Center for Child and Adolescent Medicine

Heidelberg, Germany

Center for Child and Adolescent Medicine

Heidelberg, Germany
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Lehmann R.,Center for Child and Adolescent Medicine | Bosse H.M.,Center for Child and Adolescent Medicine | Simon A.,Center for Child and Adolescent Medicine | Nikendei C.,University of Heidelberg | Huwendiek S.,University of Bern
BMC Medical Education | Year: 2013

Background: Currently only a few reports exist on how to prepare medical students for skills laboratory training. We investigated how students and tutors perceive a blended learning approach using virtual patients (VPs) as preparation for skills training. Methods. Fifth-year medical students (N=617) were invited to voluntarily participate in a paediatric skills laboratory with four specially designed VPs as preparation. The cases focused on procedures in the laboratory using interactive questions, static and interactive images, and video clips. All students were asked to assess the VP design. After participating in the skills laboratory 310 of the 617 students were additionally asked to assess the blended learning approach through established questionnaires. Tutors' perceptions (N=9) were assessed by semi-structured interviews. Results: From the 617 students 1,459 VP design questionnaires were returned (59.1%). Of the 310 students 213 chose to participate in the skills laboratory; 179 blended learning questionnaires were returned (84.0%). Students provided high overall acceptance ratings of the VP design and blended learning approach. By using VPs as preparation, skills laboratory time was felt to be used more effectively. Tutors perceived students as being well prepared for the skills laboratory with efficient uses of time. Conclusion: The overall acceptance of the blended learning approach was high among students and tutors. VPs proved to be a convenient cognitive preparation tool for skills training. © 2013 Lehmann et al.; licensee BioMed Central Ltd.

Guillard M.,Radboud University Nijmegen | Morava E.,Radboud University Nijmegen | Van Delft F.L.,Radboud University Nijmegen | Hague R.,Royal Hospital for Sick Children | And 4 more authors.
Clinical Chemistry | Year: 2011

BACKGROUND: Determination of the genetic defect in patients with a congenital disorder of glycosylation (CDG) is challenging because of the wide clinical presentation, the large number of gene products involved, and the occurrence of secondary causes of underglycosylation. Transferrin isoelectric focusing has been the method of choice for CDG screening; however, improved methods are required for the molecular diagnosis of patients with CDG type II. METHODS: Plasma samples with a typical transferrin isofocusing profile were analyzed. N-glycans were released from these samples by PNGase F [peptide-N4-(acetyl-β-glucosaminyl)-asparagine amidase] digestion, permethylated and purified, and measured on a MALDI linear ion trap mass spectrometer. A set of 38 glycans was used for quantitative comparison and to establish reference intervals for such glycan features as the number of antennae, the level of truncation, and fucosylation. Plasma N-glycans from control individuals, patients with known CDG type II defects, and patients with a secondary cause of underglycosylation were analyzed. RESULTS: CDGs due to mannosyl (α-1,6-)-glycoprotein β-1,2-N-acetylglucosaminyltransferase (MGAT2), β-1, 4-galactosyltransferase 1 (B4GALT1), and SLC35C1 (a GDP-fucose transporter) defects could be diagnosed directly from the N-glycan profile. CDGs due to defects in proteins involved in Golgi trafficking, such as subunit 7 of the conserved oligomeric Golgi complex (COG7) and subunit V0 a2 of the lysosomal H+-transporting ATPase (ATP6V0A2) caused a loss of triantennary N-glycans and an increase of truncated structures. Secondary causes with liver involvement were characterized by increased fucosylation, whereas the presence of plasma sialidase produced isolated undersialylation. CONCLUSIONS: MALDI ion trap analysis of plasma N-glycans documents features that discriminate between primary and secondary causes of underglycosylation and should be applied as the first step in the diagnostic track of all patients with an unsolved CDG type II. © 2010 American Association for Clinical Chemistry.

Schneider A.,Center for Child and Adolescent Medicine | Thiel C.,Center for Child and Adolescent Medicine | Rindermann J.,Institute For Biochemie Ii | Derossi C.,Center for Child and Adolescent Medicine | And 4 more authors.
Nature Medicine | Year: 2012

Congenital disorder of glycosylation-Ia (CDG-Ia, also known as PMM2-CDG) is caused by mutations in the gene that encodes phosphomannomutase 2 (PMM2, EC leading to a multisystemic disease with severe psychomotor and mental retardation. In a hypomorphic Pmm2 mouse model, we were able to overcome embryonic lethality by feeding mannose to pregnant dams. The results underline the essential role of glycosylation in embryonic development and may open new treatment options for this disease. © 2012 Nature America, Inc. All rights reserved.

