scholarly journals The Impact of Exogenous Insulin Input on Calculating Hepatic Clearance Parameters

2021 ◽  
pp. 193229682098687
Author(s):  
Alexander D. McHugh ◽  
J. Geoffrey Chase ◽  
Jennifer L. Knopp ◽  
Jennifer J. Ormsbee ◽  
Diana G. Kulawiec ◽  
...  
Keyword(s):  
Optimal Parameter ◽  
Hepatic Clearance ◽  
Intravenous Glucose Tolerance Test ◽  
Accurate Identification ◽  
Kinetics Parameters ◽  
Intravenous Glucose ◽  
Insulin Kinetics ◽  
First Pass ◽  
Parameter Values ◽  
The Impact

Objective: Model-based metabolic tests require accurate identification of subject-specific parameters from measured assays. Insulin assays are used to identify insulin kinetics parameters, such as general and first-pass hepatic clearances. This study assesses the impact of intravenous insulin boluses on parameter identification precision. Method: Insulin and C-peptide data from two intravenous glucose tolerance test (IVGTT) trials of healthy adults ( N = 10 × 2; denoted A and B), with (A) and without (B) insulin modification, were used to identify insulin kinetics parameters using a grid search. Monte Carlo analysis ( N = 1000) quantifies variation in simulation error for insulin assay errors of 5%. A region of parameter values around the optimum was identified whose errors are within variation due to assay error. A smaller optimal region indicates more precise practical identifiability. Trial results were compared to assess identifiability and precision. Results: Trial B, without insulin modification, has optimal parameter regions 4.7 times larger on average than Trial A, with 1-U insulin bolus modification. Ranges of optimal parameter values between trials A and B increase from 0.04 to 0.12 min-1 for hepatic clearance and from 0.07 to 0.14 for first-pass clearance on average. Trial B’s optimal values frequently lie outside physiological ranges, further indicating lack of distinct identifiability. Conclusions: A small 1-U insulin bolus improves identification of hepatic clearance parameters by providing a smaller region of optimal parameter values. Adding an insulin bolus in metabolic tests can significantly improve identifiability and outcome test precision. Assay errors necessitate insulin modification in clinical tests to ensure identifiability and precision.

scholarly journals The Impact of Obesity On Insulin Sensitivity and Secretion During Pubertal Progression: A Longitudinal Study

2020 ◽  
Vol 105 (5) ◽  
pp. e2061-e2068 ◽  
Author(s):  
Megan M Kelsey ◽  
Laura Pyle ◽  
Allison Hilkin ◽  
Cameron D Severn ◽  
Kristina Utzschneider ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Insulin Response ◽  
Tolerance Test ◽  
Intravenous Glucose Tolerance Test ◽  
Normal Weight ◽  
Β Cell ◽  
Early Puberty ◽  
Intravenous Glucose ◽  
Increased Risk ◽  
The Impact

Abstract Context Physiologic changes in glucose metabolism are well-described to occur during puberty. However, there are important gaps in understanding the interaction between obesity and the normal physiologic changes during puberty, as well as how these changes could contribute to the increased risk of comorbidities, such as type 2 diabetes and dyslipidemia, in youth with obesity. Objective The objective of this study was to compare longitudinal changes in insulin sensitivity (Si) and secretion during pubertal progression in youth with obesity versus those with normal weight. Design Longitudinal observational study evaluating youth from early puberty (Tanner [T]2-T3) until puberty completion (T5). Setting Pediatric academic hospital Clinical Translational Research Center. Participants Pubertal youth with normal weight (n = 47; 22 female, 25 male) and obesity (n = 37; 23 female, 14 male) Main Outcome Measures Si, insulin response (acute insulin response to glucose, AIRg) and disposition index (DI) by intravenous glucose tolerance test at baseline (T2-T3), T4, and T5 Results Youth with obesity had significantly lower Si and higher AIRg at each time point (P < 0.001), but DI was similar between the groups. There were no group differences in trajectory of Si, AIRg or DI over time. Leptin, insulin-like growth factor-1, and obesity were most strongly associated with Si and AIRg at all time points. Conclusions Obesity significantly impacts Si during puberty, even at the earliest stages. However, in general, obese youth have adequate β-cell compensation for the significantly reduced Si of puberty. Future studies are needed to better predict the subset of youth who fail to maintain β-cell compensation during puberty.

