48 research outputs found
Sensitive estimations of pituitary glycoprotein hormones : clinical and scientific applications
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The effect of pegylated human recombinant leptin (PEG-OB) on neuroendocrine adaptations to semi-starvation in overweight men
No full textThe effect of pegylated human recombinant leptin (PEG-OB) on neuroendocrine adaptations to semi-starvation in overweight men. Hukshorn CJ, Menheere PP, Westerterp-Plantenga MS, Saris WH. Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Department of Human Biology, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands. [email protected] OBJECTIVE: Starvation induces a complex neuroendocrine response in humans thought to have evolved to defend against reduced energy intake. The drop in leptin levels observed during fasting has been implicated as a factor that triggers this adaptive response. To explore this hypothesis, we executed a randomized, double-blind, placebo-controlled study to investigate whether elevated leptin levels using long-acting pegylated human recombinant leptin (PEG-OB) influenced the neuroendocrine responses to semi-starvation in human subjects. DESIGN: Twenty-four overweight male subjects (mean+/-s.e.m.; 34.8+/-1.3 yrs; 28.8+/-0.5 kg/m(2)) were prescribed a very low energy diet (2.1 MJ/day) to induce a state of semi-starvation for the next 46 days. In addition, all subjects received a weekly treatment of 80 mg PEG-OB or matching placebo. Hormone measurements were performed throughout the study period and included 5-h frequent hormone samplings and 24-h urine collections. RESULTS: Weekly subcutaneous administration of PEG-OB led to significant additional weight loss (2.8 kg) but it did not reverse the fasting-induced changes in the thyroid, corticotropic, somatotropic axes and sympathetic nervous system activity. However, after adjustment for weight loss, the drop in mean luteinizing hormone levels was attenuated in the PEG-OB group compared with the placebo group. CONCLUSIONS: These results suggest that a reduced level of leptin accompanying food restriction might be a component of the fasting-induced neuroendocrine inhibition of the human reproductive axi
Miglitol (Bay m 1099) has no extraintestinal effects on glucose control in healthy volunteers.
No full textMiglitol (Bay m 1099) has no extraintestinal effects on glucose control in healthy volunteers. Sels JP, Nauta JJ, Menheere PP, Wolffenbuttel BH, Nieuwenhuijzen Kruseman AC. Department of Internal Medicine, University Hospital Maastricht, The Netherlands. In this double-blind, cross-over, placebo-controlled, randomized study, possible extraintestinal effects of miglitol, an absorbable alpha-glucosidase inhibitor, were investigated. Sixteen healthy male volunteers underwent two 75 g oral glucose tolerance tests with concomitant administration of miglitol or placebo. Peak and post-peak areas under the curve values for blood glucose, serum insulin and serum C-peptide after miglitol were not different from those found after placebo. The post-peak AUC-ratio (AUC (peak, 180 min) on miglitol/AUC (peak, 180 min) on placebo) was for glucose 1.15 (CI 0.94-1.40, P = 0.16), for insulin 1.12 (CI 0.95-1.33, P = 0.17) and for C-peptide 0.98 (CI 0.81-1.18, P = 0.82). It is concluded that miglitol exerts no clinically relevant extraintestinal effects on glucose control. Publication Types: Clinical Trial Randomized Controlled Tria
Are children with cystic fibrosis who are treated with a proton-pump inhibitor at risk for vitamin B(12) deficiency?
No full textAre children with cystic fibrosis who are treated with a proton-pump inhibitor at risk for vitamin B(12) deficiency? ter Heide H, Hendriks HJ, Heijmans H, Menheere PP, Spaapen LJ, Bakker JA, Forget PP. Department of Pediatrics, University Hospital Maastricht, Maastricht, The Netherlands. BACKGROUND: In a recent study, the authors demonstrated the beneficial effect of proton-pump inhibitors (PPI) on fat malabsorption and bone mineral content in children with cystic fibrosis (CF). Prolonged use of PPI could result in vitamin B(12) deficiency as a consequence of impaired release of vitamin B(12) from food in a nonacid environment. The aim of this study was to evaluate the vitamin B 12 status of CF patients either treated with a PPI or not by measuring vitamin B(12) and homocysteine blood levels, the latter being a sensitive indicator of vitamin B(12) deficiency. METHODS: The study population consisted of 20 CF patients, 11 patients treated with a PPI for at least 2 years and 9 patients not treated with a PPI, and 10 healthy, age-matched control participants. Homocysteine blood levels were measured by high-performance liquid chromatography, and vitamin B(12) levels were measured by a competitive protein-binding assay. RESULTS: Vitamin B(12) levels were significantly higher in both CF groups compared with the control participants (PPI+, P = 0.02; PPI-, P = 0.009). There was no significant difference in vitamin B(12) levels between both CF groups. Homocysteine levels were normal and similar in all groups. CONCLUSIONS: Cystic fibrosis patients treated with a PPI for at least 2 years show no signs of vitamin B(12) deficienc
Amino acid ingestion strongly enhances insulin secretion in patients with long-term type 2 diabetes
No full textAmino acid ingestion strongly enhances insulin secretion in patients with long-term type 2 diabetes. van Loon LJ, Kruijshoop M, Menheere PP, Wagenmakers AJ, Saris WH, Keizer HA. Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, Maastricht, the Netherlands. [email protected] OBJECTIVE: Insulin secretion in response to carbohydrate intake is blunted in type 2 diabetic patients. However, it is not clear whether the insulin response to other stimuli, such as amino acids, is also diminished. Recently, we defined an optimal insulinoptropic mixture containing free leucine, phenylalanine, and a protein hydrolysate that substantially enhances the insulin response in healthy young subjects when coingested with carbohydrate. In this study, we aimed to investigate the insulinotropic capacity of this mixture in long-term type 2 diabetic patients. RESEARCH DESIGN AND METHODS: Ten type 2 diabetic patients (aged 59.1 +/- 2.0 years, BMI 26.5 +/- 0.7 kg/m(2)) and 10 healthy control subjects (58.8 +/- 2.1 years, 26.5 +/- 0.7 kg/m(2)) visited our lab twice, during which insulin responses were determined following ingestion of carbohydrate only (CHO) or carbohydrate with the free amino acid/protein mixture (CHO+PRO). All subjects received 0.7 g x kg(-1) x h(-1) carbohydrate with or without 0.35 g x kg(-1) x h(-1) of the amino acid/protein mixture. RESULTS: Insulin responses were dramatically increased in the CHO+PRO trial in both the type 2 diabetic and control groups (189 and 114%, respectively) compared with the CHO trial (P < 0.01). Plasma glucose, glucagon, growth hormone, cortisol, IGF-I, and IGF binding protein 3 responses were not different between trials within the 2-h time frame. CONCLUSIONS: The insulin secretory capacity in long-term type 2 diabetic patients is substantially underestimated, as the insulin response following carbohydrate intake can be nearly tripled by coingestion of a free amino acid/protein mixture. Future research should be performed to investigate whether such nutritional interventions can improve postprandial glucose disposa
Prognostic factors for successful insulin therapy in subjects with type 2 diabetes.
