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Rodríguez Rondón AV, Welling MS, van den Akker ELT, van Rossum EFC, Boon EMJ, van Haelst MM, Delhanty PJD, Visser JA. MC4R variants modulate α-MSH and setmelanotide induced cellular signaling at multiple levels. J Clin Endocrinol Metab 2024:dgae210. [PMID: 38567654 DOI: 10.1210/clinem/dgae210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 02/10/2024] [Indexed: 04/04/2024]
Abstract
CONTEXT Melanocortin-4 receptor (MC4R) plays an important role in body weight regulation. Pathogenic MC4R variants are the most common cause of monogenic obesity. OBJECTIVE We have identified 17 MC4R variants in adult and pediatric patients with obesity. Here, we aimed to functionally characterize these variants by analyzing four different aspects of MC4R signaling. In addition, we aimed to analyze the effect of setmelanotide, a potent MC4R agonist, on these MC4R variants. MATERIALS AND METHODS Cell surface expression and α-MSH- or setmelanotide-induced cAMP response, β-arrestin-2 recruitment, and ERK activation were measured in cells expressing either wild type (WT) or variant MC4R. RESULTS We found a large heterogeneity in the function of these variants. We identified variants with a loss of response for all studied MC4R signaling, variants with no cAMP accumulation or ERK activation but normal β-arrestin-2 recruitment, and variants with normal cAMP accumulation and ERK activation but decreased β-arrestin-2 recruitment, indicating disrupted desensitization and signaling mechanisms. Setmelanotide displayed a greater potency and similar efficacy as α-MSH, and induced significantly increased maximal cAMP responses of several variants compared to α-MSH. Despite the heterogeneity in functional response, there was no apparent difference in the obesity phenotype in our patients. DISCUSSION We show that these obesity-associated MC4R variants affect MC4R signaling differently, yet leading to a comparable clinical phenotype. Our results demonstrate the clinical importance of assessing the effect of MC4R variants on a range of molecular signaling mechanisms to determine their association with obesity, which may aid in improving personalized treatment.
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Affiliation(s)
- Alejandra V Rodríguez Rondón
- Obesity Center CGG and expertise center genetic obesity, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Mila S Welling
- Obesity Center CGG and expertise center genetic obesity, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
- Department of Pediatrics, Division of Endocrinology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Erica L T van den Akker
- Obesity Center CGG and expertise center genetic obesity, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
- Department of Pediatrics, Division of Endocrinology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Elisabeth F C van Rossum
- Obesity Center CGG and expertise center genetic obesity, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Elles M J Boon
- Department of Human Genetics, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Mieke M van Haelst
- Department of Human Genetics, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Patric J D Delhanty
- Obesity Center CGG and expertise center genetic obesity, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Jenny A Visser
- Obesity Center CGG and expertise center genetic obesity, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
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Welling MS, Kleinendorst L, van Haelst MM, van den Akker ELT. The Narrative of a Patient with Leptin Receptor Deficiency: Personalized Medicine for a Rare Genetic Obesity Disorder. Obes Facts 2023; 16:514-518. [PMID: 37393902 PMCID: PMC10601614 DOI: 10.1159/000531529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 06/05/2023] [Indexed: 07/04/2023] Open
Abstract
Leptin receptor (LEPR) deficiency is a rare genetic disorder that affects the body's ability to regulate appetite and weight. For patients and their families, the disorder seriously disrupts daily life; however, little is published about this impact. We here report the experiences of a 10.5-year-old girl with leptin receptor deficiency and her family. The diagnosis of this rare genetic obesity had a deep impact on the life of the child and her family. It led to a better understanding of the cause of the impaired appetite regulation and early-onset obesity with subsequently less judgement by others and improved cooperation of their social network and school on maintaining a healthy lifestyle for this girl. A strict eating regimen and lifestyle measures resulted in the first year after diagnosis in a significantly decreased body mass index (BMI), followed by BMI stabilization, still categorized as obesity class three. However, the troublesome challenge of how to manage the disruptive behaviour due to hyperphagia remained. Eventually, due to treatment with targeted pharmacotherapy, i.e., melanocortin-4 receptor agonists, her BMI continued to decrease due to resolving hyperphagia. The daily routine of the family and the atmosphere at home positively changed as they were no longer dominated by the food-focused behaviour of the child and the adherence to the strict eating regimen. This case report demonstrates the importance and impact of a rare genetic obesity disorder diagnosis in a family. Additionally, it highlights the value of genetic testing in patients with a high suspicion of a genetic obesity disorder as it can eventually lead to personalized treatment, such as guidance by specialized healthcare professionals and educated caregivers or targeted pharmacotherapy.
