glucose concentration detection in the anterior chamber with a differential absorption optical low-coherent interferometry (LCI) technique. Back-reflected light from the iris, passing through the anterior chamber twice, was selectively obtained with the LCI technique. Two light sources, one centered within (1625 nm) and the other centered outside (1310 nm) of a glucose absorption band were used for differential absorption measurement. In the eye model and pig eye experiments, we obtained a resolution glucose level of 26.8 mg/dL and 69.6 mg/dL, respectively. This method has a potential application for noninvasive detection of glucose concentration in aqueous humor, which is related to the glucose concentration in blood.

Zhou, Yong; Zeng, Nan; Ji, Yanhong; Li, Yao; Dai, Xiangsong; Li, Peng; Duan, Lian; Ma, Hui; He, Yonghong

2011-01-01

114

Clinical review: Consensus recommendations on measurement of blood glucose and reporting glycemic control in critically ill adults.  

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The management reporting and assessment of glycemic control lacks standardization. The use of different methods to measure the blood glucose concentration and to report the performance of insulin treatment yields major disparities and complicates the interpretation and comparison of clinical trials. We convened a meeting of 16 experts plus invited observers from industry to discuss and where possible reach consensus on the most appropriate methods to measure and monitor blood glucose in criti...

Finfer, Simon; Wernerman, Jan; Preiser, Jean-charles; Cass, Tony; Desaive, Thomas; Hovorka, Roman; Joseph, Jeffrey I.; Kosiborod, Mikhail; Krinsley, James; Mackenzie, Iain; Mesotten, Dieter; Schultz, Marcus J.; Scott, Mitchell G.; Slingerland, Robbert; Den Berghe, Greet

2013-01-01

115

Measurement of temporal asymmetries of glucose consumption using linear profiles: reproducibility and comparison with visual analysis  

International Nuclear Information System (INIS)

The aim of our study was to test the reproducibility of this method and to compare its diagnostic performance to that of visual analysis in patients with complex partial seizures (CPS). Regional cerebral glucose consumption (rCMRGLc) was measured interictally in 25 CPS patients and 10 controls using F-18-deoxyglucose and the positron emission tomography (PET) camera ECAT EXACT 47. The PET scans were visually analyzed for the occurrence of unilateral temporal hypometabolism. Furthermore, rCMRGLc was quantified on six contiguous coronal planes by manually tracing maximal values of temporal glucose consumption, thus creating line profiles of temporal glucose consumption for each side. Indices of asymmetry (ASY) were then calculated from these line profiles in four temporal regions and compared to the corresponding 95% confidence intervals of the control data. All analyses were performed by two observers independently from each other and without knowledge of the clinical findings. The agreement between the two observers with regard to focus lateralization was 96% on visual analysis and 100% on quantitative analysis. There was an excellent agreement with regard to focus lateralization between visual and quantitative evaluation. (orig.)

116

Two-operator glucose infusion test (GIT2) for vascular access recirculation measurement during hemodialysis.  

Science.gov (United States)

Vascular access recirculation rate (AR) monitoring is fundamental to guarantee treatment adequacy and to detect access failure early. We have evaluated the GIT2 test to measure AR unaffected by cardio-pulmonary recirculation (CPR), based on a short glucose infusion in place of the bolus and on a two-operator sampling, differently from the classical glucose infusion test (GIT). The GIT2 test is based on four steps: 1) basal (B) glucose arterial sample; 2) 10% glucose infusion for 1 min, by infusion pump at 600 ml/hr; (or 20% at 300 ml/hr); 3) simultaneous sampling at arterial (A) and venous (V) ports, after 35-40 sec from starting the infusion, taking care to avoid blood pump stop during the test; 4) AR=100*((A-B)/(V-B)). In vitro tests by dialysis on a 40 L tank containing a urea solution, with AR volumetrically simulated at 0, 5, 10, 20%, and in vivo comparison of GIT, GIT2 with stop-flow (SF) urea method. Our results have shown in vitro an almost perfect correspondence of SF urea method and a better reliability of GIT2 than GIT. The methylene-blue test has shown that a single color bolus in V reaches the A port after variable time, depending on blood flow and AR, while the continuous infusion determines a steady gradient after about 30". In vivo tests (n=24) show good correspondence between GIT2 (4.37 +/- 3.36) and SF (4.51 +/- 3.62), while GIT data (1.01 +/- 0.51) are significantly underestimated. In conclusion, our preliminary results have evidenced a good reliability of the new test, the continuous infusion causing a steady gradient in V and A that more precisely reflects the AR rate. PMID:20383860

Bosticardo, Gian Mario; Morellini, Veronica; Schillaci, Enrico; Battisti, Marco; Norza, Massimo; Detoma, Paolo; Forneris, Giacomo; Filiberti, Oliviero; Bajardi, Pietro

2010-01-01

117

Simultaneous measurement of blood flow and glucose metabolism by autoradiographic techniques  

International Nuclear Information System (INIS)

A double tracer autoradiographic technique using 131I-iodo-antipyrine and 14C-deoxyglucose is presented for the simultaneous measurement of blood flow and cerebral glucose utilization in the same animal. 131I is a gamma emitting isotope with a half life of 8.06 days and can be detected with adequate resolution on standard autoradiographic films. Autoradiograms are made before and after decay of 131I; the time interval between the 2 exposures and the concentration of the 2 tracers is adjusted to avoid significant cross-contamination. In this way, 2 film exposures are obtained which can be processed quantitatively like single tracer autoradiograms. The validity of the method for the investigation of local coupling of flow and metabolism was tested under various physiological and pathophysiological conditions. Coupling was tight in barbiturate-anesthetized healthy animals, but not under halothane anesthesia where uncoupling occurred in various subcortical structures. Focal seizures induced by topical application of penicillin on the cortical surface led to a coupled increase of metabolism and flow in thalamic relay nuclei but not at the site of penicillin administration where increased glucose utilization was not accompanied by similar increase in blood flow. Both coupled and uncoupled increases in local glucose utilization were observed in spreading depression and in circumscribed areas of experimental brain tumors. The results obtained demonstrate that double tracer auobtained demonstrate that double tracer autoradiography allows allows the very precise local assessment of cerebral blood flow and glucose utilization, and, therefore, is particularly suited to the study of regional coupling processes under various experimental conditions

118

Measurement of glucose metabolism in rat spinal cord slices with dynamic positron autoradiography  

International Nuclear Information System (INIS)

We attempted to measure the regional metabolic rate of glucose (MRglc) in sliced spinal cords in vitro. The thoracic spinal cord of a mature Wister rat was cut into 400-?m slices in oxygenated and cooled (1-4 deg. C) Krebs-Ringer solution. After at least 60 min of preincubation, the spinal cord slices were transferred into double polystyrene chambers and incubated in Krebs-Ringer solution at 36 deg. C, bubbled with 5% O2/5% CO2 gas. To measure MRglc, we used the dynamic positron autoradiography technique (dPAT) with F-18-2-fluoro-2-deoxy-D-glucose ([18F]FDG) and the net influx constant of [18F]FDG as an index. Uptake curves of [18F]FDG were well fitted by straight lines for more than 7 h after the slicing of the spinal cord (linear regression coefficient, r=0.99), indicating a constant uptake of glucose by the spinal cord tissue. The slope (K), which denotes MRglc, is affected by tetrodotoxin, and high K+ (50 mM) or Ca2+-free, high Mg2+ solution. After 10 min of hypoxia, the K value following reoxygenation was similar to the unloaded control value, but after 45 min of hypoxia, the K value was markedly lower than the unloaded control value, and after >90 min of reoxygenation it was nearly 0. Our results indicate that the living spinal cord slices used retained an activity-dependent metabolism to some extent. This technique may provide a new approach for measuring MRglc in sliced liapproach for measuring MRglc in sliced living spinal cord tissue in vitro and for quantifying the dynamic changes in MRglc in response to various interventions such as hypoxia

119

Measuring Deuterium Enrichment of Glucose Hydrogen Atoms by Gas Chromatography/Mass Spectrometry  

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We developed a simple and accurate method for determining deuterium enrichment of glucose hydrogen atoms by electron impact gas chromatography mass spectrometry (GC/MS). First, we prepared 18 derivatives of glucose and screened over 200 glucose fragments to evaluate the accuracy and precision of mass isotopomer data for each fragment. We identified three glucose derivatives that gave six analytically useful ions: (1) glucose aldonitrile pentapropionate (m/z 173 derived from C4?C5 bond cleav...

Antoniewicz, Maciek R.; Kelleher, Joanne K.; Stephanopoulos, Gregory

2011-01-01

120

Slope characterization in combining analog and photon count data from atmospheric lidar measurements.  

Science.gov (United States)

A transient digitizer (Licel) connecting to a photomultiplier tube (PMT) can obtain lidar backscatter profiles in both photon count and analog signal. A lidar can detect higher atmospheric regions by combining (gluing) simultaneous analog and photon count data via the slope coefficient. In this work, the output of a PMT has been measured with a transient digitizer based on an intensity-stable light source. The slope value and dynamic range of the lidar profile have been characterized. The slope value is determined only by the gain of the PMT as it works in a linear range with a fixed pulse height discrimination threshold. The dynamic range of a glued lidar profile is settled by the slope value. The fitted slope has a more exact value when the selection criterion is given in terms of the independent variable for fitting. For practical lidar data, the fitted slope is more stable and reliable when the lower limit of the data range for fitting rises. PMID:25402893

Zhang, Yunpeng; Yi, Fan; Kong, Wei; Yi, Yang

2014-11-01

 
 
 
 
121

Non-Invasive Glucose Measurement by Use of Metabolic Heat Conformation Method  

Directory of Open Access Journals (Sweden)

Full Text Available A non-invasive glucose measurement system based on the method of metabolic heat conformation (MHC is presented in this paper. This system consists of three temperature sensors, two humidity sensors, an infrared sensor and an optical measurement device. The glucose level can be deduced from the quantity of heat dissipation, blood flow rate of local tissue and degree of blood oxygen saturation. The methodology of the data process and the measurement error are also analyzed. The system is applied in a primary clinical test. Compared with the results of a commercial automated chemistry analyzer, the correlation coefficient of the collected data from the system is 0.856. Result shows that the correlation coefficient improves when the factor of heat dissipated by evaporation of the skin is added in. A non-invasive method of measuring the blood flow rate of local tissue by heat transmission between skin and contacted conductor is also introduced. Theoretical derivation and numerical simulation are completed as well. The so-called normalized difference mean (NDM is chosen to express the quantity of the blood flow rate. The correlation coefficient between the blood flow rates by this method and the results of a Doppler blood flow meter is equal to 0.914.

Junfeng Li

2008-05-01

122

Optical Rotatory Dispersion Measurement of D-Glucose with Fixed Polarizer Analyzer Accessory in Conventional Spectrophotometer  

Directory of Open Access Journals (Sweden)

Full Text Available In the sample compartment of a conventional spectrophotometer, mounting of a polarizer before sample and an analyzer behind sample allows the determination of the optical rotatory dispersion of optical active media by measurement of the transmission ratio of crossed and parallel arranged polarizer and analyzer. A formula for the determination of the angle of rotation is derived from the transmission ratio. The arrangement is applied to determine the molar optical rotation of D-glucose in water in the wavelength range from 220 nm to 820 nm.

Alfons Penzkofer

2013-10-01

123

A nonlinear model for calibration of blood glucose noninvasive measurement using near infrared spectroscopy  

Science.gov (United States)

In order to improve prediction accuracy of calibration in human blood glucose noninvasive measurement using near infrared (NIR) spectroscopy, a modified uninformative variable elimination (mUVE) method combined with kernel partial least squares (KPLS), named as mUVE-KPLS, is proposed as an alternative nonlinear modeling strategy. Under the mUVE method, high-frequency noise and matrix background can be eliminated simultaneously, which provide a optimized data for calibration in sequence; under the kernel trick, a nonlinear relationship of response variable and predictor variables is constructed, which is different with PLS that is a complex model and inappropriate to describe the underlying data structure with significant nonlinear characteristics. Two NIR spectra data of basic research experiments (simulated physiological solution samples experiment in vitro and human noninvasive measurement experiment in vivo) are introduced to evaluate the performance of the proposed method. The results indicate that, after elimination high-frequency noise and matrix background from optical absorption of water in NIR region, a high-quality spectra data is employed in calibration; and under the selection of kernel function and kernel parameter, the best prediction accuracy can be got by KPLS with Gaussian kernel compared with Spline-PLS and PLS. It is encouraging that mUVE-KPLS is a promising nonlinear calibration strategy with higher prediction accuracy for blood glucose noninvasive measurement using NIR spectroscopy.

Li, Qing-Bo; Li, Li-Na; Zhang, Guang-Jun

2010-09-01

124

Regional cerebral glucose consumption measured by positron emission tomography in patients with Wilson's disease  

International Nuclear Information System (INIS)

Using positron emission tomography (PET), the regional cerebral metabolic rate of glucose consumption (rCMRGlc) was measured in 14 patients with Wilson's disease (WD) and 23 normal subjects. In WD patients, cerebellar, striatal and - to a lesser extent - cortical and thalamic rCMRGlc were significantly decreased compared with controls. Striatal rCMRGlc was significantly reduced in those 4 patients who had recently started decoppering therapy as compared with striatal rCMRGlc measured in those 10 patients with longer duration of medication. Caudate rCMRGlc correlated significantly with various signs of extrapyramidal dysfunction. Cerebellar, thalamic and cortical rCMRGlc correlated significantly with the severity of pyramidal signs. These data indicate that the PET measurement of rCMRGlc may be a useful tool to evaluate cerebral involvement in WD and to monitor the response to treatment. (orig.)

125

Accuracy in Blood Glucose Measurement: What Will a Tightening of Requirements Yield?  

Science.gov (United States)

Nowadays, almost all persons with diabetes—at least those using antidiabetic drug therapy—use one of a plethora of meters commercially available for self-monitoring of blood glucose. The accuracy of blood glucose (BG) measurement using these meters has been presumed to be adequate; that is, the accuracy of these devices was not usually questioned until recently. Health authorities in the United States (Food and Drug Administration) and in other countries are currently endeavoring to tighten the requirements for the accuracy of these meters above the level that is currently stated in the standard ISO 15197. At first glance, this does not appear to be a problem and is hardly worth further consideration, but a closer look reveals a considerable range of critical aspects that will be discussed in this commentary. In summary, one could say that as a result of modern production methods and ongoing technical advances, the demands placed on the quality of measurement results obtained with BG meters can be increased to a certain degree. One should also take into consideration that the system accuracy (which covers many more aspects as the analytical accuracy) required to make correct therapeutical decisions certainly varies for different types of therapy. At the end, in addition to analytical accuracy, thorough and systematic training of patients and regular refresher training is important to minimize errors. Only under such circumstances will patients make appropriate therapeutic interventions to optimize and maintain metabolic control. PMID:22538158

Heinemann, Lutz; Lodwig, Volker; Freckmann, Guido

2012-01-01

126

IN SITU MEASUREMENTS OF THE SIZE AND DENSITY OF TITAN AEROSOL ANALOGS  

International Nuclear Information System (INIS)

The organic haze produced from complex CH4/N2 chemistry in the atmosphere of Titan plays an important role in processes that occur in the atmosphere and on its surface. The haze particles act as condensation nuclei and are therefore involved in Titan's methane hydrological cycle. They also may behave like sediment on Titan's surface and participate in both fluvial and aeolian processes. Models that seek to understand these processes require information about the physical properties of the particles including their size and density. Although measurements obtained by Cassini-Huygens have placed constraints on the size of the haze particles, their densities remain unknown. We have conducted a series of Titan atmosphere simulation experiments and measured the size, number density, and particle density of Titan aerosol analogs, or tholins, for CH4 concentrations from 0.01% to 10% using two different energy sources, spark discharge and UV. We find that the densities currently in use by many Titan models are higher than the measured densities of our tholins.

127

IN SITU MEASUREMENTS OF THE SIZE AND DENSITY OF TITAN AEROSOL ANALOGS  

Energy Technology Data Exchange (ETDEWEB)

The organic haze produced from complex CH{sub 4}/N{sub 2} chemistry in the atmosphere of Titan plays an important role in processes that occur in the atmosphere and on its surface. The haze particles act as condensation nuclei and are therefore involved in Titan's methane hydrological cycle. They also may behave like sediment on Titan's surface and participate in both fluvial and aeolian processes. Models that seek to understand these processes require information about the physical properties of the particles including their size and density. Although measurements obtained by Cassini-Huygens have placed constraints on the size of the haze particles, their densities remain unknown. We have conducted a series of Titan atmosphere simulation experiments and measured the size, number density, and particle density of Titan aerosol analogs, or tholins, for CH{sub 4} concentrations from 0.01% to 10% using two different energy sources, spark discharge and UV. We find that the densities currently in use by many Titan models are higher than the measured densities of our tholins.

Hoerst, S. M.; Tolbert, M. A, E-mail: sarah.horst@colorado.edu [Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO (United States)

2013-06-10

128

Are Tubes Containing Sodium Fluoride Still Needed for the Measurement of Blood Glucose in Hospital Laboratory Practice?  

Science.gov (United States)

Objectives To compare glucose values obtained using sodium flouride (NaF) tubes and serum separation tubes (SST) in a tertiary care hospital laboratory setting. Methods This study was conducted at the Clinical Biochemistry Laboratory, Royal Hospital, Oman. During the study period (1 September–30 November 2013), 50 pairs (one NaF tube and one SST) of patient’s blood specimens were randomly collected. Following separation of plasma (NaF tubes) and serum (SST), glucose concentrations were measured by hexokinase assay using the Architect c8000. Fifteen pairs of these tubes were kept in the refrigerator at 4°C and plasma/serum glucose concentrations were measured daily up to seven days after collection. Results Comparing plasma (NaF) and serum (SST) results of glucose values (n=50) showed an average difference of 0.00mmol/L (range -0.60 to +0.60mmol/L). Bland Altman analysis gave a non-significant constant bias of 0.10 ±0.195mmol/L (bias ±SD). Pearson correlation between plasma (NaF) and serum (SST) glucose concentrations revealed a significant correlation approaching unity with r2= 0.9991. No significant differences in glucose values were noted for both plasma and serum in 15 pairs of NaF and SST tubes when analyzed seven days following refrigeration. Hemolysis was observed in five (10%) NaF tubes compared with two (4%) SST. Conclusion There is no difference in glucose values collected from plasma NaF tubes or serum SST, and so SST can be used in hospital laboratory settings as there are practical advantages, including cost-effectiveness and reduction in blood volume drawn when utilizing these tubes for glucose and other tests from a single blood collection tube. PMID:25584156

Al-Kharusi, Amira; Al-Lawati, Nuha; Al-Kindi, Manal; Mula-Abed, Waad-Allah

2014-01-01

129

Are Tubes Containing Sodium Fluoride Still Needed for the Measurement of Blood Glucose in Hospital Laboratory Practice?  

Directory of Open Access Journals (Sweden)

Full Text Available Objectives: To compare glucose values obtained using sodium flouride (NaF tubes and serum separation tubes (SST in a tertiary care hospital laboratory setting.? Methods: This study was conducted at the Clinical Biochemistry Laboratory, Royal Hospital, Oman. During the study period (1 September–30 November 2013, 50 pairs (one NaF tube and one SST of patient’s blood specimens were randomly collected. Following separation of plasma (NaF tubes and serum (SST, glucose concentrations were measured by hexokinase assay using the Architect c8000. Fifteen pairs of these tubes were kept in the refrigerator at 4°C and plasma/serum glucose concentrations were measured daily up to seven days after collection.? Results: Comparing plasma (NaF and serum (SST results of glucose values (n=50 showed an average difference of 0.00mmol/L (range -0.60 to +0.60mmol/L. Bland Altman analysis gave a non-significant constant bias of 0.10 ±0.195mmol/L (bias ±SD. Pearson correlation between plasma (NaF and serum (SST glucose concentrations revealed a significant correlation approaching unity with r2= 0.9991. No significant differences in glucose values were noted for both plasma and serum in 15 pairs of NaF and SST tubes when analyzed seven days following refrigeration. Hemolysis was observed in five (10% NaF tubes compared with two (4% SST.? Conclusion: There is no difference in glucose values collected from plasma NaF tubes or serum SST, and so SST can be used in hospital laboratory settings as there are practical advantages, including cost-effectiveness and reduction in blood volume drawn when utilizing these tubes for glucose and other tests from a single blood collection tube.

Amira Al-Kharusi

2014-11-01

130

Influence of Partial Pressure of Oxygen in Blood Samples on Measurement Performance in Glucose-Oxidase-Based Systems for Self-Monitoring of Blood Glucose  

Science.gov (United States)

Background Partial pressure of oxygen (pO2) in blood samples can affect blood glucose (BG) measurements, particularly in systems that employ the glucose oxidase (GOx) enzyme reaction on test strips. In this study, we assessed the impact of different pO2 values on the performance of five GOx systems and one glucose dehydrogenase (GDH) system. Two of the GOx systems are labeled by the manufacturers to be sensitive to increased blood oxygen content, while the other three GOx systems are not. Methods Aliquots of 20 venous samples were adjusted to the following pO2 values: <45, ~70, and ?150 mmHg. For each system, five consecutive measurements on each sample aliquot were performed using the same test strip lot. Relative differences between the mean BG results at pO2 ~70 mmHg, which is considered to be similar to pO2 in capillary blood samples, and the mean BG result at pO2 <45 and ?150 mmHg were calculated. Results For all tested GOx systems, mean relative differences in the BG measurement results were between 6.1% and 22.6% at pO2 <45 mmHg and between -7.9% and -14.9% at pO2 ?150 mmHg. For both pO2 levels, relative differences of all tested GOx systems were significant (p < .0001). The GDH system showed mean relative differences of -1.0% and -0.4% at pO2 values <45 and ?150 mmHg, respectively, which were not significant. Conclusions These data suggest that capillary blood pO2 variations lead to clinically relevant BG measurement deviations in GOx systems, even in GOx systems that are not labeled as being oxygen sensitive. PMID:24351177

Baumstark, Annette; Schmid, Christina; Pleus, Stefan; Haug, Cornelia; Freckmann, Guido

2013-01-01

131

A Novel Analog Integrated Circuit Design Course Covering Design, Layout, and Resulting Chip Measurement  

Science.gov (United States)

This work describes a novel, first-year graduate-level analog integrated circuit (IC) design course. The course teaches students analog circuit design; an external manufacturer then produces their designs in three different silicon chips. The students, working in pairs, then test these chips to verify their success. All work is completed within…

Lin, Wei-Liang; Cheng, Wang-Chuan; Wu, Chen-Hao; Wu, Hai-Ming; Wu, Chang-Yu; Ho, Kuan-Hsuan; Chan, Chueh-An

2010-01-01

132

Analog earthquakes  

Energy Technology Data Exchange (ETDEWEB)

Analogs are used to understand complex or poorly understood phenomena for which little data may be available at the actual repository site. Earthquakes are complex phenomena, and they can have a large number of effects on the natural system, as well as on engineered structures. Instrumental data close to the source of large earthquakes are rarely obtained. The rare events for which measurements are available may be used, with modfications, as analogs for potential large earthquakes at sites where no earthquake data are available. In the following, several examples of nuclear reactor and liquified natural gas facility siting are discussed. A potential use of analog earthquakes is proposed for a high-level nuclear waste (HLW) repository.

Hofmann, R.B. [Center for Nuclear Waste Regulatory Analyses, San Antonio, TX (United States)

1995-09-01

133

[The net analyte preprocessing combined with radial basis partial least squares regression applied in noninvasive measurement of blood glucose].  

Science.gov (United States)

In order to improve the prediction accuracy of quantitative analysis model in the near-infrared spectroscopy of blood glucose, this paper, by combining net analyte preprocessing (NAP) algorithm and radial basis functions partial least squares (RBFPLS) regression, builds a nonlinear model building method which is suitable for glucose measurement of human, named as NAP-RBFPLS. First, NAP is used to pre-process the near-infrared spectroscopy of blood glucose, in order to effectively extract the information which only relates to glucose signal from the original near-infrared spectra, so that it could effectively weaken the occasional correlation problems of the glucose changes and the interference factors which are caused by the absorption of water, albumin, hemoglobin, fat and other components of the blood in human body, the change of temperature of human body, the drift of measuring instruments, the changes of measuring environment, and the changes of measuring conditions; and then a nonlinear quantitative analysis model is built with the near-infrared spectroscopy data after NAP, in order to solve the nonlinear relationship between glucose concentrations and near-infrared spectroscopy which is caused by body strong scattering. In this paper, the new method is compared with other three quantitative analysis models building on partial least squares (PLS), net analyte preprocessing partial least squares (NAP-PLS) and RBFPLS respectively. At last, the experimental results show that the nonlinear calibration model, developed by combining NAP algorithm and RBFPLS regression, which was put forward in this paper, greatly improves the prediction accuracy of prediction sets, and what has been proved in this paper is that the nonlinear model building method will produce practical applications for the research of non-invasive detection techniques on human glucose concentrations. PMID:24822427

Li, Qing-Bo; Huang, Zheng-Wei

2014-02-01

134

Non-invasive measurement of blood glucose level by time-resolved transmission spectroscopy: A feasibility study  

Science.gov (United States)

An optical spectroscopic method is investigated theoretically for in vivo measurement of blood glucose concentration. This method is based on dynamic dual wavelength (610 nm and 810 nm) time-resolved measurements under a condition of artificial blood flow kinetics in a human finger. The influence of glucose concentration on absorption and reduced scattering coefficients of the whole blood is simulated using the T-matrix method. The scattering centers, RBC aggregation, under the artificial — kinetics condition are modeled as spheroid. The modified parametric slopes were derived from the Laplace transformed data of the time-resolved transmittance. The results show that an appropriate selection of the Laplace parameter can lead to enhanced sensitivity for glucose measurement.

Sun, Meixiu; Chen, Nanguang

2012-03-01

135

Measurements of CO2 Carbon Stable Isotopes at Artificial and Natural Analog Sites  

Science.gov (United States)

Carbon storage in geologic formations is one method to prevent carbon dioxide (CO2), produced by fossil fuel combustion, from entering the Earth's atmosphere. The monitoring, verification and accounting (MVA) of geologically sequestered CO2 is critical to the operation of a geologic storage site. Surface MVA techniques need to identify seepage from the sequestration reservoir at or below ambient CO2 concentrations. The CO2 carbon stable isotope ratio of is a sensitive diagnostic signature that can distinguish between anthropogenic and natural sources of CO2. Frequency Modulated spectroscopy (FMS) is an ultra-sensitive version of absorption spectroscopy that is capable of detecting the CO2 carbon stable isotope ratios. The technique involves phase modulation of the laser such that two side bands, spaced wider than the absorption feature of interest (in this case +/-2 GHz) are created. The signal is mixed with the local oscillator yielding a signal proportional to the species concentration. This FMS signature is recorded at multiple wavelengths to obtain the CO2 carbon isotope ratio.Two instruments using the FMS technique have been built and tested at LANL. One instrument draws ambient air into a multi-pass cell for a measurement, point source measurements. The other instrument uses an open-air path, tested up to 160 m (round trip), to measure the CO2 carbon isotopic ratio along the beam path, column average measurements. In this paper, results from multiple field deployments of one or both of the instruments will be presented. The Zero Emissions Research & Technology (ZERT) group at Montana State University established a field test site where controlled amounts of CO2 are released to test the performance of CO2 detection instruments and measurement techniques. The field site allows a controlled flow rate of CO2 to be released into the near surface through a 100 m long horizontal pipe. In July of 2009, a release was conducted, with a uniform flow rate of 0.2 tons per day, as the subsequent seepage was measured. There was a similar release, but at a flow rate of 0.15 tons/day, in July 2010. Stable isotope measurements have also been made at several natural analog sites. Two places of interest are the Valles Caldera National Preserve in NM and Soda Springs, ID. The Valle traps CO2 at night and can have very large swings in concentrations that test the instrument range. Soda Springs, ID has many carbonated natural springs and carbon isotope information from this site can provide information regarding CO2 from the deep subsurface, useful for future MVA work.

Humphries, S. D.; Clegg, S. M.; Rahn, T.; Fessenden, J. E.; Dobeck, L.; Spangler, L.; McLing, T. L.

2010-12-01

136

Using Stochastic modelling to identify unusual continuous glucose monitor measurements and behaviour, in newborn infants  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Abnormal blood glucose (BG concentrations have been associated with increased morbidity and mortality in both critically ill adults and infants. Furthermore, hypoglycaemia and glycaemic variability have both been independently linked to mortality in these patients. Continuous Glucose Monitoring (CGM devices have the potential to improve detection and diagnosis of these glycaemic abnormalities. However, sensor noise is a trade-off of the high measurement rate and must be managed effectively if CGMs are going to be used to monitor, diagnose and potentially help treat glycaemic abnormalities. Aim To develop a tool that will aid clinicians in identifying unusual CGM behaviour and highlight CGM data that potentially need to be interpreted with care. Methods CGM data and BG measurements from 50 infants at risk of hypoglycaemia were used. Unusual CGM measurements were classified using a stochastic model based on the kernel density method and historical CGM measurements from the cohort. CGM traces were colour coded with very unusual measurements coloured red, highlighting areas to be interpreted with care. A 5-fold validation of the model was Monte Carlo simulated 25 times to ensure an adequate model fit. Results The stochastic model was generated using ~67,000 CGM measurements, spread across the glycaemic range ~2-10?mmol/L. A 5-fold validation showed a good model fit: the model 80% confidence interval (CI captured 83% of clinical CGM data, the model 90% CI captured 91% of clinical CGM data, and the model 99% CI captured 99% of clinical CGM data. Three patient examples show the stochastic classification method in use with 1 A stable, low variability patient which shows no unusual CGM measurements, 2 A patient with a very sudden, short hypoglycaemic event (classified as unusual, and, 3 A patient with very high, potentially un-physiological, glycaemic variability after day 3 of monitoring (classified as very unusual. Conclusions This study has produced a stochastic model and classification method capable of highlighting unusual CGM behaviour. This method has the potential to classify important glycaemic events (e.g. hypoglycaemia as true clinical events or sensor noise, and to help identify possible sensor degradation. Colour coded CGM traces convey the information quickly and efficiently, while remaining computationally light enough to be used retrospectively or in real-time.

Signal Matthew

2012-08-01

137

Noninvasive glucose measurement by fluorescence quenching of non toxic gold nanoparticles  

Science.gov (United States)

Effects of interaction of human body compatible gold nanoparticles with glucose on fluorescence emission spectra of the nanoparticles are investigated experimentally. It is observed that nanoparticles' fluorescence peak quenches and blue shifted because of such interaction. This procedure is sensitive even to low difference of glucose concentration. The results suggest that glucose could seriously affect the optical properties of gold nanoparticles. Furthermore, a linear range of relative shift of different fluorescence spectrum's peaks is obtained. Furthermore, comparison of fluorescence and absorption results shows that the former technique is as much as 20 times more sensitive to the variation of glucose concentration.

Bagheri, Z.; Massudi, R.; Ghanavi, J.

2014-06-01

138

The crystal structure of rabbit phosphoglucose isomerase complexed with D-sorbitol-6-phosphate, an analog of the open chain form of D-glucose-6-phosphate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Phosphoglucose isomerase (PGI) catalyzes the isomerization of D-glucose-6-phosphate (G6P) and D-fructose-6-phosphate (F6P) in glycolysis and gluconeogenesis. Analysis of previously reported X-ray crystal structures of PGI without ligand, with the cyclic form of F6P, or with inhibitors that mimic the cis-enediol intermediate led to proposed mechanisms for the ring opening and isomerization steps in the multistep catalytic mechanism. To help complete our model of the overall mechanism, informat...

Lee, Ji Hyun; Jeffery, Constance J.

2005-01-01

139

D-glucose transport system of Zymomonas mobilis  

Energy Technology Data Exchange (ETDEWEB)

The properties of the D-glucose transport system of Zymomonas mobilis were determined by measuring the uptake of nonmetabolizable analogs (2-deoxy-D-glucose and D-xylose) by wild-type cells and the uptake of D-glucose itself by a mutant lacking glucokinase. D-Glucose was transported by a constitutive, stereospecific, carrier-mediated facilitated diffusion system, whereby its intracellular concentration quickly reached a plateau close to but not above the external concentration. D-Xylose was transported by the D-glucose system, as evidenced by inhibition of its uptake by D-glucose. D-Fructose was not an efficient competitive inhibitor of D-glucose uptake, indicating that it has a low affinity for the D-glucose transport system. The apparent Km of D-glucose transport was in the range of 5 to 15 mM, with a Vmax of 200 to 300 nmol/min mg of protein. The Km of Z. mobilis glucokinase (0.25 to 0.4 mM) was 1 order of magnitude lower than the Km for D-glucose transport, although the Vmax values for transport and phosphorylation were similar. Thus, glucose transport cannot be expected to be rate limiting at concentrations of extracellular glucose normally used in fermentation processes, which greatly exceed the Km for the transport system. The low-affinity, high velocity, nonconcentrative system for D-glucose transport described here is consistent with the natural occurrence of Z. mobilis in high-sugar environments and with the capacity of Z. mobilis for rapid conversion of glucose to metabolic products with low energetic yield. 35 references.

De Marco, A.A.; Romano, A.H.

1985-01-01

140

Real-time quantitative fluorescence measurement of microscale cell culture analog systems  

Science.gov (United States)

A microscale cell culture analog (?CCA) is a cell-based lab-on-a-chip assay that, as an animal surrogate, is applied to pharmacological studies for toxicology tests. A ?CCA typically comprises multiple chambers and microfluidics that connect the chambers, which represent animal organs and blood flow to mimic animal metabolism more realistically. A ?CCA is expected to provide a tool for high-throughput drug discovery. Previously, a portable fluorescence detection system was investigated for a single ?CCA device in real-time. In this study, we present a fluorescence-based imaging system that provides quantitative real-time data of the metabolic interactions in ?CCAs with an emphasis on measuring multiple ?CCA samples simultaneously for high-throughput screening. The detection system is based on discrete optics components, with a high-power LED and a charge-coupled device (CCD) camera as a light source and a detector, for monitoring cellular status on the chambers of each ?CCA sample. Multiple samples are characterized mechanically on a motorized linear stage, which is fully-automated. Each ?CCA sample has four chambers, where cell lines MES-SA/DX- 5, and MES-SA (tumor cells of human uterus) have been cultured. All cell-lines have been transfected to express the fusion protein H2B-GFP, which is a human histone protein fused at the amino terminus to EGFP. As a model cytotoxic drug, 10 ?M doxorubicin (DOX) was used. Real-time quantitative data of the intensity loss of enhanced green fluorescent protein (EGFP) during cell death of target cells have been collected over several minutes to 40 hours. Design issues and improvements are also discussed.

Oh, Taek-il; Kim, Donghyun; Tatosian, Daniel; Sung, Jong Hwan; Shuler, Michael

2007-02-01

 
 
 
 
141

Diamagnetic loop measurements in JT-60U with precision analog integrator  

International Nuclear Information System (INIS)

It is indispensable to evaluate the plasma stored energy accurately in order to investigate energy confinement properties. Although a method based on plasma diamagnetism has difficulties in attaining satisfactory accuracy, it enable us to directly measure the time evolution of the stored energy in every shot. Diamagnetic loops were wound inside the vacuum vessel of JT-60U. The vacuum toroidal flux is compensated by the use of a loop pair with slightly different pick-up areas instead of a Rogowski coil previously adopted for JT-60. The best set with least errors among four sets of diamagnetic loops has been used for routine diamagnetic measurement. The main loop (four turns) and the compensation loop (three turns) are located along a vessel connecting ring to be rigid enough to minimize the variation of the toroidal field coupling. The main and compensating loops are separated by 31 ± 1 mm in the radial direction. The toroidal fluxes through the main and compensating loops in the case of It = 52.1 kA (Bt = 4.0 T at R = 3.32 m) are 96.9 Vs and tc = 76.5 Vs, respectively. Differential integration is made with a precision analog circuit with a potentiometer for the adjustment. Automatic cancellation of input offset voltage is implemented to achieve very low drift. The maximum pulse length of a discharge in JT-60U was extended from 15 s to 65 s in 2003. The excitation of the toroidal magnetic field coils begins 30 s ahead of plasma breakdown so that the integration time is longer than 95 s. With increased electrostatic capacity of a cancellation capacitor, the equivalent input offset voltage is less than 1 V even with an input offset voltage higher than 1 mV. The stray couplings of the loops with poloidal magnetic fields are removed by digital post-processing. The plasma stored energy is calculated by surface integrations with a fast boundary identification code which approximates the plasma current as six filaments or a code based on the Cauchy-condition surface method. The residual error arising from the direct coupling to the plasma current were determined experimentally by sweeping the plasma column vertically or horizontally during low density discharges and by making computed plasma stored energy not to be so positionally sensitive nor to be negative in extremely shifted cases. The absolute error in the dia magnetically measured plasma stored energy [MJ] is estimated to be not more than 0.10 Ip [MA] by comparison with the kinetic stored energy. (author)

142

Photoacoustic blood glucose and skin measurement based on optical scattering effect  

Science.gov (United States)

Non-invasive blood glucose determination has been investigated by more than 100 research groups in the world during the past fifteen years. The commonly optical methods are based on the capacity of near-IR light to penetrate a few hundreds micrometers or a few millimeters into human tissue where it interacts with glucose. A change of glucose concentration may modify the optical parameters in tissue, with the result that its glucose concentration can be extracted by analyzing the received optical signals. This paper demonstrates that glucose affects on the scattering coefficient of human blood, by applying the streak camera and pulsed photoacoustic techniques; and drinking water seems also affecting on PA signal from skin surface.

