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Abnormal lipid tolerance in subjects with impaired glucose tolerance and type 2 diabetes: Relationship to intima-media thickness
126
Friday. 28 May 1999 Poster presentation: Triglyceride-rich lipoproteins and atherosclerosis
EFFECTS O F LIPOPROTEIN LIPASE ACTIVITY ON HDL-APO AI METABOLISM IN TYPE II DIABETES MELLITUS: A K I N E T I C STUDY
PREPARATION OF C H Y L O M I C R O N REMNANT-LIKE PARTICLE~ FOR STUDYING THE E F F E C T O F DIETARY LIPIDS ON VASOCONSTRICTION IN PORCINE CORONARY ARTERIES
R. Fr~nais, K. Ouguerram, H. Nazih, C. Maugeais, Y. Za'ir, T. Magot, M. Krempf. C.R.N.H. Mdtabolisme & Service d'Endocrinologie, Hrtel Dieu. Nantes. France
A.B. Goulter, M.A. Avella, J. Elliott, K.M. Botham. Dept. of Veterinar), Basic Sciences, Royal Veterinary College. London NWI OTU. UK
Introduction: The reduction of plasma apolipoprotein (apo) AI in type II diabetes mellitus is related to an increase of its catabolic rate (FCR), in relationship with variations of HDL composition and plasma triglyceride concentration. The aim of the study was to show that kinetic alterations of HDL metabolism were related to alterations of lipoprotein lipase activity (LPL). Method: HDL-apo AI catabolic rate was measured in six type 11 diabetic patients (HbAlc 7.95:1.3%) and six healthy subjects, using a 14 h-primed infusion of D3-1eucine (l 0 [.tmol/kg/h). Isotopic enrichment curves of leucine in HDL-apo AI were analyzed using a one-compartment model (SAAM It modeling sofb,vare). Post heparin plasma (PHP) LPL activity was evaluated in each subject at the end of the infusion. Results: HDL-apo AI FCR was significantly increased in diabetic patients compared to healthy subjects (0.315:0.05 vs 0.215:0.06 pool/day, p < 0.05). and HDL composition was changed (HDL-cholesterol: 27.9+6.6 vs 41.3 5:12.0 mg/dL, p = 0.05 and HDL-TG: 19.4+12.1 vs 9.04-2.7 mg/dL, p = 0.07). LPL activity was decreased (6.2+2.5 vs 10.6 4- 2.6 ,ttmol/mL PHP/h, p < 0.05) and correlated to HDL-apo AI FCR (r = -0.62, p < 0.05), but not related to insulinemia, fasting blood glucose, glycosylated hemoglobin or body mass index in diabetic patients. HDL-apo AI FCR was correlated to plasma and HDL-triglyceride concentrations (r = 0.67, p < 0.05, and r = 0.79, p < 0.005, respectively), and to HDL-cholesterol (r = -0.65, p < 0.05). Conclusion: These results suggest that a decreased lipoprotein lipase activity on VLDL may induce an increase in triglycerides flux on HDL, leading to a change of their composition and catabolism. This study supports the concept that a decreased LPL activity play a key role in the alteration of HDL metabolism in type II diabetes.