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Affiliation(s)
- Mila S Welling
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Division of Endocrinology, Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Lotte Kleinendorst
- Department of Human Genetics, Amsterdam Reproduction and Development Research Institute, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands,
- Emma Center for Personalized Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands,
| | - Mieke M van Haelst
- Department of Human Genetics, Amsterdam Reproduction and Development Research Institute, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Emma Center for Personalized Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Erica L T van den Akker
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Division of Endocrinology, Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Welling MS, Mohseni M, van der Valk ES, van Hagen JM, Burgerhart JS, van Haelst MM, van Rossum EFC. Successful naltrexone-bupropion treatment after several treatment failures in a patient with severe monogenic obesity. iScience 2023; 26:106199. [PMID: 36876127 PMCID: PMC9982263 DOI: 10.1016/j.isci.2023.106199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/10/2022] [Accepted: 02/10/2023] [Indexed: 02/16/2023] Open
Abstract
We describe the therapeutic journey of a 33-year-old patient with early-onset obesity (BMI 56.7 kg/m2) and hyperphagia due to a likely pathogenic heterozygous melanocortin-4 receptor (MC4R) gene variant. She was unsuccessfully treated with several intensive lifestyle interventions, gastric bypass surgery (-40 kg weight loss, followed by +39.8 kg weight regain), liraglutide 3 mg (-3.8% weight loss with sustained hyperphagia), and metformin treatment. However, naltrexone-bupropion treatment led to -48.9 kg (-26.7%) weight loss, of which -39.9 kg (-38.3%) was fat mass, in 17 months of treatment. Importantly, she reported improved hyperphagia and quality of life. We describe the potential beneficial effects of naltrexone-bupropion on weight, hyperphagia, and quality of life in a patient with genetic obesity. This extensive journey shows that various anti-obesity agents can be initiated, subsequently terminated when ineffective and substituted with other anti-obesity agents to identify the most efficient anti-obesity treatment.
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Affiliation(s)
- Mila S Welling
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, South-Holland, the Netherlands.,Obesity Center CGG, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, South-Holland, the Netherlands
| | - Mostafa Mohseni
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, South-Holland, the Netherlands.,Obesity Center CGG, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, South-Holland, the Netherlands
| | - Eline S van der Valk
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, South-Holland, the Netherlands.,Obesity Center CGG, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, South-Holland, the Netherlands
| | - Johanna M van Hagen
- Department of Human Genetics, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, North-Holland, the Netherlands
| | - Jan Steven Burgerhart
- Department of Internal Medicine, University Medical Center Utrecht, 3584 CX Utrecht, Utrecht, the Netherlands
| | - Mieke M van Haelst
- Department of Human Genetics, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, North-Holland, the Netherlands
| | - Elisabeth F C van Rossum
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, South-Holland, the Netherlands.,Obesity Center CGG, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, South-Holland, the Netherlands
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Abawi O, Koster EC, Welling MS, Boeters SCM, van Rossum EFC, van Haelst MM, van der Voorn B, de Groot CJ, van den Akker ELT. RF02 | PSAT110 Resting Energy Expenditure and Body Composition in Children and Adolescents with Genetic, Hypothalamic, Medication-Induced or Multifactorial Severe Obesity. J Endocr Soc 2022. [PMCID: PMC9625540 DOI: 10.1210/jendso/bvac150.1323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Background Pediatric obesity is a multifactorial disease characterized by a prolonged imbalance between energy intake and expenditure. In rare cases, it is caused by underlying medical disorders arising from disruptions in the leptin-melanocortin pathway which regulates satiety and energy expenditure. Aim To investigate and compare resting energy expenditure (REE) and body composition characteristics of children and adolescents with severe obesity with and without underlying medical causes. Methods This prospective observational study included pediatric patients who underwent an extensive diagnostic workup in our academic center in which endocrine, non-syndromic and syndromic genetic, hypothalamic, and medication-induced causes of obesity were evaluated. Patients in whom no underlying medical cause was identified were classified as multifactorial obesity. REE was assessed by indirect calorimetry; body composition by air displacement plethysmography. The ratio measured REE (mREE) vs predicted REE (Schofield equations) was expressed as REE%, with decreased mREE defined as REE% ≤90% and elevated mREE as ≥110%. Additionally, the ratio mREE vs fat-free-mass (FFM) was calculated. Results We included 292 patients, of which 218 (75%) patients had multifactorial obesity and 74 (25%) had an underlying medical cause: non-syndromic and syndromic genetic (n= 29 and 28, respectively), hypothalamic (n= 10), and medication-induced (n= 7) obesity. Mean age was 10.8 ± 4.3 years, 59% were female, mean BMI SDS was 3.8 ± 1.1, indicating severe obesity. Mean REE% was higher in children with non-syndromic genetic obesity (107.4% ± 12.7) and lower in children with hypothalamic obesity (87.6% ± 14.2) compared to multifactorial obesity (100.5% ± 12.6, both p<0.01). Measured REE was decreased in 60 (21%) patients (corresponding to an average overprediction of daily caloric needs of 341 kcal/day) and elevated in 69 (24%) patients. Only in hypothalamic obesity, a larger proportion of patients showed a decreased REE compared to multifactorial obesity (6/10 vs 41/218, p<0.01). FFM was higher in children with non-syndromic obesity compared to multifactorial obesity (+7.5kg, p<0.001), but lower in syndromic obesity (-5.2kg, p=0.03), hypothalamic obesity (-12.6kg, p<0.001), and similar in medication-induced obesity (+1.5kg FFM, p=0.80). Mean mREE/FFM was 46.5 ± 10.6 kcal/day/kg FFM and did not differ between patients with underlying medical causes compared to multifactorial obesity (all p>0.05). Conclusion In this cohort of children with severe obesity due to various etiologies, large inter-individual differences in mREE were found. Almost half of patients had decreased or elevated mREE. When relating mREE to FFM, no differences were found between children with underlying medical causes versus multifactorial obesity. Thus, our study underlines the importance of measuring REE and relating mREE to FFM in children with early-onset severe obesity with or without underlying medical causes. This knowledge is important for patient-tailored treatment, e.g. personalized dietary or physical activity interventions and consideration of pharmacotherapy affecting central energy expenditure regulation in children with decreased mREE. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Saturday, June 11, 2022 1:18 p.m. - 1:23 p.m., Saturday, June 11, 2022 1:18 p.m. - 1:23 p.m.
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Abawi O, Koster EC, Welling MS, Boeters SC, van Rossum EFC, van Haelst MM, van der Voorn B, de Groot CJ, van den Akker ELT. Resting Energy Expenditure and Body Composition in Children and Adolescents With Genetic, Hypothalamic, Medication-Induced or Multifactorial Severe Obesity. Front Endocrinol (Lausanne) 2022; 13:862817. [PMID: 35898454 PMCID: PMC9309560 DOI: 10.3389/fendo.2022.862817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 06/08/2022] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Pediatric obesity is a multifactorial disease which can be caused by underlying medical disorders arising from disruptions in the hypothalamic leptin-melanocortin pathway, which regulates satiety and energy expenditure. AIM To investigate and compare resting energy expenditure (REE) and body composition characteristics of children and adolescents with severe obesity with or without underlying medical causes. METHODS This prospective observational study included pediatric patients who underwent an extensive diagnostic workup in our academic centre that evaluated endocrine, non-syndromic and syndromic genetic, hypothalamic, and medication-induced causes of obesity. REE was assessed by indirect calorimetry; body composition by air displacement plethysmography. The ratio between measured REE (mREE) and predicted REE (Schofield equations), REE%, was calculated, with decreased mREE defined as REE% ≤90% and elevated mREE ≥110%. Additionally, the influence of fat-free-mass (FFM) on mREE was evaluated using multiple linear regression. RESULTS We included 292 patients (146 [50%] with body composition measurements), of which 218 (75%) patients had multifactorial obesity and 74 (25%) an underlying medical cause: non-syndromic and syndromic genetic (n= 29 and 28, respectively), hypothalamic (n= 10), and medication-induced (n= 7) obesity. Mean age was 10.8 ± 4.3 years, 59% were female, mean BMI SDS was 3.8 ± 1.1, indicating severe obesity. Mean REE% was higher in children with non-syndromic genetic obesity (107.4% ± 12.7) and lower in children with hypothalamic obesity (87.6% ± 14.2) compared to multifactorial obesity (100.5% ± 12.6, both p<0.01). In 9 children with pseudohypoparathyroidism type 1a, mean REE% was similar (100.4 ± 5.1). Across all patients, mREE was decreased in 60 (21%) patients and elevated in 69 (24%) patients. After adjustment for FFM, mREE did not differ between patients within each of the subgroups of underlying medical causes compared to multifactorial obesity (all p>0.05). CONCLUSIONS In this cohort of children with severe obesity due to various etiologies, large inter-individual differences in mREE were found. Consistent with previous studies, almost half of patients had decreased or elevated mREE. This knowledge is important for patient-tailored treatment, e.g. personalized dietary and physical activity interventions and consideration of pharmacotherapy affecting central energy expenditure regulation in children with decreased mREE.
