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Biomedical subjects

W Kiess

Publications and source records attributed to W Kiess.

At least 19 recordsLinked to original sources

Critical evaluation of methods for determination of body fat content in children: back to basic parameters?

Considering the increasing prevalence of obesity among children and of obesity related disorders in the pediatric population, the reliable evaluation of body fat content in children is of critical importance in research and clinical medicine. In this study, we assessed the congruency of different estimates for body fat content in prepubertal children. We determined anthropometric parameters, such as BMI and skinfold thickness, and bioelectrical impedance in 676 prepubertal Caucasian children. We calculated body fat percentage (BF%) from these parameters applying 5 distinct algorithms and established raw centiles for these models. Expectedly, girls had significantly higher BF% regardless of the method applied. There were, however, significant variances in the calculated amount of BF% between the algorithms, with BIA based equations giving highest BF%, while skinfold based equations tended to provide lower BF% values. Direct comparison of the algorithms revealed a high degree of inconsistency and poor agreement in the assessment of body fat with variations of >10% BF%. Great differences in basic parameters, such as DeltaBMI (3.2 kg/m (2)) or Deltaskinfolds (1.75-fold), would be needed to reliably predict correct ranking of 10% difference in body fat with 95% probability. In summary, BF% strongly varies depending on both the method as well as the algorithm used. This questions the applicability of such field methods for the assessment of BF% for comparative analyses and the superiority of information over basic parameters such as BMI.

Adipose Tissue↗

Evaluation of patients' opinion and metabolic control after transfer of young adults with type 1 diabetes from a pediatric diabetes clinic to adult care.

BACKGROUND: Transferring adolescents with diabetes from pediatric to adult care remains a challenge and the outcome is often unknown. The aims of this study were to determine the patients' perception of transfer arrangements and to analyze health care use and metabolic control. METHODS: A telephone questionnaire was conducted for patients who had been transferred from the pediatric clinic to adult care between 1995 and 2003. Of 161 identified patients, 101 (58 females, 43 males, mean age 22.1 +/- 2.4 years) were interviewed. Pediatric case notes and, if available (n = 44), current notes were analyzed to validate answers from the interview. RESULTS: After transfer, 52.5% of patients changed their health care provider at least once. The mean frequency of changes was 1.47. There was a significant decrease in clinic attendance rate after transition (8.5 +/- 2.3/years vs. 6.7 +/- 3.2/years). Patients criticized the lack of arrangements, poor information about transfer and the specific age for transition (18 years) set by legislation. The transfer was considered a negative experience by 58 patients. The patients assumed their metabolic control (HbA1c) was better than it really was (7.5 +/- 1.3% vs. 8.3 +/- 1.6%, p < 0.05). Actual HbA1c from case notes pre- and post-transfer did not change significantly (8.5 +/- 1.5% vs. 8.4 +/- 1.7%, n = 44, p = 0.441). CONCLUSION: The establishment of transition clinics and closer cooperation between specialists in pediatric and adult medicine is mandatory. Such changes are demanded by patients and would ensure better uptake of health care services after transfer.

Adolescent↗

Sex-specific effect of the Val1483Ile polymorphism in the fatty acid synthase gene (FAS) on body mass index and lipid profile in Caucasian children.

OBJECTIVE: A Val1483Ile polymorphism in the human fatty acid sythase gene (FAS) has recently been shown to be associated with lower percentage of body fat and substrate oxidation rates in Pima Indians, but its role in other populations has not been described. Here, we investigate the effect of this variant on obesity in Caucasian children and adolescents. SUBJECTS AND METHODS: In total, 738 Caucasian children and adolescents aged 6-17 years of the Leipzig Schoolchildren cohort, which constitutes an unselected representative German population and 205 obese children (body mass index (BMI) 2.71+/-0.04 SDS) were genotyped for genotype-phenotype associations. RESULTS: The frequency of the Ile-allele was lower in German Caucasians compared with Pima Indians (0.03 compared to 0.10). Using generalized linear regression models, there was no effect of the polymorphism on BMI in the whole normal population. However, we identified a significant interaction effect between sex and genotype (P=0.004). Subsequent sex stratified analyses revealed a lower BMI SDS in boys with Ile/Val genotype compared to Val/Val (-0.36+/-0.29 vs 0.09+/-0.05, P<0.05), while an opposite effect was observed in girls (0.48+/-0.19 vs 0.09+/-0.05, P<0.05). In genotype-phenotype associations in obese children, the polymorphism did not affect parameters of insulin, glucose, or lipid metabolism in the whole population. Again, however, obese boys with Ile/Val genotype had significantly higher high-density lipoprotein (HDL) cholesterol levels (1.46+/-0.07 vs 1.23+/-0.03 mmol/l, P<0.05). CONCLUSION: In conclusion, our findings suggest a sex-specific protective effect of the Val1483Ile polymorphism in FAS for obesity in Caucasian boys. In addition, the polymorphism may be associated with a beneficial lipid profile in obese boys.

