Biomedical subjects

Peter H Bisschop

Publications and source records attributed to Peter H Bisschop.

5 recordsLinked to original sources

PubMed2004

Low-fat, high-carbohydrate and high-fat, low-carbohydrate diets decrease primary bile acid synthesis in humans.

BACKGROUND: Dietary fat content influences bile salt metabolism, but quantitative data from controlled studies in humans are scarce. OBJECTIVE: The objective of the study was to establish the effect of dietary fat content on the metabolism of primary bile salts. DESIGN: The effects of eucaloric extremely low-fat (0%), intermediate-fat (41%; control diet), and extremely high-fat (83%) diets on kinetic values of cholate and chenodeoxycholate metabolism were determined after 11 d by using stable isotope dilution in 6 healthy men. All diets contained identical amounts of cholesterol. RESULTS: The total primary bile salt pool size was not significantly affected by dietary fat content, although the chenodeoxycholate pool was significantly higher during the low-fat diet. Fractional turnover rates of both primary bile salts were 30-50% lower during the low- and high-fat diets than during the control diet. Total hepatic bile salt synthesis was approximately 30% lower during both the high- and low-fat diets, but synthesis rates of the 2 primary bile salts were differentially affected. The molar ratio of cholate to total bile salt synthesis increased from 0.50 +/- 0.05 ( +/- SD) to 0.59 +/- 0.05 and 0.66 +/- 0.04 with increasing fat intake, whereas the molar ratio of chenodeoxycholate to total bile salt synthesis decreased from 0.50 +/- 0.05 to 0.41 +/- 0.05 and 0.34 +/- 0.04. The relative concentration of deoxycholate in plasma increased during the low-fat period, which indicated increased absorption from the colon. CONCLUSIONS: Both low- and high-fat diets reduce the synthesis and turnover rates of primary bile salts in humans, although probably through different mechanisms, and consequently they affect the removal of cholesterol from the body.

Adult↗

PubMed2004

A broad-based metabolic approach to study VLDL apoB100 metabolism in patients with ESRD and patients treated with peritoneal dialysis.

BACKGROUND: Dyslipidemia is often observed in patients with end-stage renal disease (ESRD) and is associated with cardiovascular diseases. Peritoneal dialysis treatment may further deteriorate the lipoprotein abnormalities, suggesting that peritoneal dialysis alters lipid metabolism. METHODS: To study the mechanisms involved in these abnormalities in peritoneal dialysis, we measured insulin sensitivity, free fatty acids release, de novo lipogenesis (DNL), very low-density lipoprotein (VLDL) apoB100 kinetics and cholesterol synthesis in vivo in ESRD (N= 6), peritoneal dialysis patients (N= 5), and controls (N= 7) using stable isotopes. RESULTS: Insulin sensitivity, as assessed by an euglycemic hyperinsulinemic clamp, tended to be lower in ESRD and peritoneal dialysis compared to controls [P= 0.08 by analysis of variance (ANOVA)]. Free fatty acid release during the euglycemic hyperinsulinemic clamp tended to be higher in ESRD and peritoneal dialysis compared to controls (P= 0.08 by ANOVA), while DNL and fractional cholesterol synthesis were normal. VLDL-1 apoB100 (P < 0.05) and VLDL-2 apoB100 pool sizes (P < 0.05) were significantly higher in peritoneal dialysis patients compared to controls. The increased VLDL-1 apoB100 pool size was explained by increased VLDL-1 apoB100 synthesis (P < 0.05) in combination with reduced VLDL-1 apoB100 catabolism (P < 0.01), while the increased VLDL-2 apoB100 pool was explained by reduced catabolism (P < 0.01). CONCLUSION: Both VLDL-1 apoB100 and VLDL-2 apoB100 pool sizes are increased in peritoneal dialysis patients, due to disturbances both in synthesis and catabolism. VLDL-1 apoB100 production is, at least partially, explained by increased free fatty acid availability secondary to peripheral insulin resistance, thus identifying insulin resistance as potential therapeutic target in peritoneal dialysis patients.

Acetates↗

PubMed2004

A low-carbohydrate/high-fat diet improves glucoregulation in type 2 diabetes mellitus by reducing postabsorptive glycogenolysis.