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Affiliation(s)
- Ozair Abawi
- Dept. of Pediatrics, div. of Endocrinology, Erasmus MC-Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Emma C. Koster
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dept. of Dietetics, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Mila S. Welling
- Dept. of Pediatrics, div. of Endocrinology, Erasmus MC-Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dept. of Internal Medicine, div. of Endocrinology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Sanne C.M. Boeters
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dept. of Dietetics, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Elisabeth F. C. van Rossum
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dept. of Internal Medicine, div. of Endocrinology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Mieke M. van Haelst
- Dept. of Human Genetics, Amsterdam University Medical Center, Location AMC, University of Amsterdam & Location VUmc, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Bibian van der Voorn
- Dept. of Pediatrics, div. of Endocrinology, Erasmus MC-Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dept. of Internal Medicine, div. of Endocrinology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Cornelis J. de Groot
- Dept. of Pediatrics, div. of Endocrinology, Erasmus MC-Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dept. of Pediatrics, Willem-Alexander Children’s Hospital, Leiden University Medical Center, Leiden, Netherlands
| | - Erica L. T. van den Akker
- Dept. of Pediatrics, div. of Endocrinology, Erasmus MC-Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
- *Correspondence: Erica L. T. van den Akker,
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van Schaik J, Welling MS, de Groot CJ, van Eck JP, Juriaans A, Burghard M, Oude Ophuis SBJ, Bakker B, Tissing WJE, Schouten-van Meeteren AYN, van den Akker ELT, van Santen HM. Dextroamphetamine Treatment in Children With Hypothalamic Obesity. Front Endocrinol (Lausanne) 2022; 13:845937. [PMID: 35355559 PMCID: PMC8959487 DOI: 10.3389/fendo.2022.845937] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 02/09/2022] [Indexed: 12/14/2022] Open
Abstract
INTRODUCTION Hypothalamic obesity (HO) in children has severe health consequences. Lifestyle interventions are mostly insufficient and currently no drug treatment is approved for children with HO. Amphetamines are known for their stimulant side-effect on resting energy expenditure (REE) and suppressing of appetite. Earlier case series have shown positive effects of amphetamines on weight in children with acquired HO. We present our experiences with dextroamphetamine treatment in the, up to now, largest cohort of children with HO. METHODS A retrospective cohort evaluation was performed of children with HO treated with dextroamphetamine at two academic endocrine pediatric clinics. Off-label use of dextroamphetamine was initiated in patients with progressive, therapy-resistant acquired or congenital HO. Anthropometrics, REE, self-reported (hyperphagic) behavior and energy level, and side effects were assessed at start and during treatment. RESULTS Nineteen patients with a mean age of 12.3 ± 4.0 years had been treated with dextroamphetamine. In two patients, ΔBMI SDS could not be evaluated due to short treatment duration or the simultaneous start of extensive lifestyle treatment. Mean treatment duration of the 17 evaluated patients was 23.7 ± 12.7 months. Fourteen patients (n = 10 with acquired HO, n = 4 with congenital HO) responded by BMI decline or BMI stabilization (mean ΔBMI SDS of -0.6 ± 0.8, after a mean period of 22.4 ± 10.5 months). In three patients, BMI SDS increased (mean ΔBMI SDS of +0.5 ± 0.1, after a mean period of 29.7 ± 22.6 months). In 11 responders, measured REE divided by predicted REE increased with +8.9%. Thirteen patients (68.4%) reported decreased hyperphagia, improvement of energy level and/or behavior during treatment. Two patients developed hypertension during treatment, which resulted in dosage adjustment or discontinuation of treatment. Twelve children continued treatment at last moment of follow-up. CONCLUSION In addition to supportive lifestyle interventions, dextroamphetamine treatment may improve BMI in children with HO. Furthermore, dextroamphetamines have the potential to decrease hyperphagia and improve resting energy expenditure, behavior, and energy level. In patients with acquired HO, these effects seem to be more pronounced when compared to patients with congenital HO. Future studies are needed to support these results.