Zhao, Zuomin; Myllyla, Risto A.

2002-07-01

143

The relationship between HbA(1c) and fasting plasma glucose in patients with increased plasma liver enzyme measurements  

DEFF Research Database (Denmark)

Background:? HbA(1c) is currently being introduced for diagnostic purpose in diabetes. Previous studies have, however, indicated that patients with liver disease have false low HbA(1c) levels. We therefore investigated the correlation between HbA(1c) and plasma glucose in patients with different levels of increased liver enzyme concentrations. Methods:? Data from 10?065 patients with simultaneous measurement of HbA(1c) , venous fasting plasma glucose, alanine aminotransferase and ?-glutamyl transferase were extracted from our laboratory database. Correlations were investigated in four patient groups divided according to their liver enzyme concentrations. Results:? The correlation between HbA(1c) and plasma glucose was high in all groups, with r?=?0.77 for men and r?=?0.78 for women (P?

Christiansen, R; Rasmussen, L Melholt

2012-01-01

144

Glucose control.  

Science.gov (United States)

Stress-related hyperglycemia is a common finding in acutely ill patients, and is related to the severity and outcome of the critical illness. The pathophysiology of stress hyperglycemia includes hormonal and neural signals, leading to increased production of glucose by the liver and peripheral insulin resistance mediated by the translocation of transmembrane glucose transporters. In one pioneering study, tight glycemic control by intensive insulin therapy in critically ill patients was associated with improved survival. However, this major finding was not confirmed in several other prospective randomized controlled trials. The reasons underlying the discrepancy between the first and the subsequent studies could include nutritional strategy (amount of calories provided, use of parenteral nutrition), case-mix, potential differences in the optimal blood glucose level (BG) in different types of patients, hypoglycemia and its correction, and the magnitude of glucose variability. Therefore, an improved understanding of the physiology and pathophysiology of glycemic regulation during acute illness is needed. Safe and effective glucose control will need improvement in the definition of optimal BG and in the measurement techniques, perhaps including continuous monitoring of insulin algorithms and closed-loop systems. PMID:23075589

Preiser, Jean-Charles

2013-01-01

145

Fluorescence spectroscopic study on complexation of uranium(VI) by glucose: a comparison of room and low temperature measurements  

International Nuclear Information System (INIS)

Cryogenic techniques are currently used in scanning tunnelling microscopy (STM) and single molecule spectroscopy. Recently such cryogenic devices have also been adapted to time resolved laser-induced fluorescence spectroscopy (TRLFS) systems applied to uranium(VI). In our study, we interpret TRLFS results obtained for the uranyl(VI) glucose system at room temperature (RT) and under cryogenic conditions of 153 K (cryo-TRLFS). A uranyl(VI) glucose complex was only identified by cryo-TRLFS measurements at pH 5 and not by RT measurements. The uranyl(VI) glucose complex was characterized by five emission bands at 499.0, 512.1, 525.2, 541.7, and 559.3 nm and a fluorescence lifetime of 20.9 ± 2.9 ?s. The uranyl(VI) glucose complex formation constant was calculated for the first time to be log?I=0.1M 15.25 ± 0.96. Cryo-TRLFS investigation opens up new possibilities for the determination of complex formation constants since interfering quenching effects often encounter at RT are suppressed by measurements at cryogenic conditions. (author)

146

Age and sex differences in cerebral glucose consumption measured by pet using [18-F] fluorodeoxyglucose (FDG)  

International Nuclear Information System (INIS)

Resting cerebral glucose metabolic rates (CMRglc) were measured in 23 subjects by PET using FDG. Subjects were divided into several groups (mean age +- S.D.) 5 young males (YM) (27 +- 6); 6 young females (YF)(33 +9); 5 elderly males (EM)(73 +- 5); 7 elderly females (EF)(69 +- 7). Additionally, from these groups 4 YM, 3YF, 5EM and 4EF were studied again within 6 weeks under identical conditions. CMRglc in the YF group again was significantly hider than YM (p 0.05). No obvious relationships of CMRglc to the phase of the menstrual cycle was found in this small group. There was a trend (p=0.06) toward a higher CMRglc in YF than EF. These results support the findings of higher CBF in YF versus YM. The differences between the results of Kuhl et al (J. Cereb. and a reduction of CMRglc with age was found in a mixed group of males and females (58and female), and where no age effect was found the males, are also resolved by these findings. The authors suggest that the apparent age effect, in females in this study, is principally a hormonal one

147

Development of a passive air sampler to measure airborne organophosphorus pesticides and oxygen analogs in an agricultural community.  

Science.gov (United States)

Organophosphorus pesticides are some of the most widely used insecticides in the US, and spray drift may result in human exposures. We investigate sampling methodologies using the polyurethane foam passive air sampling device to measure cumulative monthly airborne concentrations of OP pesticides chlorpyrifos, azinphos-methyl, and oxygen analogs. Passive sampling rates (m(3)d(-1)) were determined using calculations using chemical properties, loss of depuration compounds, and calibration with side-by-side active air sampling in a dynamic laboratory exposure chamber and in the field. The effects of temperature, relative humidity, and wind velocity on outdoor sampling rates were examined at 23 sites in Yakima Valley, Washington. Indoor sampling rates were significantly lower than outdoors. Outdoor rates significantly increased with average wind velocity, with high rates (>4m(3)d(-1)) observed above 8ms(-1). In exposure chamber studies, very little oxygen analog was observed on the PUF-PAS, yet substantial amounts chlorpyrifos-oxon and azinphos methyl oxon were measured in outdoor samples. PUF-PAS is a practical and useful alternative to AAS because it results in little artificial transformation to the oxygen analog during sampling, it provides cumulative exposure estimates, and the measured sampling rates were comparable to rates for other SVOCs. It is ideal for community based participatory research due to low subject burden and simple deployment in remote areas. PMID:24997910

Armstrong, Jenna L; Yost, Michael G; Fenske, Richard A

2014-09-01

148

Comparison of optical coherence tomography, the pulsed photoacoustic technique, and the time-of-flight technique in glucose measurements in vitro  

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Abstract The development of a non-invasive glucose monitoring technique is very important because it would tremendously diminish the need to puncture the skin when taking blood samples and help diabetic patients in controlling their blood glucose levels and in treating Diabetes Mellitus. The focus of this thesis is on measuring the effect of glucose on the light scattering properties of a tissue-simulating phantom and biological tissues in vitro. Optical coherence tomography (OCT), the pul...

Kinnunen, Matti

2006-01-01

149

Effects of Zinc Supplementation on the Anthropometric Measurements, Lipid Profiles and Fasting Blood Glucose in the Healthy Obese Adults  

Science.gov (United States)

Purpose: The aim of this study was to assess the effects of zinc supplementation on anthropometric measures, improving lipid profile biomarkers, and fasting blood glucose level in obese people. Methods: This randomized, double- blind clinical trial was carried out on 60 obese participants in the 18-45 age range for one month. The participants were randomly divided into the intervention group, who received 30 mg/d zinc gluconate, and the placebo group who received 30mg/d starch. Anthropometric measurements (body mass index (BMI), weight and waist circumference) were recorded before and at the end of study. Lipid profile biomarkers and fasting blood glucose were determined using enzymatic procedure. Analysis of Covariance (ANCOVA) test was run to compare the post-treatment values of the two groups, and t-test was conducted to compare within group changes. Results: Serum zinc concentration was increased significantly in intervention group (p=0.024). BMI and body weight was significantly decreased (p=0.030 and p=0.020, respectively). Lipid profile biomarkers and fating blood glucose did not change significantly but triglyceride level was significantly decreased (p=0.006) in the intervention group. Conclusion: The obtained results indicate that zinc supplementation improves BMI, body weight, and triglyceride concentration without considerable effects on lipid profile and glucose level. Zinc can be suggested as a suitable supplementation therapy for obese people, but more studies are needed to verify the results. PMID:24312830

Payahoo, Laleh; Ostadrahimi, Alireza; Mobasseri, Majid; Khaje Bishak, Yaser; Farrin, Nazila; Asghari Jafarabadi, Mohammad; Mahluji, Sepide

2013-01-01

150

Effects of Zinc Supplementation on the Anthropometric Measurements, Lipid Profiles and Fasting Blood Glucose in the Healthy Obese Adults  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The aim of this study was to assess the effects of zinc supplementation on anthropometric measures, improving lipid profile biomarkers, and fasting blood glucose level in obese people. Methods: This randomized, double- blind clinical trial was carried out on 60 obese participants in the 18-45 age range for one month. The participants were randomly divided into the intervention group, who received 30 mg/d zinc gluconate, and the placebo group who received 30mg/d starch. Anthropometric measurements (body mass index (BMI, weight and waist circumference were recorded before and at the end of study. Lipid profile biomarkers and fasting blood glucose were determined using enzymatic procedure. Analysis of Covariance (ANCOVA test was run to compare the post-treatment values of the two groups, and t-test was conducted to compare within group changes. Results: Serum zinc concentration was increased significantly in intervention group (p=0.024. BMI and body weight was significantly decreased (p=0.030 and p=0.020, respectively. Lipid profile biomarkers and fating blood glucose did not change significantly but triglyceride level was significantly decreased (p=0.006 in the intervention group. Conclusion: The obtained results indicate that zinc supplementation improves BMI, body weight, and triglyceride concentration without considerable effects on lipid profile and glucose level. Zinc can be suggested as a suitable supplementation therapy for obese people, but more studies are needed to verify the results.

Sepide Mahluji

2013-02-01

151

Measurement of glucose metabolism in patients with dilated cardiomyopathy using positron emission tomography with 18F-FDG: Initial Experience  

International Nuclear Information System (INIS)

Introduction: Fluorine18 deoxyglucose (18F-FDG) has been used in numerous studies to determine the cardiac rate of glucose metabolism in normal and pathological conditions. It is known that during heart failure the metabolic pattern is altered. Patlack's graphical analysis allows the assessment of heart muscle glucose consumption in patients with non-ischaemic heart failure and normal subjects. Methods: Standardized measurement of glucose metabolism was performed in four patients with dilated cardiomyopathy and three healthy subjects. All subjects received an oral load of carbohydrates (75gr) previous to scanning. Dynamic images of the thorax were acquired. Myocardial uptake was estimated from time-activity curves in the atrium and left ventricle using Patlack's graphical analysis. Results: All subjects studied were male. 18F-FDG uptake rate for the group with dilated cardiomyopathy was 1.31±0.2, versus 1.26±0.37 ml/100gr/min in the control group. Conclusion: Measurement of cardiac glucose metabolism by 18F-FDG PET is feasible in a clinical service, allowing impact evaluation of physiologic and metabolic changes in the myocardium in different pathologic scenarios in addition to therapy assessment

152

Investigation on how to choose measurement sites for non-invasive near-infrared blood glucose sensing  

Science.gov (United States)

With the changing of human diet and the future of an aging society, the number of diabetic patients is growing rapidly and steadily. The major therapeutic method to that disease is monitoring the blood glucose concentration frequently to adjust the dose of the drugs and insulin. In order to avoid the painful finger prick, we choose the ear lobe as a measurement site with finger as a reference. Firstly, we compare the blood glucose concentration results of ear lobe and finger during an oral glucose tolerance test, the results showed a good correlation of the two sites. Secondly, the three-layered skin structure of finger and ear lobe has been studied by using optical coherence tomography (OCT) technique. The result shows that the thickness of each layer at ear lobe is thinner. Finally, the difference between reflectance spectra of finger and ear lobe is compared due to the diverse skin thickness. The results still show a higher absorbance value for ear lobe. In conclusion, the ear lobe is an ideal measurement site for noninvasive blood glucose sensing.

Jiang, Jingying; Zou, Da; Min, Xiaolin; Ma, Zhenhe; Xu, Kexin

2012-03-01

153

Measurement of regional cerebral glucose utilization in man by positron emission tomography  

International Nuclear Information System (INIS)

The various methods available for the study of regional cerebral glucose consumption in man by positron emission tomography are described and their applications, limitations and principal physiopathological results are presented

154

Experimental study for cancer diagnosis with positron-labeled fluorinated glucose analogs: [18F]-2-fluoro-2-deoxy-D-mannose  

International Nuclear Information System (INIS)

18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) and 18F-2-fluoro-2-deoxy-D-mannose (18F-FDM) were tested as tumor diagnostic agents in a transplantable rat tumor and rabbit tumors. Tissue distribution studies in rats showed high tumor uptakes of both radiopharmaceuticals. The tumor uptake reached 2.65+-0.61% dose 18F-FDG/g and 2.65+-0.81% dose 18F-FDM/g at 60 min and remained relatively constant until 120 min. Blood clearance of both 18F-FDG and 18F-FDM was very rapid and tumor-to-blood ratios reached 22.1 and 29.4 at 60 min, respectively. Tumor-to-tissue ratios of both radiopharmaceuticals were very high in most organs, especially in the liver, kidney, and pancreas. Positron emission tomography (PET) of rabbit tumor with 18F-FDM clearly delineated the main tumor, central necrosis, and lymph node metastases. These data suggested that 18F-FDM, which is a by-product of 18F-FDG synthesis, was also an excellent cancer diagnostic agent as well as 18-F-FDG. This is not only a new feature of 18F-FDM, but also an economical improvement on cancer diagnosis by PET. (orig.)

155

Intracellular Glucose Concentration in Derepressed Yeast Cells Consuming Glucose Is High Enough To Reduce the Glucose Transport Rate by 50%  

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In Saccharomyces cerevisiae cells exhibiting high-affinity glucose transport, the glucose consumption rate at extracellular concentrations above 10 mM was only half of the zero trans-influx rate. To determine if this regulation of glucose transport might be a consequence of intracellular free glucose we developed a new method to measure intracellular glucose concentrations in cells metabolizing glucose, which compares glucose stereoisomers to correct for adhering glucose. The intracellular gl...

Teusink, Bas; Diderich, Jasper A.; Westerhoff, Hans V.; Dam, Karel; Walsh, Michael C.

1998-01-01

156

Radical carbocyclization reactions of ortho-iodoallyloxybenzoate derivatives of d-glucose and d-galactose and comparison with the reactions of their benzamide analogs  

International Nuclear Information System (INIS)

Two orthoiodoallyloxybenzoates, methyl 4-O-allyl-2,3-di-O-benzyl-6-O-(2-iodobenzoyl)-?-D-glucopyranoside (3) and methyl 4-O-allyl-2,3-di-O-benzyl-6-O-(2-iodobenzoyl)-?-D-galactopyranoside (4) were synthesized in seven conventional steps from methyl ?-D glucopyranoside and methyl ?-D-galactopyranoside, respectively. Bu3SnH-mediated aryl radical cyclization of 3 provided exclusively the hydrogenolysis product 12. The reaction of 4 gave the reduced uncyclized product 13 and only traces of 4A, resulting from 11-endo aryl radical cyclization. In previous papers we described that in similar Bu3SnH-mediated radical reaction of orthoiodoallyloxybenzamides, analogs of 3 and 4, we obtained macrolactams resulting from 11-endo cyclization. An hypothesis to explain the differences is presented. It was assumed that in the aryl radical formed from iodobenzamides there is a suitable conformation to cyclization, which is stabilized by an intramolecular hydrogen bond. (author)

157

Nucleic Acid Base Analog FRET-Pair Facilitating Detailed Structural Measurements in Nucleic Acid Containing Systems  

DEFF Research Database (Denmark)

We present the first nucleobase analog fluorescence resonance energy transfer (FRET)-pair. The pair consists of tCO, 1,3-diaza-2-oxophenoxazine, as an energy donor and the newly developed tC(nitro), 7-nitro-1,3-diaza-2-oxophenothiazine, as an energy acceptor. The FRET-pair successfully monitors distances covering up to more than one turn of the DNA duplex. Importantly, we show that the rigid stacking of the two base analogs, and consequently excellent control of their exact positions and orientations, results in a high control of the orientation factor and hence very distinct FRET changes as the number of bases separating tCO and tC(nitro) is varied. A set of DNA strands containing the FRET-pair at wisely chosen locations will, thus, make it possible to accurately distinguish distance- from orientation-changes using FRET. In combination with the good nucleobase analog properties, this points toward detailed studies of the inherent dynamics of nucleic acid structures. Moreover, the placement of FRET-pair chromophores inside the base stack will be a great advantage in studies where other (biomacro)molecules interact with the nucleic acid. Lastly, our study gives possibly the first truly solid experimental support to the dependence of energy transfer efficiency on orientation of involved transition dipoles as predicted by the Forster theory.

Börjesson, Karl; Preus, SØren

2009-01-01

158

Quantitative measurement of local cerebral metabolic rate for glucose utilizing tritiated 2-deoxyglucose  

International Nuclear Information System (INIS)

The [14C]2-deoxyglucose (2-DG) technique has been widely utilized for quantitative measurement of local cerebral metabolic rate for glucose (lCMRG) in animals. The technique as presently used is limited by the energy of 14C beta-particles, which can travel relatively great distances in tissue. This results in limited autoradiographic resolution and in computed 14C concentrations which are a function of tissue section thickness. [3H]2-DG has less energetic beta-particles; hence, autoradiographs have better resolution and optical densities are independent of tissue thickness for sections greater than 5 ?m. The authors have developed a method for quantitation of lCMRG in rats using [3H]2-DG and a newly developed ultrasensitive X-ray film. Autoradiographic tissue standards were prepared by injecting rats with [3H]2-DG and assaying micro-samples of brain for 3H concentration. Ten rats were used in this study. Five rats received [3H]2-DG (300 ?Ci/100 g) and 5 rats received [14C]2-DG (7.5 ?Ci/100 g). The mean lCMRG values for selected areas of the central nervous system demonstrated no significant difference (P > 0.05) between the [14C]2-DG and the [3H]2-DG groups. Values for lCMRG from the [3H]2-DG group showed no variation attributable to inadequate microtome precision. The improved resolution obtained by utilizing [3H]2-DG is es by utilizing [3H]2-DG is especially evident where gray matter (high lCMRG) is immediately adjacent to white matter (low lCMRG). (Auth.)

159

A Multicentre Study of the New Reflotron® System for the Measurement of Urea, Glucose, Triacylglycerols, Cholesterol, ?-Glutamyltransferase and Haemoglobin  

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Reflotron®, a solid phase reagent technology capable of measuring a wide range of analytes on whole blood, plasma or serum samples has been evaluated with reference to urea, glucose, cholesterol, triacylglycerols, haemoglobin and ?-glutamyltransferase analyses. The results show good concordance with conventional wet chemistry methods, with comparable imprecision. Performance is not affected by variations in haematocrit up to 0.55 or bilirubin concentrations at least up to 250 ?mol/l.

Price, C. P.; Koller, P. U.

1988-01-01

160

Brain metabolism in autism. Resting cerebral glucose utilization rates as measured with positron emission tomography  

Energy Technology Data Exchange (ETDEWEB)

The cerebral metabolic rate for glucose was studied in ten men (mean age = 26 years) with well-documented histories of infantile autism and in 15 age-matched normal male controls using positron emission tomography and (F-18) 2-fluoro-2-deoxy-D-glucose. Positron emission tomography was completed during rest, with reduced visual and auditory stimulation. While the autistic group as a whole showed significantly elevated glucose utilization in widespread regions of the brain, there was considerable overlap between the two groups. No brain region showed a reduced metabolic rate in the autistic group. Significantly more autistic, as compared with control, subjects showed extreme relative metabolic rates (ratios of regional metabolic rates to whole brain rates and asymmetries) in one or more brain regions.

Rumsey, J.M.; Duara, R.; Grady, C.; Rapoport, J.L.; Margolin, R.A.; Rapoport, S.I.; Cutler, N.R.

1985-05-01

 
 
 
 
161

Brain metabolism in autism. Resting cerebral glucose utilization rates as measured with positron emission tomography  

International Nuclear Information System (INIS)

The cerebral metabolic rate for glucose was studied in ten men (mean age = 26 years) with well-documented histories of infantile autism and in 15 age-matched normal male controls using positron emission tomography and (F-18) 2-fluoro-2-deoxy-D-glucose. Positron emission tomography was completed during rest, with reduced visual and auditory stimulation. While the autistic group as a whole showed significantly elevated glucose utilization in widespread regions of the brain, there was considerable overlap between the two groups. No brain region showed a reduced metabolic rate in the autistic group. Significantly more autistic, as compared with control, subjects showed extreme relative metabolic rates (ratios of regional metabolic rates to whole brain rates and asymmetries) in one or more brain regions

162

Synthesis and anticancer activity of new flavonoid analogs and inconsistencies in assays related to proliferation and viability measurements.  

Science.gov (United States)

Flavonoids have been studied intensely for their ability to act as anti-carcinogenic, anti-inflammatory, anti-viral and anti-aging agents and are often marketed as supplements related to their anti-inflammatory activity. Previous studies have primarily focused on the effects of polar natural flavonoids. We examined the activity of novel hydrophobic and lipophilic flavonols against human DU-145 and PC-3 prostate cancer cell lines. All flavonol analogs were more active than the naturally occurring flavonols quercetin, kaempferol, kaempferide and galangin. The most potent analogs were 6.5-fold more active against DU-145 and PC-3 cells than quercetin and fell within the biologically relevant concentration range (low micromolar). We also evaluated the potential toxic effects of flavonol analogs on normal cells, an assessment that has frequently been ignored when studying the anticancer effects of flavonoids. During these analyses, we discovered that various metabolic and DNA staining assays were unreliable methods for assessing cell viability of flavonoids. Flavonoids reduce colorimetric dyes such as MTT and Alamar Blue in the absence of cells. We showed that flavonol-treated prostate cancer cells were stained less intensely with crystal violet than untreated cells at non-toxic concentrations. The trypan blue exclusion assay was selected as a reliable alternative for measuring cell viability. PMID:24859601

Forbes, Alaina M; Lin, Huimin; Meadows, Gary G; Meier, G Patrick

2014-08-01

163

The effects of precision, haematocrit, pH and oxygen tension on point-of-care glucose measurement in critically ill patients: a prospective study.  

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BACKGROUND: Critical care glycaemic control protocols commonly have treatment adjustment (target) ranges spanning ?2 mmol/L. These require precise point-of-care glucose measurement, unaffected by other variables, to avoid measurement errors increasing glycaemic variability and hypoglycaemic episodes (both strongly associated with mortality in critically ill patients). METHODS: A prospective 206 intensive care patient study was carried out. Arterial glucose concentrations were measured in du...

Watkinson, Pj; Barber, Vs; Amira, E.; James, T.; Taylor, R.; Young, JD

2012-01-01

164

Use of arterialised venous instead of arterial blood for measurement of myocardial glucose metabolism during euglycaemic-hyperinsulinaemic clamping  

International Nuclear Information System (INIS)

Sampling of arterialised venous blood (AVB) is often used as an alternative to sampling of arterial blood when determining the myocardial metabolic rate of glucose (MRGlu). This method, however, has not yet been validated for measurement of plasma fluorine-18 fluorodeoxyglucose (FDG) activity during a euglycaemic-hyperinsulinaemic clamp (EHC). In this study, dynamic FDG scans were performed with arterial blood sampling during EHC. Samples of arterial and AVB or venous blood were simultaneously withdrawn at five time points for measurement of FDG activity and plasma glucose in 36 patients. Both venous to arterial and AVB to arterial ratios were calculated for FDG activity and plasma glucose. Mean ratios between AVB and arterial FDG activity were then used to create calculated arterialised venous input functions from corresponding arterial input functions. The mean effect of arterialisation on the calculation of Ki was assessed. In nine additional patients, Ki obtained with continuous sampling of AVB was compared with Ki obtained with a corresponding (quality-controlled) image-derived input function from the ascending aorta. Using AVB, measurements of FDG activity were much more reliable than with venous blood sampling. As compared with arterial sampling, however, FDG activity was underestimated early after injection, while it was overestimated after 20 min. In both analyses, AVB resulted in 10%±10% overestimation of Ki. Beca10% overestimation of Ki. Because of a 5%±5% underestimation of plasma glucose concentration with AVB, the net effect on the final calculation of MRGlu was small (on average 5% overestimation). It is concluded that the use of AVB has a small average effect on the determination of MRGlu. This method does, however, contribute to variability in the results. This variability cannot be explained by different degrees of arterialisation. (orig.)

165

Noninvasive method to obtain input function for measuring tissue glucose utilization of thoracic and abdominal organs  

International Nuclear Information System (INIS)

The authors have developed a method for the noninvasive estimation of regional tissue glucose utilization in humans that employs positron emission tomography (PET) and 2-(18F)fluoro-2-deoxy-d-glucose (FDG). Unlike other methods, the input function used in this method is obtained from the corrected time-activity curve of the descending aorta, not the left ventricle, because the descending aorta is relatively free of spillover from other organs and extends from the upper thorax to the lower abdomen. With this method the time-activity curve of the descending aorta must be corrected for the partial volume effect and the difference in counts between plasma and whole blood. Using the noninvasively obtained input function, regional tissue glucose utilization was calculated by Patlak graphic analysis. k1k3/(k2 + k3) was in good agreement with k1k3/(k2 + k3) calculated from the plasma input function by arterial sampling (r = 0.9995). These results suggest that the input function and regional tissue glucose utilization (not only of myocardium but also of other thoracic and abdominal organs) can be determined noninvasively

166

Developmental expression of the glucose transporter in brain microvessels  

Energy Technology Data Exchange (ETDEWEB)

Brain microvessels were isolated from late gestation fetal (55-68 days), newborn (5-9 day old) and adult guinea pigs. Glucose transport was assessed by measuring the initial uptake of ({sup 3}H)-2-deoxy-D-glucose, a glucose analog that is transported and phosphorylated but not further metabolized. At 22C and substrate concentrations of 40 mM, uptakes were linear for 8 minutes. The data reported here were uptakes over the first 2 minutes. 2-deoxy-D-glucose uptake was 3.5 fold higher in newborn microvessels, 99.5{+-}18.4 (SEM) fmols/mg protein/2 minutes, compared to fetal, 27.8{+-}7.9. The number of glucose transporters was estimated using the ({sup 3}H) cytochalasin B which can be displaced by D-glucose (250 mM). Binding at 35 nM cytochalasin B was higher in newborn brain microvessels (8.2{+-}1.6 pmole/mg protein) than in fetal (3.4{+-}1.1) or adult (2.8{+-}0.6) brain microvessels. Initial RNA blot experiments using a cDNA for the brain/erythrocyte (HepG2) glucose transporter show increased expression in newborn microvessels compared to the fetus or the adult. The authors conclude that the brain microvessel glucose transporter is increased in the newborn period.

Hohimer, A.R.; Bissonnette, J.M.; Machida, C.M. (Oregon Health Sciences Univ., Portland (United States))

1990-02-26

167

Measurement of GLP-1 in Impaired Glucose Tolerance Subjects in Comparison to Type 2 Diabetes Patients and Healthy Subjects  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Incretin therapy of type 2 diabetes patients is based on the fact that Incretin Effect is diminished in those patients. The objective is to measure glucagon-like peptide-1 (GLP-1 levels in impaired oral glucose tolerance (IGT subjects and compare them to those of type 2 diabetes patients and healthy subjects. If the incretin hormone (GLP-1 is established to be diminished in IGT subjects, future study may assess effectiveness of incretin therapy to prevent or delay diabetes in IGT subjects. Patients and methods: GLP-1 was measured by ELISA test at 0, 30 and 120 minutes in accordance with OGTT in three groups: type 2 diabetes groups including 24 patient, impaired glucose tolerance group including 24 subject and healthy control group including 24 subject as control. Patients were classified according to the WHO criteria for diabetes diagnosis. Results: Fasting GLP-1 levels were none significantly different between the studied groups. One the other hand, GLP-1 response at 30' was significantly diminished in diabetics when compared with IGT and controls. GLP-1 levels at 120' were significantly reduced in type 2 diabetes patients when compared with IGT and controls and significantly diminished in IGT when compared with controls. Conclusions: The study indicates that the GLP-1 levels are diminished in impaired glucose tolerance subjects when it’s compared to normal subjects.

Ahmed Abdullah Ebeid

2013-10-01

168

Effective dynamic range in measurements with flash analog-to-digital convertor  

International Nuclear Information System (INIS)

Flash Analog-to-Digital Convertor (FADC) is frequently used in Nuclear and Particle Physics experiments, often as the major component in big multi-channel systems. The large data volume makes the optimization of operating parameters necessary. This article reports a study of a method to extend the dynamic range of an 8-bit FADC from the nominal 28 value. By comparing the integrated pulse area with that of a reference profile, good energy reconstruction and event identification can be achieved on saturated events from CsI(Tl) crystal scintillators. The effective dynamic range can be extended by at least four more bits. The algorithm is generic and is expected to be applicable to other detector systems with FADC readout

169

Effective Dynamic Range in Measurements with Flash Analog-to-Digital Convertor  

CERN Document Server

Flash Analog to Digital Convertor (FADC) is frequently used in nuclear and particle physics experiments, often as the major component in big multi-channel systems. The large data volume makes the optimization of operating parameters necessary. This article reports a study of a method to extend the dynamic range of an 8-bit FADC from the nominal $\\rm{2^8}$ value. By comparing the integrated pulse area with that of a reference profile, good energy reconstruction and event identification can be achieved on saturated events from CsI(Tl) crystal scintillators. The effective dynamic range can be extended by at least 4 more bits. The algorithm is generic and is expected to be applicable to other detector systems with FADC readout.

Yue, Q

2003-01-01

170

Measurement of cerebral oxidative glucose consumption in patients with type 1 diabetes and hypoglycemia unawareness using 13C nuclear magnetic resonance spectroscopy  

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The aim of the present study was to use 13C NMR to measure the cerebral oxidative metabolic rate of glucose (CMRglc(ox)) in patients with diabetes and to compare these measurements with those collected from matched controls. We elected to study a group with type 1 diabetes and hypoglycemia unawareness, since we had previously found such patients to have higher brain glucose concentrations than normal volunteers under steady state conditions. We sought to determine if this difference in steady...

Henry, Pierre-gilles; Criego, Amy B.; Kumar, Anjali; Seaquist, Elizabeth R.

2010-01-01

171

Associations between insulin and glucose concentrations and anthropometric measures of fat mass in Australian adolescents  

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Abstract Background One of the most serious, yet common co-morbidities of obesity is insulin resistance, which if untreated may progress to type 2 diabetes. This paper describes the insulin and glucose concentration distributions, the prevalence of elevated insulin, the associations between insulin and body mass index (BMI), waist circumference, waist-to-height ratio (WHtR) and fat mass index in a representative sample of Australian adolescents. Methods Cross-se...

Denney-Wilson Elizabeth; Cowell Christopher T; Okely Anthony D; Hardy Louise L; Aitken Robert; Dobbins Timothy

2010-01-01

172

Noninvasive measurement of plasma glucose from exhaled breath in healthy and type 1 diabetic subjects  

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Effective management of diabetes mellitus, affecting tens of millions of patients, requires frequent assessment of plasma glucose. Patient compliance for sufficient testing is often reduced by the unpleasantness of current methodologies, which require blood samples and often cause pain and skin callusing. We propose that the analysis of volatile organic compounds (VOCs) in exhaled breath can be used as a novel, alternative, noninvasive means to monitor glycemia in these patients. Seventeen he...

Minh, Timothy D. C.; Oliver, Stacy R.; Ngo, Jerry; Flores, Rebecca; Midyett, Jason; Meinardi, Simone; Carlson, Matthew K.; Rowland, F. Sherwood; Blake, Donald R.; Galassetti, Pietro R.

2011-01-01

173

Evaluating the blood glucose measured via glucometry in diagnosis of hypoglycemia in neonates  

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Introduction: Hypoglycemia is one of the most prevalent problems seen in neonates and can lead toirreversible brain damage if not to be diagnosed in time. Today, the blood glucose is mostly checked bylaboratory methods that have a significant delay and can result in many adverse effects such as vesselrupture. The goal of this study was to evaluate the value of the glucometry device in diagnosis ofhypoglycemia in neonates.Materials and Methods: This study has been conducted over 156 hospitaliz...

Shamsollah Nooripoor; Raheb Ghorbani; Farhad Azizzadeh; Navid Danai; Mohammad Sadegh Yazdiha

2012-01-01

174

Effect of Substrate on the Pre-Steady-State Kinetics of the Na+/Glucose Cotransporter  

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When measuring Na+/glucose cotransporter (SGLT1) activity in Xenopus oocytes with the two-electrode voltage-clamp technique, pre-steady-state currents dissipate completely in the presence of saturating ?-methyl-glucose (?MG, a nonhydrolyzable glucose analog) concentrations. In sharp contrast, two SGLT1 mutants (C255A and C511A) that lack a recently identified disulfide bridge express the pre-steady-state currents in the presence of ?MG. The dose-dependent effects of ?MG on pre-steady-stat...

Gagnon, Dominique G.; Frindel, Carole; Lapointe, Jean-yves

2007-01-01

175

Glucose Sensing  

CERN Document Server

Topics in Fluorescence Spectroscopy, Glucose Sensing is the eleventh volume in the popular series Topics in Fluorescence Spectroscopy, edited by Drs. Chris D. Geddes and Joseph R. Lakowicz. This volume incorporates authoritative analytical fluorescence-based glucose sensing reviews specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of fluorescence. Glucose Sensing is an essential reference for any lab working in the analytical fluorescence glucose sensing field. All academics, bench scientists, and industry professionals wishing to take advantage of the latest and greatest in the continuously emerging field of glucose sensing, and diabetes care & management, will find this volume an invaluable resource. Topics in Fluorescence Spectroscopy Volume 11, Glucose Sensing Chapters include: Implantable Sensors for Interstitial Fluid Smart Tattoo Glucose Sensors Optical Enzyme-based Glucose Biosensors Plasmonic Glucose Sens...

Geddes, Chris D

2006-01-01

176

The Clinical Research Tool: A High-Performance Microdialysis-Based System for Reliably Measuring Interstitial Fluid Glucose Concentration  

Science.gov (United States)

Background A novel microdialysis-based continuous glucose monitoring system, the so-called Clinical Research Tool (CRT), is presented. The CRT was designed exclusively for investigational use to offer high analytical accuracy and reliability. The CRT was built to avoid signal artifacts due to catheter clogging, flow obstruction by air bubbles, and flow variation caused by inconstant pumping. For differentiation between physiological events and system artifacts, the sensor current, counter electrode and polarization voltage, battery voltage, sensor temperature, and flow rate are recorded at a rate of 1 Hz. Method In vitro characterization with buffered glucose solutions (cglucose = 0 - 26 × 10-3 mol liter-1) over 120 h yielded a mean absolute relative error (MARE) of 2.9 ± 0.9% and a recorded mean flow rate of 330 ± 48 nl/min with periodic flow rate variation amounting to 24 ± 7%. The first 120 h in vivo testing was conducted with five type 1 diabetes subjects wearing two systems each. A mean flow rate of 350 ± 59 nl/min and a periodic variation of 22 ± 6% were recorded. Results Utilizing 3 blood glucose measurements per day and a physical lag time of 1980 s, retrospective calibration of the 10 in vivo experiments yielded a MARE value of 12.4 ± 5.7. Clarke error grid analysis resulted in 81.0%, 16.6%, 0.8%, 1.6%, and 0% in regions A, B, C, D, and E, respectively. Conclusion The CRT demonstrates exceptional reliability of system operation and very good measurement performance. The ability to differentiate between artifacts and physiological effects suggests the use of the CRT as a reference tool in clinical investigations. PMID:20144284

Ocvirk, Gregor; Hajnsek, Martin; Gillen, Ralph; Guenther, Arnfried; Hochmuth, Gernot; Kamecke, Ulrike; Koelker, Karl-Heinz; Kraemer, Peter; Obermaier, Karin; Reinheimer, Cornelia; Jendrike, Nina; Freckmann, Guido

2009-01-01

177

Analog Helper  

Science.gov (United States)

In addition to providing any number of web servicing capabilities, web servers are excellent at generating huge log files containing the details of their every activity. Analyzing these logs by hand is not practical. Fortunately, Stephen Turner has written Analog, a fast, freely-available, configurable tool for automatically analyzing log files. Previous versions have required the user to edit a detailed configuration file to customize reports, but a new shareware tool, Analog Helper, provides a graphical interface for controlling Analog's hundreds of settings. A demo version of Analog Helper is available from the Sig Software Website; the licensing fee is $25 per copy.

