Varianten von Harnstoffzyklusstörungen

Zusammenfassung: Harnstoffzyklusstörungen gehören, wie die meisten Stoffwechselkrankheiten, mit einer Häufigkeit von weniger als 1:2000 Einwohner zu den seltenen Krankheiten ("orphan diseases"). Oft besteht noch der Eindruck, diese seien nicht nur selten, sondern würden zudem lediglich Neugeborene betreffen und seien deshalb v.a. Domäne der Neonatologie. Diese Einschätzung ist nicht nur falsch, sondern auch gefährlich, denn sie verzögert die rechtzeitige Einleitung von erforderlichen diagnostischen und therapeutischen Maßnahmen. Aus diesem Grund widmet sich der vorliegende Beitrag exemplarisch den Varianten von Harnstoffzyklusstörungen, verweist aber auch darauf, dass die meisten Stoffwechselkrankheiten als ein Kontinuum von asymptomatischen biochemischen Phänotypen über milde Verlaufsformen bis zu den klassischen Präsentationen zu verstehen sin

Hyperammonämie

Zusammenfassung: Eine Erhöhung des Ammoniakgehalts des Bluts über die Referenzgrenzen hinaus wird als Hyperammonämie bezeichnet. Ein solcher Zustand kann akut oder chronisch sein. Eine akute Hyperammonämie äußert sich aufgrund eines begleitenden Hirnödems mit Symptomen im Sinne eines veränderten Bewusstseins. Jede akute Hyperammonämie stellt für den Patienten eine Bedrohung seines Lebens oder zumindest der Integrität seiner Gehirnfunktion dar. Entsprechend sind stets sofortige diagnostische und therapeutische Maßnahmen einzuleiten. Vorrangig sind die möglichst rasche Entgiftung des Ammoniaks und das Erreichen einer anabolen Stoffwechsellage. Die Prognose von Patienten mit akuter Hyperammonämie hängt weniger von der zugrunde liegenden Krankheit als vielmehr von der Dauer und Intensität einer Hyperammonämie ab

Citrullinemia type 1: genetic diagnosis and prenatal diagnosis in subsequent pregnancy

Citrullinemia type 1 was diagnosed by tandem mass spectrometry in a full term male neonate who presented with an acute catastrophic collapse on the 3rd day of life. Both parents were identified to be carriers for the exon 15 p Gly390Arg mutation in the argininosuccinate synthetase gene located at chromosome 9q34.1. Chorionic villus sampling and prenatal genetic testing in the subsequent pregnancy revealed an affected fetus resulting in termination of pregnancy

Electronic structure of cubic gallium nitride films grown on GaAs

The composition, surface structure, and electronic structure of zinc blende–GaN films grown on GaAs (100) and (110) by plasma‐assisted molecular beam epitaxy were investigated by means of core and valence level photoemission. Angle‐resolved photoelectron spectra (photon energy 30–110 eV) exhibited emission from the Ga 3d and N 2s levels, as well as a clear peak structure in the valence band region. These peaks were found to shift with photon energy, indicative of direct transitions between occupied and unoccupied GaN bands. By using a free electron final band, we are able to derive the course of the bands along the Γ‐X and Γ‐K‐X directions of the Brillouin zone and to determine the energy of critical points at the X point. The relative energies of the Ga 3d and nitrogen 2s bands were also studied, and a small amount of dispersion was detected in the latter. The resulting band structure is discussed in relation to existing band structure calculations

Urea cycle disorders in Argentine patients: clinical presentation, biochemical and genetic findings

Urea cycle defects; Argininosuccinate synthetase deficiency; HyperammonemiaDefectos del ciclo de la urea; Deficiencia de argininosuccinato sintetasa; HiperamonemiaDefectes del cicle de la urea; Dèficit d’argininosuccinat sintetasa; HiperammonèmiaBACKGROUND: The incidence, prevalence, and molecular epidemiology of urea cycle disorders (UCDs) in Argentina remain underexplored. The present study is the first to thoroughly assess the clinical and molecular profiles of UCD patients examined at a single reference center in Argentina. RESULTS: Forty-nine UCD cases were collected. About half (26/49, 53%) manifested neonatally with classical presentation and had a high mortality (25/26, 96%). Ornithine transcarbamylase deficiency (OTCD) was the most common UCD (26 patients). Argininosuccinate synthetase deficiency (ASSD) was detected in 19 cases, while argininosuccinate lyase deficiency (ASLD) was diagnosed in 4 cases. Molecular genetic analysis revealed 8 private OTC mutations and two large deletion/duplication events in the OTC gene. Most mutations in the ASS1 and ASL genes were recurrent missense changes, and four alterations were novel. The clinical outcome of our UCD cohort was poor, with an overall mortality of 57% (28/49 cases), and a 28% (6/21) disability rate among the survivors. CONCLUSIONS: Most patients in our case series showed severe neonatal onset, with high morbidity/mortality. We detected in total 19 mutations, most of them recurrent and of high frequency worldwide. Noteworthy, we highlight the presence of a geographic cluster with high prevalence of a point mutation in the ASS1 gene. This study suggests that these disorders may be more frequent than commonly assumed, and stresses the need for increased awareness amongst health professionals and greater availability of diagnostic tools for accurate identification, early diagnosis, and timely treatment.This study was supported by grants from the Secretaría de Ciencia y Tecnología, Universidad Nacional de Córdoba and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina. Work on urea cycle disorders in Zurich is supported by the Swiss National Science Foundation (grant no SNF 310030_153196 to JH)

Efficacy and safety of empagliflozin in glycogen storage disease type Ib: Data from an international questionnaire

Purpose: This paper aims to report collective information on safety and efficacy of empagliflozin drug repurposing in individuals with glycogen storage disease type Ib (GSD Ib). Methods: This is an international retrospective questionnaire study on the safety and efficacy of empagliflozin use for management of neutropenia/neutrophil dysfunction in patients with GSD Ib, conducted among the respective health care providers from 24 countries across the globe. Results: Clinical data from 112 individuals with GSD Ib were evaluated, representing a total of 94 treatment years. The median age at start of empagliflozin treatment was 10.5 years (range = 0-38 years). Empagliflozin showed positive effects on all neutrophil dysfunction-related symptoms, including oral and urogenital mucosal lesions, recurrent infections, skin abscesses, inflammatory bowel disease, and anemia. Before initiating empagliflozin, most patients with GSD Ib were on G-CSF (94/112; 84%). At the time of the survey, 49 of 89 (55%) patients previously treated with G-CSF had completely stopped G-CSF, and another 15 (17%) were able to reduce the dose. The most common adverse event during empagliflozin treatment was hypoglycemia, occurring in 18% of individuals. Conclusion: Empagliflozin has a favorable effect on neutropenia/neutrophil dysfunction-related symptoms and safety profile in individuals with GSD Ib. Keywords: GSD Ib; Glycogen storage disease type Ib; Neutropenia; SGLT2 inhibitors; SLC37A

Investigation of Living Cells in the Nanometer Regime with the Scanning Force Microscope

Membrane structures of different types of cells are imaged in the nanometer regime by scanning force microscopy (SFM). The images are compared to those obtained with a scanning electron microscope (SEM). The SFM imaging can be done on the outer cell membrane under conditions that keep the cells alive in aqueous solutions. This opens up the possibility of observing the kinematics of the structures that determine the interaction of a cell with its environment. Therefore, STM observations, together with information obtained with the electron microscope, open up new ways of studying the development of biological structures. With the currently possible resolution, the SFM gives access to processes such as antibody binding or endo- and exocytosis, including processes correlated to the infection of cells by viruses