Background: Therapy with tyrosine kinase inhibitors is associated with thyroid dysfunction. Decreased serum thyroid hormone levels during tyrosine kinase inhibitors are also observed in athyreotic... Show moreBackground: Therapy with tyrosine kinase inhibitors is associated with thyroid dysfunction. Decreased serum thyroid hormone levels during tyrosine kinase inhibitors are also observed in athyreotic patients with thyroid carcinoma. We therefore hypothesized that tyrosine kinase inhibitors may influence thyroid hormone metabolism. Aim: The aim was to study the effects of sorafenib therapy on serum thyroid hormone concentrations and iodothyronine deiodination in athyreotic patients. Design: The design included a prospective open, single-center, single-arm 26-wk study. Methods: We measured serum thyroxine (T4), free T4, 3,5,3-triiodothyronine (T3), free T3, reverse T3 (rT3), and TSH concentrations at baseline and after 26 wk in 21 patients with progressive nonmedullary thyroid carcinoma treated with sorafenib. Ratios of T3/T4 and T3/rT3, which are independent of substrate availability and reflect iodothyronine deiodination, were calculated. Results: Serum free T4 and T3 levels, adjusted for levothyroxine dose per kilogram body weight, decreased by 11 and 18%, respectively, whereas TSH levels increased. The serum T3/T4 and T3/rT3 ratios decreased by 18 and 22%, respectively, which is compatible with increased type 3 deiodination. Conclusions: Sorafenib enhances T4 and T3 metabolism, which is probably caused by increased type 3 deiodination. Show less
Background:Sphingolipids, like phytosphingosine (PS) are part of cellular membranes of yeasts, vegetables and fruits. Addition of PS to the diet decreases serum cholesterol and free fatty acid (FFA... Show moreBackground:Sphingolipids, like phytosphingosine (PS) are part of cellular membranes of yeasts, vegetables and fruits. Addition of PS to the diet decreases serum cholesterol and free fatty acid (FFA) levels in rodents and improves insulin sensitivity.Objective:To study the effect of dietary supplementation with PS on cholesterol and glucose metabolism in humans.Methods:Twelve men with the metabolic syndrome (MetS) (according to the International Diabetes Federation (IDF) criteria; age 51+/-2 years (mean+/-s.e.m.); body mass index (BMI) 32+/-1 kg/m(2)) were randomly assigned to 4 weeks of PS (500 mg twice daily) and 4 weeks of placebo (P) in a double-blind cross-over study, with a 4-week wash-out period between both interventions. At the end of each intervention anthropometric measures and serum lipids were measured and an intravenous glucose tolerance test (IVGTT) was performed.Results:Phytosphingosine did not affect body weight and fat mass compared with P. PS decreased serum total cholesterol (5.1+/-0.3 (PS) vs 5.4+/-0.3 (P) mmol/l; P<0.05) and low-density lipoprotein (LDL)-cholesterol levels (3.1+/-0.3 (PS) vs 3.4+/-0.3 (P) mmol/l; P<0.05), whereas it did not alter serum triglyceride and high-density lipoprotein (HDL)-cholesterol levels. In addition, PS lowered fasting plasma glucose levels (6.2+/-0.3 (PS) vs 6.5+/-0.3 (P) mmol/l; P<0.05). PS increased the glucose disappearance rate (K-value) by 9.9% during the IVGTT (0.91+/-0.06 (PS) vs 0.82+/-0.05 (P) %/min; P<0.05) at similar insulin levels, compared with P, thus implying enhanced insulin sensitivity. PS induced only minor gastrointestinal side effects.Conclusion:Dietary supplementation of PS decreases plasma cholesterol levels and enhances insulin sensitivity in men with the MetS.European Journal of Clinical Nutrition advance online publication, 24 February 2010; doi:10.1038/ejcn.2009.154. Show less
Jonker, J.T.; Wang, Y.N.; Haan, W. de; Diamant, M.; Rijzewijk, L.J.; Meer, R.W. van der; ... ; Smit, J.W.A. 2010
Objective: Thiazolidinediones reduce hepatic steatosis and increase high-density lipoprotein (HDL)-cholesterol levels. In mice with human-like lipoprotein metabolism (APOE*3-Leiden.CETP transgenic... Show moreObjective: Thiazolidinediones reduce hepatic steatosis and increase high-density lipoprotein (HDL)-cholesterol levels. In mice with human-like lipoprotein metabolism (APOE*3-Leiden.CETP transgenic mice), a decrease in hepatic triglyceride (TG) content is associated with a decrease in plasma cholesteryl ester transfer protein (CETP) mass and an increase in HDL levels. Therefore, the aim of the present study was to assess the effects of pioglitazone on CETP mass in patients with type 2 diabetes mellitus. Research Design and Methods: We included 78 men with type 2 diabetes mellitus (age 56.5+/-0.6 years; HbA1c 7.1+/-0.1%) who were randomized to treatment with pioglitazone (30 mg/day) or metformin (2000 mg/day) and matching placebos, in addition to glimepiride. At baseline and after 24 weeks of treatment plasma HDL-cholesterol levels and CETP mass were measured and hepatic TG content was assessed by proton magnetic resonance spectroscopy. Results: Pioglitazone decreased hepatic TG content (5.9 (2.6-17.4) vs. 4.1 (1.9-12.3)%, P<0.05), decreased plasma CETP mass (2.33+/-0.10 vs. 2.06+/-0.10 mug/mL, P<0.05) and increased plasma HDL-cholesterol levels (1.22+/-0.05 vs. 1.34+/-0.05 mM, P<0.05). Metformin did not significantly change any of these parameters. Conclusions: A decrease in hepatic TG content by pioglitazone is accompanied by a decrease in plasma CETP mass and associated with an increase in HDL-cholesterol levels. These results in patients with type 2 diabetes mellitus fully confirm recent findings in mice. Show less