178

Noninvasive measurement of glucose in artificial plasma with near-infrared and Raman spectroscopy.  

Science.gov (United States)

The goal of this research was to develop a method for noninvasive blood glucose assay. Near-infrared (NIR) spectroscopy and Raman spectroscopy, two more promising techniques compared to other methods, were investigated in two kinds of artificial plasma (AP). Calibration models were generated by performing partial least squares (PLS) regression and optimized individually by considering spectral range, spectral pretreatment methods, and number of model factors. The two spectroscopic models were validated for the determination of glucose, and the results show that the two spectroscopic models established are robust, accurate, and repeatable. Compared to Raman spectroscopy, the performance of NIR spectroscopy was much better, with lower root mean square errors of cross-validation (RMSECV) of 0.128 and 0.094 mg/ml, lower root mean square errors of validation (RMSEP) of 0.061 and 0.046 mg/ml, higher correlation coefficients (R) of 99.15% and 99.55%, and higher residual predictive deviations (RPD) of 10.8 and 15.0 for artificial plasma I and II, respectively. PMID:24694699

Xue, Jintao; Chen, Han; Xiong, Dongmei; Huang, Guo; Ai, Hong; Liang, Yan; Yan, Xinyu; Gan, Yuan; Chen, Cong; Chao, Ruobing; Ye, Liming

2014-01-01

179

Effects of nutrition?s carbohydrate content on the metabolism of pregnant women by means of indirect calorimetry, bioelectrical impedance analysis and blood glucose measurements  

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Objective: Since recommendations for nutrition in pregnancy are varying widely we assessed the effects of two diets differing in percentages of carbohydrates (CH). We measured resting energy expenditure (REE) and proportional use of macronutrients by indirect calorimetry (IC), body composition by bioelectrical impedance analysis (BIA) as well as blood glucose. Womens? carbohydrate tolerance was determined by oral glucose tolerance test (oGTT) applying O?Sullivan?s criteria in order to be a...

Brandt, Katrin

2010-01-01

180

An analog and time digitizer for two-dimensional data acquisition for time-of-flight measurements  

International Nuclear Information System (INIS)

A CAMAC module has been developed to record simultaneously the pulse height and the elapsed time of an event following a start signal. The module is based on an 8-bit (256-channel) 100 MHz fast analog to digital converter (FADC) and a 16-bit (65536-channel) time digitizer with a maximum time range of 4.9 ms and a minimum resolving time of 20 ns. A short dead time in the data acquisition equipment is required to keep count loss corrections to an acceptable level at high count rates. The processing of the signal including storage of the data in 256-word buffer takes place during the 10 ns dead time of the module. A built-in digital to analog converter (DAC) can be used to set up and test the module. The unit can be used in several different ways, for example 1. as a multiparameter neutron time-of-flight spectrometer, 2. as a transient wave recorder with a continuous read-in, 3. as a transient wave recorder with a 16-block read-in and 4. as a self-triggering digital discriminator. In this report a description is given of the use of the system in neutron transmission measurements using the pulsed neutron source HELIOS at Harwell. In these measurements the count rates were several times the highest count rate previously recorded on such experiments at Harwell. The count loss and background were more easily and more accurately calculated from the information gained from the two-dimensional recording of the data. (orig.)

 
 
 
 
181

Glucose content in human skin: relationship with blood glucose levels.  

Science.gov (United States)

In order to ascertain the dynamic relationship between the extracellular glucose in upper skin layers and blood glucose, skin suction blisters were raised in six Type 1 diabetic patients during a three-step glucose clamp. Blister glucose closely paralleled venous glucose (mean of r = 0.998). However, in three patients blister glucose was constantly lower than plasma glucose and this appeared to be related to their slower formation of skin blisters. A substantial difference in skin blister suction time was noted among patients and it was found that suction time was linearly correlated to glycosylated haemoglobin (HbA1C) (n = 6, r = 0.865, p = 0.026). It is concluded that a non-invasive blood glucose monitoring system could be successfully based on measurement of alterations in skin glucose contents. PMID:8545601

Jensen, B M; Bjerring, P; Christiansen, J S; Orskov, H

1995-08-01

182

Measurements of polyatomic molecule formation on an icy grain analog using fast atoms  

International Nuclear Information System (INIS)

Measurements are reported for production of CO2 resulting from the impact of a monoenergetic O(3P) beam upon a surface cooled to 4.8 K and covered with a CO ice. Using temperature-programmed desorption and mass spectrometer detection, one clearly detects increasing amounts of CO2 formation with O(3P) energies of 2, 5, 10, and 14 eV. This is a measurement of polyatomic molecule formation on a surface in a new regime using superthermal atoms. The chosen surface coverage, surface temperature, and superthermal atom energy simulate conditions in shock-heated circumstellar and interstellar regions

183

Glucose Tests  

Science.gov (United States)

... Insulin overdose Tumors that produce insulin ( insulinomas) Starvation Deliberate use of glucose-lowering products Urine Glucose Low ... online through http://www.merck.com . ADA Clinical Practice Recommendations. Diabetes Care 28:S37-S42, 2005. Available ...

184

Precision timing measurement of phototube pulses using a flash analog-to-digital converter  

CERN Document Server

We present the timing characteristics of the flash ADC readout of the GlueX forward calorimeter, which depends on precise measurement of arrival time of pulses from FEU 84-3 photomultiplier tubes to suppress backgrounds. The tests presented were performed using two different 250 MHz prototype flash ADC devices, one with eight-bit and one with twelve-bit sampling depth. All measured time resolutions were better than 1 ns, independent of signal size, which is the design goal for the GlueX forward calorimeter. For pulses with an amplitude of 100 mV the timing resolution is 0.57 +- 0.18 ns, while for 500 mV pulses it is 0.24 +- 0.08 ns.

Bennett, J V; Shepherd, M R; Ito, M M

2010-01-01

185

Phototelectric Emission Measurements on the Analogs of Individual Cosmic Dust Grains  

Science.gov (United States)

The photoelectric emission process is considered to be the dominant mechanism for charging of cosmic dust grains in many astrophysical environments. The grain charge and the equilibrium potentials play an important role in the dynamical and physical processes that include heating of the neutral gas in the interstellar medium, coagulation processes in the dust clouds, and levitation and dynamical processes in the interplanetary medium and planetary surfaces and rings. An accurate evaluation of photoelectric emission processes requires knowledge of the photoelectric yields of individual dust grains of astrophysical composition as opposed to the values obtained from measurements on flat surfaces of bulk materials, as it is generally assumed on theoretical considerations that the yields for the small grains are much higher than the bulk values. We present laboratory measurements of the photoelectric yields of individual dust grains of silica, olivine, and graphite of approximately 0.09 to 8 microns radii levitated in an electrodynamic balance and illuminated with W radiation at 120 to 160 nm wavelengths. The measured values and the size dependence of the yields are found to be substantially different from the bulk values given in the literature.

Abbas, Mian M.; Tankosic, D.; Craven, P. D.; Spann, J. F.; LeClair, A.; West, E. A.; Weingartner, J. C.; Tielens, A. G. G. M.; Nuth, J. A.; Camata, R. P.; Gerakines, P. A.

2005-01-01

186

Photoelectric Emission Measurements on the Analogs of Individual Cosmic Dust Grains  

Science.gov (United States)

The photoelectric emission process is considered to be the dominant mechanism for charging of cosmic dust grains in many astrophysical environments. The grain charge and equilibrium potentials play an important role in the dynamical and physical processes that include heating of the neutral gas in the interstellar medium, coagulation processes in the dust clouds, and levitation and dynamical processes in the interplanetary medium and planetary surfaces and rings. An accurate evaluation of photoelectric emission processes requires knowledge of the photoelectric yields of individual dust grains of astrophysical composition as opposed to the values obtained from measurements on flat surfaces of bulk materials, as it is generally assumed on theoretical considerations that the yields for the small grains are much different from the bulk values. We present laboratory measurements of the photoelectric yields of individual dust grains of silica, olivine, and graphite of approx. 0.09-5 micrometer radii levitated in an electrodynamic balance and illuminated with ultraviolet radiation at 120-160 nm wavelengths. The measured yields are found to be substantially higher than the bulk values given in the literature and indicate a size dependence with larger particles having order-of-magnitude higher values than for submicron-size grains.

Abbas, M. M.; Tankosic, D.; Craven, P. D.; Spann, J. F.; LeClair, A.; West, E. A.; Weingartner, J. C.; Tielens, A. G. G. M.; Nuth, J. a.; Camata, R. P.

2006-01-01

187

Avaliação de dois sensores portáteis para mensuração da glicemia em cães Evaluation of two portable meters for blood glucose measurements in dogs  

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Full Text Available Avaliou-se a precisão analítica e clínica de dois sensores portáteis para mensuração da glicemia em cães. Os valores da mensuração da glicemia obtidos com os sensores foram comparados com aqueles obtidos pelo método padrão da glicose oxidase, por meio da análise de correlação e da análise da grade de erros. Os resultados gerados pelos sensores não foram diferentes do método padrão. Conclui-se que ambos os sensores são adequados para mensuração da glicemia em cães.The clinical and analytical accuracy of two portable meters for glucose measurement in dogs was evaluated. Blood glucose values obtained by the use of portable meters were compared to those obtained using the glucose oxidase reference method, by means of correlation and error analysis. Results obtained with the blood glucose meters were not different from those obtained with the reference method. Both apparatus evaluated are adequate for use in dogs.

K. Bluwol

2007-12-01

188

Effect of postprandial hyperglycaemia in non-invasive measurement of cerebral metabolic rate of glucose in non-diabetic subjects  

International Nuclear Information System (INIS)

The aim of this study was to determine the effect of postprandial hyperglycaemia (HG) on the non-invasive measurement of cerebral metabolic rate of glucose (CMRGlc). Five patients who had a meal within an hour before a fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) examination were recruited in this study. They underwent intermittent arterial blood sampling (measured input function), and, based on this sampling, CMRGlc was calculated using an autoradiographic method (CMRGlcreal). Simulated input functions were generated based on standardised input function, body surface area and net injected dose of FDG, and simulated CMRGlc (CMRGlcsim) was also calculated. Percent error of the area under the curve (AUC) between measured (AUCreal) and simulated input function (AUCIFsim) and percent error between CMRGlcreal and CMRGlcsim were calculated. These values were compared with those obtained from a previous study conducted under fasting conditions (F). The serum glucose level in the HG group was significantly higher than that in the F group (165±69 vs 100±9 mg/dl, P=0.0007). Percent errors of AUC and CMRGlc in grey matter and white matter in HG were significantly higher than those in F (12.9%±1.3% vs 3.5%±2.2% in AUC, P=0.0015; 18.2%±2.2% vs 2.9%±1.9% in CMRGlc in grey matter, P=0.0028; 24.0%±4.6% vs 3.4%±2.2% in CMRGlc in white matter, P=0.0028). It is concluded that a non-invasivIt is concluded that a non-invasive method of measuring CMRGlc should be applied only in non-diabetic subjects under fasting conditions. (orig.)

189

Experimentally Measured Interfacial Area during Gas Injection into Saturated Porous Media: An Air Sparging Analogy  

Energy Technology Data Exchange (ETDEWEB)

The amount of interfacial area (awn) between air and subsurface liquids during air-sparging can limit the rate of site remediation. Lateral movement within porous media could be encountered during air-sparging operations when air moves along the bottom of a low-permeability lens. This study was conducted to directly measure the amount of awn between air and water flowing within a bench-scale porous flow cell during the lateral movement of air along the upper edge of the cell during air injections into an initially water-saturated flow cell. Four different cell orientations were used to evaluate the effect of air injection rates and porous media geometries on the amount of awn between fluids. Air was injected at flow rates that varied by three orders of magnitude, and for each flow cellover this range of injection rates little change in awn was noted. A wider variation in awn was observed when air moved through different regions for the different flow cell orientations. These results are in good agreement with the experimental findings of Waduge et al. (2007), who performed experiments in a larger sand-pack flow cell, and determined that air-sparging efficiency is nearly independent of flow rate but highly dependent on the porous structure. By directly measuring the awn, and showing that awn does not vary greatly with changes in injection rate, we show that the lack of improvement to remediation rates is because there is a weak dependence of the awn on the air injection rate.

Crandall, Dustin; Ahmadi, Goodarz; Smith, Duane H., Bromhal, Grant

2010-01-01

190

Troubleshooting analog circuits  

CERN Document Server

Troubleshooting Analog Circuits is a guidebook for solving product or process related problems in analog circuits. The book also provides advice in selecting equipment, preventing problems, and general tips. The coverage of the book includes the philosophy of troubleshooting; the modes of failure of various components; and preventive measures. The text also deals with the active components of analog circuits, including diodes and rectifiers, optically coupled devices, solar cells, and batteries. The book will be of great use to both students and practitioners of electronics engineering. Other

Pease, Robert A

1991-01-01

191

Measurement of local glucose transport rate constant and free glucose pool in human brain using PET and CMG: First result in normals and Huntington patients  

International Nuclear Information System (INIS)

Even in images reconstructed with the method of filtered backprojection it is possible to perform parametric images on a pixel by pixel base with use of appropriate stable algorithms. There is no doubt, that these analytical procedures are less efficient than the iterative ones, but they are doing well when relative values between pixels are of interest. The approach using a Lookup-Table was determined to be best and used in normals and Huntington patients. The first results show that in Huntington patients the transport of glucose is not regional affected, but globally reduced. Following studies on a large patient pool will challenge and proceed further this presented technique. (orig.)

192

Leishmania amazonensis chemotaxis under glucose gradient studied by the strength and directionality of forces measured with optical tweezers  

Science.gov (United States)

Chemotaxis is the mechanism microorganisms use to sense the environment surrounding them and to direct their movement towards attractive, or away from the repellent, chemicals. The biochemical sensing is almost the only way for communication between unicellular organisms. Prokaryote and Eukaryote chemotaxis has been mechanically studied mainly by observing the directionality and timing of the microorganisms movements subjected to a chemical gradient, but not through the directionality and strength of the forces it generates. To observe the vector force of microorganisms under a chemical gradient we developed a system composed of two large chambers connected by a tiny duct capable to keep the chemical gradient constant for more than ten hours. We also used the displacements of a microsphere trapped in an Optical Tweezers as the force transducer to measure the direction and the strength of the propulsion forces of flagellum of the microorganism under several gradient conditions. A 9?m diameter microsphere particle was trapped with a Nd:YAG laser and its movement was measured through the light scattered focused on a quadrant detector. We observed the behavior of the protozoa Leishmania amazonensis (eukaryote) under several glucose gradients. This protozoa senses the gradient around it by swimming in circles for three to five times following by tumbling, and not by the typical straight swimming/tumbling of bacteria. Our results also suggest that force direction and strength are also used to control its movement, not only the timing of swimming/tumbling, because we observed a higher force strength clearly directed towards the glucose gradient.

de Ysasa Pozzo, Liliana; Fontes, Adriana; de Thomaz, André A.; Barbosa, Luiz Carlos; Ayres, Diana Copi; Giorgio, Selma; Cesar, Carlos Lenz

2007-02-01

193

The influence of image resolution on the positron emission tomographic measurement of caudate glucose consumption  

International Nuclear Information System (INIS)

The aim of this study was to investigate the influence of image resolution on (a) relative and absolute values of caudate glucose consumption (rCMRGlc) determined by positron emission tomography (PET), and (b) the detection of significant differences in these metabolic values between groups of subjects. For this purpose, raw data of cerebral accumulation of fluorine-18 fluorodeoxyglucose (FDG) obtained in 11 normal subjects and in nine patients with unilateral thalamic infarction were reconstructed using filtered backprojection with four different cut-off frequencies (CFs), yielding images with a transaxial resolution of 5.7, 7.1, 8.9 and 11 mm (full-width at half-maximum; FWHM). Absolute values of candate rCMRGls decreased significantly by more than 30% over the range of image resolutions studied. Bilateral ratios of caudate rCMRGls were insensitive to variations in image resolution. Levels if significance assessing the differences in mean metabolic values between patients and controls were all below 0.01. They were, however, slightly better at image resolutions of 7,1 and 8.9 mm than at a resolution of 5.7 mm. These data indicate (a) that relative values of rCMRGls are better suited to compare quantitative results from different PET cameras than are absolute values, and (b) that th CF used for the filtered backprojection exerts a small but not negligible influence on levels of significance assessing differences in metabolic values between groups of subjects. (orig.)values between groups of subjects. (orig.)

194

Evidence for the absence of cerebral glucose-6-phosphatase activity in glycogen storage disease type I (Von Gierke's disease)  

Energy Technology Data Exchange (ETDEWEB)

Glycogen storage disease type I (GSD-I) is characterized by a functional deficit in glucose-6-phosphatase that normally hydrolyzes glucose-6-PO/sub 4/ to glucose. This enzyme is primarily found in liver, kidney, and muscle but it is also present in brain, where it appears to participate in the regulation of cerebral tissue glucose. Since most neurological symptoms in GSD-I patients involve systemic hypoglycemia, previous reports have not examined possible deficiencies in phosphatase activity in the brain. Positron computed tomography, F-18-labeled 2-fluorodeoxyglucose (FDG) and a tracer kinetic model for FDG were used to measure the cortical plasma/tissue forward and reverse transport, phosphorylation and dephosphorylation rate constants, tissue/plasma concentration gradient, tissue concentration turnover rate for this competitive analog of glucose, and the cortical metabolic rates for glucose. Studies were carried out in age-matched normals (N = 13) and a single GSD-I patient. The dephosphorylation rate constant in the GSD-I patient was about one tenth the normal value indicating a low level of cerebral phosphatase activity. The other measured parameters were within normal limits except for the rate of glucose phosphorylation which reflected a cortical glucose metabolic rate one half the normal value. Since glucose transport and tissue glucose concentration was normal, the reduced cortical glucose metabolism probably results from the use of alternative substrates (..beta..-hydroxybutyrate and acetoacetate) which are consistently elevated in the plasma of GSD-I patients.

Phelps, M.E.; Mazziotta, J.C.; Hawkins, R.A.; Philippart, M.

1981-01-01

195

Measurement of regional cerebral metabolic rate for glucose in the human subject with (F-18)-2-deoxy-2-fluoro-d-glucose and emission computed tomography: validation of the method  

International Nuclear Information System (INIS)

Tracer techniques and models of in vitro quantitative autoradiography and tissue counting for the measure of regional metabolic rates (rMR) are combined with emission computed tomography (ECT). This approach, Physiologic Tomography (PT), provides atraumatic and analytical measurements of rMR. PT is exemplified with the regional measurement of the cerebral metabolic rate for glucose (CMRGlu) in man with (18F)-2-deoxy-2-fluoro-D-glucose (FDG) and positron ECT. Our model incorporates a k4* mediated hydrolysis of FDG-6-PO4 to FDG which then competes with phosphorylation (k3*) of FDG back to FDG-6-PO4 and reverse transport (k2*) back to blood. Although small, k4* is found to be significant. The ECAT positron tomograph was used to measure the rate constants (k1*?k4*), lumped constant (LC), stability, and reproducibility of the model in man. Since these parameters have not been measured for FDG in any species, comparisons are made to values for DG in rat and monkey. Compartmental concentrations of FDG and FDG-6-PO4 were determined and show that cerebral FDG-6-PO4 steadily accumulates for about 100 mins, plateaus and then slowly decreases due to hydrolysis. Cerebral blood FDG concentration was determined to be a minor contribution to tissue activity after 10 min. Regional CMRGlu measurements are reproducible to +- 5.5% over 5 hrs. PT allows the in vivo study ofregional biochemistry and physiology in normal and pathophysiologic states in man with a unique and fundamental capability

196

Direct measurements of blood glucose concentration in the presence of saccharide interferences using slope and bias orthogonal signal correction and Fourier transform near-infrared spectroscopy  

Science.gov (United States)

Saccharide interferences such as Dextran, Galactose, etc. have a great potential to interfere with near infrared (NIR) glucose analysis since they have a similar spectroscopic fingerprint and are present physiologically at large relative concentrations. These can lead to grossly inappropriate interpretation of patient glucose levels and resultant treatment in critical care and hospital settings. This study describes a methodology to reduce this effect on glucose analysis using an NIR Fourier transform spectroscopy method combined with a multivariate calibration technique (PLS) using preprocessing by orthogonal signal correction (OSC). A mathematical approach based on the use of a single calibration based bias and slope correction was applied in addition to a standard OSC was investigated. This approach is combined with a factorial interferent calibration design to accommodate for interference effects. We named this approach as a slope and bias OSC (sbOSC). sbOSC differs from OSC in the way it handles the prediction. In sbOSC, statistics on slope and bias obtained from a set of calibration samples are then used as a validation parameter in the prediction set. Healthy human volunteer blood with different glucose (80 to 200 mg/dL) and hematocrit (24 to 48 vol.%) levels containing high expected levels of inteferents have been measured with a transmittance near-infrared Fourier transform spectrometer operates in the broadband spectral range of 1.25-2.5 ?m (4000-8000 cm-1). The effect of six interferents compounds used in intensive care and operating rooms, namely Dextran, Fructose, Galactose, Maltose, Mannitol, and Xylose, were tested on blood glucose. A maximum interference effect (MIE) parameter was used to rank the significance for the individual interferent type on measurement error relative to the total NIR whole blood glucose measurement error. For comparison, a YSI (Yellow Springs Instrument) laboratory reference glucose analyzer and NIR data were collected at the same time as paired samples. MIE results obtained by sbOSC were compared with several standard spectral preprocessing approaches and show a substantial reduced effect of saccharide interferences. NIR glucose measurement results are substantially improved when comparing standard error of prediction from validation samples; and resulting MIE values are small.

Abookasis, David; Workman, Jerome J.

2011-02-01

197

Peroxidase- and tetracyanoquinodimethane-modified graphite paste electrode for the measurement of glucose/lactate/glutamate using enzyme-packed bed reactor.  

Science.gov (United States)

A flow injection analysis sensor for the measurement of glucose/lactate/glutamate is reported. The glucose oxidase/glutamate oxidase/lactate oxidase was immobilized on silanized controlled pore glass particles and packed into a Teflon column (i.d., 1.2 mm; length, 40 mm) to give a bed for glucose/lactate/glutamate. The hydrogen peroxide formed by the enzymatic reaction in the packed bed was monitored by a horseradish peroxidase- and tetracyanoquinodimethane (TCNQ)- modified graphite paste electrode at 50 mV vs Ag/AgCl. The glucose oxidase/lactate oxidase/glutamate oxidase were regenerated in the packed bed, whereas peroxidase was regenerated in the TCNQ-mediated graphite paste electrode by the oxidation of TCNQ. The oxidized TCNQ was electrochemically reduced at 50 mV vs Ag/AgCl. The cathodic current obtained by the reduction of TCNQ determined the concentration of the injected analytes in the packed bed. The system showed very rapid response. Response curves for the analysis of peroxide, glucose, lactate, and glutamate are reported. PMID:7710104

Pandey, P C; Weetall, H H

1995-01-01

198

Theoretical treatment of analog (p,n) cross sections for odd nuclei: Application to measurements of 105Pd at 26 MeV  

International Nuclear Information System (INIS)

Differential cross sections for the (p,n) reaction to the ground-state and excited-state analogs of 105Pd have been measured at a proton bombarding energy of 26 MeV. Both the magnitude and the angular distribution of the cross sections for the analog states are found to follow the same general trend observed for the even-even palladium isotopes. Contributions to the analog transition on odd-A targets from spin-flip, higher multipoles, collective admixtures, and multistep processes are calculated and are found to be of order 1/(N-Z) or smaller, as compared to the (N-Z) scaling expected for the Fermi transition. This is in agreement with our experimental data which show that the analog cross section scales as (N-Z) relative to the neighboring nuclei. Among the excited analog states within the first MeV of excitation, the levels at 0.44 and 0.78 MeV were the most strongly populated. This is consistent with a two-step mechanism involving inelastic scattering and charge exchange, since these two states are also known to have the largest B(E2) values. Although the small predicted magnitude of the additional contributions for nonzero spin targets agrees nicely with the present measurements for 105Pd, it leaves the puzzle as to why cross sections for odd isotopes for titanium and molybdenum measured in previous work were found to be larger than corresponding cross sections for adjacent even isotopes

199

High glucose concentrations partially release hexokinase from inhibition by glucose 6-phosphate.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The phosphorylation of glucose by human erythrocyte hexokinase follows classical Michaelis-Menten kinetics; hexokinase manifests maximum activity at 5 mM glucose, and no further increase in activity can be measured at higher glucose concentrations. However, the erythrocytes of diabetics and normal erythrocytes incubated with high concentrations of glucose contain increased concentrations of glucose 6-phosphate. To elucidate the mechanism of accumulation of glucose 6-phosphate when erythrocyte...

Fujii, S.; Beutler, E.

1985-01-01

200

Correlation of fasting blood glucose and haemoglobin A1c measured with an automated analyser  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A subtype of glycohaemoglobin, haemoglobin (Hb) A1c, in specimens of whole blood was assayed on a new automated analyser that makes use of high-pressure liquid chromatography. The analyser provided precise and reproducible values. The mean of the HbA1c values was lower than that with an older instrument. The mean tended to increase with the age of the subjects, who were undergoing routine health examinations. No sex difference was found. When measurement was made 1 h after the subjects drank ...

Furota, Akira; Miyagawa, Teikichi; Tsuda, Izumi; Tatsumi, Noriyuki

1990-01-01

 
 
 
 
201

Glucose allostasis  

DEFF Research Database (Denmark)

In many organisms, normoglycemia is achieved by a tight coupling of nutrient-stimulated insulin secretion in the pancreatic beta-cell (acute insulin response [AIR]) and the metabolic action of insulin to stimulate glucose disposal (insulin action [M]). It is widely accepted that in healthy individuals with normal glucose tolerance, normoglycemia can always be maintained by compensatorily increasing AIR in response to decreasing M (and vice versa). This has been mathematically described by the hyperbolic relationship between AIR and M and referred to as glucose homeostasis, with glucose concentration assumed to remain constant along the hyperbola. Conceivably, glucose is one of the signals stimulating AIR in response to decreasing M. Hypothetically, as with any normally functioning feed-forward system, AIR should not fully compensate for worsening M, since this would remove the stimulus for the compensation. We provide evidence from cross-sectional, longitudinal, and prospective data from Pima Indians (n = 413) and Caucasians (n = 60) that fasting and postprandial glucose concentrations increase with decreasing M despite normal compensation of AIR. For this physiologic adaptation to chronic stress (insulin resistance), we propose to use the term "glucose allostasis." Allostasis (stability through change) ensures the continued homeostatic response (stability through staying the same) to acute stress at some cumulative costs to the system. With increasing severity and over time, the allostatic load (increase in glycemia) may have pathological consequences, such as the development of type 2 diabetes.

Stumvoll, Michael; Tataranni, P Antonio

2003-01-01

202

Radioimmunoassay for octapeptide analogs of somatostatin: measurement of serum levels after administration of long-acting microcapsule formulations.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The development of a long-acting delivery system for D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2 (RC-160), an octapeptide analog of somatostatin, required the establishment of a method for determining the concentration of this analog in serum during treatment. A sensitive and specific radioimmunoassay (RIA) for RC-160 was developed and used for following the rate of liberation of this peptide from microcapsules of poly(DL-lactide-coglycolide). Antibodies were generated in a rabbit against RC-160 ...

Mason-garcia, M.; Vaccarella, M.; Horvath, J.; Redding, T. W.; Groot, K.; Orsolini, P.; Schally, A. V.

1988-01-01

203

Employment of Item Response Theory to measure change in Children's Analogical Thinking Modifiability Test / Emprego da Teoria de Resposta do Item para medida de mudança no Children's Analogical Thinking Modifiability Test  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Provas assistidas, com fase intermediária de ensino, medem mudanças entre pré-teste e pós-teste pressupondo uma métrica comum entre eles. Para testar este pressuposto, aplicou-se a Teoria de Resposta ao Item nas respostas de 69 crianças à prova cognitiva assistida Children's Analogical Thinking Modi [...] fiability Test adaptada, com 12 itens, totalizando 828 respostas, para verificar se a escala original produzia os mesmos resultados em termos de quantificação de mudança que a escala equalizada obtida via Teoria de Resposta ao Item. Seguiram-se os passos: 1) ancoragem dos itens de pré e pós-teste, por uma análise cognitiva, encontrando-se três itens em comum; 2) estimação do parâmetro de dificuldade dos itens e comparação destes; 3) equalização dos itens e estimação dos "thetas"; 4) comparação das escalas. A métrica do Children's Analogical Thinking Modifiability Test foi semelhante à estimada pela Teoria de Resposta ao Item, mas é preciso diferenciar a dificuldade dos itens de pré e pós-teste, adequando-o a amostras com alto e baixo desempenho. Abstract in english Dynamic testing, with an intermediate phase of assistance, measures changes between pretest and post-test assuming a common metric between them. To test this assumption we applied the Item Response Theory in the responses of 69 children to dynamic cognitive testing Children's Analogical Thinking Mod [...] ifiability Test adapted, with 12 items, totaling 828 responses, with the purpose of verifying if the original scale yields the same results as the equalized scale obtained by Item Response Theory in terms of "changes quantifying". We followed the steps: 1) anchorage of the pre and post-test items through a cognitive analysis, finding 3 common items; 2) estimation of the items' difficulty level parameter and comparison of those; 3) equalization of the items and estimation of "thetas"; 4) comparison of the scales. The Children's Analogical Thinking Modifiability Test metric was similar to that estimated by the TRI, but it is necessary to differentiate the pre and post-test items' difficulty, adjusting it to samples with high and low performance.

Odoisa Antunes de, Queiroz; Ricardo, Primi; Lucas de Francisco, Carvalho; Sônia Regina Fiorim, Enumo.

2013-12-01

204

On-line measurements of oscillating mitochondrial membrane potential in glucose-fermenting Saccharomyces cerevisiae  

DEFF Research Database (Denmark)

We employed the fluorescent cyanine dye DiOC(2)(3) to measure membrane potential in semi-anaerobic yeast cells under conditions where glycolysis was oscillating. Oscillations in glycolysis were studied by means of the naturally abundant nicotinamide adenine dinucleotide (NADH). We found that the mitochondrial membrane potential was oscillating, and that these oscillations displayed the same frequency and duration as the NADH oscillations. It was confirmed that DiOC(2)(3) localizes itself in the mitochondrial membrane and thus reports qualitative changes solely in mitochondrial membrane potential. Our studies showed that glycolytic oscillations perturb the mitochondrial membrane potential and that the mitochondria do not have any controlling effect on the dynamics of glycolysis under these conditions. Depolarization of the mitochondrial membrane by addition of FCCP quenched mitochondrial membrane potential oscillations and delocalized DiOC(2)(3), while glycolysis continued to oscillate unaffected.

Andersen, Ann Zahle; Poulsen, Allan K

2007-01-01

205

Infrared spectroscopic analysis of human interstitial fluid in vitro and in vivo using FT-IR spectroscopy and pulsed quantum cascade lasers (QCL): Establishing a new approach to non invasive glucose measurement.  

Science.gov (United States)

Interstitial fluid, i.e. the liquid present in the outermost layer of living cells of the skin between the Stratum corneum and the Stratum spinosum, was analyzed by Fourier transform infrared spectroscopy and by infrared spectroscopy using pulsed quantum cascade infrared lasers with photoacoustic detection. IR spectra of simulated interstitial fluid samples and of real samples from volunteers in the 850-1800cm(-1) range revealed that the major components of interstitial fluid are albumin and glucose within the physiological range, with only traces of sodium lactate if at all. The IR absorbance of glucose in interstitial fluid in vivo was probed in healthy volunteers using a setup with quantum cascade lasers and photoacoustic detection previously described. A variation of blood glucose between approx. 80mg/dl and 250mg/dl in the volunteers was obtained using the standard oral glucose tolerance test (OGT). At two IR wavelengths, 1054cm(-1) and 1084cm(-1), a reasonable correlation between the photoacoustic signal from the skin and the blood glucose value as determined by conventional glucose test sticks using blood from the finger tip was obtained. The infrared photoacoustic glucose signal (PAGS) may serve as the key for a non-invasive glucose measurement, since the glucose content in interstitial fluid closely follows blood glucose in the time course and in the level (a delay of some minutes and a level of approx. 80-90% of the glucose level in blood). Interstitial fluid is present in skin layers at a depth of only 15-50?m and is thus within the reach of mid-IR energy in an absorbance measurement. A non-invasive glucose measurement for diabetes patients based on mid-infrared quantum cascade lasers and photoacoustic detection could replace the conventional measurement using enzymatic test stripes and a drop of blood from the finger tip, thus reducing pain and being a cost-efficient alternative for millions of diabetes patients. PMID:22000639

Pleitez, Miguel; von Lilienfeld-Toal, Hermann; Mäntele, Werner

2012-01-01

206

Infrared spectroscopic analysis of human interstitial fluid in vitro and in vivo using FT-IR spectroscopy and pulsed quantum cascade lasers (QCL): Establishing a new approach to non invasive glucose measurement  

Science.gov (United States)

Interstitial fluid, i.e. the liquid present in the outermost layer of living cells of the skin between the Stratum corneum and the Stratum spinosum, was analyzed by Fourier transform infrared spectroscopy and by infrared spectroscopy using pulsed quantum cascade infrared lasers with photoacoustic detection. IR spectra of simulated interstitial fluid samples and of real samples from volunteers in the 850-1800 cm -1 range revealed that the major components of interstitial fluid are albumin and glucose within the physiological range, with only traces of sodium lactate if at all. The IR absorbance of glucose in interstitial fluid in vivo was probed in healthy volunteers using a setup with quantum cascade lasers and photoacoustic detection previously described [11]. A variation of blood glucose between approx. 80 mg/dl and 250 mg/dl in the volunteers was obtained using the standard oral glucose tolerance test (OGT). At two IR wavelengths, 1054 cm -1 and 1084 cm -1, a reasonable correlation between the photoacoustic signal from the skin and the blood glucose value as determined by conventional glucose test sticks using blood from the finger tip was obtained. The infrared photoacoustic glucose signal (PAGS) may serve as the key for a non-invasive glucose measurement, since the glucose content in interstitial fluid closely follows blood glucose in the time course and in the level (a delay of some minutes and a level of approx. 80-90% of the glucose level in blood). Interstitial fluid is present in skin layers at a depth of only 15-50 ?m and is thus within the reach of mid-IR energy in an absorbance measurement. A non-invasive glucose measurement for diabetes patients based on mid-infrared quantum cascade lasers and photoacoustic detection could replace the conventional measurement using enzymatic test stripes and a drop of blood from the finger tip, thus reducing pain and being a cost-efficient alternative for millions of diabetes patients.

Pleitez, Miguel; von Lilienfeld-Toal, Hermann; Mäntele, Werner

2012-01-01

207

Quantitative measurements of regional glucose utilization and rate of valine incorporation into proteins by double-tracer autoradiography in the rat brain tumor model  

International Nuclear Information System (INIS)

We examined the rate of glucose utilization and the rate of valine incorporation into proteins using 2-[18F]fluoro-2-deoxyglucose and L-[1-14C]-valine in a rat brain tumor model by quantitative double-tracer autoradiography. We found that in the implanted tumor the rate of valine incorporation into proteins was about 22 times and the rate of glucose utilization was about 1.5 times that in the contralateral cortex. (In the ipsilateral cortex, the tumor had a profound effect on glucose utilization but no effect on the rate of valine incorporation into proteins.) Our findings suggest that it is more useful to measure protein synthesis than glucose utilization to assess the effectiveness of antitumor agents and their toxicity to normal brain tissue. We compared two methods to estimate the rate of valine incorporation: kinetic (quantitation done using an operational equation and the average brain rate coefficients) and washed slices (unbound labeled valine removed by washing brain slices in 10% trichloroacetic acid). The results were the same using either method. It would seem that the kinetic method can thus be used for quantitative measurement of protein synthesis in brain tumors and normal brain tissue using [11C]-valine with positron emission tomography

208

Quantitative measurements of regional glucose utilization and rate of valine incorporation into proteins by double-tracer autoradiography in the rat brain tumor model  

Energy Technology Data Exchange (ETDEWEB)

We examined the rate of glucose utilization and the rate of valine incorporation into proteins using 2-(/sup 18/F)fluoro-2-deoxyglucose and L-(1-14C)-valine in a rat brain tumor model by quantitative double-tracer autoradiography. We found that in the implanted tumor the rate of valine incorporation into proteins was about 22 times and the rate of glucose utilization was about 1.5 times that in the contralateral cortex. (In the ipsilateral cortex, the tumor had a profound effect on glucose utilization but no effect on the rate of valine incorporation into proteins.) Our findings suggest that it is more useful to measure protein synthesis than glucose utilization to assess the effectiveness of antitumor agents and their toxicity to normal brain tissue. We compared two methods to estimate the rate of valine incorporation: kinetic (quantitation done using an operational equation and the average brain rate coefficients) and washed slices (unbound labeled valine removed by washing brain slices in 10% trichloroacetic acid). The results were the same using either method. It would seem that the kinetic method can thus be used for quantitative measurement of protein synthesis in brain tumors and normal brain tissue using (/sup 11/C)-valine with positron emission tomography.

