Context: Reduction of 50% excess body weight, using a very low-calorie diet (VLCD; 450 kcal/d) improves insulin sensitivity in obese type 2 diabetes mellitus patients. Objective: The objective of... Show moreContext: Reduction of 50% excess body weight, using a very low-calorie diet (VLCD; 450 kcal/d) improves insulin sensitivity in obese type 2 diabetes mellitus patients. Objective: The objective of the study was to evaluate whether adding exercise to the VLCD has additional benefits. Design: This was a randomized intervention study. Setting: The study was conducted at a clinical research center in an academic medical center. Subjects: Twenty-seven obese [body mass index 37.2 ± 0.9 kg/m2 (mean ± sem)] insulin-treated type 2 diabetes mellitus patients. Intervention: Patients followed a 16-wk VLCD. Thirteen of them simultaneously participated in an exercise program (E) consisting of 1-h, in-hospital training and four 30-min training sessions on a cycloergometer weekly. Outcome Measures: Insulin resistance was measured by a hyperinsulinemic euglycemic clamp. Insulin signaling, mitochondrial DNA (mtDNA) content, and intramyocellular lipid content was measured in skeletal muscle biopsies. Results: Baseline characteristics were identical in both groups. Substantial by Browse to Save" href="http://jcem.endojournals.org/content/97/7/2512#" mce_href="http://jcem.endojournals.org/content/97/7/2512#">weight loss occurred (−23.7 ± 1.7 kg VLCD-only vs. −27.2 ± 1.9 kg VLCD+E, P = NS within groups). The exercise group lost more fat mass. Insulin-stimulated glucose disposal increased similarly in both study groups [15.0 ± 0.9 to 39.2 ± 4.7 μmol/min−1 · kg lean body mass (LBM−1) VLCD-only vs. 17.0 ± 1.0 to 37.5 ± 3.5 μmol/min−1 · kg LBM−1 in VLCD+E], as did phosphorylation of the phosphatidylinositol 3-kinase-protein kinase B/AKT insulin signaling pathway. In contrast, skeletal muscle mtDNA content increased only in the VLCD+E group (1211 ± 185 to 2288 ± 358, arbitrary units, P = 0.016 vs. 1397 ± 240 to 1196 ± 179, P = NS, VLCD-only group). Maximum aerobic capacity also only increased significantly in the VLCD+E group (+6.6 ± 1.7 ml/min−1 · kg LBM−1 vs. +0.7 ± 1.5 ml/min−1 · kg LBM−1 VLCD-only, P = 0.017). Conclusion: Addition of exercise to a 16-wk VLCD induces more fat loss. Exercise augments maximum aerobic capacity and skeletal muscle mtDNA content. These changes are, however, not reflected in a higher insulin-stimulated glucose disposal rate. Show less
Snel, M.; Sleddering, M.A.; Peijl, I.D. van der; Romijn, J.A.; Pijl, H.; Meinders, A.E.; Jazet, I.M. 2012
OBJECTIVE To assess the short- and long-term effects of addition of exercise to a very low calorie diet (VLCD) on low-grade inflammation in obese patients with type 2 diabetes mellitus (T2DM).... Show moreOBJECTIVE To assess the short- and long-term effects of addition of exercise to a very low calorie diet (VLCD) on low-grade inflammation in obese patients with type 2 diabetes mellitus (T2DM). METHODS Twenty seven obese, insulin-dependent T2DM patients followed a 4-month VLCD with (n=13) or without (n=14) exercise and were followed up to 18 months. Anthropometric measurements, metabolic and inflammatory parameters were assessed before, directly after the intervention and at 6 and 18 months follow-up. The same measurements were performed only once in 56 healthy lean and 56 healthy obese controls. RESULTS At baseline hsCRP, IL10 and IL8 were significantly elevated in obese T2DM compared to lean healthy controls. After 4 months, despite substantial weight loss (-25.4 ± 1.3 kg), neither the VLCD nor VLCD+exercise had an effect on plasma cytokines. At 6 months, in the weight-stabilizing period, measures of low-grade inflammation had decreased substantially and equally in both intervention groups. Despite subsequent weight regain, beneficial effect was sustained up to 18 months in both groups, except for IL1 and hsCRP which had returned to baseline in the VLCD-only group. CONCLUSION Our findings suggest that severe caloric restriction increases cytokine production by adipose tissue macrophages and that the beneficial effects of weight loss become apparent only in the eucaloric state. Show less