Thiel C.,Center for Child and Adolescent Medicine | Korner C.,Center for Child and Adolescent Medicine
Journal of Inherited Metabolic Disease | Year: 2011

Glycoprotein biosynthesis describes the process of co- and posttranslational attachment of sugar chains to proteins, a process that has been found in nearly all known organisms. Human deficiencies evoked by mutations in the glycosylation pathway of glycoproteins lead to congenital disorders of glycosylation (CDG), a rapidly expanding group of autosomal recessive inherited metabolic diseases with multisystemic phenotypes that are mostly combined with severe neurological impairment. Although investigations on new types of CDG have proceeded rapidly in recent years, the correlation between inaccurate protein glycosylation and pathological loss of functionality of distinct organ systems remains widely unknown, and therapeutics for the patients are mostly not available. Therefore, mouse models provide an outstanding helpful tool for investigations on different aspects of glycosylation deficiencies that cannot be performed in patients or cell culture. This review focuses on existing mouse models generated for the types of CDG that affect the N-glycosylation pathway. © 2011 SSIEM and Springer.

Ozyurt J.,Carl von Ossietzky University | Thiel C.M.,Carl von Ossietzky University | Lorenzen A.,Carl von Ossietzky University | Lorenzen A.,University of Kiel | And 4 more authors.
Journal of Pediatrics | Year: 2014

Objective To test memory performance and executive functions in patients with childhood craniopharyngioma and hypothalamic involvement. Study design Using standardized neuropsychological tests, we compared cognitive performance in a group of 15 patients with childhood craniopharyngioma and known hypothalamic involvement and a group of 24 age- and intelligence-matched control subjects. In addition, we compared individual patients' results with normative data to detect abnormal performance in the clinically relevant range. Within the patient group, we further tested whether the grade of hypothalamic involvement had an impact on cognitive performance and quality of life. Results Relative to healthy controls, the patients demonstrated significantly lower performance scores in tests of memory and executive functioning. On the individual performance level, delayed recall performance was severely impaired in one-third of the patients. Compared with patients with low-grade hypothalamic involvement, those with high-grade hypothalamic involvement showed worse performance in executive functions and reduced functional capabilities for daily life actions, indicating lower quality of life. Conclusion Our findings demonstrate that hypothalamic involvement is related to impairments in memory and executive functioning in patients with childhood craniopharyngioma and indicate that a high grade of hypothalamic involvement is related to worse outcomes. © 2014 Mosby Inc. All rights reserved.

Thiel C.,Center for Child and Adolescent Medicine | Messner-Schmitt D.,Center for Child and Adolescent Medicine | Hoffmann G.F.,Center for Child and Adolescent Medicine | Korner C.,Center for Child and Adolescent Medicine
Journal of Inherited Metabolic Disease | Year: 2013

Inherited monogenetic human disorders due to deficiencies in the complex metabolic pathways for N- and O-glycosylation of glycoconjugates are termed 'congenital disorders of glycosylation' (CDG). Since the number of these defects with mostly severe multisystemic phenotypes has been rapidly expanding in recent years, the interest of paediatricians has also increased resulting in a rising amount of patient samples with the suspicion of CDG. In general, primary diagnostics for CDG start with investigations on the glycosylation state of serum transferrin, the 'gold standard' in the field for many years. However, the use of transferrin shows an analytical problem in the time span from birth up to the 3rd month of life. In this developmental period oligosaccharide moieties N-linked to proteins are often incomplete, resembling a CDG pattern and leading to false-positive results. It is therefore necessary to establish a reliable and fast diagnostic procedure for this span of life. Here we show that the glycosylation state of serum α-1-antitrypsin is already fully existent shortly after birth allowing an alternative diagnostic approach for the investigation of CDG in the first weeks of life. The method can easily be established in every laboratory especially with previous experience in transferrin analysis. © 2012 SSIEM and Springer.

Lubbehusen J.,Center for Child and Adolescent Medicine | Thiel C.,Center for Child and Adolescent Medicine | Rind N.,Center for Child and Adolescent Medicine | Ungar D.,University of York | And 4 more authors.
Human Molecular Genetics | Year: 2010

Deficiency of subunit 6 of the conserved oligomeric Golgi (COG6) complex causes a new combined N-and O-glycosylation deficiency of the congenital disorders of glycosylation, designated as CDG-IIL (COG6-CDG). The index patient presented with a severe neurologic disease characterized by vitamin K deficiency, vomiting, intractable focal seizures, intracranial bleedings and fatal outcome in early infancy. Analysis of oligosaccharides from serum transferrin by HPLC and mass spectrometry revealed the loss of galactose and sialic acid residues, whereas import and transfer of these sugar residues into Golgi-enriched vesicles or onto proteins, respectively, were normal to slightly reduced. Western blot examinations combined with gel filtration chromatography studies in patient-derived skin fibroblasts showed a severely reduced expression of the mentioned subunit and the occurrence of COG complex fragments at the expense of the integral COG complex. Sequencing of COG6-cDNA and COG6 gene resulted in a homozygous mutation (c.G1646T), leading to amino acid exchange p.G549V in the COG6 protein. Retroviral complementation of the patients' fibroblasts with the wild-type COG6-cDNA led to normalization of the COG complex-depending retrograde protein transport after Brefeldin A treatment, demonstrated by immunofluorescence analysis. © The Author 2010. Published by Oxford University Press. All rights reserved.