CONTINUOUS COMBINED H O R M O N E R E P L A C E M E N T DOES NOT INFLUENCE POSTPRANDIAL TRIGLYCERIDES IN W O M E N W I T H CORONARY ATHEROSCLEROSIS
G. Lloyd, N. Patel, E. McGing, A. Cooper, A. Wierzbicki 1, G. Jackson. The Cardiothoracic Centre; I Department of Metabolic Medicine. Guys and St Thomas Trust, London, UK Raised postprandial triglycerides (T) have been observed in subjects with coronary heart disease and may be influenced by hormone replacement therapy (HRT). Methods: 9 women who had previously demonstrated coronary atheroma at angiography were studied at least six weeks after any lipid lowering therapy had been stopped. Following an overnight fast, cream based drink consisting of 50 g \ m 2 of fat was administered and venous blood was sampled sequentially for six hours. The test was then repeated after one month of oestrodiol valerate (E) 2 mg od and 1 month of E and noresthisterone acetate 700 mcg od (P). Results: Significant changes from baseline after E alone were seen in LDL-C (3.68 m m o l \ L (3.23-5.15) Vs 3.61 mmol\L (2.49-4.70) p = 0.03)), APO-AI (1.34 m m o l \ L (1.27-1.53) Vs (I.59 m m o l \ L (I.48-1.75) (p = 0.02), T (1.72 m m o l \ L (I.43-2.13) Vs 2.25 m m o l \ L (I.75-3.3) (p = 0.04)) and Lp(a) (I5 g \ L (4.5-70.5) Vs 6 g \ L (5--40) (p = 0.05)). No significant differences were observed in total cholesterol, HDL-C, APO-B and APOAll. Postprandial area under the curves for T (I 6.33 (12.07-23.23) Vs 20.03 (13.47-24.09 (p = 0.51)), chylomicron-T (2.38 (.84-2.82) Vs 1.12 (0.493.07) (p = .17)) and VLDL-T (6.22 (4.49-9.39) vs 0.17 (-7.02-13.3) (p = 0.07) were not significantly different. After the addition of P for one month E induced differences in T, LDL- and APO-AI were lost although Lp(a) remained suppressed (8 (4.5-47) p = 0.05). Likewise no effects were observed on the area under the curves for T ( 14.15 ( 11.49-23.76) p = 0.37), chylomicrons (0.60 (.28-3.14) (p = 0.40) or VLDL-T (6.78 (4.88-12.94 (p = 0.21)). Conclusions: The addition of P reduced the beneficial effects of E on APO-AI and LDL-C but offset the E induced increase in T. Neither E alone or in continuous combination with P had significant effects on postprandial triglyceride responses.
The aim of this study was to develop a method of making chylomi. cron remnant-like particles (CRLPs) with identical properties to porcin~ chylomicron remnants in order to investigate their effects on endothelial function and elucidate their role in the development of atherosclerosis. A lipid mixture consisting of 70% triolein, 2% non-esterified cholesterol, 3°A cholesterol oleoyl ester and 25% phospholipids was emulsified in normal saline in Tricine buffer (20 mM, pH 7.4) by sonication for 20 rain al 22-24 I.t at 55-56°C. Lipid particles of the size and density composition corresponding to chylomicron remnants were then isolated by step-wise density gradient ultracentrifugation. Porcine apolipoprotein E (apoE) was bound to the particles by incubation (overnight at 37°C) with a pig plasma density fraction (d > 1.006 g/ml) containing high density lipoproteins. CRLPs were then isolated from the top fraction after ultracentrifugation at d 1.006 g/ml. The CRLPs were found to have a mean diameter of 57.255:2.0 nm and a triacylglycerol: cholesterol ratio of 4.65:0.15: I (n = 3), properties which are consistent with those described for chylomicron remnants prepared in t;ivo. In addition, SDS-PAGE gel electrophoresis showed that particles incubated with plasma contained apoE, but not other apolipoproteins. No apoE was found in the d < 1.006 g/ml fraction in plasma incubated without lipid particles. Thus the CRLPs would be expected to mimic the effects of porcine chylomicron remnants. In studies on isolated porcine vessels, the vessel segments were incubated with CRLPs at an organ bath concentration of 16 I.tM cholesterol for 45 min before U44069 (a thromboxane mimetic constrictor) was cumulatively added. The CRLPs significantly increased the vessel sensitivity to U44069, (ECs0 decreased from 1.63 × 10-~+0.03 to 1.31 x 10-8+0.11 M; P < 0.05, paired students t test) without changing the maximum response significantly. The mechanism by which this occurs remains to be investigated. However, the results indicate that CRLPs provide a useful model for the study of the effect of dietary lipids on vascular endothelial function. A B N O R M A L LIPID T O L E R A N C E IN SUBJECTS WITH IMPAIRED G L U C O S E T O L E R A N C E AND TYPE 2 DIABETES: RELATIONSHIP TO INTIMA°MEDIA T H I C K N E S S