Adolescent↗

[Health-related quality of life of siblings of children with type 1 diabetes mellitus].

BACKGROUND INFORMATION: A chronic illness in childhood or adolescents constitutes a drastic event for the whole family, especially for the healthy siblings. This could impair their quality of life. PATIENTS AND METHODS: We designed a case-control-study in three centres (Leipzig, Giessen and Augsburg) with questionaires sent to 72 diabetic children, 71 of their siblings and 63 children of neighbourhood (controls) aged between 8 and 16 years. KINDL-Questionnaire was used for the study of the health-related quality of life of children and adolescents, supplemented by other appropriate items. RESULTS: The results indicate a positive health related quality of life of the healthy siblings of families with a child who has type 1 diabetes. Differences in the quality of life depend on factors such as age and gender of the children and relate to specific items of sibling relationship (e. g. "worried about sibling", "looked after sibling"). Generally, there was a great similarity with regard to the quality of life of healthy brothers and sisters from affected families compared with children of families without a child suffering from chronic illness. CONCLUSIONS: The results indicate that the health related quality of life of healthy siblings of children with diabetes only differs insignificantly from brothers and sisters of "healthy" families.

Adolescent↗

Glucose regulates expression of the nerve growth factor (NGF) receptors TrkA and p75NTR in rat islets and INS-1E beta-cells.

BACKGROUND: The function and survival of pancreatic beta-cells strongly depend on glucose concentration and on autocrine secretion of peptide growth factors. NGF and its specific receptors TrkA and p75NTR play a pivotal role in islet survival and glucose-dependent insulin secretion. We therefore investigated whether or not glucose concentration influences expression of TrkA and p75NTR in rat islets and in INS-1E beta-cells at the mRNA and protein level (INS-1E). METHODS: Gene expression of the NGF receptors TrkA and p75NTR but also of the metabolic gene liver-type pyruvate kinase (L-PK) and the neurotrophin receptors TrkB and TrkC was studied by semi-quantitative PCR and by real-time PCR in islets and INS-1E beta-cells. RESULTS: In rat islets, high glucose exposure (25 mmol/l) increased gene expression of TrkA, p75NTR and L-PK. Expression of TrkA, p75NTR and L-PK reflected insulin secretion at the respective glucose concentration. In rat INS-1E insulinoma cells, expression of L-PK and p75NTR was suppressed by low glucose as in the islets, while expression of TrkA was strongly increased by low glucose levels and thus was regulated differently than in islets. Expression of TrkB and TrkC was not regulated by glucose concentration at all. TrkA protein was regulated in the same fashion as its mRNA expression, while p75NTR protein was not significantly regulated within 24 h. CONCLUSION: Glucose interacts with gene expression of TrkA and p75NTR that are strongly involved in beta-cell growth and glucose-dependent insulin secretion. The fact that TrkA expression is regulated the opposite way in islets and in INS-1E beta-cells might reflect their specific grade of differentiation and tendency to proliferate.

Animals↗

Clinical and functional characteristics of the human Arg59Ter insulin-like growth factor i receptor (IGF1R) mutation: implications for a gene dosage effect of the human IGF1R.