Kirikae, M.; Diksic, M.; Yamamoto, Y.L.

1989-02-01

209

A Low Frequency Electromagnetic Sensor for Indirect Measurement of Glucose Concentration: In Vitro Experiments in Different Conductive Solutions  

Directory of Open Access Journals (Sweden)

Full Text Available In recent years there has been considerable interest in the study of glucose-induced dielectric property variations of human tissues as a possible approach for non-invasive glycaemia monitoring. We have developed an electromagnetic sensor, and we tested in vitro its ability to estimate variations in glucose concentration of different solutions with similarities to blood (sodium chloride and Ringer-lactate solutions, differing though in the lack of any cellular components. The sensor was able to detect the effect of glucose variations over a wide range of concentrations (~78–5,000 mg/dL, with a sensitivity of ~0.22 mV/(mg/dL. Our proposed system may thus be useful in a new approach for non-invasive and non-contact glucose monitoring.

Andrea Tura

2010-05-01

210

A Low Frequency Electromagnetic Sensor for Indirect Measurement of Glucose Concentration: In Vitro Experiments in Different Conductive Solutions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In recent years there has been considerable interest in the study of glucose-induced dielectric property variations of human tissues as a possible approach for non-invasive glycaemia monitoring. We have developed an electromagnetic sensor, and we tested in vitro its ability to estimate variations in glucose concentration of different solutions with similarities to blood (sodium chloride and Ringer-lactate solutions), differing though in the lack of any cellular components. The sensor was able...

Andrea Tura; Stefano Sbrignadello; Domenico Cianciavicchia; Giovanni Pacini; Paolo Ravazzani

2010-01-01

211

Continuous Glucose Monitoring  

Science.gov (United States)

... of Topics and Titles : Continuous Glucose Monitoring Continuous Glucose Monitoring On this page: What is glucose monitoring? ... Hope through Research For More Information What is glucose monitoring? Glucose monitoring helps people with diabetes manage ...

212

Effect of the peroxisome proliferator perfluoro-n-decanoic acid on glucose transport in the isolated perfused rat liver.  

Science.gov (United States)

The perfluorinated carboxylic acid, perfluoro-n-decanoic acid (PFDA), is a known peroxisome proliferator which displays toxicity in rodents. Using a paired-tracer first-pass extraction technique, the effect of PFDA on hepatic glucose transport was determined in the isolated perfused rat liver. In brief, livers isolated from PFDA-treated and control rats on day 5 posttreatment were administered the radiolabeled glucose analog, 3-O-[14C]methyl-D-glucose ([14C]3-O-MG) in addition to [fructose-1-3H(N)]sucrose ([3H]sucrose), which served as a measure of extracellular volume. Hepatic glucose transport was calculated from the change in the ratio [14C]3-O-MG/[3H]sucrose during passage through the liver. Data from this study indicate that PFDA inhibits hepatic glucose transport. Percent hepatic glucose extraction is 1.8-fold greater in controls than in PFDA-treated rats. No significant difference in lactate dehydrogenase levels was observed in the liver perfusate from PFDA-treated and control rats. This suggests that the difference in percent glucose extraction between PFDA-treated and control groups is specifically due to the PFDA treatment and is not attributed to differences in liver viability between groups. Although the exact mechanism for this inhibition in hepatic glucose transport is not known, it is hypothesized that PFDA may have a major impact on membrane structure/function which, in turn, may alter glucose transport. PMID:7703370

Goecke-Flora, C M; Wyman, J F; Jarnot, B M; Reo, N V

1995-01-01

213

An accurate spectroscopic calibration for non-invasive glucose monitoring by modeling the physiological glucose dynamics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The physiological lag between blood and interstitial fluid (ISF) glucose is a major challenge for non-invasive glucose concentration measurements. This is a particular problem for spectroscopic techniques, which predominantly probe ISF glucose, creating inconsistencies in calibration, where blood glucose measurements are used as reference. To overcome this problem, we present a dynamic concentration correction (DCC) scheme, based on the mass transfer of glucose between blood and ISF, to ensur...

Barman, Ishan; Kong, Chae-ryon; Singh, Gajendra P.; Dasari, Ramachandra R.; Feld, Michael S.

2010-01-01

214

Avaliação de dois sensores portáteis para mensuração da glicemia em cães / Evaluation of two portable meters for blood glucose measurements in dogs  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Avaliou-se a precisão analítica e clínica de dois sensores portáteis para mensuração da glicemia em cães. Os valores da mensuração da glicemia obtidos com os sensores foram comparados com aqueles obtidos pelo método padrão da glicose oxidase, por meio da análise de correlação e da análise da grade d [...] e erros. Os resultados gerados pelos sensores não foram diferentes do método padrão. Conclui-se que ambos os sensores são adequados para mensuração da glicemia em cães. Abstract in english The clinical and analytical accuracy of two portable meters for glucose measurement in dogs was evaluated. Blood glucose values obtained by the use of portable meters were compared to those obtained using the glucose oxidase reference method, by means of correlation and error analysis. Results obtai [...] ned with the blood glucose meters were not different from those obtained with the reference method. Both apparatus evaluated are adequate for use in dogs.

K., Bluwol; R., Duarte; M.D., Lustoza; D.M.N., Simões; M.M., Kogika.

1408-14-01

215

Low-power adaptive control scheme using switching activity measurement method for reconfigurable analog-to-digital converters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Power consumption is a critical issue for portable devices. The ever-increasing demand for multimode wireless applications and the growing concerns towards power-aware green technology make dynamically reconfigurable hardware an attractive solution for overcoming the power issue. This is due to its advantages of flexibility, reusability, and adaptability. During the last decade, reconfigurable analog-to-digital converters (ReADCs) have been used to support multimode wireless applications. Wit...

Ab Razak, Mohd Zulhakimi

2014-01-01

216

Comparison of polyurethane foam and XAD-2 sampling matrices to measure airborne organophosphorus pesticides and their oxygen analogs in an agricultural community.  

Science.gov (United States)

Side-by-side active air sampling for the organophosphorus (OP) pesticide, chlorpyrifos (CPF) and its oxygen analog, chlorpyrifos-oxon (CPF-O) was conducted with two recommended air sampling matrices: OSHA Versatile Sampling (OVS) tubes with XAD-2 resin, polyurethane foam (PUF) tubes, and passive PUF deposition disks. The study compared the proportion of artificially transformed CPF-O in the laboratory and in the field during a tree fruit application in Washington State. Lab results demonstrated that the NIOSH-recommended OVS tubes artificially transformed up to 32% of CPF to CPF-O during the sampling process, whereas PUF tubes had little to no artificial transformation (?0.1%). In the field, the proportion of CPF-O in the sample was significantly higher on OVS tubes than on PUF tubes (ptoxic oxygen analogs when measuring for OP pesticide mixtures. PMID:23466277

Armstrong, Jenna L; Fenske, Richard A; Yost, Michael G; Tchong-French, Maria; Yu, Jianbo

2013-07-01

217

Partitioning and extraction of glucose regulates cerebral glucose utilization in newborn dogs.  

Science.gov (United States)

We investigated the amount of fasting steady-state systemic glucose production utilized by the neonatal canine cerebral cortex. The relationship of systemic glucose production and cerebral glucose utilization were analyzed as functions of cerebral blood flow, cerebral oxygen uptake, and indirect measures of alternate fuel utilization. Fasting arterial blood glucose was 3.36 mM and glucose production was 49.6 mumol/kg/min. Average cerebral blood flow was 0.83 ml/g/min, and cerebral glucose uptake was 0.60 +/- 0.15 mumol/g/min. 36.6% of systemic glucose production was utilized by the cerebral cortex. There were no correlations between systemic glucose production, cerebral blood flow, or cerebral glucose uptake with blood glucose concentration. Furthermore, total cerebral glucose uptake was static across a wide range of glucose levels. Nonetheless, the percent of glucose production used by the brain was an inverse function of systemic glucose production (r = -0.71, p less than 0.001). The cerebral extraction of glucose (27.6 +/- 4.1%) decreased as a function of increasing blood glucose levels (r = -0.51, p less than 0.05), while brain uptake index correlated with increasing systemic glucose production (r = 0.61, p less than 0.02). We can conclude that the canine neonatal cerebral cortex may utilize only 37% of systemic glucose production. At low rates of glucose turnover, a larger proportion of systemic glucose production is allotted to the brain. Mechanisms that may regulate total cerebral glucose influx may be glucose permeability, or the increased extraction of glucose at lower blood glucose levels. PMID:2497802

Huang, M M; Kliegman, R M; Chau, K

1989-01-01

218

A novel method based solely on FPGA units enabling measurement of time and charge of analog signals in Positron Emission Tomography  

CERN Document Server

This article presents a novel technique for precise measurement of time and charge based solely on FPGA (Field Programmable Gate Array) device and few satellite discrete electronic components used in Positron Emission Tomography (PET). Described approach simplifies electronic circuits, reduces the power consumption, lowers costs, merges front-end electronics with digital electronics and also makes more compact final design. Furthermore, it allows to measure time when analog signals cross a reference voltage at different threshold levels with a very high precision of $\\sim$ 10ps (rms) and thus enables sampling of signals in a voltage domain.

Pa?ka, M; Bia?as, P; Czerwi?ski, E; Kap?on, ?; Kochanowski, A; Korcyl, G; Kowal, J; Kowalski, P; Kozik, T; Krzemie?, W; Molenda, M; Moskal, P; Nied?wiecki, Sz; Pawlik, M; Raczy?ski, L; Rudy, Z; Salabura, P; Sharma, N G; Silarski, M; S?omski, A; Smyrski, J; Strzelecki, A; Wi?licki, W; Zieli?ski, M; Zo?, N

2013-01-01

219

[A miniaturized, highly sensitive polarimeter as detector in an implantable glucose probe. II. Opto-electronic amplification and processing of measuring signals].  

Science.gov (United States)

There is a clinical requirement for an implantable telemetric probe for monitoring glucose levels in humans. This probe can measure the glucose content of the intercellular tissue fluid, which reflects glucose levels in the blood. The lifespan of such an implantable probe should be maximal, so that presumably only physical measuring detectors, but not aging-sensitive bio-sensors can be considered. We are in the process of developing a very sensitive miniaturised detector based on polarimetry, capable of determining the measuring parameter--the spatial orientation of the in-plane vibration of a polarised light beam--with high accuracy. This is necessary for our purpose, since the physiological and pathological glucose levels modify in in-plane vibration by only a tiny angle of rotation. The high level of accuracy is achieved by various specific mechanisms both of the measuring parameters and the electric signal. Two suitable optoelectronic amplification methods are described. The first makes use of the ratio of the signal provided by the intensity of two consecutive beams, derived from the original light beam with the aid of a beam splitter. In this way, the sensitivity of determining the spatial position of the in-plane vibration of the polarised light beam can be increased by up to 50-fold in comparison with a "simple" polarimetry. The second method requires two very closely approximated (quasi united) or actually united beams from two sources, which are both "fixed-phase" time-coupled and quantitatively periodically intensity-modulated in opposite sense. Together with the already-mentioned ratio of the intensity signals of two consecutive beams, a periodically modulated signal generated from the individual signals is derived from this quasi-unified beam that enables the use of a phase sensitive rectifier-amplifier (lock-in amplifier) with its enormous amplification factor and noise elimination in the following circuitry. PMID:11721581

Zirk, K; Pötzschke, H; Barnikol, W K

2001-10-01

220

Credibility of measurement of fructosamine and hemoglobin A1C in estimating blood glucose level of diabetic patients with thalassemia major  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background and Aim: Patients with thalassemia major are classified in high risk group for diabetes mellitus, and therefore monitoring blood glucose level has a vital importance in these people. As high fetal hemoglobin level in thalassemia patients interferes with measurement of glycosylated hemoglobin (hemoglobin A1C), fructosamine evaluation as an alternative approach is suggested.Materials and Methods: This descriptive study was carried out on 33 diabetes mellitus patients with beta-thalas...

Mehrnoush Kosaryan; Mohammad Reza Mahdavi2; Ayli Aliasgharian; Masoumeh Mousavi; Payam Roshan

2012-01-01

 
 
 
 
221

The Usefulness of Homeostatic Measurement Assessment-Insulin Resistance (HOMA-IR) for Detection of Glucose Intolerance in Thai Women of Reproductive Age with Polycystic Ovary Syndrome  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objectives. To study the cut-off point of Homeostatic Measurement Assessment-Insulin Resistance (HOMA-IR) as a screening test for detection of glucose intolerance in Thai women with polycystic ovary syndrome (PCOS). Study Design. Cross-sectional study. Setting. Department of Obstetrics and Gynecology, Faculty of Medicine Siriraj Hospital. Subject. Two hundred and fifty Thai PCOS women who attended the Gynecologic Endocrinology Unit, during May 2007 to January 2009. Materials and Methods. The ...

Prasong Tanmahasamut; Surasak Angsuwathana; Kitirat Techatraisak; Suchada Indhavivadhana; Pichai Leerasiri; Manee Rattanachaiyanont; Thanyarat Wongwananuruk; Chongdee Dangrat

2012-01-01

222

Estimating Plasma Glucose from Interstitial Glucose: The Issue of Calibration Algorithms in Commercial Continuous Glucose Monitoring Devices  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Evaluation of metabolic control of diabetic people has been classically performed measuring glucose concentrations in blood samples. Due to the potential improvement it offers in diabetes care, continuous glucose monitoring (CGM) in the subcutaneous tissue is gaining popularity among both patients and physicians. However, devices for CGM measure glucose concentration in compartments other than blood, usually the interstitial space. This means that CGM need calibration against blood glucose va...

Paolo Rossetti; Josep Vehí; Jorge Bondia; Fanelli, Carmine G.

2010-01-01

223

Noninvasive measurement of blood flow, oxygen consumption, and glucose utilization in the same brain regions in man by positron emission tomography: concise communication  

International Nuclear Information System (INIS)

Local cerebral blood flow (CBF), oxygen consumption (CMRO2), and glucose utilization (CMR-Glc) have been measured in three patients by positron emission tomography (PET), together with continuous inhalation of 15O labeled gases and i.v. injection of [18F]fluoro-2-deoxy-D-glucose. In normal brain, the close local coupling between CBF and CMR-Glc, and that between CMRO2 and CMR-Glc, were well demonstrated. The coupling held for the asymptomatic areas and for parts of the affected hemispheres in two patients with cerebral ischemia. In one patient the CBF/CMR-Glc couple, but not the CMRO2/CMR-Glc couple, was disrupted in the acute ischemic core. This preliminary work demonstrates the local quantification of these important functional parameters, and indicates the potential usefulness of studying their pathophysiological interrelationship in brain disease

224

Affinity of glucose transport in Saccharomyces cerevisiae is modulated during growth on glucose.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

By using a modified technique to measure glucose uptake in Saccharomyces cerevisiae, potential uncertainties have been identified in previous determinations. These previous determinations had led to the proposal that S. cerevisiae contained a constitutive low-affinity glucose transporter and a glucose-repressible high-affinity transporter. We show that, upon transition from glucose-repressed to -derepressed conditions, the maximum rate of glucose transport is constant and only the affinity fo...

Walsh, M. C.; Smits, H. P.; Scholte, M. E.; Dam, K.

1994-01-01

225

Glucose urine test  

Science.gov (United States)

... If it is, further testing is needed. Normal glucose range in urine: 0 - 0.8 mmol/l (0 - 15 mg/dL) The examples above are common measurements for results of these tests. Normal value ranges may vary ...

226

Glucose uptake-stimulatory activity of Tinospora cordifolia stem extracts in Ehrlich ascites tumor cell model system.  

Science.gov (United States)

Diabetes mellitus is a multifunctional disorder with several causes and multiple consequences. Nutraceuticals play a vital role in ameliorating diabetic condition. The stems of the plant, Tinospora cordifolia (T. cordifolia) are often used in Ayurvedic medicine for the management of diabetes. Earlier studies have shown that T. cordifolia to be a potent antidiabetic plant material by virtue of being rich in nutraceuticals. In the present study we were interested to know if, T. cordifolia stem extracts are able to promote glucose uptake through glucose transporters, 1 (GLUT1) and 3 (GLUT3), which are responsible for basal glucose uptake. Hence, Ehrlich ascites tumor (EAT) cells were chosen as a model which harbours both GLUT1 and GLUT3 and glucose uptake was measured using a fluorescent analog 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose (2-NBDG). Serially, solvent extracted T. cordifolia stems, especially water, ethanol and methanol extracts showed glucose uptake activity. Uptake was stimulated in a dose dependent manner at dosages of 1-100 ?g. Glucose-stimulating activity does not seem to be solely due to polyphenol content since methanol extract, with high amount of polyphenol content (9.5?±?0.1 g?kg(-1)), did not stimulate higher glucose uptake activity when compared to water extract. PMID:24426067

Joladarashi, Darukeshwara; Chilkunda, Nandini D; Salimath, Paramahans Veerayya

2014-01-01

227

Precision of glucose measurements in control sera by isotope dilution/mass spectrometry: proposed definitive method compared with a reference method  

International Nuclear Information System (INIS)

This improved isotope-dilution gas chromatographic/mass spectrometric (GC/MS) method, in which [13C]glucose is the internal standard, meets the requirements of a Definitive Method. In a first study with five reconstituted lyophilized sera, a nested analysis of variance of GC/MS values indicated considerable among-vial variation. The CV for 32 measurements per serum ranged from 0.5 to 0.9%. However, concentration and uncertainty values (mmol/L per gram of serum) assigned to one serum by the NBS Definitive Method (7.56 +/- 0.28) were practically identical to those obtained with the proposed method (7.57 +/- 0.20). In the second study, we used twice more [13C]glucose diluent to assay four serum pools and two lyophilized sera. The CV ranged from 0.26 to 0.5% for the serum pools and from 0.28 to 0.59% for the lyophilized sera. In comparison, results by the hexokinase/glucose-6-phosphate dehydrogenase reference method agreed within acceptable limits with those by the Definitive Method but tended to be slightly higher (up to 3%) for lyophilized serum samples or slightly lower (up to 2.5%) for serum pools

228

Michaelis-Menten constraints improved cerebral glucose metabolism and regional lumped constant measurements with [18F]fluorodeoxyglucose  

International Nuclear Information System (INIS)

In the three-compartment model of transfer of native glucose and [18F]fluorodeoxyglucose (FDG) into brain, both transport across the blood-brain barrier and phosphorylation by hexokinase can be described by the Michaelis-Menten equation. This permits the use of fixed transport (tau = K*1/K1) and phosphorylation (psi = k*3/k3) ratios and a common partition volume (Ve = K1/k2) for tracer and glucose. By substituting transfer constants of FDG for those of glucose, using tau and psi, the lumped constant was determined directly by positron tomography. The same constraints also eliminated k*2 and k*3 from the model, thus limiting the parameters to K* [equivalent to K*1k*3/(k*2 + k*3)], K*1, and the cerebral vascular volume (Vo). In six healthy elderly men (aged 61 +/- 5 years), time-activity records of cerebral cortical regions were analyzed with tau = 1.1 and psi = 0.3. The results were compared with those of the conventional FDG method. At 20 min, the goodness of fit by the new equation was as good as that of the conventional method at 45 min. The estimates obtained by the constrained method had stable coefficients of variation. After 20 min, regional differences between the estimates were independent of time, although we observed steady decreases of K* and (k*3). The decrease strongly suggested dephosphorylation of FDG-6-phosphate, particularly after 20 min. All estimates of variables with the constrained method were more accurate than those of the conventional method, ie than those of the conventional method, including the cerebral glucose metabolic rate itself, as well as physiologically more meaningful, particularly with respect to k*2 and k*3

229

Blood glucose level reconstruction as a function of transcapillary glucose transport.  

Science.gov (United States)

A diabetic patient occasionally undergoes a detailed monitoring of their glucose levels. Over the course of a few days, a monitoring system provides a detailed track of their interstitial fluid glucose levels measured in their subcutaneous tissue. A discrepancy in the blood and interstitial fluid glucose levels is unimportant because the blood glucose levels are not measured continuously. Approximately five blood glucose level samples are taken per day, and the interstitial fluid glucose level is usually measured every 5min. An increased frequency of blood glucose level sampling would cause discomfort for the patient; thus, there is a need for methods to estimate blood glucose levels from the glucose levels measured in subcutaneous tissue. The Steil-Rebrin model is widely used to describe the relationship between blood and interstitial fluid glucose dynamics. However, we measured glucose level patterns for which the Steil-Rebrin model does not hold. Therefore, we based our research on a different model that relates present blood and interstitial fluid glucose levels to future interstitial fluid glucose levels. Using this model, we derived an improved model for calculating blood glucose levels. In the experiments conducted, this model outperformed the Steil-Rebrin model while introducing no additional requirements for glucose sample collection. In subcutaneous tissue, 26.71% of the calculated blood glucose levels had absolute values of relative differences from smoothed measured blood glucose levels less than or equal to 5% using the Steil-Rebrin model. However, the same difference interval was encountered in 63.01% of the calculated blood glucose levels using the proposed model. In addition, 79.45% of the levels calculated with the Steil-Rebrin model compared with 95.21% of the levels calculated with the proposed model had 20% difference intervals. PMID:25150823

Koutny, Tomas

2014-10-01

230

Ice analog halos.  

Science.gov (United States)

Crystals of sodium fluorosilicate are used to produce easy to set up visual displays of atmospheric halos, including the 22 degrees halo, the Parry arc, and upper tangent arcs. Scattering phase functions for single ice-analog rosettes, including a rough one, and a column aggregate, measured in randomized orientation, are also given. The phase functions show prominent halo features, with the exception of the rough crystal. PMID:16201438

Ulanowski, Zbigniew

2005-09-20

231

Simple noninvasive quantification method for measuring myocardial glucose utilization in humans employing positron emission tomography and fluorine-18 deoxyglucose  

International Nuclear Information System (INIS)

To estimate regional myocardial glucose utilization (rMGU) with positron emission tomography (PET) and 2-[18F]fluoro-2-deoxy-D-glucose (FDG) in humans, we studied a method which simplifies the experimental procedure and is computationally efficient. This imaging approach uses a blood time-activity curve derived from a region of interest (ROI) drawn over dynamic PET images of the left ventricle (LV), and a Patlak graphic analysis. The spillover of radioactivity from the cardiac chambers to the myocardium is automatically removed by this analysis. Estimates of rMGU were obtained from FDG PET cardiac studies of six normal human subjects. Results from this study indicate that the FDG time-activity curve obtained from the LV ROI matched well with the arterial plasma curve. The rMGU obtained by Patlak graphic analysis was in good agreement with direct curve fitting results (r = 0.90). The average standard error of the estimate of the Patlak rMGU was low (3%). These results demonstrate the practical usefulness of a simplified method for the estimation of rMGU in humans by PET. This approach is noninvasive, computationally fast, and highly suited for developing parametric images of myocardial glucose utilization rate

232

A Tale of Two Compartments: Interstitial Versus Blood Glucose Monitoring  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Cengiz, Eda; Tamborlane, William V.

2009-01-01

233

2-Deoxy-D-glucose targeting of glucose metabolism in cancer cells as a potential therapy.  

Science.gov (United States)

Cancer cells are characterized by altered glucose metabolism known as the Warburg effect in which aerobic glycolysis is increased. Glucose is converted to lactate even under sufficient oxygen tension. Interfering with this process may be a potential effective strategy to cause cancer cell death because these cells rely heavily on glucose metabolism for survival and proliferation. 2-Deoxy-D-glucose (2DG), a glucose analog, targets glucose metabolism to deplete cancer cells of energy. In addition, 2DG increases oxidative stress, inhibits N-linked glycosylation, and induces autophagy. It can efficiently slow cell growth and potently facilitate apoptosis in specific cancer cells. Although 2DG itself has limited therapeutic effect in many types of cancers, it may be combined with other therapeutic agents or radiotherapy to exhibit a synergistic anticancer effect. In this review, we describe the Warburg effect and discuss 2DG and its underlying mechanisms and potential application for cancer treatment. PMID:25218591

Zhang, Dongsheng; Li, Juan; Wang, Fengzhen; Hu, Jun; Wang, Shuwei; Sun, Yueming

2014-12-28

234

Evaluation of the relationship between capillary and venous plasma glucose concentrations obtained by the HemoCue Glucose 201+ system during an oral glucose tolerance test  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract In 55 women with previous gestational diabetes mellitus, simultaneous capillary and venous plasma glucose concentrations were measured at 0, 30 and 120 min during a 75 g oral glucose tolerance test (OGTT). The aims of the study were to examine the relationship between capillary and venous glucose measurements, and to establish equations for the conversion of capillary and venous glucose concentrations using the HemoCue Glucose 201+ system. Additionally, the correlation between the ca...

Ignell, Claes; Berntorp, Kerstin

2011-01-01

235

Measurement of lumbar muscle glucose utilization rate can be as useful in estimating skeletal muscle insulin resistance as that of thigh muscle  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Skeletal muscle glucose utilization (SMGU can be accessed by positron emission tomography (PET and18F-FDG to characterize insulin resistance. The quantity of skeletal muscle in the lumbar is sufficient to indicate that SMGU in the lumbar (SMGU- lumbar can be measured with18F-FDG PET of the chest instead of obtaining thigh muscle SMGU (SMGU-thigh. This would reduce PET scan time to avoid thigh muscle PET scan. This study was aimed to compare SMGU-lumbar and thigh muscle SMGU under insulin clamping to identify the validity of measurements of SMGU in the lumbar for studies of insulin resistance. Methods: Thirty-three patients underwent sequential dynamic18F-FDG PET of both the thoracic (37 min and thigh region (22 min during hyperinsulinemic euglycemic insulin clamping. Both SMGU-lumbar and SMGU-thigh were calculated by Patlak graphical analysis. Whole body insulin resistance was assessed by a whole body glucose disposal rate during hyperinsulinemic euglycemic insulin clamping. Input function was obtained from the time activity curve of the descending aorta and venous blood sampling as previously validated. Results: SMGU-thigh (0.0506 ± 0.0334 ?mol/min/g was comparable to SMGU-lumbar (0.0497 ± 0.0255 ?mol/min/g. The Bland-Altman method of difference plot analysis showed a significant correlationship between SMGU- thigh and SMGU-lumbar (r = 0.506, p = 0.0028. There were seen very good significant correlationship between whole body glucose utilization rate in both thigh (r = 0.737, p = 0.0001 and lumbar (r = 0.772, p = 0.0001. Conclusion: These results support the validity of measuring SMGU-lumbar to estimate insulin resistance during PET imaging of the chest.

Ikuo Yokoyama

2013-02-01

236

Determination of Glucose Concentration in Yeast Culture Medium  

Science.gov (United States)

The present paper describes a sensor for measuring the glucose concentration of yeast culture medium. The sensor determines glucose concentration by measuring the yield of hydrogen peroxide produced by glucose oxidase, which is monitored as luminescence using photomultiplier. The present sensor is able to measure low glucose concentration in media in which yeast cells keep respiration state. We herein describe the system and the characteristics of the glucose sensor.

Hara, Seiichi; Kishimoto, Tomokazu; Muraji, Masafumi; Tsujimoto, Hiroaki; Azuma, Masayuki; Ooshima, Hiroshi

237

A CAMAC unit for charge measuring and pulse shape recording based on a fast, 8-bit parallel analog-to-digital converter  

International Nuclear Information System (INIS)

A device designed mainly for measuring systems for testing parameters of some type of detectors used in the high energy physics is described. The device is one-module CAMAC unit. It is equipped in a fast, 8-bit parallel analog-to-digital converter ''flash''type with a gated integrator at the input and a static RAM (4096 x 8 bit) at the output. The device enables measurements of the charge in pulses from detectors or registration of the shape of these pulses. The construction, operation and parameters of the circuits of the device are described and the way of programming functions using CAMAC dataway is given. 8 refs., 9 figs. (author)

238

Effects of metoclopramide on duodenal motility and flow events, glucose absorption, and incretin hormone release in response to intraduodenal glucose infusion.  

Science.gov (United States)

The contribution of small intestinal motor activity to nutrient absorption is poorly defined. A reduction in duodenal flow events after hyoscine butylbromide, despite no change in pressure waves, was associated with reduced secretion of the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) and a delay in glucose absorption. The aim of this study was to investigate the effect of metoclopramide on duodenal motility and flow events, incretin hormone secretion, and glucose absorption. Eight healthy volunteers (7 males and 1 female; age 29.8 ± 4.6 yr; body mass index 24.5 ± 0.9 kg/m²) were studied two times in randomized order. A combined manometry and impedance catheter was used to measure pressure waves and flow events in the same region of the duodenum simultaneously. Metoclopramide (10 mg) or control was administered intravenously as a bolus, followed by an intraduodenal glucose infusion for 60 min (3 kcal/min) incorporating the ¹?C-labeled glucose analog 3-O-methylglucose (3-OMG). We found that metoclopramide was associated with more duodenal pressure waves and propagated pressure sequences than control (P < 0.05 for both) during intraduodenal glucose infusion. However, the number of duodenal flow events, blood glucose concentration, and plasma 3-[¹?C]OMG activity did not differ between the two study days. Metoclopramide was associated with increased plasma concentrations of GLP-1 (P < 0.05) and GIP (P = 0.07) but lower plasma insulin concentrations (P < 0.05). We concluded that metoclopramide was associated with increased frequency of duodenal pressure waves but no change in duodenal flow events and glucose absorption. Furthermore, GLP-1 and GIP release increased with metoclopramide, but insulin release paradoxically decreased. PMID:20829521

Kuo, Paul; Bellon, Max; Wishart, Judith; Smout, André J; Holloway, Richard H; Fraser, Robert J L; Horowitz, Michael; Jones, Karen L; Rayner, Christopher K

2010-12-01

239

An economic analogy to thermodynamics  

Science.gov (United States)

The author develops analogies between economic systems and thermodynamics, and shows how economic quantities can characterize the state of an economic system in equilibrium. We argue that just as a physical system in thermodynamic equilibrium requires a nonmechanical variable (the temperature) to specify its state, so does an economic system. In addition, both systems must have a corresponding conjugate quantity, the entropy. We also develop economic analogies to the free energy, Maxwell relations, and the GibbsâDuhem relation. Assuming that economic utility can be measured, we develop an operational definition of an economic temperature scale. We also develop an analogy to statistical mechanics, which leads to Gaussian fluctuations.

Saslow, Wayne M.

2011-08-31

240

Paricalcitol does not improve glucose metabolism in patients with stage 3-4 chronic kidney disease.  

Science.gov (United States)

Patients with chronic kidney disease are often insulin resistant and glucose intolerant--abnormalities that promote cardiovascular disease. Administration of 1,25-dihydroxyvitamin D (calcitriol) has improved glucose metabolism in patients with end-stage renal disease. We conducted a randomized, placebo-controlled clinical trial to test whether paricalcitol, a 1,25-dihydroxyvitamin D analog, changes glucose tolerance in earlier stages of chronic kidney disease. In a crossover design, 22 nondiabetic patients with estimated glomerular filtration rates of stage 3-4 chronic kidney disease and fasting plasma glucose of 100-125 mg/dl were given daily oral paricalcitol for 8 weeks and matching placebo for 8 weeks, separated by an 8-week washout period. The order of interventions was random and blinded to both participants and investigators. Paricalcitol significantly reduced serum concentrations of parathyroid hormone, 1,25-dihydroxyvitamin D, and 25-hydroxyvitamin D while significantly increasing serum concentrations of fibroblast growth factor-23 and 24,25-dihydroxyvitamin D. Paricalcitol, however, had no significant effect on glucose tolerance (the primary outcome measure), insulin sensitivity, beta-cell insulin response, plasma free fatty acid suppression, or urinary F2-isoprostane excretion. Thus, despite substantial effects on vitamin D metabolism, paricalcitol did not improve glucose metabolism in nondiabetic patients with stage 3-4 chronic kidney disease. PMID:22913981

de Boer, Ian H; Sachs, Michael; Hoofnagle, Andrew N; Utzschneider, Kristina M; Kahn, Steven E; Kestenbaum, Bryan; Himmelfarb, Jonathan

2013-02-01

 
 
 
 
241

A sensitive LC-MS/MS method for measurement of organophosphorus pesticides and their oxygen analogs in air sampling matrices.  

Science.gov (United States)

A rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for determination of levels of the organophosphorus (OP) pesticides chlorpyrifos (CPF), azinphos methyl (AZM), and their oxygen analogs chlorpyrifos-oxon (CPF-O) and azinphos methyl-oxon (AZM-O) on common active air sampling matrices. XAD-2 resin and polyurethane foam (PUF) matrices were extracted with acetonitrile containing stable-isotope labeled internal standards (ISTD). Analysis was accomplished in Multiple Reaction Monitoring (MRM) mode, and analytes in unknown samples were identified by retention time (±0.1 min) and qualifier ratio (±30% absolute) as compared to the mean of calibrants. For all compounds, calibration linearity correlation coefficients were ?0.996. Limits of detection (LOD) ranged from 0.15-1.1 ng/sample for CPF, CPF-O, AZM, and AZM-O on active sampling matrices. Spiked fortification recoveries were 78-113% from XAD-2 active air sampling tubes and 71-108% from PUF active air sampling tubes. Storage stability tests also yielded recoveries ranging from 74-94% after time periods ranging from 2-10 months. The results demonstrate that LC-MS/MS is a sensitive method for determining these compounds from two different matrices at the low concentrations that can result from spray drift and long range transport in non-target areas following agricultural applications. In an inter-laboratory comparison, the limit of quantification (LOQ) for LC-MS/MS was 100 times lower than a typical gas chromatography-mass spectrometry (GC-MS) method. PMID:24328542

Armstrong, Jenna L; Dills, Russell L; Yu, Jianbo; Yost, Michael G; Fenske, Richard A

2014-01-01

242

Glucose sensing by means of silicon photonics  

Science.gov (United States)

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.

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

2014-03-01

243

POF based glucose sensor incorporating grating wavelength filters  

DEFF Research Database (Denmark)

Medtronic has already developed a plastic fiber based optical sensor to detect the concentration of glucose both in vivo and in-vitro. The glucose sensor is based on a competitive glucose binding affinity assay consisting of a glucose receptor and glucose analog (ligand) contained in a compartment made up of permeable membrane for exchanging of only small molecules such as glucose, salts etc. (Fig 1). The binding between the glucose binding protein labeled with flourophore and glucose like molecules labelled with dye, is reversible. In the presence of glucose, the glucose analog competes with the glucose on binding to the protein. The system reaches an equilibrium, which correlates with the glucose concentration.The assay chemistry makes donor and acceptor pair for FRET (Förster Resonance Energy Transfer). FRET results in decrease in donor emission intensity. Higher the concentration of glucose, more donor acceptor pairs got separated resulting in high intensity and vice versa. This change in optical signal is correlated to glucose concentration. (Fig.1) Medtronic Diabetes and DTU FOTONIK has been working together under the consortium of Marie Curie Research Framework called TRAINING AND RESEARCH IN POLYMER OPTICAL DEVICES; TRIPOD. Within the domain of TRIPOD, research is conducted on "Plastic Optical Fiber based Glucose Sensors Incorporating Grating Wavelength Filters". Research will be focused to optimized fiber tips for better coupling efficiency, reducing the response time of sensor, improve the mechanical stabilization of assay compartment by exploring the side excitation and side coupling method, ease of manufacturing and feasibility of Polymer Fiber Bragg gratings as filters. During the project, fibers will be drawn and fiber bragg gratings will be inscribed at DTU Fotonik and they will be characterized for glucose sensor at Medtronic Diabetes.

Hassan, Hafeez Ul; Aasmul, SØren

2014-01-01

244

Thresholds of whole-blood ?-hydroxybutyrate and glucose concentrations measured with an electronic hand-held device to identify ovine hyperketonemia.  