Wang, Y.A.; Snel, M.; Jonker, J.T.; Hammer, S.; Lamb, H.J.; Roos, A. de; ... ; Rensen, P.C.N. 2011
This thesis shows the results of a 16-week very low calorie diet on insulin resistance, Quality of Life, low-grade inflammation and ectopic fat depositions
Aziz, N.A.; Pijl, H.; Frolich, M.; Snel, M.; Streefland, T.C.M.; Roelfsema, F.; Roos, R.A.C. 2010
Background Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by an increased number of CAG repeats in the HTT gene. Apart from neurological impairment, the disease is also... Show moreBackground Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by an increased number of CAG repeats in the HTT gene. Apart from neurological impairment, the disease is also accompanied by progressive weight loss, abnormalities in fat and glucose homeostasis and a higher prevalence of diabetes mellitus, the causes of which are unknown. Therefore, a detailed analysis of systemic energy homeostasis in HD patients in relation to disease characteristics was performed. Methods Indirect calorimetry combined with a hyperinsulinaemic-euglycaemic clamp with stable isotopes ([6,6-2H2]-glucose and [2H5]- glycerol) was performed to assess energy expenditure and glucose and fat metabolism in nine early stage, medication free HD patients and nine age, sex and body mass index matched controls. Results Compared with controls, fasting energy expenditure was higher in HD patients (1616 +/- 72 vs 1883 +/- 93 kcal/24 h, p=0.037) and increased even further after insulin stimulation (1667 +/- 87 vs 2068 +/- 122 kcal/24 h, p=0.016). During both basal and hyperinsulinaemic conditions, glucose and glycerol disposal rates, endogenous glucose production and hepatic insulin sensitivity were similar between HD patients and controls. In HD patients, energy expenditure increased with disease duration but not with a greater degree of motor or functional impairment. Moreover, a higher mutant CAG repeat size was associated with lower insulin sensitivity (r=-0.84, p=0.018). Conclusion These findings suggest sympathetic hyperactivity as an underlying mechanism of increased energy expenditure in HD, as well as peripheral polyglutamine length dependent interference of mutant huntingtin with insulin signalling that may become clinically relevant in carriers of mutations with large CAG repeat sizes. Show less
Wijngaarden, M.A.; Snel, M.; Bizino, M.B.; Grond, J. van der; Jazet, I.M.; Romijn, J.A.; ... ; Pijl, H. 2010
Type 2 diabetes is associated with alterations in protein kinase B (PKB/Akt) and mammalian target of rapamycin complex 1 (mTORC1) signalling. The proline-rich Akt substrate of 40-kDa (PRAS40) is a... Show moreType 2 diabetes is associated with alterations in protein kinase B (PKB/Akt) and mammalian target of rapamycin complex 1 (mTORC1) signalling. The proline-rich Akt substrate of 40-kDa (PRAS40) is a component of mTORC1, which has a regulatory function at the intersection of the PKB/Akt and mTORC1 signalling pathway. Phosphorylation of PRAS40-Thr246 by PKB/Akt, and PRAS40-Ser183 and PRAS40-Ser221 by mTORC1 results in dissociation from mTORC1, and its binding to 14-3-3 proteins. Although all phosphorylation sites within PRAS40 have been implicated in 14-3-3 binding, substitution of Thr246 by Ala alone is sufficient to abolish 14-3-3 binding under conditions of intact mTORC1 signalling. This suggests that phosphorylation of PRAS40-Thr246 may facilitate