CONTEXT: Signaling via the IGF-I receptor (IGF-IR) is crucial for normal prenatal and postnatal growth. The heterozygous IGF-IR mutation Arg59Ter resulted in reduced IGF-IR expression and represents haploinsufficiency of the human IGF1R gene. OBJECTIVE: We studied clinical and in vitro aspects of a human IGF1R gene dosage effect. We provide detailed clinical data on the two half-brothers and their mother with the Arg59Ter mutation. Arg59Ter and control fibroblasts were examined for functionality of IGF-I and insulin-stimulated receptor phosphorylation and signal transduction. RESULTS: The two brothers presented with primary microcephaly, mild mental retardation, and intrauterine as well as postnatal growth deficits. After GH therapy (30 microg/kg.d) for 24 months, the growth deficit in the propositus decreased by +1.0 sd. There was no clinical evidence for impaired glucose tolerance or hypoglycemia in all Arg59Ter subjects. In vitro, IGF-IR-deficient Arg59Ter cells expressed less IGF-IR and unchanged insulin receptor (IR) protein. Receptor autophosphorylation and phosphorylation of downstream protein kinase B/Akt exhibited resistance to IGF-I but showed an augmented response to insulin in Arg59Ter cells. Decreased IGF-IR content was accompanied by a reduction of IGF-IR/IR receptor hybrids, and therefore, increased levels of IR/IR homodimers probably explain increased insulin-stimulated receptor autophosphorylation and Akt phosphorylation. CONCLUSIONS: In vivo and in vitro IGF-I resistance in Arg59Ter subjects and fibroblasts indicates a human IGF1R gene dosage effect involving not only the IGF-IR, but also IGF-IR/IR hybrids. The abundance of both the IGF-IR protein and IGF-IR/IR hybrid receptors may have an impact on human growth, organ function, and glucose metabolism.

Body Weight↗

Metabolic decompensation in children with type 1 diabetes mellitus associated with increased serum levels of the soluble leptin receptor.

OBJECTIVE: Type 1 diabetes mellitus (T1DM) leads to increased serum levels of the soluble leptin receptor (sOB-R) by an as yet unknown cellular mechanism. The aim of our study was to investigate potential metabolic factors that may be associated with the induction of the sOB-R release from its membrane receptor. MATERIALS AND METHODS: Twenty-five children (aged between 1.5 and 17.0 years) were studied at the onset of T1DM. Blood samples were collected before (n = 25), during the first 18 h (mean +/- S.D. 11.1 +/- 4.3 h, n = 16) and 92 h (47.5 +/- 22.5 h; n = 14) after beginning insulin therapy. Serum sOB-R and leptin levels were determined by in-house immunoassays. RESULTS: The sOBR-level and the molar sOB-R/leptin ratio were significantly higher before than after starting insulin treatment (P < 0.05). In contrast, leptin levels were significantly lower (P < 0.05) before insulin therapy. The correlation between sOB-R and blood glucose (r = 0.49; P < 0.05), as well as sOB-R with parameters of ketoacidosis, such as pH (r = -0.72), base excess (r = -0.70), and bicarbonate (r = -0.69) (P < 0.0001) at diagnosis of T1DM remained significant during the first 18 h of insulin treatment. Multiple regression analysis revealed that base excess predicted 41.0% (P < 0.001), age 16.4% (P < 0.05), and height SDS 13.9% (P < 0.01) of the sOB-R variance. CONCLUSIONS: Metabolic decompensation in children with new onset T1DM is associated with dramatic changes of the leptin axis; serum levels of sOB-R are elevated and of leptin are reduced. The molar excess of sOB-R over leptin (median 11.3) in this condition may contribute to leptin insensitivity. Upregulation of the soluble leptin receptor appears to be a basic mechanism to compensate for intracellular substrate deficiency and energy-deprivation state.

Adolescent↗

Glucose concentration and AMP-dependent kinase activation regulate expression of insulin receptor family members in rat islets and INS-1E beta cells.