scholarly journals Multidimensional Analysis of Copper Ore Flotation in Terms of Applied Hydrophobizing Agents

2018 ◽  
Vol 35 ◽  
pp. 01010
Author(s):  
Paulina Pięta ◽  
Tomasz Niedoba ◽  
Agnieszka Surowiak
Keyword(s):  
Aqueous Solution ◽  
High Efficiency ◽  
Optimal Parameter ◽  
Multidimensional Analysis ◽  
Copper Ore ◽  
Ethyl Xanthate ◽  
Sodium Ethyl ◽  
Solid Liquid ◽  
Parameter Values ◽  
The Impact

Flotation is a method of enrichment used to distribute particles, which differ in their surface properties. Hydrophobic solids intrinsically create contact at the solid-liquid-gas interface. However, not all minerals, including copper minerals, can be characterized by this crucial ability. In that case it is necessary to use the collector reagents which guarantees a high efficiency of the enrichment process. The main aim of the paper was to examine the impact of selected collector types and dosages on the results of Polish sandstone copper ore flotation and to find optimal parameter values for products that meet quality and quantity requirements. The laboratory tests were carried out with an application of two types of collectors (Hostaflot, sodium ethyl xanthate aqueous solution) in dosages 100 and 150 g/Mg. Data analysis was based on the use of the taxonomy methods in order to select optimal conditions of collector dosage and type. Based on the indexes, it was found that the best enrichment effects were obtained with a sodium ethyl xanthate aqueous solution 150 g/Mg.

An Interpretation of the Intravenous Glucose Tolerance Test in the Light of Recent Findings on the Kinetics of Glucose and Insulin in Man

1978 ◽  
Vol 54 (2) ◽  
pp. 161-173 ◽  
Author(s):  
V. J. Cunningham ◽  
D. F. Heath
Keyword(s):  
Glucose Tolerance ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Intravenous Glucose Tolerance Test ◽  
Glucose Turnover ◽  
Published Data ◽  
Intravenous Glucose ◽  
Insulin Kinetics ◽  
Intravenous Glucose Tolerance ◽  
Insulin Dependent

1. A theoretical investigation of the intravenous glucose tolerance test has been carried out based on recent findings on the kinetics in man of insulin production, distribution, disposal and action, and of glucose turnover and distribution. 2. A good fit to published data on four groups of subjects required a scheme that includes two extravascular glucose spaces and separate venous, arterial and capillary volumes. The fit to the data was little affected by variations within the physiological range of venous and arterial volumes, cardiac output, glycosuria and the properties of the less-accessible glucose pool. 3. The only variables needed to account for the differences between the groups were kinsulin (a measure of the mean sensitivity of insulin-dependent tissues to insulin action) and the readily accessible glucose space. 4. Three published schemes for insulin kinetics were used. They were all consistent with the data and gave very similar relative values of kinsulin in the four groups. 5. It is shown that a rigorous interpretation of the test requires a knowledge of the hepatic response to the glucose load during the test. These effects are not well characterized in pathological states, e.g. diabetes and injury. Consequently conclusions about insulin resistance in these states drawn only from the test are doubtful.

scholarly journals Analysis of the Impact of Randomization of Search-Control Parameters in Monte-Carlo Tree Search

2021 ◽  
Vol 72 ◽  
pp. 717-757
Author(s):  
Chiara F. Sironi ◽  
Mark H. M. Winands
Keyword(s):  
Monte Carlo ◽  
Optimal Parameter ◽  
Parameter Tuning ◽  
Tree Search ◽  
Control Parameters ◽  
Monte Carlo Tree Search ◽  
The One ◽  
Parameter Values ◽  
Search Control ◽  
The Impact