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Affiliation(s)
- Jiska van Schaik
- Division of Pediatric Endocrinology, Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht, Netherlands
- Department of Pediatric Oncology, Princess Máxima Center for Pediatric Oncology, Utrecht, Netherlands
- *Correspondence: Jiska van Schaik,
| | - Mila S. Welling
- Obesity Centre Centrum Gezond Gewicht (CGG), Erasmus Medical Center (MC) Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
- Division of Pediatric Endocrinology, Erasmus Medical Center (MC) Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Corjan J. de Groot
- Obesity Centre Centrum Gezond Gewicht (CGG), Erasmus Medical Center (MC) Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
- Division of Pediatric Endocrinology, Erasmus Medical Center (MC) Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Judith P. van Eck
- Obesity Centre Centrum Gezond Gewicht (CGG), Erasmus Medical Center (MC) Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
- Division of Pediatric Endocrinology, Erasmus Medical Center (MC) Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Alicia Juriaans
- Division of Pediatric Endocrinology, Erasmus Medical Center (MC) Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Marcella Burghard
- Department of Pediatric Oncology, Princess Máxima Center for Pediatric Oncology, Utrecht, Netherlands
- Department of Exercise Physiology, Child Development & Exercise Center, Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht, Netherlands
| | - Sebastianus B. J. Oude Ophuis
- Department of Pediatric Oncology, Princess Máxima Center for Pediatric Oncology, Utrecht, Netherlands
- Department of Pediatric Psychiatry, Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht, Netherlands
| | - Boudewijn Bakker
- Division of Pediatric Endocrinology, Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht, Netherlands
- Department of Pediatric Oncology, Princess Máxima Center for Pediatric Oncology, Utrecht, Netherlands
| | - Wim J. E. Tissing
- Department of Pediatric Oncology, Princess Máxima Center for Pediatric Oncology, Utrecht, Netherlands
- Department of Pediatric Oncology/ Hematology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | | | - Erica L. T. van den Akker
- Obesity Centre Centrum Gezond Gewicht (CGG), Erasmus Medical Center (MC) Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
- Division of Pediatric Endocrinology, Erasmus Medical Center (MC) Sophia Children’s Hospital, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Hanneke M. van Santen
- Division of Pediatric Endocrinology, Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht, Netherlands
- Department of Pediatric Oncology, Princess Máxima Center for Pediatric Oncology, Utrecht, Netherlands
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Welling MS, Abawi O, van den Eynde E, van Rossum EFC, Halberstadt J, Brandsma AE, Kleinendorst L, van den Akker ELT, van der Voorn B. Impact of the COVID-19 Pandemic and Related Lockdown Measures on Lifestyle Behaviors and Well-Being in Children and Adolescents with Severe Obesity. Obes Facts 2022; 15:186-196. [PMID: 34743080 PMCID: PMC8805051 DOI: 10.1159/000520718] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Accepted: 11/01/2021] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION COVID-19 lockdown measures have large impact on lifestyle behaviors and well-being of children. The aim of this mixed-methods study was to investigate the impact of COVID-19 lockdown measures on eating styles and behaviors, physical activity (PA), screen time, and health-related quality of life (HRQoL) in children (0-18 years) with severe obesity. METHODS During the first COVID-19 wave (April 2020), validated questionnaires were completed and semi-structured telephone interviews were conducted with parents of children with severe obesity (adult body mass index [BMI]-equivalent ≥35 kg/m2) and/or with the children themselves. Changes in pre-pandemic versus lockdown scores of the Dutch Eating Behavior Questionnaire Children, Pediatric Quality of Life Inventory, and Dutch PA Questionnaire were assessed. Qualitative analyses were performed according to the Grounded Theory. RESULTS Ninety families were approached of which 83 families were included. Characteristics of the included children were: mean age 11.2 ± 4.6 years, 52% female, mean BMI SD-score +3.8 ± 1.0. Emotional, restrained, and external eating styles, HRQoL, and (noneducational) screen time did not change on group level (all p > 0.05). However, weekly PA decreased (mean difference -1.9 h/week, p = 0.02) mostly in adolescents. In the majority of children, mean weekly PA decreased to ≤2 h/week. Children with high emotional or external eating scores during lockdown or pre-existent psychosocial problems had the lowest HRQoL (p < 0.01). Qualitative analyses revealed an increased demand for food in a significant proportion of children (n = 21), mostly in children <10 years (19/21). This was often attributed to loss of daily structure and perceived stress. Families who reported no changes (n = 15) or improved eating behaviors (n = 11) attributed this to already existing strict eating schemes that they kept adhering to during lockdown. CONCLUSION This study shows differing responses to COVID-19 lockdown measures in children with severe obesity. On group level, PA significantly decreased and in substantial minorities eating styles and HRQoL deteriorated. Children with pre-existent psychosocial problems or pre-pandemic high external or emotional eating scores were most at risk. These children and their families should be targeted by health care professionals to minimize negative physical and mental health consequences.