Science.gov (United States)

Metabolic disorders, especially hyperketonemia, are very common in dairy sheep. The whole-blood concentrations of ?-hydroxybutyrate (BHBA) and glucose can be determined by commercially available electronic hand-held devices, which are used in human medicine and for the detection of ketosis in dairy cows. The aim of this study was to evaluate the suitability of the hand-held device Precision Xceed (PX; Abbott Diabetes Care Inc., Abbott Park, IL) to detect hyperketonemia in ewes. An additional objective of this study was to evaluate the agreement between samples obtained by minimal invasive venipuncture of an ear vein and measurements of whole-blood samples from the jugular vein (vena jugularis, v. jug.). Blood samples taken from the v. jug. were collected from 358 ewes on 4 different farms. These samples and a blood drop obtained from an ear vein were analyzed simultaneously on farm with the PX. For method comparison, the samples obtained from the v. jug. were also analyzed by standard methods, which served as the gold standard at the Central Laboratory of the University of Veterinary Medicine Vienna, Austria. The correlation coefficients between the serum BHBA concentration and the concentrations measured with the hand-held meter in the whole blood from an ear vein and the v. jug. were 0.94 and 0.96, respectively. The correlation coefficients of plasma and whole-blood glucose concentration were 0.68 for the v. jug. and 0.47 for the ear vein. The mean glucose concentration was significantly lower in animals classified as hyperketonemic (BHBA ? 1.6 mmol/L) compared with healthy ewes. Whole-blood concentrations of BHBA and glucose measured with the PX from v. jug. showed a constant negative bias of 0.15 mmol/L and 8.4 mg/dL, respectively. Hence, a receiver operating characteristic analysis was performed to determine thresholds for the PX to detect hyperketonemia in ewes. This resulted in thresholds for moderate ketosis of BHBA concentrations of 0.7 mmol/L in blood from an ear vein and the v. jug. Cutoffs of 1.0 mmol/L (ear vein) and 1.1 mmol/L (v. jug.) BHBA were determined to detect animals at greater risk to develop severe hyperketonemia. Applying these thresholds, excellent test characteristics, with sensitivities of 1.00 for both samples and specificities of 0.98 for the ear vein and 0.97 for the v. jug. were determined. These results demonstrate that the PX is a useful tool for detection of hyperketonemia in ewes. PMID:24440266

Pichler, M; Damberger, A; Schwendenwein, I; Gasteiner, J; Drillich, M; Iwersen, M

2014-03-01

245

Analog elements for transuranic chemistries  

International Nuclear Information System (INIS)

The analytical technique for measuring trace concentrations of the analog rare earth elements has been refined for optimal detection. The technique has been used to determine the rare earth concentrations in a series of geological and biological materials, including samples harvested from controlled lysimeter investigations. These studies have demonstrated that any of the trivalent rare earth elements may be used as analog elements for the trivalent transuranics, americium and curium

246

Glucose and fructose 6-phosphate cycle in humans  

International Nuclear Information System (INIS)

We have determined the rate of glucose cycling by comparing turnovers of [2-3H]- and [6-3H]glucose under basal conditions and during a glucose infusion. Moreover, the activity of the fructose 6-phosphate cycle was assessed by comparing [3-3H]- and [6-3H]glucose. The study included eight lean subjects with normal glucose tolerance. They participated in two randomly performed investigations. In one experiment [2-3H]- and [6-3H]glucose were given simultaneously, while in the other only [3-3H]glucose was given. The basal rate of glucose cycling was 0.32 +/- 0.08 mg X kg-1 X min-1 or 17% of basal glucose production (P less than 0.005). During glucose infusion the activity of endogenous glucose cycling did not change but since glucose production was suppressed it amounted to 130% of glucose production. The basal fructose 6-phosphate cycle could be detected only in three subjects and was suppressed during glucose infusion. In conclusion, the glucose cycle is active in healthy humans both in basal conditions and during moderate hyperglycemia. In some subjects, the fructose 6-phosphate cycle also appears to be active. Thus it is preferable to use [6-3H]glucose rather than [3-3H]glucose when measuring glucose production and particularly when assessing glucose cycle

247

Effects of 5 Thio-D-Glucose on cellular adenosine triphosphate levels and deoxyribonucleic acid rejoining in hypoxic and aerobic Chinese hamster cells  

International Nuclear Information System (INIS)

Intracellular adenosine triphosphate (ATP) levels were measured in both hypoxic and aerobic cultures of V79 Chinese hamster cells treated with 5-thio-D-glucose (5-SH-D-Glc). This glucose analog, a known inhibitor of D-glucose transport and metabolism, reduced ATP in cell cultures allowed to become hypoxic by cell metabolism, but not in aerobic cultures treated similarly. Cells depleted of ATP were unable to rejoin x-ray induced deoxyribonucleic acid (DNA) strand breaks as measured by the alkaline sucrose gradient sedimentation technique. The inference for radiation therapy is that inhibition of glucose metabolism selectively depletes energy reserves in hypoxic cells, rendering these cells more radiosensitive and leading to a more effective tumor treatment

248

Estimating Plasma Glucose from Interstitial Glucose: The Issue of Calibration Algorithms in Commercial Continuous Glucose Monitoring Devices  

Directory of Open Access Journals (Sweden)

Full Text Available Evaluation of metabolic control of diabetic people has been classically performed measuring glucose concentrations in blood samples. Due to the potential improvement it offers in diabetes care, continuous glucose monitoring (CGM in the subcutaneous tissue is gaining popularity among both patients and physicians. However, devices for CGM measure glucose concentration in compartments other than blood, usually the interstitial space. This means that CGM need calibration against blood glucose values, and the accuracy of the estimation of blood glucose will also depend on the calibration algorithm. The complexity of the relationship between glucose dynamics in blood and the interstitial space, contrasts with the simplistic approach of calibration algorithms currently implemented in commercial CGM devices, translating in suboptimal accuracy. The present review will analyze the issue of calibration algorithms for CGM, focusing exclusively on the commercially available glucose sensors.

Paolo Rossetti

2010-12-01

249

The ketosis-resistance in fibro-calculous-pancreatic-diabetes. 1. Clinical observations and endocrine-metabolic measurements during oral glucose tolerance test.  

Science.gov (United States)

We measured circulating levels of C-peptide, pancreatic glucagon, cortisol, growth hormone and metabolites (glucose, non-esterified fatty acids, glycerol and 3-hydroxybutyrate) in fibro-calculous-pancreatic diabetic (FCPD, n = 28), insulin-dependent diabetic (IDDM, n = 28) and non-diabetic control (n = 27) subjects during an oral glucose tolerance test. There was no difference in the two diabetic groups in age (FCPD 24 +/- 2, IDDM 21 +/- 2 years, mean +/- SEM), BMI (FCPD 16.0 +/- 0.6, IDDM 15.7 +/- 0.4 kg/m2), triceps skinfold thickness (FCPD 8 +/- 1, IDDM 7 +/- 1 mm), glycaemic status (fasting plasma glucose, FCPD 12.5 +/- 1.5, IDDM 14.5 +/- 1.2 mmol/l), fasting plasma C-peptide (FCPD 0.13 +/- 0.03, IDDM 0.08 +/- 0.01 nmol/l), peak plasma C-peptide during OGTT (FCPD 0.36 +/- 0.10, IDDM 0.08 +/- 0.03 nmol/l) and fasting plasma glucagon (FCPD 35 +/- 4, IDDM 37 +/- 4 ng/l). FCPD patients, however, showed lower circulating concentrations of non-esterified fatty acids (0.73 +/- 0.11 mmol/l), glycerol (0.11 +/- 0.02 mmol/l) and 3-hydroxybutyrate (0.15 +/- 0.03 mmol/l) compared to IDDM patients (1.13 +/- 0.14, 0.25 +/- 0.05 and 0.29 +/- 0.08 mmol/l, respectively). This could be due to enhanced sensitivity of adipose tissue lipolysis to the suppressive action of circulating insulin and possibly also to insensitivity of hepatic ketogenesis to glucagon. Our results also demonstrate preservation of alpha-cell function in FCPD patients when beta-cell function is severely diminished, suggesting a more selective beta-cell dysfunction or destruction than hitherto believed. PMID:1563331

Yajnik, C S; Shelgikar, K M; Naik, S S; Kanitkar, S V; Orskov, H; Alberti, K G; Hockaday, T D

1992-02-01

250

Detection of correct and incorrect measurements in real-time continuous glucose monitoring systems by applying a postprocessing support vector machine.  

Science.gov (United States)

Support vector machines (SVMs) are an attractive option for detecting correct and incorrect measurements in real-time continuous glucose monitoring systems (RTCGMSs), because their learning mechanism can introduce a postprocessing strategy for imbalanced datasets. The proposed SVM considers the geometric mean to obtain a more balanced performance between sensitivity and specificity. To test this approach, 23 critically ill patients receiving insulin therapy were monitored over 72 h using an RTCGMS, and a dataset of 537 samples, classified according to International Standards Organization (ISO) criteria (372 correct and 165 incorrect measurements), was obtained. The results obtained were promising for patients with septic shock or with sepsis, for which the proposed system can be considered as reliable. However, this approach cannot be considered suitable for patients without sepsis. PMID:23380841

Leal, Yenny; Gonzalez-Abril, Luis; Lorencio, Carol; Bondia, Jorge; Vehi, Josep

2013-07-01

251

Blood Glucose Log  

Science.gov (United States)

... meal plan, physical activity, or diabetes medicines. Having low blood glucose means that your blood glucose level is too low (below 70 mg/dl). Low blood glucose can be dangerous. Symptoms include being: • hungry • light- ...

252

Blood Glucose Log  

Science.gov (United States)

... here ¢ cut here ¢ If you have high blood glucose , make notes in your log and talk with ... physical activity, or diabetes medicines. Having low blood glucose means that your blood glucose level is too ...

253

Estimation of liver glucose metabolism after refeeding  

International Nuclear Information System (INIS)

Refeeding or infusing glucose to rats fasted for 24 hr or more causes rapid liver glycogen synthesis, the carbon source now considered to be largely from gluconeogenesis. While substrate cycling between plasma glucose and liver glucose-6P is known to occur, this cycling has apparently been ignored when calculations are made of % contribution of direct and indirect pathways to liver glycogen synthesis, or when hepatic glucose output is calculated from glucose turnover minus the glucose infusion rate. They show that, isotopically, an estimate of the fluxes of liver glucokinase and glucose-6-phosphatase is required to quantitate sources of carbon for liver glycogen synthesis, and to measure hepatic glucose output (or uptake). They propose a method to estimate these fluxes, involving a short infusion of a 14C labelled gluconeogenic precursor plus (6T)glucose, with determination of isotopic yields in liver glycogen and total glucose. Given also the rate of liver glycogen synthesis, this procedure permits the estimation of net gluconeogenesis and hepatic glucose output or uptake. Also, in vitro evidence against the notion of a drastic zonation of liver carbohydrate metabolism is presented, e.g. raising the glucose concentration from 10 to 25 mM increases the 14C yield from H14CO3- in lactate, with the increased pyruvate kinase flux and decreased gluconeogenesis occurring in the same cell type, not opposing pathways in dsame cell type, not opposing pathways in different hepatocyte types (as has been postulated by some to occur in vivo after refeeding

254

Estimation of liver glucose metabolism after refeeding  

Energy Technology Data Exchange (ETDEWEB)

Refeeding or infusing glucose to rats fasted for 24 hr or more causes rapid liver glycogen synthesis, the carbon source now considered to be largely from gluconeogenesis. While substrate cycling between plasma glucose and liver glucose-6P is known to occur, this cycling has apparently been ignored when calculations are made of % contribution of direct and indirect pathways to liver glycogen synthesis, or when hepatic glucose output is calculated from glucose turnover minus the glucose infusion rate. They show that, isotopically, an estimate of the fluxes of liver glucokinase and glucose-6-phosphatase is required to quantitate sources of carbon for liver glycogen synthesis, and to measure hepatic glucose output (or uptake). They propose a method to estimate these fluxes, involving a short infusion of a /sup 14/C labelled gluconeogenic precursor plus (6T)glucose, with determination of isotopic yields in liver glycogen and total glucose. Given also the rate of liver glycogen synthesis, this procedure permits the estimation of net gluconeogenesis and hepatic glucose output or uptake. Also, in vitro evidence against the notion of a drastic zonation of liver carbohydrate metabolism is presented, e.g. raising the glucose concentration from 10 to 25 mM increases the /sup 14/C yield from H/sup 14/CO/sub 3//sup -/ in lactate, with the increased pyruvate kinase flux and decreased gluconeogenesis occurring in the same cell type, not opposing pathways in different hepatocyte types (as has been postulated by some to occur in vivo after refeeding.

Rognstad, R.

1987-05-01

255

Spectral Reflectance Measurements of Sulfides at the Planetary Emissivity Laboratory — Analogs for Hollow-Forming Material on Mercury?  

Science.gov (United States)

We present spectral reflectance measurements at visible and near-infrared wavelengths of fresh and heated samples of MnS, CaS, and MgS, as well as elemental sulfur. We infer that sulfides display a diagnostic feature at or near 0.6 µm.

Helbert, J.; Maturilli, A.; D'Amore, M.; Vaughan, W. M.; Head, J. W.; Klima, R. L.; Blewett, D. T.; McCoy, T. J.

2012-03-01

256

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

Science.gov (United States)

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

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

2014-11-01

257

Biological evaluation of two iodine-123-labeled D-glucose acetals prepared as glucose transporter radioligands  

International Nuclear Information System (INIS)

Two iodinated acetals of D-glucose, 4,6-(R)-O-(2'-iodoethylidene)-?, ?-D-glucose and 4,6-(R)-O-(4'-iodobenzylidene)-?, ?-D-glucose , were prepared and their potential as suitable SPECT radioligands for imaging of glucose transporters was studied. Both are analogs of acetal D-glucose derivatives, which are known to bind to the exofacial sites of the glucose transport protein (GluT). To assess whether iodinated acetals 1 and 2 interacted with the glucose transporter, they were tested in vitro in human erythrocytes (GluT1) and neonatal rat cardiomyocytes (GluT4). The results indicated that 1 and 2 had a very low affinity for the glucose transporter and probably accumulated in cells. Study of their tissue distribution was carried out in the mouse in vivo: Both compounds showed fast tissue clearance with preferential renal elimination. It is concluded that iodinated acetals of D-glucose 1 and 2 are not suitable for GluT targeting in vivo

258

Biological evaluation of two iodine-123-labeled D-glucose acetals prepared as glucose transporter radioligands  

Energy Technology Data Exchange (ETDEWEB)

Two iodinated acetals of D-glucose, 4,6-(R)-O-(2'-iodoethylidene)-{alpha}, {beta}-D-glucose and 4,6-(R)-O-(4'-iodobenzylidene)-{alpha}, {beta}-D-glucose , were prepared and their potential as suitable SPECT radioligands for imaging of glucose transporters was studied. Both are analogs of acetal D-glucose derivatives, which are known to bind to the exofacial sites of the glucose transport protein (GluT). To assess whether iodinated acetals 1 and 2 interacted with the glucose transporter, they were tested in vitro in human erythrocytes (GluT1) and neonatal rat cardiomyocytes (GluT4). The results indicated that 1 and 2 had a very low affinity for the glucose transporter and probably accumulated in cells. Study of their tissue distribution was carried out in the mouse in vivo: Both compounds showed fast tissue clearance with preferential renal elimination. It is concluded that iodinated acetals of D-glucose 1 and 2 are not suitable for GluT targeting in vivo.

Brunet-Desruet, Marie-Dominique; Ghezzi, Catherine; Morin, Christophe; Comet, Michel; Fagret, Daniel

1998-07-01

259

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

DEFF Research Database (Denmark)

OBJECTIVEWe 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 -cell function measured by gold-standard tests were reflected in the corresponding OGTT-derived estimates.RESEARCH DESIGN AND METHODSWith 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 -cell function were measured with the euglycemic-hyperinsulinemic clamp and intravenous glucose tolerance tests, respectively. Surrogate markers of both conditions were calculated from OGTTs.RESULTSMore rapid glucose absorption (P 0.036) and reduced late glucose absorption (P 0.039) were observed in thei-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 -cell function, reflected the differences for these parameters between those with normal and impaired glucose regulation as measured by gold-standard tests.CONCLUSIONSGlucose absorption patterns during an OGTT are significantly related to plasma glucose levels and body size, which should be taken into account when estimating -cell function from OGTTs in epidemiological studies.

Faerch, K.; Pacini, G.

2013-01-01

260

The determination of solubility and diffusion coefficient for solids in liquids by an inverse measurement technique using cylinders of amorphous glucose as a model compound  

International Nuclear Information System (INIS)

The importance of sugar and sugar-containing materials is well recognized nowadays, owing to their application in industrial processes, particularly in the food, pharmaceutical and cosmetic industries. Because of the large numbers of those compounds involved and the relatively small number of solubility and/or diffusion coefficient data for each compound available, it is highly desirable to measure the solubility and/or diffusion coefficient as efficiently as possible and to be able to improve the accuracy of the methods used. In this work, a new technique was developed for the measurement of the diffusion coefficient of a stationary solid solute in a stagnant solvent which simultaneously measures solubility based on an inverse measurement problem algorithm with the real-time dissolved amount profile as a function of time. This study differs from established techniques in both the experimental method and the data analysis. The experimental method was developed in which the dissolved amount of solid solute in quiescent solvent was investigated using a continuous weighing technique. In the data analysis, the hybrid genetic algorithm is used to minimize an objective function containing a calculated and a measured dissolved amount with time. This is measured on a cylindrical sample of amorphous glucose in methanol or ethanol. The calculated dissolved amount, that is a function of the unknown physical properties of the solid solute in the solvent, is calculated by the solution of the two-dimensional nonlinear inverse natural convection problem. The estimated values of the solubility of amorphous glucose in methanol and ethanol at 293 K were respectively 32.1 g/100 g methanol and 1.48 g/100 g ethanol, in agreement with the literature values, and support the validity of the simultaneously measured diffusion coefficient. These results show the efficiency and the stability of the developed technique to simultaneously estimate the solubility and diffusion coefficient. Also the influence of the solution density change and the initial concentration conditions on the dissolved amount was investigated by the numerical results using the estimated parameters. It is found that the theoretical assumption to simplify the inverse measurement problem algorithm is reasonable for low solubility

 
 
 
 
261

The determination of solubility and diffusion coefficient for solids in liquids by an inverse measurement technique using cylinders of amorphous glucose as a model compound  

Science.gov (United States)

The importance of sugar and sugar-containing materials is well recognized nowadays, owing to their application in industrial processes, particularly in the food, pharmaceutical and cosmetic industries. Because of the large numbers of those compounds involved and the relatively small number of solubility and/or diffusion coefficient data for each compound available, it is highly desirable to measure the solubility and/or diffusion coefficient as efficiently as possible and to be able to improve the accuracy of the methods used. In this work, a new technique was developed for the measurement of the diffusion coefficient of a stationary solid solute in a stagnant solvent which simultaneously measures solubility based on an inverse measurement problem algorithm with the real-time dissolved amount profile as a function of time. This study differs from established techniques in both the experimental method and the data analysis. The experimental method was developed in which the dissolved amount of solid solute in quiescent solvent was investigated using a continuous weighing technique. In the data analysis, the hybrid genetic algorithm is used to minimize an objective function containing a calculated and a measured dissolved amount with time. This is measured on a cylindrical sample of amorphous glucose in methanol or ethanol. The calculated dissolved amount, that is a function of the unknown physical properties of the solid solute in the solvent, is calculated by the solution of the two-dimensional nonlinear inverse natural convection problem. The estimated values of the solubility of amorphous glucose in methanol and ethanol at 293 K were respectively 32.1 g/100 g methanol and 1.48 g/100 g ethanol, in agreement with the literature values, and support the validity of the simultaneously measured diffusion coefficient. These results show the efficiency and the stability of the developed technique to simultaneously estimate the solubility and diffusion coefficient. Also the influence of the solution density change and the initial concentration conditions on the dissolved amount was investigated by the numerical results using the estimated parameters. It is found that the theoretical assumption to simplify the inverse measurement problem algorithm is reasonable for low solubility.

Hu, Chengyao; Huang, Pei

2011-05-01

262

Carbon Dioxide Monitoring, Verification and Accounting (MVA) by Carbon Stable Isotope Measurements at Artificial and Natural Analog Sites  

Science.gov (United States)

Storage of carbon dioxide (CO2) in geologic formations is one method to mitigate greenhouse gas emissions from fossil fuel combustion. Monitoring, verification and accounting (MVA) of geologically sequestered CO2 is critical to the operation of a geologic storage site. Surface MVA techniques capable of identifying seepage from the sequestration reservoir at or below ambient CO2 concentrations are desired. The CO2 carbon stable isotope ratio (?13CO2) is a sensitive diagnostic signature that can distinguish between anthropogenic (?13CO2<-20%) and natural (?13CO2=-1 to -20%) sources. Frequency Modulated spectroscopy (FMS) is an ultra-sensitive version of absorption spectroscopy that is capable of detecting the CO2 carbon stable isotope ratios. The technique involves modulation of the laser such that two side bands spaced wider than the absorption feature of interest (in this case +/-2 GHz) are created. The signal is mixed with the local oscillator yielding a signal proportional to the species concentration. This FMS signature is recorded at multiple wavelengths to obtain the CO2 carbon isotope ratio. Two instruments using the FMS technique have been built and tested at LANL. The first instrument is an in situ instrument that draws ambient air into a multi-pass cell for a point source measurement. The second instrument uses an open-air path, tested up to 160 m round trip, to measure the column average CO2 carbon isotopic ratio. In this paper, results from laboratory tests and field deployments will be presented. The Zero Emissions Research & Technology (ZERT) group at Montana State University established a field test site where 0.15 - 0.20 tons of CO2 per day were released approximately 2 m below the soil surface to test the performance of CO2 detection instruments and measurement techniques. The in situ instrument was also deployed to the Valles Caldera National Preserve in the Jemez Mountains of New Mexico where CO2 is trapped at night which results in large concentration swings. Finally, the instruments were deployed to the Juniper-Pinion field site at Los Alamos National Laboratory.

Clegg, S. M.; Humphries, S. D.; McInroy, R. E.; Rahn, T.; Fessenden, J. E.; Dobeck, L.; Barr, J. L.; Spangler, L.

2011-12-01

263

Intuitive analog circuit design  

CERN Document Server

Intuitive Analog Circuit Design outlines ways of thinking about analog circuits and systems that let you develop a feel for what a good, working analog circuit design should be. This book reflects author Marc Thompson's 30 years of experience designing analog and power electronics circuits and teaching graduate-level analog circuit design, and is the ideal reference for anyone who needs a straightforward introduction to the subject. In this book, Dr. Thompson describes intuitive and ""back-of-the-envelope"" techniques for designing and analyzing analog circuits, including transistor amplifi

Thompson, Marc

2013-01-01

264

Enhancing the characterization of bedload transport in rivers using the analogy between the Hertz contact theory and plate hydrophone measurements  

Science.gov (United States)

Vibration measurements performed with plate or pipe geophone/hydrophone systems are of growing interest for bedload transport monitoring since they allow performing high temporal resolution and continuous records. Our set-up is constituted by a piezoelectric hydrophone acting as a "sediment vibration sensor" in contact with a steel plate located on the streambed. With such an apparatus, the signal processing is generally reduced to power spectral analysis or impact counting. However, a large amount of useful information is contained in the waveform of the impact signal, which conveys the force and the contact time that the bedload imposes on the plate. The wave amplitude is not well constrained because it varies a lot with changing impact location and velocity. The wave frequency is a more relevant parameter, less sensitive to these variables. According to the Hertz contact theory the frequency of the first signal arrival (flexural wave) is directly proportional to the bed-material grain size. Then, an appropriate analysis of the frequency attributes (central frequency, modulation) is needed to estimate the size of bedload particles. In this way, we have developed a complete processing algorithm based on a high dimensional decomposition method (chirplet transform) to get an accurate estimation of the first arrival frequency content. Results on summer flood events in a lowland river show that impacts are well separated by their central frequency and that most of transport occurs during larger peak flows. The portion of coarser sediment which is characterized by low frequencies is preferentially transported during the rising limb whereas the finer sand fraction identified by higher frequencies is transported during both rising and falling limb. Such a processing offers the opportunity to better understand the bedload signature of vibration measurements and is promising in view of quantifying processes of bedload transport and deposition. This final objective of quantification is an ongoing research by performing a flume experiment with various impact velocity and granulometry (collaboration with the Hydrology Department of Trier University).

Barrière, Julien; Oth, Adrien; Schenkluhn, Reimar; Krein, Andreas

2014-05-01

265

Evaluation and clinically relevant applications of a fluorescent imaging analog to fluorodeoxyglucose positron emission tomography  

Science.gov (United States)

A fluorescent analog to 2-deoxy-2 [18F] fluoro-D-glucose position emission tomography (FDG-PET) would allow for the introduction of metabolic imaging into intraoperative and minimally invasive settings. We present through in vitro and in vivo experimentation an evaluation of 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), a fluorescently labeled glucose molecule, as a molecular beacon of glucose utilization. The competitive inhibition of 2-NBDG uptake by excess free glucose is directly compared against FDG uptake inhibition in cultured cells. 2-NBDG uptake in the brain of a mouse experiencing a generalized seizure is measured, as well as in subcutaneously implanted tumors in mice during fed and fasting states. Localization of 2-NBDG into malignant tissues is studied by laser scanning microscopy. The clinical relevance of 2-NBDG imaging is examined by performing fluorescence colonoscopy, and by correlating preoperative FDG-PET with intraoperative fluorescence imaging. 2-NBDG exhibits a similar uptake inhibition to FDG by excess glucose in the growth media. Uptake is significantly increased in the brain of an animal experiencing seizures versus control, and in subcutaneous tumors after the animals are kept nil per os (NPO) for 24 h versus ad libidum feeding. The clinical utility of 2-NBDG is confirmed by the demonstration of very high target-to-background ratios in minimally invasive and intraoperative imaging of malignant lesions. We present an optical analog of FDG-PET to extend the applicability of metabolic imaging to minimally invasive and intraoperative settings.

Sheth, Rahul A.; Josephson, Lee; Mahmood, Umar

2009-11-01

266

Evidence for the presence of glucose cycling in pancreatic islets of the ob/ob mouse  

International Nuclear Information System (INIS)

Pancreatic islets from ob/ob mice incubated with 3H2O and 5.5 mM glucose formed 3H-labeled glucose, 74 picoatoms incorporated/islet/h. Sixty-three percent of the 3H was bound to carbon 2 of the glucose. The amount of glucose-6-P dephosphorylated to glucose, determined from this incorporation, was 48 pmol/islet/h. Glucose utilization, measured by the formation of 3H2O from [5-3H]glucose, was 72 pmol/islet/h. The amount of glucose dephosphorylated was then about 40% of that phosphorylated. Thus, glucose-6-P is dephosphorylated to glucose to a significant extent by intact islets in vitro and presumably by the beta cells of the islets. The extent of this glucose cycling, i.e. glucose----glucose-6-P----glucose, may play a role in determining the extent of glucose-induced insulin secretion

267

Assessing liver function by magnetic resonance imaging two-dimensional phase-shift flow measurement of portal venous blood flow after oral intake of glucose  

International Nuclear Information System (INIS)

We have already reported that the ratio of portal venous flow 30 min after oral intake of glucose 75 g to that before intake (PVFR30), measured using pulsed-Doppler ultrasonography (US), correlated significantly with other indicators of liver function and that it could be used to estimate hepatic function before surgery, including liver resection. In this study, to assess the disadvantages of pulsed-Doppler ultrasonography, PVFR30 was measured using two-dimensional (2D) phase-shift (PS) magnetic resonance imaging (MRI). PVFR30 was measured in 17 patients and 7 volunteers: 13 with liver cirrhosis (LC) and 11 without LC (non-LC). Portal venous flow could be measured in all patients without any disturbance of intestinal gas or patient fat, or the high degree of technical skill that Doppler US requires. PVFR30 was significantly lower in the LC group than in the non-LC group. In addition, it correlated significantly with other indicators of liver function, including the indocyanine green clearance test, prothrombin time, hepaplastin test, and cholinesterase activity. These results suggest that PVFR30 measured by 2D PS MRI can be used to estimate liver function, and that this MRI method can be performed more easily than pulsed-Doppler US. (author)

268

Parsing glucose entry into the brain: novel findings obtained with enzyme-based glucose biosensors.  

Science.gov (United States)

Extracellular levels of glucose in brain tissue reflect dynamic balance between its gradient-dependent entry from arterial blood and its use for cellular metabolism. In this work, we present several sets of previously published and unpublished data obtained by using enzyme-based glucose biosensors coupled with constant-potential high-speed amperometry in freely moving rats. First, we consider basic methodological issues related to the reliability of electrochemical measurements of extracellular glucose levels in rats under physiologically relevant conditions. Second, we present data on glucose responses induced in the nucleus accumbens (NAc) by salient environmental stimuli and discuss the relationships between local neuronal activation and rapid glucose entry into brain tissue. Third, by presenting data on changes in NAc glucose induced by intravenous and intragastric glucose delivery, we discuss other mechanisms of glucose entry into the extracellular domain following changes in glucose blood concentrations. Lastly, by showing the pattern of NAc glucose fluctuations during glucose-drinking behavior, we discuss the relationships between "active" and "passive" glucose entry to the brain, its connection to behavior-related metabolic activation, and the possible functional significance of these changes in behavioral regulation. These data provide solid experimental support for the "neuronal" hypothesis of neurovascular coupling, which postulates the critical role of neuronal activity in rapid regulation of vascular tone, local blood flow, and entry of glucose and oxygen to brain tissue to maintain active cellular metabolism. PMID:25490002

Kiyatkin, Eugene A; Wakabayashi, Ken T

2015-01-21

269

Glucose Uptake and Its Effect on Gene Expression in Prochlorococcus  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The marine cyanobacteria Prochlorococcus have been considered photoautotrophic microorganisms, although the utilization of exogenous sugars has never been specifically addressed in them. We studied glucose uptake in different high irradiance- and low irradiance-adapted Prochlorococcus strains, as well as the effect of glucose addition on the expression of several glucose-related genes. Glucose uptake was measured by adding radiolabelled glucose to Prochlorococcus cultures, followed by flow cy...

Go?mez-baena, Guadalupe; Lo?pez-lozano, Antonio; Gil-marti?nez, Jorge; Lucena, Jose? Manuel; Candau, Pedro; Garci?a-ferna?ndez, Jose? Manuel

2008-01-01

270

Performance of response scales of activity and functional measures of ankylosing spondylitis: numerical rating scale versus visual analog scale.  

Science.gov (United States)

The aim of this study was to compare the performance characteristics of two answer modalities for BASDAI and BASFI in patients with AS and to show validity and reliability of NRS in Turkish version. BASDAI and BASFI were simultaneously employed with a 10-cm VAS and an 11-point NRS. Internal consistency was assessed by using Cronbach's alpha coefficients. Testing was performed on baseline and next day under standardized conditions. Construct validity was determined by association of these measures with ASDAS, DFI, global disease activity, pain scores, ASQOL, HAQ, and SF-36. We also tested the ability of NRS version of BASDAI and BASFI to detect changes. A total 114 patients with AS according to the modified New York criteria were included. There was a good agreement between the total scores of each instrument on day 0 (ICC values were 0.894-0.934). Scores of the both answering modality of each instrument were correlated with ASDAS-CRP, and the scores of DFI, patient global assessment of disease activity and patient-reported pain, ASQOL, HAQ. Response time for BASDAI and BASFI was significantly shorter in NRS answer modality (P < 0.001). Our patients found NRS modality more comprehensible and easier to understand (P < 0.001). Our results showed the validity of NRS version of BASDAI and BASFI and provided an evidence for using these questionnaires in 11-point NRS answer modality in Turkish AS patients. PMID:23736275

Akad, Kivanc; Solmaz, Dilek; Sari, Ismail; Onen, Fatos; Akkoc, Nurullah; Akar, Servet

2013-10-01

271

The analog readout of the LHCb vertex detector and study of the measurement of the B$_s$ oscillation frequency  

CERN Document Server

The LHCb detector is one of the four experimental setups built to detect high-energy proton collisions to be produced by the Large Hadron Collider (LHC). Located at CERN (Geneva, Switzerland), the LHC machine and the LHCb experiment are expected to start in 2008, and will then operate for several years. Being the largest collider of its kind, the LHC will open the way to new investigations, in the very-high energies, but also in terms of statistics for the study of rare-phenomena and flavor physics. In this framework LHCb is dedicated to precise measurements of CP-violating and rare decays of beauty hadrons, in order to test (or over-constrain) the Standard Model of particle physics. From the hardware point of view, the construction of such detectors represents several challenges; one of them is the routing at a very high frequency of many signals in a harsh radiation environment. We designed to this purpose a hardware setup and a software filter which together reduce the cross-talk present in the readout of ...

Borel, J

2008-01-01

272

Glucose metabolism in diabetic blood vessels  

Energy Technology Data Exchange (ETDEWEB)

Since glycolysis appears to be coupled to active ion transport in vascular smooth muscle, alterations in glucose metabolism may contribute to cellular dysfunction and angiopathy in diabetes. Uptake and utilization of glucose were studied in perfused blood vessels in which pulsatile flow and perfusion pressure were similar to those measured directly in vivo. Thoracic aortae isolated from 8-wk alloxan diabetic (D) and nondiabetic control rabbits were cannulated, tethered, and perfused with oxygenated buffer containing 7 or 25 mM glucose and tracer amounts of glucose-U/sup -14/ C. Norepinephrine (NE) (10/sup -6/ M) and/or insulin (I) (150 ..mu..U/ml) and albumin (0.2%) were added. NE-induced tension development increased glucose uptake 39% and /sup 14/CO/sub 2/ and lactate production 2.3-fold. With 7 mM glucose, marked decreases in glucose uptake (74%), /sup 14/CO/sub 2/ (68%), lactate (30%), total tissue glycogen (75%), and tissue phospholipids (70%) were observed in D. Addition of I or elevation of exogenous glucose to 25 mM normalized glucose uptake, but had differential effects on the pattern of substrate utilization. Thus, in D, there was a marked depression of vascular glucose metabolism that was partially reversed by addition of low concentrations of insulin or D levels of glucose.

Brown, B.J.; Crass, M.F. III

1986-03-05

273

Glucose metabolism in diabetic blood vessels  

International Nuclear Information System (INIS)

Since glycolysis appears to be coupled to active ion transport in vascular smooth muscle, alterations in glucose metabolism may contribute to cellular dysfunction and angiopathy in diabetes. Uptake and utilization of glucose were studied in perfused blood vessels in which pulsatile flow and perfusion pressure were similar to those measured directly in vivo. Thoracic aortae isolated from 8-wk alloxan diabetic (D) and nondiabetic control rabbits were cannulated, tethered, and perfused with oxygenated buffer containing 7 or 25 mM glucose and tracer amounts of glucose-U-14 C. Norepinephrine (NE) (10-6 M) and/or insulin (I) (150 ?U/ml) and albumin (0.2%) were added. NE-induced tension development increased glucose uptake 39% and 14CO2 and lactate production 2.3-fold. With 7 mM glucose, marked decreases in glucose uptake (74%), 14CO2 (68%), lactate (30%), total tissue glycogen (75%), and tissue phospholipids (70%) were observed in D. Addition of I or elevation of exogenous glucose to 25 mM normalized glucose uptake, but had differential effects on the pattern of substrate utilization. Thus, in D, there was a marked depression of vascular glucose metabolism that was partially reversed by addition of low concentrations of insulin or D levels of glucose

274

Glucose kinetics in infants of diabetic mothers  

Energy Technology Data Exchange (ETDEWEB)

Glucose kinetic studies were performed to define the glucose turnover rate with 78% enriched D-(U-13C) glucose by the prime constant infusion technique at less than or equal to 6 hours of age in nine infants of diabetic mothers (four insulin-dependent and five chemical diabetic patients) at term. Five normal infants were studied as control subjects. All infants received 0.9% saline intravenously during the study with the tracer. Fasting plasma glucose, insulin, and glucose13/12C ratios were measured during the steady state, and the glucose turnover rate was derived. The average plasma glucose concentration was similar during the steady state in the infants of the diabetic mothers and in the control infants, and the glucose turnover rate was not significantly different among the groups: 2.3 +/- 0.6 mg . kg-1 min-1 in infants of insulin-dependent diabetic patients; 2.4 +/- 0.4 mg . kg-1 min-1 in infants of chemical diabetic patients; and 3.2 +/- 0.3 mg . kg-1 min-1 in the control subjects. Good control of maternal diabetes evidenced by the normal maternal hemoglobin A1c and plasma glucose concentration at delivery and cord plasma glucose concentration resulted in glucose kinetic values in the infants of diabetic mothers that were indistinguishable from those of control subjects. The data further support the importance of good control of the diabetic state in the pregnant woman to minimize or prevent neonatal hypoglycemia.

Cowett, R.M.; Susa, J.B.; Giletti, B.; Oh, W.; Schwartz, R.