No full textDepartment of Endocrinology and Metabolism, University Hospital Maastricht, The Netherlands. [email protected] OBJECTIVE: To assess which factors influence or predict the efficacy of insulin therapy in subjects with type 2 diabetes, who were poorly controlled despite maximal doses of oral glucose lowering agents. RESEARCH DESIGN AND METHODS: Seventy-five patients with type 2 diabetes participated (mean age (+/- SD), 67 +/- 8 years; body mass index, 25.8 +/- 5.0 kg/m2; median time since diagnosis of diabetes, 8 years (range 1-36); 27 males and 48 females). They were transferred to insulin therapy, in which case either insulin alone, or a combination of insulin and glibenclamide was employed. The importance of baseline parameters (glycaemic control, beta-cell function, measures of insulin resistance) was assessed by comparing good and poor responders (defined as achieved HbA1c 9.0%) to insulin therapy, and by multiple logistic regression analysis of these baseline parameters and achieved metabolic control. RESULTS: During insulin therapy, HbA1c levels decreased from 10.9 +/- 1.3 to 8.2 +/- 1.1% (p < 0.001), and fasting blood glucose levels decreased from 14.0 +/- 2.3 to 8.2 +/- 2.1 mmol/l (p < 0.001). Thirty patients reached HbA1c levels < 8.0%, 21 of them even < 7.5%. The mean increase in body weight was 4.5 kg. HbA1c after 6 months was 7.0 +/- 0.6% in the good responders, and 9.8 +/- 0.6% in the poor responders (p < 0.001), despite a comparable insulin dose. Baseline metabolic control was similar in both groups. Also, glucagon-stimulated and calculated insulin secretion, as well as parameters of insulin resistance, such as fasting serum insulin levels, free fatty acids, and serum triglycerides, were not different between both groups, and certainly not higher in the poor responders. Also previous metformin use was not different. However, poor responders were more obese than good responders, and had significantly longer known duration of diabetes. Multiple logistic regression confirmed that only duration of diabetes and body mass index were independent predictors of response to insulin therapy. CONCLUSIONS: We conclude that in elderly patients with type 2 diabetes improvement of glycaemic control can be achieved at the expense of some weight gain. Measurement of residual insulin secretion prior to institution of insulin treatment does not discriminate between good and poor responders to this model of therapy. Especially in obese patients with longer duration of diabetes more attention is needed in order to achieve optimal glycaemic control. Combination of insulin with newer drugs, like thiazolidinediones, may perhaps achieve this
Effects of energy restriction on acute adrenoceptor and metabolic responses to exercise in obese subjects
No full textEffects of energy restriction on acute adrenoceptor and metabolic responses to exercise in obese subjects. Kempen KP, Saris WH, Senden JM, Menheere PP, Blaak EE, van Baak MA. Department of Human Biology, University of Limburg, Maastricht, The Netherlands. This study was intended to investigate the effects of energy restriction on the acute responses of platelet alpha 2- and lymphocyte beta 2-adrenoceptors to exercise in obese female subjects. Seven obese females were restricted to a low-energy formula diet (2.0 MJ/day) for 4 wk. As result of the diet, there was a 7.8-kg weight loss. No significant changes could be detected in sleeping and resting metabolic rate expressed per kilogram fat-free mass. Basal venous glucose, insulin, and norepinephrine levels decreased as a result of the diet, whereas free fatty acid values increased. Before the diet, 60 min of exercise (45% peak mechanical power) caused no alteration in the density of lymphocyte beta 2-adrenoceptors. At the end of 4 wk of dieting, the density was significantly increased in response to exercise, together with a higher thermogenic and lipolytic response and decreased venous insulin levels. Energy restriction resulted in an increased basal platelet alpha 2-adrenoceptor density, whereas exercise did not modify density and affinity of platelet alpha 2-adrenoceptors. The results indicate that adrenoceptor numbers can be modulated by energy restriction in obesity. Modulation of adrenoceptor density may play a role in increased exercise-induced lipolysis during energy restrictio
The consensus statement on the standardization and evaluation of growth hormone and insulin-like growth factor assays lacks a recommendation to attempt efficacious harmonization
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