E. Henkel, W. Leonhardt, W. Metzler, G. B6hmer, M. Hanefeld. Instimw for Clinical Metabolic Research, Technical Universi o, Dresden, Germany Postprandial lipaemia may play an important role in atherogenesis. The magnitude of postprandial lipaemia is defined as the extent and duration of the increase of plasma triglycerides after ingestion of standardized fat load. An oral fat meal (93 g fat, 82 g glucose) was administered in ageand body mass index-matched men with impaired glucose tolerance (IGT; n > I 1), in patients with Type 2 diabetes in > l I ) and control subjects with normal glucose tolerance (NGT; n > I I). All individuals examined were nonsmokers. Plasma lipoprotein levels were analysed in a fasting state as well as every our within 6 hours after the load. lntima-media thickness of the carotid arteries was measured by B-mode ultrasound. All subjects have fasting tiglycerides < 2.3 mmol/I. Postprandial hypertriglyceridaemia was prolonged in subjects with IGT compared with controls. The postprandial hypertriglyceridaemia by calculation of the "areas under the curves" (AUC) was greater in patients with type 2 diabetes compared with IGT (p < 0.05). AUC of TG significantly correlated to AUC of insulin (p < 0.05), AUC of plasma glucose (PG; p < 0.05) and fasting PG (p < 0.05). Subjects with NGT, IGT and type 2 diabetes have IMT as follows: 1.0 ram; 1.14 mm; 1.21 ram. Our data show that IGT and type2 diabetes are associated with lipid intolerance. Lipid intolerance may play an important part in for atherosclerosis in the early status of impaired glucose tolerance. TRIGLYCERIDES, R E M N A N T L I P O P R O T E I N PARTICLES AND P R E C L I N I C A L A T H E R O S C L E R O S I S IN T H E C Z E C H POPULATION
J. Pitha, J. Kovac, V. Lanska, R. Cifkova, Z. Skodova, P. Stavek, R. Poledne. Institute for Clinical and Experimental Medicine, Prague, Czech Republic Introduction: The importance of the high level of plasma triglycerides (TG) as a risk factor for ischemic heart disease was recently re-established. The
71st EA~/ Congress and Satellite Symposia
Friday. 28 May 1999 Poster presentation: Triglyceride-rich lipoproteins and atherosclerosis
EFFECTS O F LIPOPROTEIN LIPASE ACTIVITY ON HDL-APO AI METABOLISM IN TYPE II DIABETES MELLITUS: A K I N E T I C STUDY
PREPARATION OF C H Y L O M I C R O N REMNANT-LIKE PARTICLE~ FOR STUDYING THE E F F E C T O F DIETARY LIPIDS ON VASOCONSTRICTION IN PORCINE CORONARY ARTERIES
R. Fr~nais, K. Ouguerram, H. Nazih, C. Maugeais, Y. Za'ir, T. Magot, M. Krempf. C.R.N.H. Mdtabolisme & Service d'Endocrinologie, Hrtel Dieu. Nantes. France
A.B. Goulter, M.A. Avella, J. Elliott, K.M. Botham. Dept. of Veterinar), Basic Sciences, Royal Veterinary College. London NWI OTU. UK
Introduction: The reduction of plasma apolipoprotein (apo) AI in type II diabetes mellitus is related to an increase of its catabolic rate (FCR), in relationship with variations of HDL composition and plasma triglyceride concentration. The aim of the study was to show that kinetic alterations of HDL metabolism were related to alterations of lipoprotein lipase activity (LPL). Method: HDL-apo AI catabolic rate was measured in six type 11 diabetic patients (HbAlc 7.95:1.3%) and six healthy subjects, using a 14 h-primed infusion of D3-1eucine (l 0 [.tmol/kg/h). Isotopic enrichment curves of leucine in HDL-apo AI were analyzed using a one-compartment model (SAAM It modeling sofb,vare). Post heparin plasma (PHP) LPL activity was evaluated in each subject at the end of the infusion. Results: HDL-apo AI FCR was significantly increased in diabetic patients compared to healthy subjects (0.315:0.05 vs 0.215:0.06 pool/day, p < 0.05). and HDL composition was changed (HDL-cholesterol: 27.9+6.6 vs 41.3 5:12.0 mg/dL, p = 0.05 and HDL-TG: 19.4+12.1 vs 9.04-2.7 mg/dL, p = 0.07). LPL activity was decreased (6.2+2.5 vs 10.6 4- 2.6 ,ttmol/mL PHP/h, p < 0.05) and correlated to HDL-apo AI FCR (r = -0.62, p < 0.05), but not related to insulinemia, fasting blood glucose, glycosylated hemoglobin or body mass index in diabetic patients. HDL-apo AI FCR was correlated to plasma and HDL-triglyceride concentrations (r = 0.67, p < 0.05, and r = 0.79, p < 0.005, respectively), and to HDL-cholesterol (r = -0.65, p < 0.05). Conclusion: These results suggest that a decreased lipoprotein lipase activity on VLDL may induce an increase in triglycerides flux on HDL, leading to a change of their composition and catabolism. This study supports the concept that a decreased LPL activity play a key role in the alteration of HDL metabolism in type II diabetes.