1983-08-01

275

Glucose promotes intracellular sequestration of manganese in pancreatic beta-cells.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

D-glucose reduces the outflow of manganese from pancreatic beta-cells in analogy to what has previously been reported for 45Ca. The decrease can be accounted for by an enhanced intracellular sequestration. The effect of D-glucose on manganese fluxes seems to be restricted to inhibition of the efflux; no stimulation of the influx being noted. The glucose-dependence of manganese uptake is hyperbolic with half maximal stimulation between 5 and 6 mM D-glucose.

Rorsman, P.

1982-01-01

276

Ionogel-biosensor: novel ionogels based on ionic liquids as a platform to measure enzyme activity of glucose oxdase in real time  

Digital Repository Infrastructure Vision for European Research (DRIVER)

It is estimated that there are 170 million diabetics worldwide, and the number continues to rise alarmingly. The management of diabetes is therefore critical to future society, and this is driving demand for point-of-care (POC) glucose biosensors, and they play a central role in the management blood sugar levels in patients with diabetes. Glucose Oxidase (GOx) is a biorecognition enzyme, which recognises the glucose molecule and acts as a catalyst to produce gluconic acid and hydrogen peroxid...

Barry, Caroline; Byrne, Robert; Benito-lopez, Fernando; Diamond, Dermot

2010-01-01

277

FRET-based glucose monitoring for bioprocessing  

Science.gov (United States)

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.

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

2006-02-01

278

Analogous: Digital / Analogue Metaphors.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

When discussing our understanding of the world, the term ‘analogue’ has become shorthand for anything not digital, and has become an analogy of its own. ‘Digital’ has also become an analogy for anything requiring a computer. This essay starts to investigate some of the analogies of analogue and digital media to reveal the complexity of thinking about animation.

Carpenter, Ele

2011-01-01

279

Uptake of 13C-glucose by cell suspensions of carrot (Daucus carota) measured by in vivo NMR: Cycling of triose, pentose- and hexose-phosphates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

After a lag phase of 2 days, batch-grown cells of carrot (Daucus carota L.) cv. Flakkese entered the exponential growth phase and started to accumulate sucrose and hexoses. Short-term feeding 13C-glucose in this period resulted in only minor labelling of sucrose or fructose. CO2 production from [1-13C]- and [6-13C]-glucose revealed, that at least 40?f the added glucose passed through the oxidative pentose phosphate pathway (OPPP), up to 40?hrough glycolysis leaving only minor 13C-glucose ...

Krook, J.; Vreugdenhil, D.; Dijkema, C.; Plas, L. H. W.

2000-01-01

280

Accuracy of different methods for blood glucose measurement in critically ill patients / Acurácia de diferentes métodos para mensuração de glicemia em pacientes graves  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese CONTEXTO E OBJETIVO: Apesar de glicosímetros não serem validados para unidades de terapia intensiva (UTI), seu uso é corriqueiro. O objetivo foi avaliar a acurácia e concordância clínica entre a glicemia arterial por colorimetria (glicA-lab), glicemias capilar (glicC-fita) e arterial (glicA-fita) po [...] r glicosimetria, e venosa central por colorimetria (glicV-lab). TIPO DE ESTUDO E LOCAL: Estudo transversal realizado em hospital universitário. MÉTODO: Foram incluídos 40 pacientes com choque séptico e indivíduos estáveis, sem infecção. A correlação entre medidas foi avaliada tanto na amostra global quanto nos subgrupos em uso de noradrenalina e com sinais de hipoperfusão tecidual. RESULTADOS: A glicC-fita mostrou pior correlação (r = 0,8289) e concordância (-9,87 ± 31,76). Esta superou os limites aceitáveis de variação do Clinical and Laboratory Standards Institute em 23,7% dos casos, sendo maior que a glicA-lab em 90% das vezes. A glicA-fita teve a melhor correlação (r = 0,9406), com concordância de -6,75 ± 19,07 e variação significativa em 7,9%. Para a glicV-lab, obteve-se r = 0,8549, concordância de -4,20 ± 28,37 e variação significativa em 15,7%. Variação significativa foi mais frequente em pacientes com noradrenalina (36,4% versus 6,3%, P = 0,03), mas não nos com hipoperfusão. Houve discordância de conduta clínica em 25%, 22,5% e 15% dos casos para glicC-fita, glicV-lab e glicA-fita, respectivamente. CONCLUSÃO: O uso de glicC-fita deveria ser evitado, principalmente se há uso de noradrenalina. Geralmente, este método superestima a glicemia real e acarreta erros de conduta. REGISTRO DO ENSAIO CLÍNICO: ACTRN12608000513314 (registrado como estudo observacional transversal). Abstract in english CONTEXT AND OBJECTIVE: Although glucometers have not been validated for intensive care units, they are regularly used. The aim of this study was to compare and assess the accuracy and clinical agreement of arterial glucose concentration obtained using colorimetry (Agluc-lab), capillary (Cgluc-strip) [...] and arterial (Agluc-strip) glucose concentration obtained using glucometry and central venous glucose concentration obtained using colorimetry (Vgluc-lab). DESIGN AND SETTING: Cross-sectional study in a university hospital. METHOD: Forty patients with septic shock and stable individuals without infection were included. The correlations between measurements were assessed both in the full sample and in subgroups using noradrenalin and presenting signs of tissue hypoperfusion. RESULTS: Cgluc-strip showed the poorest correlation (r = 0.8289) and agreement (-9.87 ± 31.76). It exceeded the limits of acceptable variation of the Clinical and Laboratory Standards Institute in 23.7% of the cases, and was higher than Agluc-lab in 90% of the measurements. Agluc-strip showed the best correlation (r = 0.9406), with agreement of -6.75 ± 19.07 and significant variation in 7.9%. For Vgluc-lab, r = 0.8549, with agreement of -4.20 ± 28.37 and significant variation in 15.7%. Significant variation was more frequent in patients on noradrenalin (36.4% versus 6.3%; P = 0.03) but not in the subgroup with hypoperfusion. There was discordance regarding clinical management in 25%, 22% and 15% of the cases for Cgluc-strip, Vgluc-lab and Agluc-strip, respectively. CONCLUSION: Cgluc-strip should be avoided, particularly if noradrenalin is being used. This method usually overestimates the true glucose levels and gives rise to management errors. CLINICAL TRIAL REGISTRATION: ACTRN12608000513314 (registered as an observational, cross-sectional study).

Sérgio Antônio, Pulzi Júnior; Murillo Santucci Cesar de, Assunção; Bruno Franco, Mazza; Haggéas da Silveira, Fernandes; Mirian, Jackiu; Flávio Geraldo Resende, Freitas; Flávia Ribeiro, Machado.

2009-09-01

 
 
 
 
281

Alternations in salivary glucose during ramadan fasting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

During the holly month of Ramadan, Muslims fast every day from dawn to sunset. Although the effect of Ramadan fasting on general health has been widely studied, the impact of fasting on oral health and possible changes in salivary biochemicals, such as glucose, has not received much attentiom. The aim of our study was to evaluate the influence of fasting on the level of glucose in the saliva of healthy individuals. Salivary glucose was measured using an enzymatic method based on oxidation of ...

Ali Erfani; Reyhaneh Sariri; Abdolali Varasteh

2010-01-01

282

The Impact of Melatonin on Glucose Homeostasis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objective: Melatonin is a pineal product mainly charged with the maintenance of antioxidant conditions in human. This study is performed to identify the short-term effect of melatonin on glucose homeostasis in diabetic patients. Materials and Methods: Melatonin and placebo were given perorally to sixty patients. Blood glucose and insulin levels were measured with constant intervals. Results: No significant correlation was found among the levels of glucose, insulin and HOMA-IR index at any ti...

Zeynep Arzu Ye?in; Rüya Mutluay; ?ehri Elbeg; Resul Karaku?; Nuri Çak?r

2009-01-01

283

pH-Insensitive Glucose Indicators  

Digital Repository Infrastructure Vision for European Research (DRIVER)

There is an urgent need for developing a biosensor that can real-time and noninvasively determine glucose concentration within living cells. In our previous study, we have engineered a glucose indicator protein (GIP) that can provide continuous glucose monitoring through a conformation change-induced Förster resonance-energy transfer measurement. Because of the pH-sensitivity of the fluorescent proteins used in the GIP construction, the GIP made from these fluorescent proteins is less tolera...

Garrett, Jared R.; Wu, Xinxin; Jin, Sha; Ye, Kaiming

2008-01-01

284

Structured Analog CMOS Design  

CERN Document Server

Structured Analog CMOS Design describes a structured analog design approach that makes it possible to simplify complex analog design problems and develop a design strategy that can be used for the design of large number of analog cells. It intentionally avoids treating the analog design as a mathematical problem, developing a design procedure based on the understanding of device physics and approximations that give insight into parameter interdependences. The proposed transistor-level design procedure is based on the EKV modeling approach and relies on the device inversion level as a fundament

Stefanovic, Danica

2008-01-01

285

A multistep algorithm for processing and calibration of microdialysis continuous glucose monitoring data  

DEFF Research Database (Denmark)

The deviation of continuous subcutaneous glucose monitoring (CGM) data from reference blood glucose measurements is substantial, and adequate signal processing is required to reduce the discrepancy between subcutaneous glucose and blood glucose values. The purpose of this study was to develop a multistep algorithm for the processing and calibration of continuous subcutaneous glucose monitoring data with high accuracy and short delay. Algorithm

Mahmoudi, Zeinab; Dencker Johansen, Mette

2013-01-01

286

Four grams of glucose  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Four grams of glucose circulates in the blood of a person weighing 70 kg. This glucose is critical for normal function in many cell types. In accordance with the importance of these 4 g of glucose, a sophisticated control system is in place to maintain blood glucose constant. Our focus has been on the mechanisms by which the flux of glucose from liver to blood and from blood to skeletal muscle is regulated. The body has a remarkable capacity to satisfy the nutritional need for glucose, while ...

Wasserman, David H.

2008-01-01

287

The BIGTT test : a novel test for simultaneous measurement of pancreatic beta-cell function, insulin sensitivity, and glucose tolerance  

DEFF Research Database (Denmark)

Insulin resistance and impaired beta-cell function are key elements in the pathogenesis of type 2 diabetes. We aimed to develop valid algorithms for estimation of the insulin sensitivity index (S(I)) and acute insulin response (AIR) derived from simple and cheap physiological measurements that could be used in large-scale metabolic, genetic, and epidemiological studies.

Hansen, Torben; Drivsholm, Thomas

2007-01-01

288

Alternations in salivary glucose during ramadan fasting  

Directory of Open Access Journals (Sweden)

Full Text Available During the holly month of Ramadan, Muslims fast every day from dawn to sunset. Although the effect of Ramadan fasting on general health has been widely studied, the impact of fasting on oral health and possible changes in salivary biochemicals, such as glucose, has not received much attentiom. The aim of our study was to evaluate the influence of fasting on the level of glucose in the saliva of healthy individuals. Salivary glucose was measured using an enzymatic method based on oxidation of glucose by glucoseoxidase followed by determination of resulting H2O2 in the presence of peroxidase. A reduction in mean concentration of glucose was observed in the saliva of all fasting subjects as compared to the control group. It was concluded that reduction in salivary glucose is mostly due to reduced food intake and may be beneficial to dental health.

Ali Erfani

2010-07-01

289

Radiometric assays for glycerol, glucose, and glycogen  

Energy Technology Data Exchange (ETDEWEB)

We have developed radiometric assays for small quantities of glycerol, glucose and glycogen, based on a technique described by Thorner and Paulus for the measurement of glycerokinase activity. In the glycerol assay, glycerol is phosphorylated with (32P)ATP and glycerokinase, residual (32P)ATP is hydrolyzed by heating in acid, and free (32P)phosphate is removed by precipitation with ammonium molybdate and triethylamine. Standard dose-response curves were linear from 50 to 3000 pmol glycerol with less than 3% SD in triplicate measurements. Of the substances tested for interference, only dihydroxyacetone gave a slight false positive signal at high concentration. When used to measure glycerol concentrations in serum and in media from incubated adipose tissue, the radiometric glycerol assay correlated well with a commonly used spectrophotometric assay. The radiometric glucose assay is similar to the glycerol assay, except that glucokinase is used instead of glycerokinase. Dose response was linear from 5 to 3000 pmol glucose with less than 3% SD in triplicate measurements. Glucosamine and N-acetylglucosamine gave false positive signals when equimolar to glucose. When glucose concentrations in serum were measured, the radiometric glucose assay agreed well with hexokinase/glucose-6-phosphate dehydrogenase (H/GDH)-based and glucose oxidase/H2O2-based glucose assays. The radiometric method for glycogen measurement incorporates previously described isolation and digestion techniques, followed by the radiometric assay of free glucose. When used to measure glycogen in mouse epididymal fat pads, the radiometric glycogen assay correlated well with the H/GDH-based glycogen assay. All three radiometric assays offer several practical advantages over spectral assays.

Bradley, D.C.; Kaslow, H.R. (Univ. of Southern California School of Medicine, Los Angeles (USA))

1989-07-01

290

Radiometric assays for glycerol, glucose, and glycogen  

International Nuclear Information System (INIS)

We have developed radiometric assays for small quantities of glycerol, glucose and glycogen, based on a technique described by Thorner and Paulus for the measurement of glycerokinase activity. In the glycerol assay, glycerol is phosphorylated with [32P]ATP and glycerokinase, residual [32P]ATP is hydrolyzed by heating in acid, and free [32P]phosphate is removed by precipitation with ammonium molybdate and triethylamine. Standard dose-response curves were linear from 50 to 3000 pmol glycerol with less than 3% SD in triplicate measurements. Of the substances tested for interference, only dihydroxyacetone gave a slight false positive signal at high concentration. When used to measure glycerol concentrations in serum and in media from incubated adipose tissue, the radiometric glycerol assay correlated well with a commonly used spectrophotometric assay. The radiometric glucose assay is similar to the glycerol assay, except that glucokinase is used instead of glycerokinase. Dose response was linear from 5 to 3000 pmol glucose with less than 3% SD in triplicate measurements. Glucosamine and N-acetylglucosamine gave false positive signals when equimolar to glucose. When glucose concentrations in serum were measured, the radiometric glucose assay agreed well with hexokinase/glucose-6-phosphate dehydrogenase (H/GDH)-based and glucose oxidase/H2O2-based glucose assays. The radiometric method for glycogen measurement incorporates previously described isolation and digestion techniy described isolation and digestion techniques, followed by the radiometric assay of free glucose. When used to measure glycogen in mouse epididymal fat pads, the radiometric glycogen assay correlated well with the H/GDH-based glycogen assay. All three radiometric assays offer several practical advantages over spectral assays

291

Prognostic significance of the Complex "Visceral Adiposity Index" vs. simple anthropometric measures: Tehran lipid and glucose study  

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Abstract Background Visceral adiposity index (VAI) has recently been suggested to be used as a surrogate of visceral adiposity. We examined if VAI could improve predictive performances for CVD of the Framingham's general CVD algorithm (a multivariate model incorporating established CVD risk factors). We compared the predictive abilities of the VAI with those of simple anthropometric measures i.e. BMI, waist-to-height ratio (WHtR) or waist-to-hip ratio (WHpR). Design an...

Mohammadreza Bozorgmanesh; Farzad Hadaegh; Davoud Khalili; Prof Azizi

2012-01-01

292

DXA-measured visceral adipose tissue predicts impaired glucose tolerance and metabolic syndrome in obese Caucasian and African-American women.  

Science.gov (United States)

Background/Objectives:New methods to measure visceral adipose tissue (VAT) by dual-energy X-ray absorptiometry (DXA) may help discern sex, race and phenotype differences in the role of VAT in cardiometabolic risk. This study was designed (1) to compare relationships of DXA-VAT, anthropometric and body composition variables with cardiometabolic risk factors in obese women; (2) to determine which variables most robustly predict impaired glucose tolerance (IGT) and metabolic syndrome (MetSx); and (3) to determine thresholds for DXA-VAT by race.Subjects/Methods:VAT mass (g) and volume (cm(3)) were measured in 229 obese (body mass index (BMI), 30-49.9) women aged 21-69 years of European-American (EA=123) and African-American (AA=106) descent using the CoreScan algorithm on a Lunar iDXA scanner. Linear regression modeling and areas under the curve (AUC of ROC (receiver operating characteristic) curves) compared relationships with cardiometabolic risk. Bootstrapping with LASSO (least absolute shrinkage and selection operator) regression modeling determined thresholds and predictors of IGT and MetSx.Results:DXA-VAT explained more of the variance in triglycerides, blood pressure, glucose and homeostatic model assessment-insulin resistance (HOMA-IR) compared with anthropometric and other body composition variables. DXA-VAT also had the highest AUC for IGT (0.767) and MetSx (0.749). Including race as a variable and the interaction between VAT and race in modeling did not significantly change the results. Thresholds at which the probability of developing IGT or MetSx was?50% were determined separately for AA women (IGT: 2120?cm(3); MetSx: 1320?cm(3)) and EA women (IGT: 2550?cm(3); MetSx: 1713?cm(3)). The odds for IGT or MetSx were fourfold greater with each standard deviation increase in DXA-VAT.Conclusions:DXA-VAT provides robust clinical information regarding cardiometabolic risk in AA and EA obese women and offers potential utility in the risk reduction interventions.European Journal of Clinical Nutrition advance online publication, 22 October 2014; doi:10.1038/ejcn.2014.227. PMID:25335442

Bi, X; Seabolt, L; Shibao, C; Buchowski, M; Kang, H; Keil, C D; Tyree, R; Silver, H J

2014-10-22

293

Isolation of a Mutant of Kluyveromyces marxianus Resistant to Glucose Repression  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, we isolated a mutant of Kluyveromyces marxianus resistance to glucose repression. To screen for depression mutants, the strains were treated with UV rays. Fifteen resistant mutant strains were isolated. The mutants were further screened for glucose-repression-resistant mutants in the presence of 2-deoxy-D-glucose, an analog to glucose and lactose as the sole carbon source. In this condition, one glucose-repression-resistant mutant was isolated. The enzyme activity in this mutant strain and the wild type strain was compared using different mediums containing 4% of each lactose and glucose and 2% glucose+2% lactose. The results demonstrated significant decreasing in glucose repression in the mutant strain as compared to the wild type. This mutant was unable to grow anaerobically on glucose in present of antimycin A, the property of rag1 mutants. This mutant is, therefore, capable of constitutive expression of ?-galactosidase, which makes it suitable for industrial purposes.

Moeini Hassan

2006-01-01

294

The effect of glucose stimulation on 45calcium uptake of rat pancreatic islets and their total calcium content as measured by a fluorometric micro-method  

International Nuclear Information System (INIS)

Glucose-stimulated 45calcium uptake and total calcium content of rat pancreatic islets has been studied, using a new fluorometric micro-method to estimate total calcium. Extracellular calcium was separated from incubated tissue by a rapid micro-filtration procedure. Islets incubated up to 60 min with calcium chloride 2.5 mmol/l and glucose 2.5 mmol/l maintained the same calcium content (670 +- 7.5 pmol/?g DNA). When the glucose concentration was raised to 15 mmol/l no change in the total calcium content could be detected. On incubation with glucose 2.5 mmol/l in the absence of calcium, the calcium content decreased to 488 +- 27 pmol/?g DNA. On incubation with 45calcium chloride 2.5 mmol/l for 5 or 30 min at 2.5 mmol/l glucose, islets exchanged 21 +- 2 and 28 +- 1% of their total calcium content and, at 15 mmol/l glucose, 30 +- 3 and 45 +- 2%, respectively. Thus, islet calcium has a high turn-over rate. Glucose stimulation results in an increase of the calcium uptake without enhancing the total calcium content and hence must increase the calcium-exchangeable pool. (orig.)

295

Hyperglycemia (High Blood Glucose)  

Medline Plus

Full Text Available ... Blood Pressure Physical Activity High Blood Glucose My Health Advisor Tools To Know Your Risk Alert Day ... DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & ...

296

Hyperglycemia (High Blood Glucose)  

Medline Plus

Full Text Available ... Español Hyperglycemia (High Blood Glucose) Hyperglycemia is the technical term for high blood glucose (blood sugar). High ... Food Recipes Planning Meals What Can I Eat Weight Loss Fitness In My Community Calendar of Events ...

297

Hyperglycemia (High Blood Glucose)  

Medline Plus

Full Text Available ... Español Hyperglycemia (High Blood Glucose) Hyperglycemia is the technical term for high blood glucose (blood sugar). High ... a Difference About Us Who We Are Careers Contact Us Policies Corporate Support Newsroom Press Releases For ...

298

Hyperglycemia (High Blood Glucose)  

Medline Plus

Full Text Available ... Nephropathy) Gastroparesis Mental Health Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & More Oral Health & Hygiene Women ... Living With Diabetes > Treatment and Care > Blood Glucose Testing Share: Print Page Text Size: A A A ...

299

Continuous Glucose Monitoring  

Science.gov (United States)

... RT-CGM has some drawbacks: Costs more than blood glucose meter testing May not be covered by health insurance Is not as accurate as standard blood glucose meters Who should use CGM? The Endocrine Society’s expert ...

300

Fructose vs. Glucose  

Science.gov (United States)

... right-hand corner of the player. Fructose vs. Glucose HealthDay December 12, 2014 Related MedlinePlus Page Carbohydrates ... make you hungrier than eating foods that contain glucose? A new study suggests fructose may rev up ...

 
 
 
 
301

Diabetes prediction, lipid accumulation product, and adiposity measures; 6-year follow-up: Tehran lipid and glucose study  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The body mass index (BMI is the most commonly used marker for evaluating obesity related risks, however, central obesity measures have been proposed to be more informative. Lipid accumulation product (LAP is an alternative continuous index of lipid accumulation, which is computed from waist circumference (WC, cm and triglycerides (TGs, mmol/l: (WC-65 ×TG (men and (WC-58 ×TG (women. We sought in this study to assess if LAP can outperform BMI, waist-to-height-ratio (WHtR, or waist-to-hip-ratio (WHpR in identifying prevalent and predicting incident diabetes. Results The cross-sectional analyses were performed on a sample included 3,682 men and 4,989 women who were not pregnant, aged ? 20 years. According to the age (? 50 and For longitudinal analyses, a total of 5,018 non-diabetic subjects were followed for ~6 years. The ORs of BMI, WHpR, and WHtR were the same as those of LAP in both sexes and across age groups; except in young men where LAP was superior to the BMI. AROCs of LAP were relatively the same as anthropometric adiposity measures. Conclusions LAP was a strong predictor of diabetes and in young individuals had better predictability than did BMI; it was, however, similar to WHpR and WHtR in prediction of incident diabetes.

Azizi Fereidoun

2010-05-01

302

Analog synthetic biology.  

Science.gov (United States)

We analyse the pros and cons of analog versus digital computation in living cells. Our analysis is based on fundamental laws of noise in gene and protein expression, which set limits on the energy, time, space, molecular count and part-count resources needed to compute at a given level of precision. We conclude that analog computation is significantly more efficient in its use of resources than deterministic digital computation even at relatively high levels of precision in the cell. Based on this analysis, we conclude that synthetic biology must use analog, collective analog, probabilistic and hybrid analog-digital computational approaches; otherwise, even relatively simple synthetic computations in cells such as addition will exceed energy and molecular-count budgets. We present schematics for efficiently representing analog DNA-protein computation in cells. Analog electronic flow in subthreshold transistors and analog molecular flux in chemical reactions obey Boltzmann exponential laws of thermodynamics and are described by astoundingly similar logarithmic electrochemical potentials. Therefore, cytomorphic circuits can help to map circuit designs between electronic and biochemical domains. We review recent work that uses positive-feedback linearization circuits to architect wide-dynamic-range logarithmic analog computation in Escherichia coli using three transcription factors, nearly two orders of magnitude more efficient in parts than prior digital implementations. PMID:24567476

Sarpeshkar, R

2014-03-28

303

Nonvolatile Analog Memory  

Science.gov (United States)

A nonvolatile analog memory uses pairs of ferroelectric field effect transistors (FFETs). Each pair is defined by a first FFET and a second FFET. When an analog value is to be stored in one of the pairs, the first FFET has a saturation voltage applied thereto, and the second FFET has a storage voltage applied thereto that is indicative of the analog value. The saturation and storage voltages decay over time in accordance with a known decay function that is used to recover the original analog value when the pair of FFETs is read.

MacLeod, Todd C. (Inventor)

2007-01-01

304

Prognostic significance of the Complex "Visceral Adiposity Index" vs. simple anthropometric measures: Tehran lipid and glucose study  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Visceral adiposity index (VAI has recently been suggested to be used as a surrogate of visceral adiposity. We examined if VAI could improve predictive performances for CVD of the Framingham's general CVD algorithm (a multivariate model incorporating established CVD risk factors. We compared the predictive abilities of the VAI with those of simple anthropometric measures i.e. BMI, waist-to-height ratio (WHtR or waist-to-hip ratio (WHpR. Design and methods In a nine-year population-based follow-up, 6 407 (2 778 men participants, free of CVD at baseline, aged ? 30 years were eligible for the current analysis. The risk of CVD was estimated by incorporating VAI, BMI, WHpR, and WHtR, one at a time, into multivariate accelerated failure time models. Results We documented 534 CVD events with the annual incidence rate (95%CIs being 7.3 (6.4-8.3 among women and 13.0 (11.7-14.6 among men. Risk of future CVD increased with increasing levels of VAI among both men and women. VAI was associated with multivariate-adjusted increased risk of incident CVD among women. However, the magnitude of risk conferred by VAI was not significantly higher than those conferred by BMI, WHpR, or WHtR. Among men, after adjustment for established CVD risk factors, VAI was no longer associated with increased risk of CVD. VAI failed to add to the predictive ability of the Framingham general CVD algorithm. Conclusions Using VAI instead of simple anthropometric measures may lead to loss of much information needed for predicting incident CVD.

Mohammadreza Bozorgmanesh

2012-03-01

305

Hyperglycemia (High Blood Glucose)  

Medline Plus

Full Text Available ... Carbohydrate Counting Make Your Carbs Count Glycemic Index Low-Calorie Sweeteners Sugar and Desserts Fitness Exercise & Type ... Checking Your Blood Glucose A1C and eAG Hypoglycemia (Low blood glucose) Hyperglycemia (High blood glucose) Dawn Phenomenon ...

306

Imaging atherosclerosis in the carotid arteries with F-18-Fluoro-2-deoxy-D-glucose positron emission tomography: effect of imaging time after injection on quantitative measurement  

International Nuclear Information System (INIS)

To compare F-18-fluoro-2-deoxy-D-glucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) imaging at two different circulation times after injection of F-18 FDG in order to measure atherosclerosis in carotid arteries. We assessed 12 patients with recent symptomatic plaques in the carotid arteries. F-18 FDG PET/CT carotid plaque imaging was performed for 20 min at 2 h after F-18 FDG injection in five patients and at 3 h in seven patients. We measured vessel wall uptake using the maximal standardized uptake value (SUV), and the mean and maximal blood target-to-background ratios (TBR) of the symptomatic carotid arteries. Blood pool activity (BPA) was measured as the mean SUV of the superior vena cava (SVC) and jugular vein of these 12 patients, and in 14 age-and gender-matched patients who underwent whole-body F-18 FDG PET/CT examinations 1 h after injection. F-18 FDG PET/CT revealed visible F-18 FDG uptake in all patients with symptomatic carotid plaques. Maximal SUV did not differ between groups evaluated at 2 h and 3 h (2.62±0.45 vs 3.00±0.85, p=0.335). However mean (2.04±0.22 vs 3.54±0.62, p<0.05) and maximal (1.65±0.15 vs 2.70±0.42, p<0.05) TBR values that were normalized to BPA in the SVC differ significantly. Symptomatic carotid plaques are visualized for a relatively short period of imaging time on ?1-h PET/CT images. Quantitative parameters of atherosclerotic carotid arteries are preserved or even increased over time, whereas those ofreased over time, whereas those of blood pools are decreased

307

Imaging atherosclerosis in the carotid arteries with F-18-Fluoro-2-deoxy-D-glucose positron emission tomography: effect of imaging time after injection on quantitative measurement  

Energy Technology Data Exchange (ETDEWEB)

To compare F-18-fluoro-2-deoxy-D-glucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) imaging at two different circulation times after injection of F-18 FDG in order to measure atherosclerosis in carotid arteries. We assessed 12 patients with recent symptomatic plaques in the carotid arteries. F-18 FDG PET/CT carotid plaque imaging was performed for 20 min at 2 h after F-18 FDG injection in five patients and at 3 h in seven patients. We measured vessel wall uptake using the maximal standardized uptake value (SUV), and the mean and maximal blood target-to-background ratios (TBR) of the symptomatic carotid arteries. Blood pool activity (BPA) was measured as the mean SUV of the superior vena cava (SVC) and jugular vein of these 12 patients, and in 14 age-and gender-matched patients who underwent whole-body F-18 FDG PET/CT examinations 1 h after injection. F-18 FDG PET/CT revealed visible F-18 FDG uptake in all patients with symptomatic carotid plaques. Maximal SUV did not differ between groups evaluated at 2 h and 3 h (2.62{+-}0.45 vs 3.00{+-}0.85, p=0.335). However mean (2.04{+-}0.22 vs 3.54{+-}0.62, p<0.05) and maximal (1.65{+-}0.15 vs 2.70{+-}0.42, p<0.05) TBR values that were normalized to BPA in the SVC differ significantly. Symptomatic carotid plaques are visualized for a relatively short period of imaging time on {>=}1-h PET/CT images. Quantitative parameters of atherosclerotic carotid arteries are preserved or even increased over time, whereas those of blood pools are decreased

Oh, Min Young; Kim, Ji Young; Shin, Kwang Ho; Park, Seol Hoon; Ryu, Jin Sook; Kim, Jae Seung; Kim, Hye Jin; Kang, Dong Wha; Moon, Dae Hyuk [University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of)

2010-12-15

308

Detecting early kidney damage in horses with colic by measuring matrix metalloproteinase -9 and -2, other enzymes, urinary glucose and total proteins  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The aim of the study was to investigate urine matrix metalloproteinase (MMP-2 and -9 activity, alkaline phosphatase/creatinine (U-AP/Cr and gamma-glutamyl-transpeptidase/creatinine (U-GGT/Cr ratios, glucose concentration, and urine protein/creatinine (U-Prot/Cr ratio and to compare data with plasma MMP-2 and -9 activity, cystatin-C and creatinine concentrations in colic horses and healthy controls. Horses with surgical colic (n = 5 were compared to healthy stallions (n = 7 that came for castration. Blood and urine samples were collected. MMP gelatinolytic activity was measured by zymography. Results We found out that horses with colic had significantly higher urinary MMP-9 complex and proMMP-9 activities than horses in the control group. Colic horses also had higher plasma MMP-2 activity than the control horses. Serum creatinine, although within reference range, was significantly higher in the colic horses than in the control group. There was no significant increase in urinary alkaline phosphatase, gamma-glutamyltranspeptidase or total proteins in the colic horses compared to the control group. A human cystatin-C test (Dako Cytomation latex immunoassay® based on turbidimetry did not cross react with equine cystatin-C. Conclusion The results indicate that plasma MMP-2 may play a role in the pathogenesis of equine colic and urinary MMP-9 in equine kidney damage.

Salonen Hanna

2007-01-01

309

Role of oxygen vs. glucose in energy metabolism in a mammary carcinoma perfused ex vivo: direct measurement by 31P NMR.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The role of glycolysis vs. respiration in tumor energy metabolism has been studied, to date, primarily in vitro by using single cells, multicellular spheroids, or tissue slices. With the advent of in vivo NMR spectroscopy, several investigators have shown that tumor energy status depends on its blood flow. Since manipulation of blood flow alters both oxygen and glucose delivery to a solid tumor, these studies have not been able to separate the relative contribution of oxygen vs. glucose in en...

Eskey, C. J.; Koretsky, A. P.; Domach, M. M.; Jain, R. K.

1993-01-01

310

Diabetic hypoglycemia: a case of different capillary blood glucose readings from two identical glucose meters  

Directory of Open Access Journals (Sweden)

Full Text Available A 61-year old male with a 54-year history of type 1 diabetes, hypertension and ischemic heart disease became drowsy while attending the hospital diabetes outpatient department. Capillary blood glucose was measured at 3.8 mmol/l and he was treated for presumed hyopglycemia with a glucose drink followed by intravenous dextrose; 25 minutes later, a different glucose meter was used to record a capillary blood glucose value of 7.8 mmol/l. Because recovery was slow, the patient was transferred to the Emergency Department. A laboratory blood glucose result from a sample taken 5 minutes before the second glucose meter measurement reported levels of 2.5 mmol/l. This case illustrates how two blood glucose meters of the same make and model can give significantly different results; other sources of diagnostic inaccuracy are discussed. Clinical suspicion of hypoglycemia requires prompt treatment whether or not capillary blood glucose can be measured immediately. When possible, confirmatory laboratory measurement of venous blood glucose should be obtained in cases of suspected severe hypoglycemia.

Alex J Graveling

2010-10-01

311

Total and high molecular weight (HMW) adiponectin levels and measures of glucose and lipid metabolism following pioglitazone treatment in a randomized placebo-controlled study in polycystic ovary syndrome  

DEFF Research Database (Denmark)

OBJECTIVE: Recent studies suggested that the effect of adiponectin on insulin-stimulated glucose metabolism is mediated primarily by the high molecular weight (HMW) form of adiponectin. In the present study we evaluated total and HMW adiponectin in polycystic ovary syndrome (PCOS) patients and controls and examined possible mechanisms for increased insulin sensitivity during pioglitazone treatment. STUDY SUBJECTS: Thirty PCOS patients randomized to pioglitazone, 30 mg/day, or placebo for 16 weeks and 14 weight-matched healthy females were studied. DESIGN: Total and HMW adiponectin levels were measured, and euglycaemic hyperinsulinaemic clamps and indirect calorimetry were performed. Delta-values denoted changes during pioglitazone treatment (16 weeks--basal). RESULTS: Pretreatment adiponectin levels were decreased in PCOS patients vs. controls (P < 0.05), whereas no significant differences were found in HMW adiponectin levels. Following pioglitazone treatment, total and HMW adiponectin increased (all P < 0.05), whereas no significant changes were observed with placebo. Delta-total adiponectin levels correlated positively with the rate of Delta-insulin-stimulated glucose disposal (R(d)) (r = 0.89) and Delta-oxidative glucose metabolism (r = 0.71) and inversely with Delta-fasting free fatty acid (FFA) levels (r = -0.69) and Delta-lipid oxidation (r = -0.73) during insulin stimulation (all P < 0.01). Weaker correlations were found between Delta-HMW adiponectin levels and Delta-measures of glucose and lipid metabolism during insulin stimulation than with Delta-total adiponectin. CONCLUSION: A close correlation between increased total adiponectin levels and increased insulin-stimulated glucose metabolism during pioglitzone treatment supports the hypothesis that the insulin-sensitizing effect of pioglitazone in PCOS is, at least in part, mediated by adiponectin. Measures of changes in HMW adiponectin did not add further information to this relationship Udgivelsesdato: 2008/2

Glintborg, D.; Frystyk, J.

2008-01-01

312

Hydraulic Capacitor Analogy  

Science.gov (United States)

Students have difficulties in physics because of the abstract nature of concepts and principles. One of the effective methods for overcoming students' difficulties is the use of analogies to visualize abstract concepts to promote conceptual understanding. According to Iding, analogies are consistent with the tenets of constructivist learning…

Baser, Mustafa

2007-01-01

313

2-deoxy-glucose-6-phosphate utilization in the study of glucose-6-phosphate dehydrogenase mosaicism.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The electrophoretic difference between normal glucose-6-phosphate dehydrogenase (G6PD) and two common variants (G6PD A and G6PD A-) has made the G6PD enzyme system very useful for genetic studies and for investigation on the clonal origin of tumors. This approach has not been possible for another common variant, G6PD mediterranean, which has a normal electrophoretic pattern. The different utilization of 2-deoxy-glucose-6-phosphate (2dG6P), an analog of the normal substrate, by the normal enzy...

Ferraris, A. M.; Giuntini, P.; Galiano, S.; Gaetani, G. F.

