| 1. |
- Adiels, Martin, 1976, et al.
(författare)
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A new combined multicompartmental model for apolipoprotein B-100 and triglyceride metabolism in VLDL subfractions
- 2005
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Ingår i: J Lipid Res. - 0022-2275 .- 1539-7262. ; 46:1, s. 58-67
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Tidskriftsartikel (refereegranskat)abstract
- The use of stable isotopes in conjunction with compartmental modeling analysis has greatly facilitated studies of the metabolism of the apolipoprotein B (apoB)-containing lipoproteins in humans. The aim of this study was to develop a multicompartment model that allows us to simultaneously determine the kinetics of apoB and triglyceride (TG) in VLDL(1) and VLDL(2) after a bolus injection of [(2)H(3)]leucine and [(2)H(5)]glycerol and to follow the catabolism and transfer of the lipoprotein particles. Here, we describe the model and present the results of its application in a fasting steady-state situation in 17 subjects with lipid values representative of a Western population. Analysis of the correlations showed that plasma TG was determined by the VLDL(1) and VLDL(2) apoB and TG fractional catabolic rate. Furthermore, the model showed a linear correlation between VLDL(1) TG and apoB production. A novel observation was that VLDL TG entered the circulation within 21 min after its synthesis, whereas VLDL apoB entered the circulation after 33 min. These observations are consistent with a sequential assembly model of VLDL and suggest that the TG is added to a primordial apoB-containing particle in the liver.
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| 2. |
- Adiels, Martin, 1976, et al.
(författare)
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Overproduction of VLDL1 driven by hyperglycemia is a dominant feature of diabetic dyslipidemia
- 2005
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Ingår i: Arterioscler Thromb Vasc Biol. - 1524-4636 .- 1079-5642. ; 25:8, s. 1697-703
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: We sought to compare the synthesis and metabolism of VLDL1 and VLDL2 in patients with type 2 diabetes mellitus (DM2) and nondiabetic subjects. METHODS AND RESULTS: We used a novel multicompartmental model to simultaneously determine the kinetics of apolipoprotein (apo) B and triglyceride (TG) in VLDL1 and VLDL2 after a bolus injection of [2H3]leucine and [2H5]glycerol and to follow the catabolism and transfer of the lipoprotein particles. Our results show that the overproduction of VLDL particles in DM2 is explained by enhanced secretion of VLDL1 apoB and TG. Direct production of VLDL2 apoB and TG was not influenced by diabetes per se. The production rates of VLDL1 apoB and TG were closely related, as were the corresponding pool sizes. VLDL1 and VLDL2 compositions did not differ in subjects with DM2 and controls, and the TG to apoB ratio of newly synthesized particles was very similar in the 2 groups. Plasma glucose, insulin, and free fatty acids together explained 55% of the variation in VLDL1 TG production rate. CONCLUSIONS: Insulin resistance and DM2 are associated with excess hepatic production of VLDL1 particles similar in size and composition to those in nondiabetic subjects. We propose that hyperglycemia is the driving force that aggravates overproduction of VLDL1 in DM2.
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| 6. |
- Anguelova, Milena, 1978, et al.
(författare)
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Input-Output Representation and Identifiability of Delay Parameters for Nonlinear Systems with Multiple Time-Delays
- 2009
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Ingår i: Lecture Notes in Control and Information Sciences: TOPICS IN TIME DELAY SYSTEMS: ANALYSIS, ALGORITHMS AND CONTROL; 7th IFAC Workshop on Time Delay Systems. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0170-8643. - 9783642028960 ; 388, s. 243-253
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have analyzed the identifiability of time-lag parameters in nonlinear delay systems using an algebraic framework. The identifiability is determined by the form of the system's input-output representation. The values of the time lags can be found directly from the input-output equations, if these can be obtained explicitly. Linear-algebraic criteria are formulated to decide the identifiability of the delay parameters when explicit computation of the input-output relations is not possible.
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| 7. |
- Anguelova, Milena, 1978, et al.
(författare)
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On analytic and algebraic observability of nonlinear delay systems
- 2010
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Ingår i: Automatica. - : Elsevier BV. - 0005-1098. ; 46:4, s. 682-686
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Tidskriftsartikel (refereegranskat)abstract
- The observability of nonlinear delay systems has previously been defined in an algebraic setting by a rank condition on modules over noncommutative rings. We introduce an analytic definition of observability to ensure the local uniqueness of state and initial conditions that correspond to a given input-output behaviour. It is shown that an algebraically observable delay system can be reformulated as a system of ordinary differential equations. Analytic observability is then decided by the local uniqueness of solutions to a boundary value problem for this ODE system. (C) 2010 Elsevier Ltd. All rights reserved.
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| 8. |
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| 9. |
- Anguelova, Milena, 1978, et al.
(författare)
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State elimination and identifiability of the delay parameter for nonlinear time-delay systems
- 2008
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Ingår i: Automatica. - : Elsevier BV. - 0005-1098. ; 44:5, s. 1373-1378
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Tidskriftsartikel (refereegranskat)abstract
- The identifiability of the delay parameter for nonlinear systems with a single constant time delay is analyzed. We show the existence of input–output equations and relate the identifiability of the delay parameter to their form. Explicit criteria based on rank calculations are formulated. The identifiability of the delay parameter is shown not to be directly related to the well-characterized identifiability/observability of the other system parameters/states.
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| 10. |
- Bagland, Véronique, et al.
(författare)
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Stationary states for the noncutoff Kac equation with a Gaussian thermostat
- 2007
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Ingår i: Nonlinearity. - : Institute of Physics Publishing (IOPP). - 0951-7715 .- 1361-6544. ; 20:3, s. 583-604
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Tidskriftsartikel (refereegranskat)abstract
- We study the stationary states of a Kac equation with a Gaussian thermostat in the case of a noncutoff cross section. We investigate the existence, smoothness and uniqueness of the stationary states. The theoretical results are illustrated by some numerical simulations.
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