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Affiliation(s)
- Mila S Welling
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Division of Endocrinology, Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Ozair Abawi
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands,
- Division of Endocrinology, Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands,
| | - Emma van den Eynde
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Division of Endocrinology, Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Elisabeth F C van Rossum
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Division of Endocrinology, Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Jutka Halberstadt
- Department of Health Sciences, Amsterdam Public Health Research Institute, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Annelies E Brandsma
- Division of Endocrinology, Department of Pediatrics, Obesity Center CGG, Maasstad Ziekenhuis, Rotterdam, The Netherlands
| | - Lotte Kleinendorst
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Department of Clinical Genetics, Amsterdam UMC location AMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Erica L T van den Akker
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Division of Endocrinology, Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Bibian van der Voorn
- Obesity Center CGG, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Division of Endocrinology, Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Division of Endocrinology, Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Welling MS, de Groot CJ, Kleinendorst L, van der Voorn B, Burgerhart JS, van der Valk ES, van Haelst MM, van den Akker ELT, van Rossum EFC. Effects of glucagon-like peptide-1 analogue treatment in genetic obesity: A case series. Clin Obes 2021; 11:e12481. [PMID: 34291582 PMCID: PMC9286843 DOI: 10.1111/cob.12481] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/02/2021] [Accepted: 07/06/2021] [Indexed: 12/19/2022]
Abstract
Obesity is highly prevalent and comes with serious health burden. In a minority, a genetic cause is present which often results in therapy-resistant obesity. Liraglutide is a glucagon-like peptide-1 (GLP-1) analogue, which has beneficial effects on satiety and weight in common obesity. We present the effects of GLP-1 analogues in adults with a molecularly proven genetic cause of their overweight or obesity. All patients were treated with liraglutide 3.0 mg daily, in addition to intensive supportive lifestyle treatment. Anthropometrics, metabolic parameters, resting energy expenditure (REE), side effects, and subjectively reported satiety and quality of life were assessed. Two patients with 16p11.2 deletion syndrome and two patients with heterozygous pathogenic melanocortin-4 receptor variants were treated. At baseline, their age ranged between 21 and 32 years and body mass index (BMI) ranged between 28.1 and 55.7 kg/m2 . At follow-up (ranges 43 weeks-12 years), a mean change in BMI and waist circumference was observed of -5.7 ± 3.8 kg/m2 and -15.2 ± 21.1 cm, respectively. All patients achieved ≥5% weight loss, three of them lost ≥10% of their body weight. All patients reported improved quality of life and three of them reported ameliorated satiety. Moreover, improvement of glycaemic control and dyslipidaemia were seen. In two patients, REE before and during treatment was measured, which either increased (+26% of predicted REE) or decreased (-18% of predicted REE). Two patients experienced mild side effects for a brief period. In conclusion, our case series shows beneficial effects of GLP-1 analogues on weight, metabolic parameters and quality of life in all four patients with genetic obesity.
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Affiliation(s)
- Mila S. Welling
- Obesity Center CGG, Erasmus MCUniversity Medical Center RotterdamRotterdamThe Netherlands
- Department of Pediatrics, Division of EndocrinologyErasmus MC‐Sophia Children's Hospital, University Medical Center RotterdamRotterdamThe Netherlands
- Department of Internal Medicine, Division of EndocrinologyErasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
| | - Cornelis J. de Groot
- Obesity Center CGG, Erasmus MCUniversity Medical Center RotterdamRotterdamThe Netherlands
- Department of Pediatrics, Division of EndocrinologyErasmus MC‐Sophia Children's Hospital, University Medical Center RotterdamRotterdamThe Netherlands
- Department of Pediatrics, Division of EndocrinologyWillem‐Alexander Children's Hospital, Leiden University Medical CenterLeidenThe Netherlands
| | - Lotte Kleinendorst
- Department of Clinical GeneticsAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
| | - Bibian van der Voorn
- Obesity Center CGG, Erasmus MCUniversity Medical Center RotterdamRotterdamThe Netherlands
- Department of Pediatrics, Division of EndocrinologyErasmus MC‐Sophia Children's Hospital, University Medical Center RotterdamRotterdamThe Netherlands
- Department of Internal Medicine, Division of EndocrinologyErasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
| | | | - Eline S. van der Valk
- Obesity Center CGG, Erasmus MCUniversity Medical Center RotterdamRotterdamThe Netherlands
- Department of Internal Medicine, Division of EndocrinologyErasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
| | - Mieke M. van Haelst
- Department of Clinical GeneticsAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Department of Clinical GeneticsAmsterdam UMC, Vrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Erica L. T. van den Akker
- Obesity Center CGG, Erasmus MCUniversity Medical Center RotterdamRotterdamThe Netherlands
- Department of Pediatrics, Division of EndocrinologyErasmus MC‐Sophia Children's Hospital, University Medical Center RotterdamRotterdamThe Netherlands
| | - Elisabeth F. C. van Rossum
- Obesity Center CGG, Erasmus MCUniversity Medical Center RotterdamRotterdamThe Netherlands
- Department of Internal Medicine, Division of EndocrinologyErasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
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9
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van Rossum EFC, Welling MS, van der Voorn B, van der Valk ES, Abawi O, van den Akker ELT. [Pharmacotherapy for obesity]. Ned Tijdschr Geneeskd 2021; 165:D4907. [PMID: 33560612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Obesity is a complex endocrine disease, mainly caused by environmental, behavioral and biological factors. Maintaining weight loss is extremely difficult due to the neuro-endocrine dysregulations that stimulate the body to return to the previous, increased, weight. Identifying underlying weight-gaining factors is needed, including medication-related, psychological and endocrine factors, as well as monogenic obesity. The cornerstone of treatment is optimization of lifestyle and all other contributing factors. Achieving at least 5% weight loss already has important health benefits. If combined lifestyle intervention (CLI) alone is not successful, pharmacotherapy or bariatric surgery can be added for patients with increased weight-related health risks. Recently, novel pharmacotherapy became available, among which, liraglutide 3 mg and the combination therapy naltrexone/bupropion, which leads to an additional 5-6% mean weight loss compared to CLI alone. For rare forms of obesity there are specific drugs that target defects in the regulation of hunger and satiety. Promising new pharmacotherapy for obesity is under development.