Thiel C.,Center for Child and Adolescent Medicine | Korner C.,Center for Child and Adolescent Medicine
Glycoconjugate Journal | Year: 2013

Inborn errors in glycoconjugate biosynthesis termed 'Congenital Disorders of Glycosylation' (CDG) comprise a rapidly expanding group of metabolic diseases in man. Up till now more than 60 different inherited disorders in N- and O-glycosylation pathways have been identified. They affect the biosynthesis of glycan moieties linked to proteins as well as lipids. Due to failures in protein glycosylation, CDG patients suffer from multi systemic disorders, which mostly present with severe psychomotor and mental retardations, muscular impairment, ataxia, failure to thrive and developmental delay. Although improved biochemical and genetic investigations led to identification of a variety of new molecular defects in glycoconjugate biosynthesis, effective therapies for most types of the CDG are so far not available. Therefore, intensive investigations on treatment options for this group of diseases have been carried out in recent years. © 2012 Springer Science+Business Media, LLC.

Rind N.,Center for Child and Adolescent Medicine | Schmeiser V.,University of Regensburg | Thiel C.,Center for Child and Adolescent Medicine | Absmanner B.,University of Regensburg | And 6 more authors.
Human Molecular Genetics | Year: 2010

A new type of congenital disorders of glycosylation, designated CDG-Ip, is caused by the deficiency of GDP-Man:Man3GlcNAc2-PP-dolichol-α1,2-mannosyltransferase, encoded by the human ortholog of ALG11 from yeast. The patient presented with a multisystemic disorder characterized by muscular hypotonia, seizures, developmental retardation and death at the age of 2 years. The isoelectric focusing pattern of the patient's serum transferrin showed the partial loss of complete N-glycan side chains, which is a characteristic sign for CDG-I. Analysis of dolichol-linked oligosaccharides in patient-derived fibroblasts revealed an accumulation of Man3GlcNAc2-PP-dolichol and Man4GlcNAc2-PP-dolichol. Determination of mannosyltransferase activities of early steps of lipid-linked oligosaccharide biosynthesis in fibroblasts indicated that the patient was deficient in elongating Man3GlcNAc2-PP-dolichol. These findings gave rise to genetic analysis of the hALG11 cDNA, in which homozygosity for mutation c.T257C (p.L86S) was identified. Verification of the mutation as a primary cause for the genetic defect was proved by retroviral expression of human wild-type and mutated ALG11 cDNA in patient-derived fibroblasts as well as using a yeast alg11 deletion strain as a heterologous expression system for hALG11 variants. Immunofluorescence examinations combined with western blotting showed no differences of intracellular localization or expression of ALG11 between control and patient fibroblasts, respectively, indicating no mislocalization or degradation of the mutated transferase. © The Author 2010. Published by Oxford University Press. All rights reserved. For Permissions, please email:

Lu L.,Yeshiva University | Hou X.,Yeshiva University | Shi S.,Yeshiva University | Shi S.,Mount Sinai School of Medicine | And 2 more authors.
Journal of Biological Chemistry | Year: 2010

Mammalian Notch receptors require modification by fucose on epidermal growth factor-like (EGF) repeats of their extracellular domain to respond optimally to signal induction by canonical Notch ligands. Inactivation of the Golgi GDP-fucose transporter Slc35c1 in mouse or human does not cause marked defects in Notch signaling during development, and shows milder fucosylation defects than those observed in mice unable to synthesize GDP-fucose, indicating the existence of another mechanism for GDP-fucose transport into the secretory pathway. We show here that fibroblasts from mice or humans lacking Slc35c1 exhibit robust Notch signaling in co-culture signaling assays. A potential candidate for a second GDP-fucose transporter is the related gene Slc35c2. Overexpression of Slc35c2 reduces expression of the fucosylated epitopes Lewis X and sialylated Lewis X in CHO cells, indicating competition with Slc35c1. The fucosylation of a Notch1 EGF repeat fragment that occurs in the endoplasmic reticulum was increased in CHO transfectants overexpressing Slc35c2. In CHO cells with low levels of Slc35c2, both Delta1- and Jagged1-induced Notch signaling were reduced, and the fucosylation of a Notch1 fragment was also decreased. Immunofluorescence microscopy of rat intestinal epithelial cells and HeLa cells, and analysis of rat liver membrane fractions showed that Slc35c2 is primarily colocalized with markers of the cis-Golgi network and endoplasmic reticulum-Golgi intermediate compartment (ERGIC). The combined results suggest that Slc35c2 is either a GDP-fucose transporter that competes with Slc35c1 for GDP-fucose, or a factor that otherwise enhances the fucosylation of Notch and is required for optimal Notch signaling in mammalian cells. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.

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