CONTINUOUS COMBINED H O R M O N E R E P L A C E M E N T DOES NOT INFLUENCE POSTPRANDIAL TRIGLYCERIDES IN W O M E N W I T H CORONARY ATHEROSCLEROSIS
G. Lloyd, N. Patel, E. McGing, A. Cooper, A. Wierzbicki 1, G. Jackson. The Cardiothoracic Centre; I Department of Metabolic Medicine. Guys and St Thomas Trust, London, UK Raised postprandial triglycerides (T) have been observed in subjects with coronary heart disease and may be influenced by hormone replacement therapy (HRT). Methods: 9 women who had previously demonstrated coronary atheroma at angiography were studied at least six weeks after any lipid lowering therapy had been stopped. Following an overnight fast, cream based drink consisting of 50 g \ m 2 of fat was administered and venous blood was sampled sequentially for six hours. The test was then repeated after one month of oestrodiol valerate (E) 2 mg od and 1 month of E and noresthisterone acetate 700 mcg od (P). Results: Significant changes from baseline after E alone were seen in LDL-C (3.68 m m o l \ L (3.23-5.15) Vs 3.61 mmol\L (2.49-4.70) p = 0.03)), APO-AI (1.34 m m o l \ L (1.27-1.53) Vs (I.59 m m o l \ L (I.48-1.75) (p = 0.02), T (1.72 m m o l \ L (I.43-2.13) Vs 2.25 m m o l \ L (I.75-3.3) (p = 0.04)) and Lp(a) (I5 g \ L (4.5-70.5) Vs 6 g \ L (5--40) (p = 0.05)). No significant differences were observed in total cholesterol, HDL-C, APO-B and APOAll. Postprandial area under the curves for T (I 6.33 (12.07-23.23) Vs 20.03 (13.47-24.09 (p = 0.51)), chylomicron-T (2.38 (.84-2.82) Vs 1.12 (0.493.07) (p = .17)) and VLDL-T (6.22 (4.49-9.39) vs 0.17 (-7.02-13.3) (p = 0.07) were not significantly different. After the addition of P for one month E induced differences in T, LDL- and APO-AI were lost although Lp(a) remained suppressed (8 (4.5-47) p = 0.05). Likewise no effects were observed on the area under the curves for T ( 14.15 ( 11.49-23.76) p = 0.37), chylomicrons (0.60 (.28-3.14) (p = 0.40) or VLDL-T (6.78 (4.88-12.94 (p = 0.21)). Conclusions: The addition of P reduced the beneficial effects of E on APO-AI and LDL-C but offset the E induced increase in T. Neither E alone or in continuous combination with P had significant effects on postprandial triglyceride responses.