1981-01-01

314

Glucose turnover, gluconeogenesis from glycerol, and estimation of net glucose cycling in cancer patients  

International Nuclear Information System (INIS)

A double isotope method was used in patients with progressive malignancy and in control patients to measure: glucose turnover, conversion rate of carbon skeleton of glycerol into glucose, and the interorgan cycling of glucose carbons (Cori-cycle plus alanine-glucose cycle). [U-14C]glycerol and [6-3H]glucose were given intravenously as a single dose injection. The time course of the specific radioactivities of [6-3H] and [U-14C]glucose was followed in blood. The pool size and the turnover rate of glucose were increased in the cancer group as compared with the control patients. The net recycling of glucose carbons was not increased in the cancer group, despite the increased turnover of glucose. The alterations in the metabolism of glucose did not correlate with the plasma levels of insulin or thyroid hormones (T4, T3, rT3) neither in the entire cancer group nor in those cancer patients who were repeatedly investigated at different intervals of time. The turnover rate of glucose in the cancer patients correlated inversely to their body weight index. The gluconeogenesis rate, given as the fractional conversion rate of the injected radioactive dose of [14C]glycerol, or as mol glucose . kg body weight-1 . day-1, was increased in the cancer group, but still contributed only 3% of the glucose turnover rate in both cancer and control patients. We conclude that an increased gluconeogenesis from glycerol is not significant igenesis from glycerol is not significant in terms of energy expenditure in patients with progressive malignancy, as has previously been concluded for the gluconeogenesis from alanine. It seems that increased turnover of glucose may contribute to inappropriately high energy expenditure in cancer patients

315

Novel PEGylated basal insulin LY2605541 has a preferential hepatic effect on glucose metabolism.  

Science.gov (United States)

The impact of the novel basal insulin LY2605541 (LY) on hepatic and nonhepatic glucose uptake (non-HGU) was evaluated. Conscious dogs underwent euglycemic clamps with tracer and hepatic balance measurements. Clamp period infusions were peripheral venous regular insulin (0.1 nmol ? kg(-1) ? h(-1) [control], n = 6) or LY (bolus [nmol/kg], continuous [nmol ? kg(-1) ? h(-1)]: 0.5, 0.5 [n = 6]; 0.375, 0.375 [n = 5]; 0.25, 0.25 [n = 4]), somatostatin, and glucose, as well as intraportal glucagon (basal). During the clamp, the dogs switched from net hepatic glucose output to uptake (rates reached 2.1 ± 1.2, 0.9 ± 2.1, 8.6 ± 2.3, and 6.0 ± 1.1 µmol ? kg(-1) ? min(-1) within 5 h in control, LY0.25, LY0.375, and LY0.5, respectively). Non-HGU in LY increased less than in control; the ratio of change from basal in non-HGU to change in net hepatic glucose balance, calculated when glucose infusion rates (GIRs) were ~20 µmol ? kg(-1) ? min(-1) in all groups, was higher in control (1.17 ± 0.38) versus LY0.25 (0.39 ± 0.33), LY0.375 (-0.01 ± 0.13), and LY0.5 (-0.09 ± 0.07). Likewise, the change from baseline in glucose Rd-to-Ra ratio was greatest in control (1.4 ± 0.3 vs. 0.6 ± 0.4, 0.5 ± 0.2, and 0.6 ± 0.2 in LY0.25, LY0.375, and LY0.5, respectively). In contrast to exogenously administered human insulin, LY demonstrated preferential hepatic effects, similar to endogenously secreted insulin. Therefore, the analog might reduce complications associated with current insulin therapy. PMID:24089512

Moore, Mary Courtney; Smith, Marta S; Sinha, Vikram P; Beals, John M; Michael, M Dodson; Jacober, Scott J; Cherrington, Alan D

2014-02-01

316

An intracellular glucose biosensor based on nanoflake ZnO  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study, an improved potentiometric intracellular glucose biosensor was fabricated with immobilization of glucose oxidase on a ZnO nanoporous material. The ZnO nanoporous material with a wall thickness around 200 nm was grown on the tip of a borosilicate glass capillary and used as a selective intracellular glucose sensor for the measurement of glucose concentrations in human adipocytes and frog oocytes. The results showed a fast response within 4 s and a linear glucosedependent electro...

Fulati, Alimujiang; Usman Ali, Syed M.; Asif, Muhammad H.; Hassan Alvi, Naveed Ul; Willander, Magnus; Bra?nnmark, Cecilia; Stra?lfors, Peter; Bo?rjesson, Sara I.; Elinder, Fredrik; Danielsson, Bengt

2010-01-01

317

Effects of lindane on the glucose metabolism in rat brain cortex cells  

International Nuclear Information System (INIS)

The influence of 0.5 mM ?-hexachlorocyclohexane (?-HCH, lindane) on glucose transport has been investigated using the analog 3-O-methyl-D(U-14C) glucose. The glucose uptake was lineal for at least 10 sec. Preincubation of dissociated brain cortex cells with lindane decreased the transport of glucose with respect to the controls. The treatment of brain cortex cells with other organochlorine compounds indicated that the ?-, ?-HCH isomers and dieldrin reproduced the same inhibitory pattern, while ?-HCH and endrin were inactive. The total radioactivity incorporated into CO2 from (U-14C) glucose in the cerebral cortex is also inhibited by lindane in a time dependent manner

318

Cytotoxicity,radiosensitization, and chemosensitization of tumor cells by 2-deoxy-D-glucose In vitro  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The glucose analog 2-deoxy-D-glucose (2-DG), an inhibitor of glucose transport and glycolytic ATP production, is the most widely investigated metabolic inhibitor for targeting glucose metabolism. Besides depleting energy in cells, 2-DG has also been found to alter N-linked glycosylation leading to unfolded protein responses and induce changes in gene expression and phosphorylation status of proteins involved in signaling, cell cycle control, DNA repair, calcium influx, and apoptosis. Inhibiti...

Dwarakanath B

2009-01-01

319

Maternal glucose level and body mass index measured at gestational diabetes mellitus screening and the risk of macrosomia: results from a perinatal cohort study  

Science.gov (United States)

Objective To examine the impact of maternal blood glucose (BG) level and body mass index (BMI) measured at gestational diabetes mellitus (GDM) screening on the risk of macrosomia. Design A perinatal cohort of women were followed up from receiving perinatal healthcare to giving birth. Setting Beichen District, Tianjin, China between June 2011 and October 2012. Participants 1951 women aged 19–42?years with valid values of BMI and BG level at GDM screening (24–28?weeks gestation), singleton birth and birth weight (BW)>2500?g. Main outcomes and measures Primary outcome was macrosomia (BW>4000?g). BG level and BMI were measured at GDM screening. Results 191 (9.7%) newborns were macrosomia. The ORs (95% CIs) of macrosomia from multiple logistic regression were 1.14 (1.10 to 1.19, p<0.0001) for BMI and 1.11 (1.01 to 1.23, p=0.03) for BG. When BMI and BG levels (continuous) were modelled simultaneously, the OR for BMI was similar, but significantly attenuated for BG. Areas of receiver operating characteristics (ROC) were 0.6530 (0.6258 to 0.6803) for BMI and 0.5548 (0.5248 to 0.5848) for BG (?2=26.17, p<0.0001). BG (mmol/L, <6.7, 6.7–7.8 or ?7.8) and BMI in quintiles (Q1–Q5) were evaluated with BG <6.7 and Q2 BMI as the reference group. The ORs of macrosomia were not statistically different for mothers in Q1 or Q2 of BMI regardless of the BG levels; the ORs for ?Q3 of BMI were elevated significantly with the highest OR observed in Q5 of BMI and BG levels ?7.8 (6.93 (2.61 to 18.43), p<0.0001). Conclusions High BMI measured at GDM screening was the most important determinant for risk of macrosomia. These findings suggest that GDM screening may be a critical gestational time point to initiate maternal weight control oriented intervention strategy to lower the risk. PMID:24844269

Liu, Jian; Leng, Junhong; Tang, Chen; Liu, Gongshu; Hay, John; Wang, Jing; Wen, Shiwu; Li, Zhenling; She, Ye

2014-01-01

320

Analog modelling of obduction processes  

Science.gov (United States)

Obduction corresponds to one of plate tectonics oddities, whereby dense, oceanic rocks (ophiolites) are presumably 'thrust' on top of light, continental ones, as for the short-lived, almost synchronous Peri-Arabic obduction (which took place along thousands of km from Turkey to Oman in c. 5-10 Ma). Analog modelling experiments were performed to study the mechanisms of obduction initiation and test various triggering hypotheses (i.e., plate acceleration, slab hitting the 660 km discontinuity, ridge subduction; Agard et al., 2007). The experimental setup comprises (1) an upper mantle, modelled as a low-viscosity transparent Newtonian glucose syrup filling a rigid Plexiglas tank and (2) high-viscosity silicone plates (Rhodrosil Gomme with PDMS iron fillers to reproduce densities of continental or oceanic plates), located at the centre of the tank above the syrup to simulate the subducting and the overriding plates - and avoid friction on the sides of the tank. Convergence is simulated by pushing on a piston at one end of the model with velocities comparable to those of plate tectonics (i.e., in the range 1-10 cm/yr). The reference set-up includes, from one end to the other (~60 cm): (i) the piston, (ii) a continental margin containing a transition zone to the adjacent oceanic plate, (iii) a weakness zone with variable resistance and dip (W), (iv) an oceanic plate - with or without a spreading ridge, (v) a subduction zone (S) dipping away from the piston and (vi) an upper, active continental margin, below which the oceanic plate is being subducted at the start of the experiment (as is known to have been the case in Oman). Several configurations were tested and over thirty different parametric tests were performed. Special emphasis was placed on comparing different types of weakness zone (W) and the extent of mechanical coupling across them, particularly when plates were accelerated. Displacements, together with along-strike and across-strike internal deformation in all plates were systematically measured, allowing for a very precise and reproducible tracking of deformation. Experiments demonstrate that obduction chiefly depends on how the overall shortening (or convergence) is partitionned between the weakness zone (W) and the preexisting subduction zone (S). Conditions favorable to obduction are shown to correspond to a specific range of coupling across (S) and resistance across (W). Our results thereby (1) constrain the range of physical conditions required for obduction to develop/nucleate and (2) underline the key role of acceleration for triggering obduction (rather than ridge subduction or slab resistance to penetration at the 660 km discontinuity). They also demonstrate that the emplacement of dense, oceanic material on continental lithosphere is not a mysterious process but results from some large scale, normal subduction process that do not require exotic boundary conditions. Agard P., Jolivet L., Vrielynck B., Burov E. & Monié P., 2007. Plate acceleration : the obduction trigger? Earth and Planetary Science Letters, 258, 428-441.

Agard, P.; Zuo, X.; Funiciello, F.; Bellahsen, N.; Faccenna, C.; Savva, D.

2012-04-01

 
 
 
 
321

Evidence that humans can taste glucose polymers.  

Science.gov (United States)

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 ?-amylase, and 3) to investigate the role that salivary ?-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 ?-amylase activity was assayed. Results showed that the perceived intensities of glucose, sucrose, and NaCl were significantly correlated (r = 0.75-0.85, P maltose that were inherently present in the glucose polymer stimuli and to determine whether the amounts were within a perceptually detectable range. Results revealed that the amounts of simple sugars present in the test stimuli were trivial and were mostly at an undetectable level. These data together provide strong evidence that humans can taste glucose polymers and that the responsiveness to glucose polymers is independent of that to simple sugars. PMID:25326592

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

2014-11-01

322

Development of Analogy Experiment Methodologies  

International Nuclear Information System (INIS)

Hydrogen is expected to help address concerns about global climate change and energy security. The HTGR (High-Temperature Gas-cooled Reactor) drew attention as one of the most competitive heat source for producing hydrogen. The knowledge of detailed heat transfer phenomena in gaseous phase emerges as an important factor for HTGR, where buoyancy effect plays a significant role. Large and expensive test facilities are to be constructed to assess the detailed mixed convection phenomena. However, using analogy concept, heat transfer system can be transformed to mass transfer system(copper electroplating system) and vice versa. If we could devise simple mass transfer system and find experimental solution from that system, then theoretically it is not difficult to find solution for similar heat transfer system. This study explores the applicability of simple mass transfer experiments to heat transfer researches using analogy concept. A copper electroplating system with limiting current technique has a good advantage to simulate heat transfer system as mass transfer coefficient, analogous with heat transfer coefficient, can be directly obtained from the information of the bulk concentration and electric current between electrodes. Therefore, the validity of the analogy experimental method was confirmed through comparison between the test results obtained by measuring limiting current and corresponding well-known heat transfer correlations. Three different forced and natural tions. Three different forced and natural convection mass transfer systems were constructed to simulate Poiseuille flow at horizontal geometry and laminar and turbulent buoyant flows at vertical geometry. it was shown that the close agreement between results for mass transfer experiment and heat transfer correlation is an encouraging indication of the validity of the analogy theory and the experiment method. It may also be concluded that analogy method using electroplating system make it possible to predict the unknown heat transfer correlations. Thus, Analogy methodology is expected to be a useful tool for heat transfer studies for HTGR development as the electroplating method not only provide with useful information on heat transfer but also has cost-effective advantage than any other experiments

323

Analogies in theoretical physics  

CERN Document Server

Analogies have had and continue to have an important role in the development of theoretical physics. They may start from similarities of physical concepts followed by similarities in the mathematical formalization or it may be a purely mathematical aspect to suggest the development of analogous physical concepts. More often a subtle non obvious interplay between these levels is involved. In this paper I will discuss two cases sufficiently intricate to illustrate some ways of how analogies work. The first topic is the introduction of spontaneous symmetry breaking in particle physics. The second one is the use of the renormalization group in the theory of critical phenomena and its statistical interpretation.

Jona-Lasinio, Giovanni

2010-01-01

324

Diabetic hypoglycemia: a case of different capillary blood glucose readings from two identical glucose meters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A 61-year old male with a 54-year history of type 1 diabetes, hypertension and ischemic heart disease became drowsy while attending the hospital diabetes outpatient department. Capillary blood glucose was measured at 3.8 mmol/l and he was treated for presumed hyopglycemia with a glucose drink followed by intravenous dextrose; 25 minutes later, a different glucose meter was used to record a capillary blood glucose value of 7.8 mmol/l. Because recovery was slow, the patient was transferred to t...

Graveling, Alex J.

2010-01-01

325

Glucose Recognition in Vitro Using Fluorescent Spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

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.

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

326

Early change in glucose metabolic rate measured using FDG-PET in patients with high-grade glioma predicts response to temozolomide but not temozolomide plus radiotherapy  

International Nuclear Information System (INIS)

Purpose: To compare the ability of positron emission tomography (PET) to predict response to temozolomide vs. temozolomide plus radiotherapy. Methods and Materials: Nineteen patients with high-grade glioma (HGG) were studied. Patients with recurrent glioma received temozolomide 75 mg/m2 daily for 7 weeks (n = 8). Newly diagnosed patients received temozolomide 75 mg/m2 daily plus radiotherapy 60 Gy/30 fractions over 6 weeks, followed by six cycles of adjuvant temozolomide 200 mg/m2/day (Days 1-5 q28) starting 1 month after radiotherapy (n = 11). [18F]Fluorodeoxyglucose ([18F]FDG) PET scan and magnetic resonance imaging (MRI) were performed at baseline, and 7 and 19 weeks after initiation of temozolomide administration. Changes in glucose metabolic rate (MRGlu) and MRI response were correlated with patient survival. Results: In the temozolomide-alone group, patients who survived >26 vs. ?26 weeks showed a greater reduction in MRGlu measured at 7 weeks with median changes of -34% and -4%, respectively (p = 0.02). PET responders, defined as a reduction in MRGlu ?25%, survived longer than nonresponders with mean survival times of 75 weeks (95% CI, 34-115 vs. 20 weeks (95% CI, 14-26) (p = 0.0067). In the small group of patients studied, there was no relationship between MRI response and survival (p = 0.52). For patients receiving temozolomide plus radiotherapy, there was no difference in survival between PET responderence in survival between PET responders and nonresponders (p = 0.32). Conclusions: Early changes in MRGlu predict response to temozolomide, but not temozolomide plus radiotherapy

327

Detecção de trombose venosa em retalhos livres por medidas de glicemia capilar / Detection of venous thrombosis in free flaps by measurement of capillary blood glucose  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese INTRODUÇÃO: A monitorização do retalho livre após a cirurgia é de vital importância, especialmente nas primeiras horas de pós-operatório, pois o momento de reabordagem pode ser o definidor entre o salvamento ou a perda do retalho. Até o momento, não existe trabalho na literatura estudando a decisão [...] de abordagem do retalho baseada em medidas objetivas ou a comparação da glicemia entre retalhos que evoluíram bem com os que sofreram sofrimento vascular. O objetivo deste estudo é avaliar a validade da medida da glicemia capilar do retalho como método de monitorização de retalhos microcirúrgicos comparando com a avaliação clínica. MÉTODO: Foram estudados prospectivamente 16 pacientes portadores de retalhos livres, realizados de maio de 2012 a julho de 2012. A glicemia capilar foi avaliada por equipe formada por profissionais não envolvidos com a cirurgia realizada. A avaliação clínica do retalho foi realizada no pós-operatório imediato, na chegada à UTI, a cada 3 horas e sempre que necessário. RESULTADOS: Dos 16 pacientes, 5 (31,3%) apresentaram complicações nas primeiras 24 horas. Todas as complicações observadas foram trombose venosa. Foi observada diferença estatisticamente significante na glicemia capilar de portadores de retalhos que apresentaram trombose venosa em comparação àqueles que não tiveram a complicação, nas medidas realizadas 6 horas, 9 horas e 12 horas após a operação (P Abstract in english BACKGROUND: Monitoring of free flaps after surgery is vitally important, especially in the first few hours because the timing of reoperation can determine flap salvage or loss. To date, no study has examined the decision to reoperate on a flap based on the objective measure of glycemia or a comparis [...] on between flaps that showed good outcomes and those that showed vascular damage. The objective of this study was to evaluate the validity of blood glucose measurements within the flap as a method for monitoring free flaps and to compare the efficacy of this method with that of clinical assessments. METHODS: The study was prospective, included 16 patients with free flaps, and was conducted from May 2012 to July 2012. A team of professionals not involved in the surgery evaluated capillary glycemia. Flaps were clinically evaluated during the immediate postoperative period, on ICU admission, at every 3 hours, and as needed. RESULTS: Of the 16 patients, 5 (31.3%) had venous thrombosis in the first 24 hours. Statistically significant differences were noted in capillary glycemia in patients with or without venous thrombosis in measurements obtained 6, 9, and 12 hours after surgery (P

Lincoln Saito, Millan; Luiz Carlos, Ishida; Esther Mihwa Oh, Choi; Enio Cesar, Giacchetto Junior; Teng Hsiang, Wei; Rames, Mattar Júnior; Marcus Castro, Ferreira.

2012-12-01

328

Fatty acid analogs  

Science.gov (United States)

In one aspect, a radioactively labeled analog of a fatty acid which is capable of being taken up by mammalian tissue and which exhibits an in vivo beta-oxidation rate below that with a corresponding radioactively labeled fatty acid.

Elmaleh, David R. (Newton Center, MA); Livni, Eli (Brookline, MA)

1985-01-01

329

Evaluation of quantitative models of the effect of insulin on lipolysis and glucose disposal  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effects of insulin on the suppression of lipolysis are neither fully understood nor quantified. We examined a variety of mathematical models analogous to the minimal model of glucose disposal (MMG) to quantify the combined influence of insulin on lipolysis and glucose disposal during an insulin-modified frequently sampled intravenous glucose tolerance test. The tested models, which include two previously published ones, consisted of separate compartments for plasma free fatty acids (FFA),...

Periwal, Vipul; Chow, Carson C.; Bergman, Richard N.; Ricks, Madia; Vega, Gloria L.; Sumner, Anne E.

2008-01-01

330

Chemosensitizing and cytotoxic effects of 2-deoxy-D-glucose on breast cancer cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: Accelerated glucose uptake for anerobic glycolysis is one of the major metabolic changes found in malignant cells. This property has been exploited for imaging malignancies and as a possible anticancer therapy. The nonmetabolizable glucose analog 2-deoxyglucose (2?DG) interferes with glucose metabolism leading to breast cancer cell death. Aims: To determine whether 2DG can synergize with chemotherapeutic agents commonly used in breast cancer treatment and id...

Zhang Fanjie; Aft Rebecca

2009-01-01

331

Clinical studies for improving radiotherapy with 2-deoxy-D-glucose: Present status and future prospects  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Higher rates of glucose usage generally correlate with poor prognosis in several types of malignant tumours. Experimental studies (both in vitro and in vivo) have shown that 2-deoxy-D-glucose (2-DG), a glucose analog and glycolytic inhibitor, enhances radiation-induced damage selectively in tumor cells while protecting normal cells, thereby suggesting that 2-DG can be used as a differential radiomodifier to improve the efficacy of radiotherapy. Clinical trials undertaken to study the feasibil...

Dwarakanath B; Singh Dinesh; Banerji Ajit; Sarin Rajiv; Venkataramana N; Jalali R; Vishwanath P; Mohanti B; Tripathi R; Kalia V; Jain Viney

2009-01-01

332

FGF growth factor analogs  

Science.gov (United States)

The present invention provides a fibroblast growth factor heparin-binding analog of the formula: ##STR00001## where R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, X, Y and Z are as defined, pharmaceutical compositions, coating compositions and medical devices including the fibroblast growth factor heparin-binding analog of the foregoing formula, and methods and uses thereof.

Zamora, Paul O. (Gaithersburg, MD); Pena, Louis A. (Poquott, NY); Lin, Xinhua (Plainview, NY); Takahashi, Kazuyuki (Germantown, MD)

2012-07-24

333

Analog for the Mac  

Science.gov (United States)

In addition to providing any number of web servicing capabilities, web servers are excellent at generating huge log files containing the details of their every activity. Analyzing these logs by hand is not practical. Fortunately, Stephen Turner has written Analog, a fast, freely-available, configurable tool for automatically analyzing log files. Jason T. Linhart, author of the shareware log analysis tool, Summary, has ported Analog to the MacOS.

334

Analog Models beyond Kinematics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper I discuss the extension of the analogy between gravitation and some systems of condensed matter physics from kinematics to dynamics. I will focus my attention on two applications of the analogy to the dynamics of fluids that have been recently proposed: the study of backreaction effects and the calculation of the depletion in Bose-Einstein condensates, showing how this extension is possible and stressing the main differences with respect to the gravitational co...

Fagnocchi, Serena

2006-01-01

335

Interaction of ZnS nanoparticles with flavins and glucose oxidase: A fluorimetric investigation  

International Nuclear Information System (INIS)

Interactions of luminescence, water soluble ZnS nanoparticles (NPs) with flavins and glucose oxidase have been thoroughly investigated through optical spectroscopy. The photoluminescence of ZnS nanoparticles was quenched severely (?60%) by riboflavin while other flavins such as flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) show quenching to different extents under analogous conditions. However, interestingly no effect in luminescence intensity of ZnS NPs was observed with protein bound flavins such as in glucose oxidase. Fluorescence lifetime measurement confirmed the quenching to be static in nature. Scavenging of photo-generated electron of ZnS nanoparticles by the flavin molecules may be attributed to the decrease in luminescence intensity. Quenching of ZnS nanoparticles with flavins follows the linear Stern–Volmer plot. The Stern–Volmer constants decreased in the following order: KS?V (Riboflavin)> KS?V (FAD)> KS?V (FMN). This interaction study could generate useful protocol for the fluorimetric determination of riboflavin (vitamin B2) content and also riboflavin status in biological systems. - Highlights: ? Unique interaction specificity of ZnS nanoparticles with flavins has been explored. ? Unlike protein-bound flavin, fluorescence of free flavins was quenched by ZnS nanoparticles. ? FMN and FAD show quenching to different extents under analogous conditions. ? Fluorescence lifeti ? Fluorescence lifetime measurement confirmed the quenching to be static in nature. ? This study is useful for probing riboflavin in biological systems.

336

Analog-antianalog transitions in arsenic isotopes  

International Nuclear Information System (INIS)

The ? decay of analog resonances in arsenic isotopes has been experimentally studied. The investigation was carried out at the 5 MeV Van de Graaff accelerator. The ? spectrum was measured by Ge(Li) detectors. Calculations of the strength functions and probabilities of the MI transitions from the gsub(9/2) and dsub(5/2) analog in 73As and 75As isotopes as well as from the Psub(1/2) analog in 75As are presented . The calculations were performed in terms of the model with the Gamow-Teller residual interaction

337

Glucose metabolism in a rat mammary adenocarcinoma  

International Nuclear Information System (INIS)

Full text: Tumor hypoxia, which decreases therapy response is common in tumors. Glucose metabolism is closely tied to tumor oxygenation and alteration of its metabolism could improve tumor oxygenation. The objective of the study was to compare tissue pharmacokinetics of 14C-2-deoxyglucose (14C2DG) and 14C-glucose in an adenocarcinoma (R3230Ac) and normal control tissue (subcutis:SQ) using a novel fiberoptic scintillation detector. Fischer 344 rats with R3230Ac tumors were anesthetized with Isoflurane and detectors were inserted. Baseline data was acquired for 45 minutes, then 14C2DG or 14C-glucose (i.v.) was injected and data was acquired for 3 hours. After 100mCi of 14C2DG both tissues reached peaks (R3230Ac, 0.4mCi/g; SQ, 0.75mCi/g) 20 minutes post-injection that remained stable for 3 hours. With 200mCi 14C2DG R3230Ac peaked and plateaued at 1.75mCi/g by 50 minutes. SQ peaked (2.25mCi/g) at 20 minutes and decreased to a stable plateau (0.75mCi/g) at 50 minutes. Kinetics of 14C-glucose were different from 14C2DG. R3230Ac and SQ increased over 20 minutes, reaching peaks of 2.4mCi/g and 1.5mCi/g, respectively. A slow decrease followed, but tumor signal (1.25mCi/g) remained higher than SQ (0.5mCi/g). Kinetics of 14C2DG and 14C-glucose were distinctly different. In SQ a wash-in/wash-out effect was observed at 200mCi of 14C2DG. In tumor 00mCi of 14C2DG. In tumor 14C2DG accumulated to a plateau (1.75mCi/g) that persisted out to 3 hours. 14C-glucose signal declined below 14C2DG signal in both tissues, suggesting they both metabolize 14C-glucose and excrete 14C-containing metabolites. PET can assess flouride-deoxyglucose uptake in tumors, which is analogous to our 14C2DG studies. However, PET cannot provide data on glucose metabolism and excretion because there is not a metabolizable fluorinated-glucose analogue that is imageable by PET. In summary, this novel detector has the unique capability to evaluate real-time accumulation, metabolism, and excretion of radiolabeled glucose in tissues before and after metabolic manipulation

338

Glucose cycling is markedly enhanced in pancreatic islets of obese hyperglycemic mice  

Energy Technology Data Exchange (ETDEWEB)

Pancreatic islets from fed 7-month old lean and obese hyperglycemic mice (ob/ob) were incubated with 3H2O and 5.5 mM or 16.7 mM glucose. Incorporation of 3H into the medium glucose was taken as the measure of glucose-6-P hydrolysis to glucose. Glucose utilization was measured from the yield of 3H2O from (5-3H)glucose. Only 3-4% of the glucose phosphorylated was dephosphorylated by the lean mouse islets irrespective of the glucose concentration. In contrast, the ob/ob mouse islets at 5.5 mM glucose dephosphorylated 18% of the glucose phosphorylated and 30% at 16.7 mM. Thus, the islets of hyperglycemic mice demonstrate increased glucose cycling as compared to the islets of normoglycemic lean mice.

Khan, A.; Chandramouli, V.; Ostenson, C.G.; Berggren, P.O.; Loew, H.L.; Landau, B.R.; Efendic, S. (Karolinska Hospital, Stockholm (Sweden))

1990-05-01

339

Automated Generation of Cross-Domain Analogies via Evolutionary Computation  

CERN Document Server

Analogy plays an important role in creativity, and is extensively used in science as well as art. In this paper we introduce a technique for the automated generation of cross-domain analogies based on a novel evolutionary algorithm (EA). Unlike existing work in computational analogy-making restricted to creating analogies between two given cases, our approach, for a given case, is capable of creating an analogy along with the novel analogous case itself. Our algorithm is based on the concept of "memes", which are units of culture, or knowledge, undergoing variation and selection under a fitness measure, and represents evolving pieces of knowledge as semantic networks. Using a fitness function based on Gentner's structure mapping theory of analogies, we demonstrate the feasibility of spontaneously generating semantic networks that are analogous to a given base network.

Baydin, Atilim Gunes; Ontanon, Santiago

2012-01-01

340

Glucose Biosensor Using Selected Indonesian Bacteria  

Directory of Open Access Journals (Sweden)

Full Text Available Microbial glucose sensors have been developed using Escherichia coli bacterial strains from Japan. However, there is interest in developing local bacteria as glucose sensors in Indonesia. In this research, the stability and the potential of a selected number of Indonesian bacteria as glucose biosensors was explored. Results of this study indicate that three of them, E. coli, Bacillus subtilis, and Thermus filiformis exhibit properties of high viability and stability at high temperature (30-60 ºC. Spectrophotometrical and electrochemical measurements showed significant absorbance values and highly stable current features for E. coli as indicated by its high capacity to produce glucose dehydrogenase. E. coli, B. subtilis, and T. filiformis produced currents of 3.25 µA, 0.2 µA, and 0.02 µA respectively, and E. coli also produced a much higher activity of glucose dehydrogenase. Electrochemical measurement using E. coli-modified carbon paste electrode allowed the determination of glucose concentration of up to 20 mM. Therefore, Indonesian E. coli has a high stability and can be used as a glucose biosensor

DYAH ISWANTINI

2011-03-01

 
 
 
 
341

GLUT2, glucose sensing and glucose homeostasis.  

Science.gov (United States)

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. PMID:25421524

Thorens, Bernard

2015-02-01

342

Brain Glucose Metabolism Controls Hepatic Glucose and Lipid Production  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Brain glucose-sensing mechanisms are implicated in the regulation of feeding behavior and hypoglycemic-induced hormonal counter-regulation. This commentary discusses recent findings indicating that the brain senses glucose to regulate both hepatic glucose and lipid production.

Lam, Tony K. T.

2007-01-01

343

Uptake and release of glucose by the human kidney. Postabsorptive rates and responses to epinephrine.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Despite ample evidence that the kidney can both produce and use appreciable amounts of glucose, the human kidney is generally regarded as playing a minor role in glucose homeostasis. This view is based on measurements of arteriorenal vein glucose concentrations indicating little or no net release of glucose. However, inferences from net balance measurements do not take into consideration the simultaneous release and uptake of glucose by the kidney. Therefore, to assess the contribution of rel...

Stumvoll, M.; Chintalapudi, U.; Perriello, G.; Welle, S.; Gutierrez, O.; Gerich, J.

1995-01-01

344

Cross-validity of a portable glucose capillary monitors in relation to enzymatic spectrophotometer methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The glucose is an important substrate utilizaded during exercise. Accurate measurement of glucose is vital to obtain trustworthy results. The enzymatic spectrophotometer methods are generally considered the “goldstandard” laboratory procedure for measuring of glucose (GEnz), is time consuming, costly, and inappropriate for large scale field testing. Compact and portable glucose monitors (GAccu) are quick and easy methods to assess glucose on large numbers of subjects. So, this study aimed...

William Alves Lima; Maria Glaner

2006-01-01

345

Construction of a Panel of Glucose Indicator Proteins for Continuous Glucose Monitoring  

Science.gov (United States)

The development of implantable glucose sensors for use in diabetes treatment has been pursued for decades. However, enzyme-based glucose sensors often fail in vivo. In our previous work, we engineered a novel glucose indicator protein (GIP) that can sense glucose without relying on any enzymes and cofactors. Nevertheless, this GIP is unsuitable for blood glucose monitoring due to its low dissociation constant. Here, we report a novel approach to creating a new GIP that can be used to monitor blood glucose level. By disrupting pi-pi stacking around GIP’s glucose binding site through site-directed mutagenesis, we showed that GIP’s dissociation constant can be manipulated from 0.026 mM to 7.86 mM. This approach yielded four GIP mutants. We showed that one of the mutants can be used to detect glucose from 0 to 32 mM, while another mutant can be employed to visualize intracellular glucose (0–200 ?M) within living cells through FRET imaging microscopy measurement. PMID:21333521

Jin, Sha; Veetil, Jithesh V.; Garrett, Jared R; Ye, Kaiming

2011-01-01

346

Hyperglycemia (High Blood Glucose)  

Medline Plus

Full Text Available ... ketones are present may make your blood glucose level go even higher. You'll need to work with your doctor to find the safest way for you to lower your blood glucose level. Cutting down on the amount of food you ...

347

Fructose vs. Glucose  

Medline Plus

Full Text Available ... right-hand corner of the player. Fructose vs. Glucose HealthDay December 12, 2014 Related MedlinePlus Page Carbohydrates ... make you hungrier than eating foods that contain glucose? A new study suggests fructose may rev up ...

348

Kidney transplantation improves arterial function measured by pulse wave analysis and endothelium-independent dilatation in uraemic patients despite deterioration of glucose metabolism  

DEFF Research Database (Denmark)

BACKGROUND: The aim of this study is to investigate the effect of kidney transplantation on arterial function in relation to changes in glucose metabolism. METHODS: Included were 40 kidney recipients (Tx group, age 38 ± 13 years) and 40 patients without known diabetes remaining on the waiting list for kidney transplantation (uraemic control group, age 47 ± 11 years). Arterial function was estimated by the pulse wave velocity (PWV) of the carotid-femoral pulse wave, aortic augmentation index (AIX), flow-mediated (FMD) and nitroglycerin-induced vasodilatation (NID) of the brachial artery performed before transplantation and after 12 months. PWV recorded sequentially at the carotid and femoral artery is an estimate of arterial stiffness; AIX is an integrated index of vascular and ventricular function. FMD and NID are the dilatory capacities of the brachial artery after increased flow (endothelium dependent) and after nitroglycerin administration (endothelium independent). The insulin resistance was estimated by the insulin sensitivity index (ISI). RESULTS: AIX was reduced from 27% (17-33) to 14% (7-25) (P = 0.01) after 1 year in the Tx group and remained stable in uraemic controls (P = 0.001, between groups), and NID increased from 11% (7-16) to 18% (12-23) (P = 0.0005). At baseline, carotid-femoral PWV was similar in the Tx group, uraemic controls and healthy controls and it did not change significantly after transplantation. ISI deteriorated in the Tx group from 7.2 ± 4.0 to 5.0 ± 3.0 (P = 0.005) and remained stable in uraemic controls (7.9 ± 5.1 vs 8.5 ± 4.9, NS). Mean arterial blood pressure decreased from 105 ± 13 to 96 ± 11 mmHg (P = 0.005) in the Tx group despite a 20% lower use of antihypertensive agents. CONCLUSIONS: Arterial function measured by AIX and NID was improved 1 year after kidney transplantation. This was associated with a decline in blood pressure and seen inspite of an increase in insulin resistance.

Hornum, Mads; Clausen, Peter

2011-01-01

349

Changes in Glucose Homeostasis after Roux-en-Y Gastric Bypass Surgery for Obesity at Day Three, Two Months, and One Year after Surgery : Role of Gut Peptides  

DEFF Research Database (Denmark)

Context: Endocrine effects of gastric bypass (GBP) surgery for obesity on glucose homeostasis are not fully understood. Main Objective: The main objective of the study was to assess the changes in plasma glucose, insulin, glucagon-like peptide-1 (GLP-1), leptin, somatostatin, glucose-dependent insulinotropic peptide, enteroglucagon, and glucagon early after GBP. Method: Twelve obese subjects (body mass index 45.3 ± 1.9 kg/m2) were subjected to a liquid meal without lipids before and 3 d, 2 months, and 1 yr after GBP. Plasma concentrations of glucose, insulin, leptin, and gut peptide hormones were assessed before and for 180 min after the meal. Satiety was measured with visual analog scales. The absorption rate of acetaminophen added to the liquid meal was measured. Insulin resistance was measured by the homeostasis model assessment of insulin resistance. Results: All subjects lost weight (body mass index 30.3 ± 1.8 kg/m2 at 1 yr). Fasting glucose was significantly lower on d 3 (P < 0.05). There was a progressive decrease in the homeostasis model assessment of insulin resistance after 2 months postoperatively. Postprandially, there was a progressive rise of GLP-1 and enteroglucagon and a transient increase in pancreatic glucagon release over the study period. There was a leftward shift of the time course of plasma glucose and insulin. Somatostatin release was lower on d 3 (P < 0.05) but then unchanged. The absorption rate of acetaminophen was twice as fast after GBP compared with before surgery and did not change over time. Satiety scores increased markedly postoperatively. Conclusion: Both enhanced insulin sensitivity and incretin hormones, such as GLP-1, contribute to the early control of glucose homeostasis. Progressively increasing postprandial levels of enteroglucagon (oxyntomodulin) and GLP-1 facilitate weight loss and enhance insulin effectiveness.

Falkén, Y; Hellström, P M

2011-01-01

350

Glucose sensor with a Sagnac interference optical system.  