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Affiliation(s)
- E F C van Rossum
- Erasmus MC, afd. Interne Geneeskunde, Rotterdam
- Contact: E. F.C. van Rossum
| | - M S Welling
- Erasmus MC, afd. Interne Geneeskunde, Rotterdam
| | | | | | - O Abawi
- Erasmus MC, afd. Kindergeneeskunde, Rotterdam
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10
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Welling MS, Husen SC, Go ATJI, Groenenberg IAL, Willemsen SP, Bijma HH, Steegers-Theunissen RPM. Growth trajectories of the human fetal brain in healthy and complicated pregnancies and associations with neurodevelopmental outcome in the early life course. Early Hum Dev 2020; 151:105224. [PMID: 33091852 DOI: 10.1016/j.earlhumdev.2020.105224] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 09/03/2020] [Accepted: 10/03/2020] [Indexed: 01/21/2023]
Abstract
BACKGROUND There is a need for non-invasive prenatal markers of the brain to assess fetuses at risk for poor postnatal neurodevelopmental outcome. Periconceptional maternal conditions and pregnancy complications impact prenatal brain development. AIMS To investigate associations between growth trajectories of fetal brain structures and neurodevelopmental outcome in children in the early life course. STUDY DESIGN Periconceptional prospective observational cohort. SUBJECTS Singleton pregnancies were included in the Rotterdam periconception cohort. Two- and three-dimensional ultrasound scans at 22, 26 and 32 weeks gestational age were analysed. OUTCOME MEASURES Head circumference (HC), cerebellum, corpus callosum (CC), Sylvian fissure, insula and parieto-occipital fissure (POF) were measured. Neurodevelopment was evaluated using the Age-and-Stages-questionnaire-3 (ASQ-3) and the Child-Behaviour-Checklist (CBCL) at 2 years of age. Linear mixed models, used to estimate the prenatal brain growth trajectories, and linear regression models, used to evaluate the associations between prenatal brain structures and neurodevelopmental outcomes, were applied in the total study population, and in subgroups: fetal growth restriction (FGR), preterm birth (PTB), fetal congenital heart disease (CHD), and uncomplicated controls. RESULTS Consent for participation was received from parents on behalf of their child 138/203 (68%). ASQ-3 was completed in 128/203 children (63%) and CBCL in 93/203 children (46%). Significant smaller subject-specific growth trajectories (growth rate of CC, HC, left insula, left POF and right POF and the baseline size of CC, HC, left POF and right POF) were found in the FGR subgroup, compared to the other subgroups (all p-values <0.05). In the total group (n = 138), the growth rate of the left insula was associated with poorer ASQ-3 score (β = -869.51; p < 0.05). Healthy controls (n = 106) showed a comparable association (β = -1209.87; p < 0.01). FGR (n = 10) showed a larger baseline size of the right Sylvian fissure in association with poorer CBCL-score (β = 4.13; p < 0.01). In CHD (n = 12) the baseline size of the left Sylvian fissure and its growth rate were associated with respectively poorer and better CBCL-scores (β = 3.11; p < 0.01); (β = -171.99; p < 0.01). In PTB (n = 10) no associations were found. CONCLUSIONS This explorative study suggests associations between ultrasound measurements of fetal brain growth and neurodevelopmental outcome at 2 years of age. In future, this non-invasive technique may improve early identification of fetuses at risk for neurodevelopmental outcome and follow-up postnatal clinical care.
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Affiliation(s)
- Mila S Welling
- Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, 3000, CA, Rotterdam, the Netherlands
| | - Sofie C Husen
- Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, 3000, CA, Rotterdam, the Netherlands
| | - Attie T J I Go
- Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, 3000, CA, Rotterdam, the Netherlands
| | - Irene A L Groenenberg
- Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, 3000, CA, Rotterdam, the Netherlands
| | - Sten P Willemsen
- Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, 3000, CA, Rotterdam, the Netherlands; Department of Biostatistics, Erasmus MC, University Medical Center, 3000, CA, Rotterdam, the Netherlands
| | - Hilmar H Bijma
- Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, 3000, CA, Rotterdam, the Netherlands
| | - Régine P M Steegers-Theunissen
- Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, 3000, CA, Rotterdam, the Netherlands; Department of Pediatrics, Division of Neonatology, Sophia Children's Hospital, 3000, CA, Rotterdam, the Netherlands.
