A.J.H.H.M. van Oostrom

Diurnal triglyceride profiles: a novel approach to study triglyceride changes

Fasting plasma triglycerides (TG) show a high intra-individual variability, and therefore, repeated measurements and alternative methodology are necessary when studying TG metabolism. In search for novel approaches to study TG changes, we evaluated the feasibility of determining ambulatory capillary TG. In addition, well-known characteristics (e.g. gender differences) of TG metabolism in healthy subjects were determined. In 18 subjects with a wide range of fasting plasma TG, the results of standardised oral fat loading tests (50 g m(-2)) were compared to their diurnal capillary TG profiles, measured on 3 different days, six times each day in an out-patient clinic setting. The diurnal TG-profile was calculated as area under the capillary TG curve (TGc-AUC) and as incremental area (dTGc-AUC). Clearance of plasma TG after the acute oral fat load correlated well with the diurnal TGc-AUC (r=0.77; P<0.01). In addition, hypertriglyceridemic subjects (plasma TG >2.0 mmol l(-1)) had a higher diurnal triglyceridemia (49.83+/-15.37 h mmol l(-1)) as well as a higher response of plasma TG to the oral fat load (42.10+/-15.37 h mmol l(-1)), than the subjects with normal fasting plasma TG (29.83+/-11.75 h mmol l(-1) (P<0.05) and 20.75+/-5.89 h mmol l(-1) (P<0.01), respectively). In an observational study, 106 volunteers (54 females and 52 males) measured capillary triglycerides. Food intake was recorded and fasting blood was drawn once at the start of the study. Body composition was assessed by anthropometric parameters and body-impedance. Repeated measurements of diurnal triglyceridemia tended to be less variable than fasting capillary triglycerides (mean coefficients of variation 15.1% (range: 0.60-45.9%) and 24.9% (range: 1.44-72.7%), respectively; P=0.09) for the whole group and in males (18.6% (0.60-45.9%) and 24.0% (1.4-58.2%), respectively; P=0.07). The mean diurnal TGc-AUC and dTGc-AUC were lower in females (16.50+/-4.85 and 1.82+/-3.46 h mmol l(-1), respectively) than in males (23.44+/-6.50 and 6.93+/-4.67 h mmol l(-1); P<0.001 for each). The total daily energy intake was lower in females (8911+/-1905 kJ) than in males (11042+/-2604 kJ, P<0.001) because of a lower intake of all nutrients. In females, estrogen status determined significantly the capillary TG profiles. Stepwise multiple regression analysis for females and males, with TGc-AUC as the dependent variable, showed that the best predictors were fasting capillary TG, gender, systolic blood pressure and mean daily energy intake, explaining 72% of the variation. Incremental triglyceridemia was best described by gender, mean daily protein intake and systolic blood pressure, explaining 42% of the variation. Diurnal capillary TG profiles may be used to estimate the total daily load of potential atherogenic particles to which individuals are subjected during the day without the need for metabolic ward studies.

Diurnal triglyceride profiles in healthy normolipidemic male subjects are associated to insulin sensitivity, body composition and diet

Elevated fasting and postprandial triglycerides (TG) are established risk factors for Coronary Heart Disease (CHD). Usually, fasting plasma TG are measured, although TG are mainly produced in a postprandial state. Our objective was to investigate diurnal TG profiles using serial capillary TG measurements, in normolipidemic healthy males.

Mannose binding lectin deficiency and triglyceride-rich lipoprotein metabolism in normolipidemic subjects

Mannose binding lectin (MBL) is one of the three initiators of complement activation and is therefore closely linked to inflammation. MBL deficiency has been associated with the generation of atherosclerosis. Since atherosclerosis, the complement system and postprandial lipemia are linked to inflammation, we studied postprandial lipoprotein metabolism in MBL deficiency. An observational study was carried out in 107 volunteers (21% MBL deficient). Classical cardiovascular risk factors were not different between subjects with and without MBL deficiency. Oral fat loading tests in 8 MBL deficient and 14 MBL sufficient subjects showed similar postprandial triglyceride, free fatty acid, hydroxybutyric acid and complement component 3 concentrations. MBL deficient subjects had 2.4 times lower postprandial Sf>400 (chylomicron)-apoB48 concentrations, but in contrast a 2-3.5 times increased Sf 60-400 (VLDL1-TG) and Sf 60-400-apoB100 response. MBL activity was inversely related to the postprandial Sf 60-400-TG increase. Despite lower postprandial Sf>400-apoB48 concentrations, MBL deficient subjects show an accumulation of Sf 60-400 lipoproteins.