The aim of this study was to develop a method of making chylomi. cron remnant-like particles (CRLPs) with identical properties to porcin~ chylomicron remnants in order to investigate their effects on endothelial function and elucidate their role in the development of atherosclerosis. A lipid mixture consisting of 70% triolein, 2% non-esterified cholesterol, 3°A cholesterol oleoyl ester and 25% phospholipids was emulsified in normal saline in Tricine buffer (20 mM, pH 7.4) by sonication for 20 rain al 22-24 I.t at 55-56°C. Lipid particles of the size and density composition corresponding to chylomicron remnants were then isolated by step-wise density gradient ultracentrifugation. Porcine apolipoprotein E (apoE) was bound to the particles by incubation (overnight at 37°C) with a pig plasma density fraction (d > 1.006 g/ml) containing high density lipoproteins. CRLPs were then isolated from the top fraction after ultracentrifugation at d 1.006 g/ml. The CRLPs were found to have a mean diameter of 57.255:2.0 nm and a triacylglycerol: cholesterol ratio of 4.65:0.15: I (n = 3), properties which are consistent with those described for chylomicron remnants prepared in t;ivo. In addition, SDS-PAGE gel electrophoresis showed that particles incubated with plasma contained apoE, but not other apolipoproteins. No apoE was found in the d < 1.006 g/ml fraction in plasma incubated without lipid particles. Thus the CRLPs would be expected to mimic the effects of porcine chylomicron remnants. In studies on isolated porcine vessels, the vessel segments were incubated with CRLPs at an organ bath concentration of 16 I.tM cholesterol for 45 min before U44069 (a thromboxane mimetic constrictor) was cumulatively added. The CRLPs significantly increased the vessel sensitivity to U44069, (ECs0 decreased from 1.63 × 10-~+0.03 to 1.31 x 10-8+0.11 M; P < 0.05, paired students t test) without changing the maximum response significantly. The mechanism by which this occurs remains to be investigated. However, the results indicate that CRLPs provide a useful model for the study of the effect of dietary lipids on vascular endothelial function. A B N O R M A L LIPID T O L E R A N C E IN SUBJECTS WITH IMPAIRED G L U C O S E T O L E R A N C E AND TYPE 2 DIABETES: RELATIONSHIP TO INTIMA°MEDIA T H I C K N E S S E. Henkel, W. Leonhardt, W. Metzler, G. B6hmer, M. Hanefeld. Instimw for Clinical Metabolic Research, Technical Universi o, Dresden, Germany Postprandial lipaemia may play an important role in atherogenesis. The magnitude of postprandial lipaemia is defined as the extent and duration of the increase of plasma triglycerides after ingestion of standardized fat load. An oral fat meal (93 g fat, 82 g glucose) was administered in ageand body mass index-matched men with impaired glucose tolerance (IGT; n > I 1), in patients with Type 2 diabetes in > l I ) and control subjects with normal glucose tolerance (NGT; n > I I). All individuals examined were nonsmokers. Plasma lipoprotein levels were analysed in a fasting state as well as every our within 6 hours after the load. lntima-media thickness of the carotid arteries was measured by B-mode ultrasound. All subjects have fasting tiglycerides < 2.3 mmol/I. Postprandial hypertriglyceridaemia was prolonged in subjects with IGT compared with controls. The postprandial hypertriglyceridaemia by calculation of the "areas under the curves" (AUC) was greater in patients with type 2 diabetes compared with IGT (p < 0.05). AUC of TG significantly correlated to AUC of insulin (p < 0.05), AUC of plasma glucose (PG; p < 0.05) and fasting PG (p < 0.05). Subjects with NGT, IGT and type 2 diabetes have IMT as follows: 1.0 ram; 1.14 mm; 1.21 ram. Our data show that IGT and type2 diabetes are associated with lipid intolerance. Lipid intolerance may play an important part in for atherosclerosis in the early status of impaired glucose tolerance. TRIGLYCERIDES, R E M N A N T L I P O P R O T E I N PARTICLES AND P R E C L I N I C A L A T H E R O S C L E R O S I S IN T H E C Z E C H POPULATION
J. Pitha, J. Kovac, V. Lanska, R. Cifkova, Z. Skodova, P. Stavek, R. Poledne. Institute for Clinical and Experimental Medicine, Prague, Czech Republic Introduction: The importance of the high level of plasma triglycerides (TG) as a risk factor for ischemic heart disease was recently re-established. The
71st EA~/ Congress and Satellite Symposia