Monte-Carlo Tree Search (MCTS) has been applied successfully in many domains, including games. However, its performance is not uniform on all domains, and it also depends on how parameters that control the search are set. Parameter values that are optimal for a task might be sub-optimal for another. In a domain that tackles many games with different characteristics, like general game playing (GGP), selecting appropriate parameter settings is not a trivial task. Games are unknown to the player, thus, finding optimal parameters for a given game in advance is not feasible. Previous work has looked into tuning parameter values online, while the game is being played, showing some promising results. This tuning approach looks for optimal parameter values, balancing exploitation of values that performed well so far in the search and exploration of less sampled values. Continuously changing parameter values while performing the search, combined also with exploration of multiple values, introduces some randomization in the process. In addition, previous research indicates that adding randomization to certain components of MCTS might increase the diversification of the search and improve the performance. Therefore, this article investigates the effect of randomly selecting values for MCTS search-control parameters online among predefined sets of reasonable values. For the GGP domain, this article evaluates four different online parameter randomization strategies by comparing them with other methods to set parameter values: online parameter tuning, offline parameter tuning and sub-optimal parameter choices. Results on a set of 14 heterogeneous abstract games show that randomizing parameter values before each simulation has a positive effect on the search in some of the tested games, with respect to using fixed offline-tuned parameters. Moreover, results show a clear distinction between games for which online parameter tuning works best and games for which online randomization works best. In addition, the overall performance of online parameter randomization is closer to the one of online parameter turning than the one of sub-optimal parameter values, showing that online randomization is a reasonable parameter selection strategy. When analyzing the structure of the search trees generated by agents that use the different parameters selection strategies, it is clear that randomization causes MCTS to become more explorative, which is helpful for alignment games that present many winning paths in their trees. Online parameter tuning, instead, seems more suitable for games that present narrow winning paths and many losing paths.

APPLICATION DE LA DOUBLE ÉPREUVE D'HYPERGLYCÉMIE INTRAVEINEUSE À L'ÉTUDE DU DIABÈTE

1960 ◽  
Vol XXXIII (II) ◽  
pp. 157-167
Author(s):  
T. Rodari ◽  
G. Specchia
Keyword(s):  
Glucose Tolerance ◽  
Pancreatic Islet ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Intravenous Glucose Tolerance Test ◽  
Intravenous Glucose ◽  
Intravenous Glucose Tolerance ◽  
Glucose Assimilation

ABSTRACT The double intravenous glucose tolerance test does not modify the assimilation coefficient in normal and thin diabetic subjects. On the contrary, in fat diabetic subjects the second coefficient of assimilation increases significantly, but not the first one. From these researches it is evident that the valuation of glucose assimilation by double venous hyperglycaemic test indicates the functional behaviour of the pancreas in different diabetic states. The interpretation of this behaviour of pancreatic islet response to the double venous hyperglycaemic test is discussed.

Heterotrophic Kinetic Parameter Estimation for Enhanced Biological Phosphorus Removal Processes Operated in Conventional and Membrane-Assisted Modes

2006 ◽  
Vol 41 (1) ◽  
pp. 72-83 ◽  
Author(s):  
Zhe Zhang ◽  
Eric R. Hall
Keyword(s):  
Parameter Estimation ◽  
Phosphorus Removal ◽  
Growth Yield ◽  
Pilot Scale ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Nitrogen And Phosphorus ◽  
Parameter Values ◽  
The Impact ◽  
Biological Phosphorus

Abstract Parameter estimation and wastewater characterization are crucial for modelling of the membrane enhanced biological phosphorus removal (MEBPR) process. Prior to determining the values of a subset of kinetic and stoichiometric parameters used in ASM No. 2 (ASM2), the carbon, nitrogen and phosphorus fractions of influent wastewater at the University of British Columbia (UBC) pilot plant were characterized. It was found that the UBC wastewater contained fractions of volatile acids (SA), readily fermentable biodegradable COD (SF) and slowly biodegradable COD (XS) that fell within the ASM2 default value ranges. The contents of soluble inert COD (SI) and particulate inert COD (XI) were somewhat higher than ASM2 default values. Mixed liquor samples from pilot-scale MEBPR and conventional enhanced biological phosphorus removal (CEBPR) processes operated under parallel conditions, were then analyzed experimentally to assess the impact of operation in a membrane-assisted mode on the growth yield (YH), decay coefficient (bH) and maximum specific growth rate of heterotrophic biomass (µH). The resulting values for YH, bH and µH were slightly lower for the MEBPR train than for the CEBPR train, but the differences were not statistically significant. It is suggested that MEBPR simulation using ASM2 could be accomplished satisfactorily using parameter values determined for a conventional biological phosphorus removal process, if MEBPR parameter values are not available.

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