The aim of this study was to examine the mechanisms by which dietary carbohydrate and fat modulate fasting glycemia. We compared the effects of an eucaloric high-carbohydrate (89% carbohydrate) and high-fat (89% fat) diet on fasting glucose metabolism and insulin sensitivity in seven obese patients with type 2 diabetes using stable isotopes and euglycemic hyperinsulinemic clamps. At basal insulin levels glucose concentrations were 148 +/- 11 and 123 +/- 11 mg/dl (8.2 +/- 0.6 and 6.8 +/- 0.6 mmol/liter) on the high-carbohydrate and high-fat diet, respectively (P < 0.001), with insulin concentrations of 12 +/- 2 and 10 +/- 1 microIU/ml (82 +/- 11 and 66 +/- 10 pmol/liter) (P = 0.08). Glucose production was higher on the high-carbohydrate diet (1.88 +/- 0.06 vs. 1.55 +/- 0.05 mg/kg.min (10.44 +/- 0.33 vs. 8.61 +/- 0.28 micromol/kg.min) (P < 0.001) because of higher glycogenolysis. Gluconeogenic rates were not different between the diets. During the use of hyperinsulinemic euglycemic clamps, insulin-mediated suppression of glucose production and stimulation of glucose disposal were not different between the diets. Free fatty concentrations were suppressed by 89 and 62% (P < 0.0001) on the high-carbohydrate and high-fat diet, respectively. We conclude that short-term variations in dietary carbohydrate to fat ratios affect basal glucose metabolism in people with type 2 diabetes merely through modulation of the rate of glycogenolysis, without affecting insulin sensitivity of glucose metabolism.

Diabetes Mellitus, Type 2↗

PubMed2003

Endogenous cholesterol synthesis is associated with VLDL-2 apoB-100 production in healthy humans.

Subjects with high plasma cholesterol levels exhibit a high production of VLDL apolipoprotein B-100 (apoB-100), suggesting that cholesterol is a mediator for VLDL production. The objective of the study was to examine whether endogenous cholesterol synthesis, reflected by the lathosterol-cholesterol ratio (L-C ratio), affects the secretory rates of different VLDL subfractions. Ten healthy subjects were studied after overnight fasting. During a 10 h primed, constant infusion of 13C-valine (15 micromol/kg/h), enrichment was determined in apoB-100 from ultracentrifugally isolated VLDL-1 and VLDL-2 by gas chromatography mass spectrometry. The synthesis rates of VLDL-1 apoB-100 and VLDL-2 apoB-100, catabolism, and transfer were estimated by compartmental analysis. Mean VLDL-1 apoB-100 pool size was 90 +/- 15 mg, and mean VLDL-2 apoB-100 pool size was 111 +/- 14 mg. Absolute synthesis rate of VLDL-1 apoB-100 was 649 +/- 127 mg/day and 353 +/- 59 mg/day for VLDL-2 apoB-100. There was a strong association between the absolute synthesis rate of VLDL-2 apoB-100 and L-C ratio (r 2 = 0.61, P < 0.01). In contrast, no correlation was observed between L-C ratio and absolute synthesis rate of VLDL-1 apoB-100 (r 2 = 0.302, P = 0.09). In conclusion, these data provide additional support for an independent regulation of VLDL-1 apoB-100 and VLDL-2 apoB-100 production. Endogenous cholesterol synthesis is correlated only with the VLDL-2 apoB-100 production.

Adult↗

PubMed2002

The effect of carbohydrate and fat variation in euenergetic diets on postabsorptive free fatty acid release.

Diet composition and energy content modulate free fatty acid (FFA) release. The aim of this study was to evaluate the dose-response effects of euenergetic variations in dietary carbohydrate and fat content on postabsorptive FFA release. The rate of appearance (Ra) of palmitate was measured by infusion of [2,2-2H2]palmitate after an overnight fast in six healthy men on three separate occasions, i.e. after 7 d on euenergetic control, high-carbohydrate and high-fat diets. The protein content and composition was identical for each diet. Postabsorptive plasma fatty acid concentrations were not different between the high-carbohydrate and control diets (0.36 (se 0.07) v. 0.43 (se 0.04) mmol/l), but were increased after the high-fat diet (0.75 (se 0.09) mmol/l, (P<0.01 compared with the other diets). Ra palmitate was not different between the high-carbohydrate and control diets (1.36 (se 0.20) v. 1.47 (se 0.15) micromol/kg per min). However, Ra palmitate was increased to 2.36 (se 0.26) micromol/kg per min after the high-fat diet (P<0.01 compared with the other diets). The fatty acid flux and whole-body fat oxidation were not affected by the high-carbohydrate diet compared with the control diet, but were increased by 67 and 47 % respectively, on the high-fat diet (P<0.01 compared with the other diets). A euenergetic high-fat diet results in increased postabsorptive FFA release and fat oxidation, whereas a euenergetic high-carbohydrate diet does not affect these variables of fat metabolism.

Adult↗