Publications by authors named "Marieke J H van Summeren"

Clinicians have to assess children's competence frequently. In order to do justice to children who are competent to make decisions and to protect incompetent children, valid assessment is essential. We address this issue by using bariatric surgery for morbidly obese minors as a case study.

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Despite the reported limited success of conventional treatments and growing evidence of the effectiveness of adult bariatric surgery, weight loss operations for (morbidly) obese children and adolescents are still considered to be controversial by health care professionals and lay people alike. This paper describes an explorative, qualitative study involving obesity specialists, morbidly obese adolescents, and parents and identifies attitudes and normative beliefs regarding pediatric bariatric surgery. Views on the etiology of obesity-whether it should be considered primarily a medical condition or more a psychosocial problem-seem to affect the specialists' normative opinions concerning the acceptability of bariatric procedures as a treatment option, the parents' feelings regarding both being able to influence their child's health and their child being able to control their own condition, and the adolescents' sense of competence and motivation for treatment.

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Vitamin K contributes to bone health, probably through its role as cofactor in the carboxylation of osteocalcin. Intervention studies in adults have demonstrated that markedly higher osteocalcin carboxylation is obtained by intakes of vitamin K well above the current recommended dietary intake. However, the relationship between increased vitamin K2 intake and enhanced osteocalcin carboxylation has never been shown in healthy children.

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Pediatric transplant patients are known to have vascular abnormalities. The calcification inhibitors matrix Gla protein (MGP) and fetuin-A play an important role in the pathophysiology of vascular calcification. In the cross-sectional study reported here, we examined the circulating levels of fetuin-A and MGP in children after renal transplantation compared to healthy children and the association of these factors with vascular properties of the carotid artery.

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In adult bone, vitamin K contributes to bone health, probably through its role as co-factor in the carboxylation of osteocalcin. In children, the significance of vitamin K in bone-mass acquisition is less well known. The objective of this longitudinal study was to determine whether biochemical indicators of vitamin K status are related to (gains in) bone mineral content (BMC) and markers of bone metabolism in peripubertal children.

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