AIMS/HYPOTHESIS: Glucose and the peptide growth factors insulin, IGF-I and IGF-II strongly regulate beta cell mass. Furthermore, beta cell expression of IGF-I receptor (Igf1r) and insulin receptor (Insr) is mandatory for several steps of insulin secretion. MATERIALS AND METHODS: We hypothesised that glucose concentration might regulate expression of Igf1r, Insr and insulin receptor-related receptor (Insrr) in islets and beta cells. Moreover, since the ratio of ATP:ADP is the most important intracellular mechanism involved in insulin secretion, and since depletion of ATP leads to AMP accumulation, we evaluated the role of AMP-activated protein kinase (AMPK) in glucose-dependent receptor regulation. RESULTS: In rat islets, high glucose exposure (25 mmol/l) increased gene expression of Igf1r, Insr and Insrr but also of the metabolic glycolysis gene liver-type pyruvate kinase (Pklr) compared with intermediate (6.2 mmol/l) or low glucose concentration (1.6 mmol/l) after 24 h. In rat INS-1E beta cells, only Pklr expression was suppressed by low glucose as in islets, while Insr and Insrr were suppressed by high and increased by low glucose levels. Igf1r expression was suppressed by both high- and low- glucose concentration. Activation of AMPK by 5-amino-imidazolecarboxamide riboside (AICAR, 0.5 mmol/l) suppressed Pklr expression, but strongly stimulated gene expression of Igf1r, Insr and Insrr. Protein expression of IR and IGF-IR reflected glucose and AICAR-regulated mRNA expression of both receptors in INS-1E cells. CONCLUSIONS/INTERPRETATION: We conclude that glucose directly interacts with islet and beta cell expression of growth factor receptors that are mandatory for both beta cell growth and insulin secretion. Stimulation of Igf1r and Insr gene expression by the AMPK-activator AICAR might indicate involvement of AMPK in the regulation of Igf1r, Insr and Insrr expression in beta cells.

Animals↗

Serum resistin levels of obese and lean children and adolescents: biochemical analysis and clinical relevance.

OBJECTIVE: It was hypothesized that resistin links obesity with diabetes, but this has not been studied in children and adolescents to date. PATIENTS: We determined serum resistin levels of 135 obese (body mass index, 32.0 +/- 6.2 kg/m2; age, 12.6 +/- 3.4 yr) and 201 lean children (body mass index, 18.7 +/- 2.4 kg/m2; age, 12.5 +/- 2.5 yr) by a newly developed and extensively evaluated in-house immunoassay. These results were controlled for their association with markers of puberty, obesity, and insulin sensitivity. RESULTS: The analytical evaluation of our assay revealed different resistin isoforms with major peaks of higher than 660 and 55 kDa in the size exclusion chromatography. Using this assay system we found no difference in the resistin levels of obese compared with lean subjects (P = 0.48). However, resistin was significantly higher in girls than in boys (6.74 +/- 2.42 vs. 5.79 +/- 2.45; P < 0.001). Interestingly, in both obese and lean children, resistin correlated with age (P < 0.01), Tanner stage, and testosterone and estradiol levels (P < 0.05). In contrast, no significant correlation was found with parameters of insulin resistance such as homeostasis model assessment, insulin sensitivity index, or insulin, proinsulin, and glucose concentrations in obese subjects. CONCLUSIONS: Resistin appears to be not the main link between obesity and insulin resistance in children and adolescents but because of its association with Tanner stage, it may be related to the maturation of children during pubertal development. Additionally, we have demonstrated the presence of different molecular isoforms of resistin in human blood, and this may raise problems in comparing data from diverse assay systems.

Adolescent↗

Inverse changes in the serum levels of the soluble leptin receptor and leptin in neonates: relations to anthropometric data.

We aimed to evaluate the role of the soluble leptin receptor (sOB-R), the major leptin-binding protein in blood, for the regulation of growth and development of neonates. Therefore, human arterial and venous cord blood samples were taken from newborns of 45 healthy mothers to investigate correlations with anthropometric data. Furthermore, we compared changes in sOB-R and leptin in neonatal serum between postnatal d 1, 3, and 5. Cord blood levels of leptin (direct correlation) and the molar sOB-R/leptin ratio (inverse correlation) correlated significantly (P < 0.05) with weight, triceps, biceps, iliacal, and subscapular skinfolds at birth as well as on d 3 and 5 of life. During the first week of life, median leptin levels decreased significantly (P < 0.001) from 3.4 ng/ml in venous cord blood to 2.2 ng/ml in venous blood on d 1 after birth to 0.88 ng/ml on d 3 and 0.75 ng/ml on d 5. In contrast and most interestingly, median levels of sOB-R increased significantly (P < 0.001) from 14.5 ng/ml in cord blood to 18.9 ng/ml on d 1, 83 ng/ml on d 3, and 79.4 ng/ml on d 5. Consequently, the molar sOB-R/leptin ratio increased from 0.45 to 1.30 (d 1), 10.5 (d 3), and 13.7 (d 5) during the same period (P < 0.001). We found a remarkable postnatal change in the leptin-sOB-R axis with decreasing leptin and increasing sOB-R levels. Hence, the sOB-R may block leptin function by its competition with the membrane receptor for the ligand. These suppressive effects may be an important stimulus for energy uptake in the first week of life or in other conditions with a high energy demand.