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Abawi O, Welling MS, van den Eynde E, van Rossum EFC, Halberstadt J, van den Akker ELT, van der Voorn B. COVID-19 related anxiety in children and adolescents with severe obesity: A mixed-methods study. Clin Obes 2020; 10:e12412. [PMID: 32920993 PMCID: PMC7685119 DOI: 10.1111/cob.12412] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 08/26/2020] [Accepted: 08/30/2020] [Indexed: 12/11/2022]
Abstract
Recent studies report negative mental health effects of the COVID-19 related lockdown measures in general paediatric cohorts. Since obesity is a risk factor for COVID-19 in adults, children (including adolescents) with obesity might perceive themselves to be vulnerable. Using a combined quantitative and qualitative approach, we explored COVID-19 related anxiety in paediatric patients with severe obesity in the Netherlands using semi-structured telephone interviews and the Paediatric Quality of Life Inventory (PedsQL) questionnaire, which had also been completed by the study population at baseline in the year prior to the COVID-19 outbreak. In total, 75 families participated in the semi-structured telephone interviews during the lockdown, April 2020. Characteristics of included patients were: median age 10.5 years (interquartile range = 7.6-15.2); 52% female; mean BMI standard deviation score 3.8 (SD = 1.0). COVID-19 related anxiety was reported for 24/75 (32%) children. The mean decrease in PedsQL score between baseline visit and COVID-19 outbreak did not differ between children for whom anxiety was reported vs those for whom it was not (mean change -10.3 ± 36.5 vs -3.3 ± 24.4, P = .54). Self-imposed strict quarantine measures were taken by 19/75 (25%) families. During follow-up, several families reported that the previous contact alleviated their anxiety. In conclusion, healthcare professionals should address possible COVID-19 related anxiety in children with severe obesity. Addressing COVID-19 related anxiety could mitigate its potential negative effects.
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Affiliation(s)
- Ozair Abawi
- Obesity Center CGG, Erasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
- Department of Pediatrics, Division of EndocrinologyErasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
| | - Mila S. Welling
- Obesity Center CGG, Erasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
- Department of Pediatrics, Division of EndocrinologyErasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
| | - Emma van den Eynde
- Obesity Center CGG, Erasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
| | - Elisabeth F. C. van Rossum
- Obesity Center CGG, Erasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
- Department of Internal Medicine, Division of EndocrinologyErasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
| | - Jutka Halberstadt
- Department of Health SciencesFaculty of Science, Vrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Erica L. T. van den Akker
- Obesity Center CGG, Erasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
- Department of Pediatrics, Division of EndocrinologyErasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
| | - Bibian van der Voorn
- Obesity Center CGG, Erasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
- Department of Pediatrics, Division of EndocrinologyErasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
- Department of Internal Medicine, Division of EndocrinologyErasmus MC, University Medical Center RotterdamRotterdamThe Netherlands
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Aegerter CM, Lorincz KA, Welling MS, Wijngaarden RJ. Extremal dynamics and the approach to the critical state: experiments on a three dimensional pile of rice. Phys Rev Lett 2004; 92:058702. [PMID: 14995349 DOI: 10.1103/physrevlett.92.058702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2003] [Indexed: 05/24/2023]
Abstract
The evolution of the growth of a ricepile is studied in three dimensions. With time, the pile approaches a critical state with a certain slope. Assuming extremal dynamics in the evolution of the pile, the way the critical state is approached is dictated by the scaling properties of the critical state itself. Experimentally, we determine the envelope of the maximal slope, which is a measure for the distance from the critical state, as well as the growth of the average avalanche size with time. These quantities obey power-law scaling, where the experimental exponents are in good agreement with those obtained from an earlier determination of the critical state properties and extremal dynamics. Furthermore, we discuss the influence of the transient state on the avalanche size distribution, which may have applications in the prevention of large avalanches in natural systems.
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Affiliation(s)
- C M Aegerter
- Division of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081HV Amsterdam, The Netherlands
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13
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Welling MS, Griessen R. Correlated electromigration of H in the switchable mirror YH(3-delta). Phys Rev Lett 2000; 85:3882-3885. [PMID: 11041951 DOI: 10.1103/physrevlett.85.3882] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2000] [Indexed: 05/23/2023]
Abstract
Electromigration of hydrogen in YH(3-delta) is studied by exploiting the H concentration dependence of the optical transmission of YH(3-delta). We find the effective valence Z* of H in YH(3-delta) to be negative. Its value is dominated by a huge wind-force-like term, i.e., Z* approximately K/rho, with K approximately -60 mOmega cm. This value is 3 orders of magnitude larger than typical for H in metals. In an Arrhenius plot, the ratio of hydrogen and electron fluxes extrapolates to unity at infinite temperature, suggesting a one-to-one correlation of hydrogen and electron hopping. We discuss our results in the light of strong electron correlation theories which predict each proton to bind two electrons in a sort of Zhang-Rice singlet.
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