Science.gov (United States)

The angle of optical rotation was measured by detecting the phase difference between clockwise and counterclockwise circular polarized light that propagated in a sensing loop. This polarimeter, or glucose sensor, consisted of a Sagnac interference optical system with a polarization-maintaining optical fiber, so it was not affected by the control limitations of the polarization rotation angle or the optical power fluctuation that occurs with scattered light, reflection, or polarization rotation in an optical system. The angle of rotation was measured from the phase difference of the glucose sensor when the concentration of glucose was changed. We confirmed that the resolution of optical rotation was 5×10(-4)??deg, and the resolution of the glucose concentration was 1??mg/dl accordingly. The measured specific rotation of glucose was mostly equal to a physical property value. One applications of this glucose sensor is in measuring the blood sugar levels of diabetic patients. PMID:24514189

Kumagai, Tatsuya; Tottori, Yusaku; Miyata, Ryusuke; Kajioka, Hiroshi

2014-02-01

351

On the role of glucose-dependent insulintropic polypeptide in postprandial metabolism in humans  

DEFF Research Database (Denmark)

We investigated the role of glucose-dependent insulintropic polypeptide (GIP) in the regulation of gastric emptying (GE), appetite, energy intake (EI), energy expenditure (EE), plasma levels of triglycerides (TAG), and free fatty acids (FFA) in humans. First, 20 healthy males received intravenous infusion of GIP (0.8 pmol.kg(-1).min(-1)) or saline for 300 min during and after a fixed meal (protocol 1). GE was measured using paracetamol, appetite sensations using visual analog scales, EE using indirect calorimetry, and EI during a subsequent ad libitum meal (at 300 min). Next, 10 healthy males received intravenous infusions of Intralipid, glucose, or Intralipid plus glucose, with and without GIP (1.5 pmol.kg(-1).min(-1)) for 300 min (protocol 2). In protocol 1, GIP did not have any effect on GE, EI, EE, removal of TAG, or FFA and did not influence the subjective feeling of hunger, satiety, fullness or prospective food consumption compared with saline. In protocol 2, no difference was seen in the plasma TAG on Intralipid + GIP/saline and Intralipid + glucose + GIP/saline days. FFA concentrations were lower on Intralipid + glucose + GIP/saline days (P <0.05) compared with Intralipid + GIP/saline days and on Intralipid + GIP day (P <0.004) compared with Intralipid + saline day. Insulin increased on all GIP days compared with saline days (P <0.05). In conclusion, while confirming its insulinotropic effects, these data suggest that GIP does not affect GE, appetite, energy intake, EE, or the clearance rate of the applied TAG formulation in humans. However, both insulin and GIP lower post-Intralipid FFA concentration, GIP probably via stimulation of insulin secretion, increasing FFA reesterification.

Asmar, Meena; Tangaa, Winnie

2010-01-01

352

Analog Optical Links  

Science.gov (United States)

Unlike books that focus on the devices used in links, such as lasers and photodiodes, among others, this text focuses on the next level. It covers the collection of devices that form a link, how the individual device performance affects the link performance, or the reverse. Analog links are used for the distribution of cable TV signals, and in conveying the signals to and from antennas (so called antenna remoting). The design of analog links differs significantly from digital links which are primarily used in telecommunications.

Cox, Charles H., III

2004-05-01

353

Analog layout synthesis  

CERN Document Server

Integrated circuits are fundamental electronic components in biomedical, automotive and many other technical systems. A small, yet crucial part of a chip consists of analog circuitry. This part is still in large part designed by hand and therefore represents not only a bottleneck in the design flow, but also a permanent source of design errors responsible for re-designs, costly in terms of wasted test chips and in terms of lost time-to-market. Layout design is the step of the analog design flow with the least support by commercially available, computer-aided design tools. This book provides a

Graeb, Helmut E

2010-01-01

354

The immediate effects of a single bout of aerobic exercise on oral glucose tolerance across the glucose tolerance continuum  

DEFF Research Database (Denmark)

We investigated glucose tolerance and postprandial glucose fluxes immediately after a single bout of aerobic exercise in subjects representing the entire glucose tolerance continuum. Twenty-four men with normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or type 2 diabetes (T2D; age: 56 ± 1 years; body mass index: 27.8 ± 0.7 kg/m(2), P > 0.05) underwent a 180-min oral glucose tolerance test (OGTT) combined with constant intravenous infusion of [6,6-(2)H2]glucose and ingestion of [U-(13)C]glucose, following 1 h of exercise (50% of peak aerobic power) or rest. In both trials, plasma glucose concentrations and kinetics, insulin, C-peptide, and glucagon were measured. Rates (mg kg(-1) min(-1)) of glucose appearance from endogenous (RaEndo) and exogenous (oral glucose; Ra OGTT) sources, and glucose disappearance (Rd) were determined. We found that exercise increased RaEndo, RaOGTT, and Rd (all P < 0.0001) in all groups with a tendency for a greater (~20%) peak RaOGTT value in NGT subjects when compared to IGT and T2D subjects. Accordingly, following exercise, the plasma glucose concentration during the OGTT was increased in NGT subjects (P < 0.05), while unchanged in subjects with IGT and T2D. In conclusion, while a single bout of moderate-intensity exercise increased the postprandial glucose response in NGT subjects, glucose tolerance following exercise was preserved in the two hyperglycemic groups. Thus, postprandial plasma glucose responses immediately following exercise are dependent on the underlying degree of glycemic control.

Knudsen, Sine H; Karstoft, Kristian

2014-01-01

355

Analog interfacing to embedded microprocessor systems  

CERN Document Server

Analog Interfacing to Embedded Microprocessors addresses the technologies and methods used in interfacing analog devices to microprocessors, providing in-depth coverage of practical control applications, op amp examples, and much more. A companion to the author''s popular Embedded Microprocessor Systems: Real World Design, this new embedded systems book focuses on measurement and control of analog quantities in embedded systems that are required to interface to the real world. At a time when modern electronic systems are increasingly digital, a comprehensive source on interfacing the real world to microprocessors should prove invaluable to embedded systems engineers, students, technicians, and hobbyists. Anyone involved in connecting the analog environment to their digital machines, or troubleshooting such connections will find this book especially useful. Stuart Ball is also the author of Debugging Embedded Microprocessor Systems, both published by Newnes. Additionally, Stuart has written articles for period...

Ball, Stuart

2003-01-01

356

Problems and Practical Solutions in the External Quality Control of Point of Care Devices with Respect to the Measurement of Blood Glucose  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Point of care testing (POCT) is evolving at an ever increasing rate. This article deals mainly with the aspect of POCT for blood glucose and the problems of external quality assessment (EQA) of point of care devices (POCD). At the present time it is only possible to control precision with EQA, independent of the matrix of the test materials (synthetic polymer-base, plasma/serum, or processed whole blood). The German Federal Medical Council guidelines for laboratory performance allow an interl...

Wood, William Graham

2007-01-01

357

Radiotracers in the study of marine food chains. The use of compartmental analysis and analog modelling in measuring utilization rates of particulate organic matter by benthic invertebrates  

International Nuclear Information System (INIS)

The present study assesses the problem of recycling when using radiotracers to quantify ingestion and assimilation rates of particulate organic matter by benthic invertebrates. The rapid production of dissolved organic matter and its subsequent utilization by benthic invertebrates constitutes a major bias in this kind of study. However recycling processes may also concern POM through the production and reingestion of faeces. The present paper shows that compartmental analysis of the diffusion kinetics of the radiotracer between the different compartments of the system studied and the analog modelling of the exchanges of radioactivity between compartments may be used in order to determine ingestion and assimilation rates. This method is illustrated by the study of a system composed of the bacteria Lactobacillus sp. and the filter-feeding bivalve Venerupis decussata. The advantages and drawbacks of this approach relative to other existing methods are briefly discussed. (Author)

358

Cycloheximide decreases glucose transporters in rat adipocyte plasma membranes without affecting insulin-stimulated glucose transport.  

Science.gov (United States)

This study examines the relationship between insulin-stimulated glucose transport and insulin-induced translocation of glucose transporters in isolated rat adipocytes. Adipose cells were incubated with or without cycloheximide, a potent inhibitor of protein synthesis, for 60 min and then for an additional 30 min with or without insulin. After the incubation we measured 3-O-methylglucose transport in the adipose cells, and subcellular membrane fractions were prepared. The numbers of glucose transporters in the various membrane fractions were determined by the cytochalasin B binding assay. Basal and insulin-stimulated 3-O-methylglucose uptakes were not affected by cycloheximide. Furthermore, cycloheximide affected neither Vmax. nor Km of insulin-stimulated 3-O-methylglucose transport. In contrast, the number of glucose transporters in plasma membranes derived from cells preincubated with cycloheximide and insulin was markedly decreased compared with those from cells incubated with insulin alone (10.5 +/- 0.8 and 22.2 +/- 1.8 pmol/mg of protein respectively; P less than 0.005). The number of glucose transporters in cells incubated with cycloheximide alone was not significantly different compared with control cells. SDS/polyacrylamide-gel-electrophoretic analysis of [3H]cytochalasin-B-photolabelled plasma-membrane fractions revealed that cycloheximide decreases the amount of labelled glucose transporters in insulin-stimulated membranes. However, the apparent molecular mass of the protein was not changed by cycloheximide treatment. The effect of cycloheximide on the two-dimensional electrophoretic profile of the glucose transporter in insulin-stimulated low-density microsomal membranes revealed a decrease in the pI-6.4 glucose-transporter isoform, whereas the insulin-translocatable isoform (pI 5.6) was decreased. Thus the observed discrepancy between insulin-stimulated glucose transport and insulin-induced translocation of glucose transporters strongly suggests that a still unknown protein-synthesis-dependent mechanism is involved in insulin activation of glucose transport. PMID:3041964

Matthaei, S; Olefsky, J M; Karnieli, E

1988-04-15

359

Analog signal isolation techniques  

International Nuclear Information System (INIS)

This paper discusses several techniques for isolating analog signals in an accelerator environment. The techniques presented here encompass isolation amplifiers, voltage-to-frequency converters (VIFCs), transformers, optocouplers, discrete fiber optics, and commercial fiber optic links. Included within the presentation of each method are the design issues that must be considered when selecting the isolation method for a specific application

360

Predicting Plasma Glucose From Interstitial Glucose Observations Using Bayesian Methods  

DEFF Research Database (Denmark)

One way of constructing a control algorithm for an artificial pancreas is to identify a model capable of predicting plasma glucose (PG) from interstitial glucose (IG) observations. Stochastic differential equations (SDEs) make it possible to account both for the unknown influence of the continuous glucose monitor (CGM) and for unknown physiological influences. Combined with prior knowledge about the measurement devices, this approach can be used to obtain a robust predictive model. A stochastic-differential-equation-based gray box (SDE-GB) model is formulated on the basis of an identifiable physiological model of the glucoregulatory system for type 1 diabetes mellitus (T1DM) patients. A Bayesian method is used to estimate robust parameters from clinical data. The models are then used to predict PG from IG observations from 2 separate study occasions on the same patient. First, all statistically significant diffusion terms of the model are identified using likelihood ratio tests, yielding inclusion of ?Isc, ?Gp, and ?Gsc . Second, estimates using maximum likelihood are obtained, but prediction capability is poor. Finally a Bayesian method is implemented. Using this method the identified models are able to predict PG using only IG observations. These predictions are assessed visually. We are also able to validate these estimates on a separate data set from the same patient. This study shows that SDE-GBs and a Bayesian method can be used to identify a reliable model for prediction of PG using IG observations obtained with a CGM. The model could eventually be used in an artificial pancreas.

Hansen, Alexander Hildenbrand; Duun-Henriksen, Anne Katrine

2014-01-01

 
 
 
 
361

Accelerated intestinal glucose absorption in morbidly obese humans - relationship to glucose transporters, incretin hormones and glycaemia.  

Science.gov (United States)

Context: 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. Objective: This study aimed to examine intestinal glucose absorption in morbidly obese humans, and its relationship to the expression of STR and glucose transporters, glycaemia, and incretin responses. Design/Setting/Participants: 17 non-diabetic, morbidly obese subjects (BMI:48±4kg/m(2)) and 11 lean controls (BMI:25±1kg/m(2)) underwent endoscopic duodenal biopsies before and after a 30-min intraduodenal glucose infusion (30g glucose & 3g 3-O-methylglucose (3-OMG)). Main Outcome Measures: 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 270min. Expression of duodenal SGLT-1, GLUT2 and STR was quantified by PCR. Results: The rise in plasma 3-OMG (P<0.001) and blood glucose (P<0.0001) were greater in obese than lean subjects. Plasma 3-OMG correlated directly with blood glucose (r=0.78, P<0.01). In response to intraduodenal glucose, plasma GIP (P<0.001), glucagon (P<0.001), and insulin (P<0.001) were higher, but GLP-1 (P<0.001) was less, in the obese compared to lean. Expression of SGLT-1 (P=0.035), but not GLUT2 or T1R2, was higher in the obese, and related to peak plasma 3-OMG (r=0.60, P=0.01), GIP (r=0.67, P=0.003) and insulin (r=0.58, P=0.02). Conclusions: 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. PMID:25423571

Nguyen, Nam Q; Debreceni, Tamara L; Bambrick, Jenna E; Chia, Bridgette; Wishart, Judith; Deane, Adam M; Rayner, Chris K; Horowitz, Michael; Young, Richard L

2014-11-25

362

Chemosensitizing and cytotoxic effects of 2-deoxy-D-glucose on breast cancer cells  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Accelerated glucose uptake for anerobic glycolysis is one of the major metabolic changes found in malignant cells. This property has been exploited for imaging malignancies and as a possible anticancer therapy. The nonmetabolizable glucose analog 2-deoxyglucose (2?DG interferes with glucose metabolism leading to breast cancer cell death. Aims: To determine whether 2DG can synergize with chemotherapeutic agents commonly used in breast cancer treatment and identify cellular characteristics associated with sensitivity to 2DG. Materials and Methods: SkBr3 breast cancer cells were incubated with varying concentrations of 5-fluorouracil (5FU, doxorubicin, cisplatin, cyclophosphamide, or herceptin with or without 2DG. Cell viability was measured using the MTT (3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide assay. Results: Combining 2DG with doxorubicin, 5?FU, cyclophosphamide, and herceptin resulted in enhanced cell death compared with each agent alone, while in combination with cisplatin, the amount of cell death was additive. Mouse embryo fibroblasts (MEF mutated for p53 (-/- were 30% more sensitive to the cytotoxic effects of 2DG than the parental cell lines. Cells mutated for Bax/Bac, genes involved in protection from apoptosis, are slightly more sensitive than the parental cell lines. Conclusions: These results indicate that 2DG acts synergistically with specific chemotherapeutic agents in causing cell death and the class of chemicals most sensitive appear to be those which cause DNA damage.

Zhang Fanjie

2009-09-01

363

Hyperglycemia (High Blood Glucose)  

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Full Text Available ... Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & More Oral ... 2 Diabetes Know Your Rights Employment Discrimination Health Care Professionals Law Enforcement Driver's License For Lawyers Food & ...

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Hyperglycemia (High Blood Glucose)  

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Full Text Available ... ketones, do not exercise. Exercising when ketones are present may make your blood glucose level go even ... a Difference About Us Who We Are Careers Contact Us Policies Corporate Support Newsroom Press Releases For ...

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Hyperglycemia (High Blood Glucose)  

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Full Text Available ... You at Risk? Home Prevention Diagnosing Diabetes and Learning About Prediabetes Type 2 Diabetes Risk Test Lower Your Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity High Blood Glucose My Health Advisor Tools To ...

366

Hyperglycemia (High Blood Glucose)  

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Full Text Available ... may make your blood glucose level go even higher. You'll need to work with your doctor ... html Learn More Have questions? We can help. Contact our Center for Information and Community Support. » « Connect ...

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Hyperglycemia (High Blood Glucose)  

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Full Text Available ... Care Blood Glucose Testing Medication Doctors, Nurses & More Oral Health & Hygiene Women A1C Insulin Pregnancy 8 Tips for ... Resources Online We Support Your Doctor Clinical Practice Guidelines Patient Education Materials Scientific Sessions Journals for Professionals ...

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Hyperglycemia (High Blood Glucose)  

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Full Text Available ... Support Legal Assistance Success Stories Complications Hypoglycemia Hyperglycemia Skin Complications Eye Complications Neuropathy Foot Complications DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Treatment & Care Blood Glucose ...

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Hyperglycemia (High Blood Glucose)  

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Full Text Available ... Glucose Testing Medication Doctors, Nurses & More Oral Health & Hygiene Women A1C Insulin Pregnancy 8 Tips for Caregivers ... updated, this is the "take-you-by-the-hand" guide that will become a trusted friend and ...

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Hyperglycemia (High Blood Glucose)  

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Full Text Available ... a.m. to 5:00 a.m.). What are the Symptoms of Hyperglycemia? The signs and symptoms ... have ketones, do not exercise. Exercising when ketones are present may make your blood glucose level go ...

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Hyperglycemia (High Blood Glucose)  

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Full Text Available ... your blood and then treating high blood glucose early will help you avoid problems associated with hyperglycemia. ... to detect hyperglycemia so you can treat it early — before it gets worse. If you're new ...

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Hyperglycemia (High Blood Glucose)  

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Full Text Available ... Care Blood Glucose Testing Medication Doctors, Nurses & More Oral Health & Hygiene Women A1C Insulin Pregnancy 8 Tips ... that smells fruity Nausea and vomiting Very dry mouth Talk to your doctor about how to handle ...

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Hyperglycemia (High Blood Glucose)  

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Full Text Available ... may make your blood glucose level go even higher. You'll need to work with your doctor ... a Difference About Us Who We Are Careers Contact Us Policies Corporate Support Newsroom Press Releases For ...

375

All about Blood Glucose  

Science.gov (United States)

What are the blood glucose targets for people with diabetes? TargetssetbytheAmerican DiabetesAssociation (ADA)arelistedbelow. Talkwithyourhealthcareteam aboutyour personalgoals. What’s the best way to keep track of ...

376

Hyperglycemia (High Blood Glucose)  

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Full Text Available ... Home Take Action Take Action at the State Level Advocacy Priorities State Priorities Federal Priorities Advocacy Accomplishments ... symptoms include the following: High blood glucose High levels of sugar in the urine Frequent urination Increased ...

377

Fructose vs. Glucose  

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Full Text Available ... 12, 2014 Related MedlinePlus Page Carbohydrates Transcript Could eating foods sweetened with fructose make you hungrier than eating foods that contain glucose? A new study suggests ...

378

Blood Test: Glucose  

Science.gov (United States)

... a vein, the skin surface is cleaned with antiseptic, and an elastic band (tourniquet) is placed around ... Teens For Kids For Parents MORE ON THIS TOPIC Blood Glucose Record Definition: Hyperglycemia Definition: Hypoglycemia Helping ...

379

Hyperglycemia (High Blood Glucose)  

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Full Text Available ... Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & More Oral Health & Hygiene Women A1C Insulin Pregnancy 8 Tips ...

380

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Full Text Available ... Assistance Success Stories Complications Hypoglycemia Hyperglycemia Skin Complications Eye Complications Neuropathy Foot Complications DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & ...

 
 
 
 
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382

Fructose vs. Glucose  

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Full Text Available ... may rev up the reward circuits in your brain more, promoting feeding behavior. Researchers had 24 young ... glucose. Then, using magnetic resonance imaging, they examined brain responses when the participants were shown images of ...

383

Hyperglycemia (High Blood Glucose)  

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Full Text Available ... way for you to lower your blood glucose level. Cutting down on the amount of food you eat might also help. Work with your dietitian to make changes in your meal plan. If exercise and changes ...

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Hyperglycemia (High Blood Glucose)  

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Full Text Available ... Size: A A A Listen En Español Hyperglycemia (High Blood Glucose) Hyperglycemia is the technical term for ... your doctor about how to handle this condition. Medical IDs Many people with diabetes, particularly those who ...

385

Patient-specific Glucose Metabolism Models for Model Predictive Control of T1DM Glycemia  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The development of a predictive control algorithm for glycaemia regulation in diabetic subjects requires patient-specific models of the glucose metabolism which are physiologically relevant, parsimonious, yet able to accurately forecast blood glucose. Given the measured data: total plasma insulin mIU/L; plasma glucose mg/dL; plasma glucose rate of appearance after intestinal absorption mg/kg/min, the objective was to find individualized, simple and plausible glucose-insulin int...

Cescon, Marzia; Johansson, Rolf

2012-01-01

386

Glucose Monitoring During Pregnancy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Self-monitoring of blood glucose in women with mild gestational diabetes has recently been proven to be useful in reducing the rates of fetal overgrowth and gestational weight gain. However, uncertainty remains with respect to the optimal frequency and timing of self-monitoring. A continuous glucose monitoring system may have utility in pregnant women with insulin-treated diabetes, especially for those women with blood sugars that are difficult to control or who experience nocturnal hypoglyce...

Hawkins, J. Seth

2010-01-01

387

Comparison of salivary and serum glucose levels in diabetic patients.  

Science.gov (United States)

Diabetes mellitus is a noncommunicable disease with a rising prevalence worldwide and in developing countries. The most commonly used diagnostic biofluid for detection of glucose levels is blood, but sample collection is an invasive and painful procedure. Thus, there arises a need for a noninvasive and painless technique to detect glucose levels. The objectives of the present study were to estimate the glucose levels of saliva, to assess if any significant correlation existed between the serum and salivary glucose levels, and to correlate salivary glucose levels with regard to duration of diabetes, age, and gender. In the present study, serum and salivary glucose levels of 200 subjects (100 diabetic subjects and 100 nondiabetic subjects) were estimated by glucose oxidase method. Glycosylated hemoglobin levels were also measured in randomly selected 40 diabetic subjects. The findings of present study revealed a significant correlation between salivary and serum glucose levels in both diabetic and nondiabetic subjects. No significant relationship was observed between salivary glucose levels and gender or age in both diabetics and nondiabetics and between salivary glucose levels and duration of diabetes in diabetics. On the basis of the findings, it was concluded that salivary glucose levels could serve as a potentially noninvasive adjunct to monitor glycemic control in diabetic patients. PMID:25294888

Gupta, Shruti; Sandhu, Simarpreet Virk; Bansal, Himanta; Sharma, Deepti

2015-01-01

388

An acoustic glucose sensor.  

Science.gov (United States)

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 ?l/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. PMID:22472531

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

2012-05-15

389

Glucose variability and mortality in patients with sepsis*  

Science.gov (United States)

Objective Treatment and prevention of hyperglycemia has been advocated for subjects with sepsis. Glucose variability, rather than the glucose level, has also been shown to be an important factor associated with in-hospital mortality, in general, critically ill patients. Our objective was to determine the association between glucose variability and hospital mortality in septic patients and the expression of glucose variability that best reflects this risk. Design Retrospective, single-center cohort study. Setting Academic, tertiary care hospital. Patients Adult subjects hospitalized for >1 day, with a diagnosis of sepsis were included. Interventions None. Measurements Glucose variability was calculated for all subjects as the average and standard deviation of glucose, the mean amplitude of glycemic excursions, and the glycemic lability index. Hospital mortality was the primary outcome variable. Logistic regression was used to determine the odds of hospital death in relation to measures of glucose variability after adjustment for important covariates. Main results Of the methods used to measure glucose variability, the glycemic lability index had the best discrimination for mortality (area under the curve = 0.67, p < 0.001). After adjustment for confounders, including the number of organ failures and the occurrence of hypoglycemia, there was a significant interaction between glycemic lability index and average glucose level, and the odds of hospital mortality. Higher glycemic lability index was not independently associated with mortality among subjects with average glucose levels above the median for the cohort. However, subjects with increased glycemic lability index, but lower average glucose values had almost five-fold increased odds of hospital mortality (odds ratio = 4.73, 95% confidence interval = 2.6 – 8.7) compared with those with lower glycemic lability index. Conclusions Glucose variability is independently associated with hospital mortality in septic patients. Strategies to reduce glucose variability should be studied to determine whether they improve the outcomes of septic patients. PMID:18596625

Ali, Naeem A.; O’Brien, James M.; Dungan, Kathleen; Phillips, Gary; Marsh, Clay B.; Lemeshow, Stanley; Connors, Alfred F.; Preiser, Jean-Charles

2011-01-01

390

Abnormal temporal lobe response in Alzheimer's disease during cognitive processing as measured by 11C-2-deoxy-D-glucose and PET  

International Nuclear Information System (INIS)

Elderly controls and probable Alzheimer's disease patients underwent serial positron emission tomography (PET) studies during a baseline condition and while performing a verbal memory task. For the temporal lobes, all 7 Alzheimer patients demonstrated a relative shift in glucose metabolic rates to the right hemisphere during the memory condition relative to baseline, and 5 of 7 controls showed a shift to the left hemisphere. Baseline absolute regional metabolic rates replicate previous findings and were somewhat less useful than the memory challenge in differentiating patients from controls. These results indicate that a temporal lobe abnormality in Alzheimer's disease is related to memory performance

391

Entanglement and thermodynamical analogies  

CERN Document Server

We provide some new properties of entanglement of formation. In particular, we obtain an additive lower bound for entanglement of formation. Subsequently we develop the concept of local orthogonality of ensembles which leads to the mixed states with distillable entanglement equal to entanglement of formation. Then we consider thermodynamical analogies within the entanglement processing domain. Especially, we exploit analogy entanglement -- energy. In this scheme the total entanglement i.e. the amount of singlet pairs needed for local preparation of a state corresponds to internal energy while the free entanglement defined as the number of pairs which can be recovered from the state (distillable entanglement) is the counterpart of free energy. In particular, it leads us to the question about ``temperature'' of entanglement. We also propose a scheme of the search of representative state for given entanglement which can be viewed as an analogue of the Jaynes maximum entropy principle.

Horodecki, P; Horodecki, M; Horodecki, Pawel; Horodecki, Ryszard; Horodecki, Michal

1998-01-01

392

D-Glucose and D-mannose-based metabolic probes. Part 3: Synthesis of specifically deuterated D-glucose, D-mannose, and 2-deoxy-D-glucose.  

Science.gov (United States)

Altered carbohydrate metabolism in cancer cells was first noted by Otto Warburg more than 80 years ago. Upregulation of genes controlling the glycolytic pathway under normoxia, known as the Warburg effect, clearly differentiates malignant from non-malignant cells. The resurgence of interest in cancer metabolism aims at a better understanding of the metabolic differences between malignant and non-malignant cells and the creation of novel therapeutic and diagnostic agents exploiting these differences. Modified d-glucose and d-mannose analogs were shown to interfere with the metabolism of their respective monosaccharide parent molecules and are potentially clinically useful anticancer and diagnostic agents. One such agent, 2-deoxy-d-glucose (2-DG), has been extensively studied in vitro and in vivo and also clinically evaluated. Studies clearly indicate that 2-DG has a pleiotropic mechanism of action. In addition to effectively inhibiting glycolysis, 2-DG has also been shown to affect protein glycosylation. In order to better understand its molecular mechanism of action, we have designed and synthesized deuterated molecular probes to study 2-DG interference with d-glucose and d-mannose metabolism using mass spectrometry. We present here the synthesis of all desired probes: 2-deutero-d-glucose, 2-deutero-d-mannose, 6-deutero-d-glucose, 6-deutero-d-mannose, and 2-deutero-2-deoxy-d-glucose as well as their complete chemical characterization. PMID:23376241

Fokt, Izabela; Skora, Stanislaw; Conrad, Charles; Madden, Timothy; Emmett, Mark; Priebe, Waldemar

2013-03-01

393

Analog Signal Processing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Analog signal processing (ASP) is presented as a systematic approach to address future challenges in high speed and high frequency microwave applications. The general concept of ASP is explained with the help of examples emphasizing basic ASP effects, such as time spreading and compression, chirping and frequency discrimination. Phasers, which represent the core of ASP systems, are explained to be elements exhibiting a frequency-dependent group delay response, and hence a no...

Caloz, Christophe; Gupta, Shulabh; Zhang, Qingfeng; Nikfal, Babak

2013-01-01

394

Geologic Time Discussion Analogies  

Science.gov (United States)

The slides provide a fun way of discussing the immensity of geologic time and help to grasp the age of the earth, the time gaps between major geologic events, and the relative minuteness of humans time on earth. After the discussion with the class, students are given opportunity to develop their own analogies using "everyday" things (other than the calendar and money examples used in this activity).

Fay, Noah

395

Genetic Algorithm Tuning of PID Controller in Smith Predictor for Glucose Concentration Control  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper focuses on design of a glucose concentration control system based on nonlinear model plant of E. coli MC4110 fed-batch cultivation process. Due to significant time delay in real time glucose concentration measurement, a correction is proposed in glucose concentration measurement and a Smith predictor (SP) control structure based on universal PID controller is designed. To reduce the influence of model error in SP structure the estimate of measured glucose concentration is used. For...

Tsonyo Slavov; Olympia Roeva

2011-01-01

396

Spatial relationship between tumor perfusion and endogeneous glucose distribution  

International Nuclear Information System (INIS)

Earlier studies detecting glucose in tissue and solid tumors by bioluminescence imaging suggested, that glucose distribution patterns may be spatially related to functional vascularity. The purpose of this study was to evaluate this relationship by comparing glucose distribution patterns as determined by bioluminescence imaging to perfusion patterns of endogeneous Hoechst 33342 in rats bearing mammary carcinomas. R 3230 mammary carcinoma cells have been implanted subcutaneously into 7 female Fischer 344 rats. Two months post implantation, after injection of Hoechst 33342 the tumors were removed and snap frozen to conserve metabolite levels. Concomitantly, blood was sampled from the animals for analysis of glucose concentrations using a micodialysis analyzer. Cryosections of the tumors have been prepared, and every slice has been analyzed for both, Hoechst binding by fluorescence microscopy, and for glucose distribution patterns using bioluminescence imaging. In many cases vascular structures could be retrieved by the spatial pattern of glucose distribution. In some cases however, higher glucose concentrations could be found independent from Hoechst signal. On the other hand, regions of high Hoechst signal are not necessarily correlated with high glucose concentrations. When comparing blood and tissue glucose levels, tissue glucose content as measured with bioluminescence imaging (1.9-3.5 mM) is considerably lower than blood glucose (5.6-8.0 mM), demonstrating the expeucose (5.6-8.0 mM), demonstrating the expected gradient from blood to tissue. This study demonstrates the feasibility of monitoring glucose gradients in relation to functional vasculature throughout the body, from blood down to tissue or tumor and further, throughout the microenvironment of the solid tumor. Glucose distribution patterns may be an important tool in perfusion studies, e. g. in detecting the direction of blood flow in ex-vivo samples or in estimating glucose consumption rates of tumor cells adjacent to or in between perfused vessels

397

High glucose impairs superoxide production from isolated blood neutrophils  

DEFF Research Database (Denmark)

Superoxide (O(2)(-)), a key antimicrobial agent in phagocytes, is produced by the activity of NADPH oxidase. High glucose concentrations may, however, impair the production of O(2)(-) through inhibition of glucose-6-phosphate dehydrogenase (G6PD), which catalyzes the formation of NADPH. This study measured the acute effects of high glucose or the G6PD inhibitor dehydroepiandrosterone (DHEA) on the production of O(2)(-) from isolated human neutrophils.

Perner, A; Nielsen, S E

2003-01-01

398

A non-invasive frequent home blood glucose monitor  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Attaining near-normoglycaemia in patients with diabetes is essential if diabetes-related complications are to be minimised. Attempts to optimise glycaemic control are often limited by the infrequent nature of current home blood glucose monitoring systems and fear of hypoglycaemia. We evaluated the potential benefit of the GlucoWatch® Biographer, a non-invasive glucose monitoring device designed to give a frequent measure of blood glucose and provide early warning of hypoglycaemia or hypergly...

Lenzen, H.; Barrow, Ba; White, S.; Holman, Rr

2002-01-01

399

The Young Solar Analogs Project  

Science.gov (United States)

We are carrying out a long-term project of measuring chromospheric activity and brightness variations in 31 young solar analogs (YSAs) using facilities at the Dark Sky Observatory (DSO - Appalachian State University) and the Vatican Advanced Technology Telescope (VATT). These YSAs are solar-type (spectral types F8 - K2) stars with ages ranging from 0.3 - 1.5 Gyr. The goal of this project is to gain better understanding of the magnetic activity of the early Sun, and especially how that activity may have impacted the development of life on the Earth. This project will also yield insights into the space environments experienced by young Earth analogs. We are currently in the 6th year of spectroscopic measurements of these stars: these data include Ca II H & K chromospheric flux measurements, and narrow-band measurements in the photospheric G-band, both obtained with the G/M spectrograph on the DSO 32-inch telescope. We will present evidence of activity cycles in a number of our stars, as well as periods determined from rotational modulation of the spectroscopic indices. The relationship between the Ca II activity index and the G-band index will be explored. NSF support for our project has provided funds for the construction of a robotic photometric telescope to monitor the program stars in a 5-passband system (Strömgren-v, Johnson-Cousins B, V, and R, and a 3-nm wide H? filter). The robotic telescope has been functional since April 2012 and observes the program stars on every clear night; combined with the Piggy-back telescope attached to the DSO 32-inch, we now have photometric observations on over 130 nights stretching over nearly 2 years. We will examine the relationships between variations in the Ca II H & K index, the G-band index and the photometric bands. This project is supported by the National Science Foundation, grant AST-1109158.

Gray, Richard O.; Saken, J. M.; Corbally, C. J.; Fuller, V.; Kahvaz, Y.; Lambert, R.; Newsome, I.; Seeds, M.

2013-01-01

400

Towards Analog Reverse Time Computation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report the consequences of a destabilization process on a simulated General Purpose Analog Computer. This new technology overcomes problems linked with serial ambiguity, and provides an analog bias to encode algorithms whose complexity is over polynomial. We also implicitly demonstrate how countermesures of the Stochastic Aperture Degeneracy could efficiently reach higher computational classes, and would open a road towards Analog Reverse Time Computation.

Habibi, O.; Patihnedj, U. R.; Dhar, M. O.

2006-01-01

 
 
 
 
401

Nanomaterial-mediated Biosensors for Monitoring Glucose.  

Science.gov (United States)

Real-time monitoring of physiological glucose transport is crucial for gaining new understanding of diabetes. Many techniques and equipment currently exist for measuring glucose, but these techniques are limited by complexity of the measurement, requirement of bulky equipment, and low temporal/spatial resolution. The development of various types of biosensors (eg, electrochemical, optical sensors) for laboratory and/or clinical applications will provide new insights into the cause(s) and possible treatments of diabetes. State-of-the-art biosensors are improved by incorporating catalytic nanomaterials such as carbon nanotubes, graphene, electrospun nanofibers, and quantum dots. These nanomaterials greatly enhance biosensor performance, namely sensitivity, response time, and limit of detection. A wide range of new biosensors that incorporate nanomaterials such as lab-on-chip and nanosensor devices are currently being developed for in vivo and in vitro glucose sensing. These real-time monitoring tools represent a powerful diagnostic and monitoring tool for measuring glucose in diabetes research and point of care diagnostics. However, concerns over the possible toxicity of some nanomaterials limit the application of these devices for in vivo sensing. This review provides a general overview of the state of the art in nanomaterial-mediated biosensors for in vivo and in vitro glucose sensing, and discusses some of the challenges associated with nanomaterial toxicity. PMID:24876594

Taguchi, Masashige; Ptitsyn, Andre; McLamore, Eric S; Claussen, Jonathan C

2014-03-01

402

Analogical scaffolding: Making meaning in physics through representation and analogy  

Science.gov (United States)

This work reviews the literature on analogy, introduces a new model of analogy, and presents a series of experiments that test and confirm the utility of this model to describe and predict student learning in physics with analogy. Pilot studies demonstrate that representations (e.g., diagrams) can play a key role in students' use of analogy. A new model of analogy, Analogical Scaffolding, is developed to explain these initial empirical results. This model will be described in detail, and then applied to describe and predict the outcomes of further experiments. Two large-scale (N>100) studies will demonstrate that: (1) students taught with analogies, according to the Analogical Scaffolding model, outperform students taught without analogies on pre-post assessments focused on electromagnetic waves; (2) the representational forms used to teach with analogy can play a significant role in student learning, with students in one treatment group outperforming students in other treatment groups by factors of two or three. It will be demonstrated that Analogical Scaffolding can be used to predict these results, as well as finer-grained results such as the types of distracters students choose in different treatment groups, and to describe and analyze student reasoning in interviews. Abstraction in physics is reconsidered using Analogical Scaffolding. An operational definition of abstraction is developed within the Analogical Scaffolding framework and employed to explain (a) why physicists consider some ideas more abstract than others in physics, and (b) how students conceptions of these ideas can be modeled. This new approach to abstraction suggests novel approaches to curriculum design in physics using Analogical Scaffolding.

Podolefsky, Noah Solomon

403

Analog-microchip for ALICE TRD  

International Nuclear Information System (INIS)

For the ALICE Transition Radiation Detector (TRD) a first version of an analog chip was impleme