Adolescent↗

Ghrelin levels before and after reduction of overweight due to a low-fat high-carbohydrate diet in obese children and adolescents.

BACKGROUND: There are conflicting results for ghrelin changes in reduction of overweight. Increasing ghrelin levels in weight reduction are considered to be responsible for compensatory mechanisms that make the reduction of overweight unlikely to be sustained. METHODS: We have analyzed fasting serum ghrelin levels, weighed dietary record and, as biochemical markers of clinically relevant reduction of overweight, leptin, adiponectin and insulin levels and insulin resistance measured by homeostasis model assessment (HOMA) at baseline and after a 1-y outpatient weight reduction program based on a high-carbohydrate and low-fat diet in 37 obese children (median age 10 y). We divided these children into two subgroups according to their degree of weight loss (substantial reduction of overweight: decrease in SDS-BMI > or = 0.5). Furthermore, we analyzed ghrelin levels in 16 normal-weight children. RESULTS: Obese children demonstrated significant (P<0.001) lower ghrelin levels compared to normal-weight children. Daily caloric intake (P = 0.004) and percentage fat content decreased significantly (P<0.001), while percentage carbohydrate content increased significantly (P = 0.003) between baseline and 1-y follow-up in the obese children. The substantial reduction of overweight in 16 children (median SDS-BMI = -0.7) was associated with significant changes in insulin resistance (median decrease of HOMA 27%; P = 0.013), insulin (median decrease 25%, P = 0.036), adiponectin (median increase 15%; P = 0.003), and leptin levels (median decrease 19%; P = 0.023), while there were no significant changes in ghrelin levels (median increase 4%; P = 0.326). In the 21 children without substantial reduction of overweight (median SDS-BMI = -0.3), there were no significant changes in insulin resistance and in insulin, adiponectin, leptin and ghrelin levels. CONCLUSIONS: We conclude that in obese children, low-fat high-carbohydrate diet-induced weight loss does not change ghrelin secretion, but significantly decreases leptin levels, increases adiponectin levels and improves insulin resistance determined by significantly decreased insulin resistance indices as well as lowered serum insulin levels.

Adiponectin↗

Circulating soluble leptin receptor, leptin, and insulin resistance before and after weight loss in obese children.

OBJECTIVE: To study the relationships between leptin, soluble leptin receptor (sOB-R), and insulin resistance in obese children before and after weight reduction. METHODS: We determined fasting serum leptin, sOB-R, and insulin resistance index (Homeostasis model assessment (HOMA)) in 36 obese children at baseline and 1 y later and compared them to 72 lean children matched for age, gender, and pubertal stage. The changes of leptin (Deltaleptin) and sOB-R (DeltasOB-R) over the 1 y period were correlated to the changes of HOMA (DeltaHOMA), the changes of weight status, and the changes of percentage body fat (Delta%BF) based on skinfold measurements. Multiple linear regression analyses were conducted for the dependent variables Deltaleptin and DeltasOB-R, including DeltaBMI and DeltaHOMA as independent variables adjusted for age, gender, and pubertal stage. Changes of leptin and sOB-R levels were analyzed in 11 obese children after they had lost weight substantially (decrease SDS-BMI>0.5) and compared to 11 obese children without substantial weight loss matched for age, gender, and pubertal stage. RESULTS: Obese children showed significantly (P<0.001) higher leptin and lower sOB-R levels. Deltaleptin correlated significantly to DeltaSDS-BMI (r=0.28, P<0.05), Delta%BF (r=0.44, P<0.05), and DeltaHOMA (r=0.42, P<0.01), while DeltasOB-R correlated significantly to DeltaSDS-BMI (r=-0.42, P<0.01) and Delta%BF (r=-0.47, P<0.01), but not to DeltaHOMA. In contrast to DeltasOB-R, Deltaleptin correlated significantly to DeltaHOMA (P=0.02) in multiple linear regression analysis. Substantial weight loss led to a significant increase in sOB-R (P=0.02) and to a decrease in HOMA (P=0.02). In children without substantial weight loss, there were no changes in sOB-R, while HOMA (P=0.04) and leptin (P=0.02) increased significantly. CONCLUSIONS: The decrease of sOB-R and the increase of leptin levels in obese children normalized after weight loss. Therefore, these changes are consequences rather than the cause of overweight. In contrast to sOB-R, leptin levels are associated with insulin resistance.