efficient phosphorylation of PRAS40 on its mTORC1-dependent sites. In the present study, we investigated the mechanism of PRAS40-Ser183 phosphorylation in response to insulin. Insulin promoted PRAS40-Ser183 phosphorylation after a euglycaemic-hyperinsulinaemic clamp in human skeletal muscle. The insulin-induced PRAS40-Ser183 phosphorylation was further evidenced in vivo in rat skeletal and cardiac muscle, and in vitro in A14 fibroblasts, 3T3L1 adipocytes and L6 myotubes. Inhibition of mTORC1 by rapamycin or amino acid deprivation partially abrogated insulin-mediated PRAS40-Ser183 phosphorylation in cultured cell lines. However, lowering insulin-induced PRAS40-Thr246 phosphorylation using wortmannin or palmitate in cell lines, or by feeding rats a high-fat diet, completely abolished insulin-mediated PRAS40-Ser183 phosphorylation. In addition, replacement of Thr246 by Ala reduced insulin-mediated PRAS40-Ser183 phosphorylation. We conclude that PRAS40-Ser183 is a component of insulin action, and that efficient phosphorylation of PRAS40-Ser183 by mTORC1 requires the phosphorylation of PRAS40-Thr246 by PKB/Akt. (C) 2010 Elsevier Inc. All rights reserved. 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 ... 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 (500mg 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 (2010) 64, 419-423; doi: 10.1038/ejcn.2009.154; published online 24 February 2010 Show less
Snel, M.; Sleddering, M.A.; Pijl, H.; Nieuwenhuizen, W.F.; Frolich, M.; Havekes, L.M.; ... ; Jazet, I.M. 2010
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
Nascimento, E.B.M.; Snel, M.; Guigas, B.; Zon, G.C.M. van der; Kriek, J.; Maassen, J.A.; ... ; Ouwens, D.M. 2010
Type 2 diabetes is associated with alterations in protein kinase B (PKB/Akt) and mammalian target of rapamycin complex 1 (mTORC1) signalling. The proline-rich Akt substrate of 40-kDa (PRAS40) is a... Show moreType 2 diabetes is associated with alterations in protein kinase B (PKB/Akt) and mammalian target of rapamycin complex 1 (mTORC1) signalling. The proline-rich Akt substrate of 40-kDa (PRAS40) is a component of mTORC1, which has a regulatory function at the intersection of the PKB/Akt and mTORC1 signalling pathway. Phosphorylation of PRAS40-Thr246 by PKB/Akt, and PRAS40-Ser183 and PRAS40-Ser221 by mTORC1 results in dissociation from mTORC1, and its binding to 14-3-3 proteins. Although all phosphorylation sites within PRAS40 have been implicated in 14-3-3 binding, substitution of Thr246 by Ala alone is sufficient to abolish 14-3-3 binding under conditions of intact mTORC1 signalling. This suggests that phosphorylation of PRAS40-Thr246 may facilitate efficient phosphorylation of PRAS40 on its mTORC1-dependent sites. In the present study, we investigated the mechanism of PRAS40-Ser183 phosphorylation in response to insulin. Insulin promoted PRAS40-Ser183 phosphorylation after a euglycaemic-hyperinsulinaemic clamp in human skeletal muscle. The insulin-induced PRAS40-Ser183 phosphorylation was further evidenced in vivo in rat skeletal and cardiac muscle, and in vitro in A14 fibroblasts, 3T3L1 adipocytes and L6 myotubes. Inhibition of mTORC1 by rapamycin or amino acid deprivation partially abrogated insulin-mediated PRAS40-Ser183 phosphorylation in cultured cell lines. However, lowering insulin-induced PRAS40-Thr246 phosphorylation using wortmannin or palmitate in cell lines, or by feeding rats a high-fat diet, completely abolished insulin-mediated PRAS40-Ser183 phosphorylation. In addition, replacement of Thr246 by Ala reduced insulin-mediated PRAS40-Ser183 phosphorylation. We conclude that PRAS40-Ser183 is a component of insulin action, and that efficient phosphorylation of PRAS40-Ser183 by mTORC1 requires the phosphorylation of PRAS40-Thr246 by PKB/Akt. Show less