Adolescent↗

Clinical characteristics of type 2 diabetes mellitus in overweight European caucasian adolescents.

AIM: To present the clinical features of Type 2 diabetes mellitus (T2DM) in overweight European Caucasian children and adolescents. METHODS: We report the clinical characteristics of 16 non-syndromal overweight European Caucasian adolescents with T2DM (10 boys, 6 girls, SDS-BMI in median +2.8, range +1.6 to +3.4) treated in 5 specialised centres for obesity and diabetes. RESULTS: None of the adolescents manifested with ketoacidosis. 13 were asymptomatic (3 adolescents with polyuria), 12 showed features of metabolic syndrome (dyslipidaemia or hypertension), 8 demonstrated acanthosis nigricans and 12 had relatives with T2DM. 11 adolescents were extremely obese and all patients were pubertal. Mean age at diagnosis was 14.2 years (range 11.0 - 16.9). Median insulin was 19 microU/ml, insulin resistance index (HOMA) 8.5, C-peptide 2.3 ng/ml, HbA1c 6.9 %, fasting blood glucose 176 mg/dl and blood glucose at 2 hours with the oGTT 229 mg/dl at manifestation. Fasting blood glucose and HBA1c were in the normal range in 4 and 6 adolescents respectively, while oGTT always fitted the diagnosis of T2DM. CONCLUSION: Since T2DM occurred in Caucasian overweight adolescents and is frequently asymptomatic, it is essential that clinicians perform diagnostic procedures to identify T2DM in high-risk groups of overweight Caucasian adolescents (extreme obesity, features of metabolic syndrome, relatives with T2DM).

Acanthosis Nigricans↗

Gonadoblastomas in 5 patients with 46,XY gonadal dysgenesis.

We describe five patients with 46,XY gonadal dysgenesis who developed gonadoblastomas, dysgerminomas, a mature teratoma, and a testicular intraepithelial neoplasia. The age of the patients was between 12.2 and 18.5 years. The external genitalia were normal female in two cases, in three they were intersexual. Four of our patients presented with slight retardation of puberty followed by stagnation. Most importantly the development of the breast (Tanner stage 2-4) did not correspond with pubic hair stage (Tanner stage 4). The patients can be classified as virilized phenotypical females. Serum testosterone was detectable in three, estradiol in two patients. None of the gonadoblastomas showed immunoreactivity with antibodies against steroid hormone receptors and against testosterone and estradiol, respectively. Probably the immature cells are able to produce steroid hormones. Only steroid-like cells with Leydig cell appearance showed positive cytoplasmatic immunostaining for testosterone in three patients. The findings in our patients underline that dysgenetic gonads must be removed as early as possible to prevent development of malignant tumors.

Adolescent↗

Knowing more by fewer measurements: about the (In)ability of bioelectric impedance to enhance obesity research in children.

The prevalence of obesity is increasing worldwide. The implications for human health can already be observed in children. Consequently, it is desirable to provide good quantitative descriptions of the relationship of body fat and health risks, such as hypertension. Bioelectric impedance analysis has been frequently praised to be useful for assessing body fat. Devices to analyse body composition based on this technique seem to be selling well, while the real gain in information they provide is unclear. Here we show in a cohort of 2,218 schoolchildren that the body mass index (which is more easily and less costly to determine) is a better predictor of hypertension than the data delivered by impedance analysis. Moreover, we demonstrate that the output of a random number generator is competitive with impedance measurement for this purpose. It is explained by simple arguments from physics why the formulas for the computation of body fat from bioelectric impedance obliterate rather than clarify the relationship of obesity and hypertension. As a consequence, we suggest questioning the opinion propagated by others that bioelectric impedance analysis is a useful tool in field studies on body fat in children. Measurements requiring more effort (compared to simpler methods) should be proved to add worthwhile information, otherwise they should be avoided.

Adolescent↗