Natural ligand motifs of H-2E molecules are allele specific and illustrate homology to HLA-DR molecules

Motifs of peptldes naturally associated with H-2Ek and Ed molecules were determined by (i) pool sequencing of natural ligand mixtures and (ii) sequencing of individual natural ligands followed by their alignment to the basic motif suggested by pool sequencing. The data reveal nine amino acid motifs with interaction sites at relative positions P1, P4, P6 and P9, with specificities that are identical at some but different at other anchor positions between Ed and Ek motifs, illustrating the different requirements for peptides to be presented by these two MHC molecules. The anchors with the most restricted specificity are P1 and P9. P1 is aliphatic for Ek and predominantly aromatic for Ed. P9 is positively charged for both molecules. P4 and P6 show a totally different amino acid preference between Ek and Ed ligand motifs. An alignment of Ed and Ek protein sequences to the recently reported HLA-DR1 pocket residues is in agreement with observed anchor residues in Ek and Ed motifs, thus confirming the predicted similarity of mouse class II E molecules with human DR molecules. Furthermore, this alignment was extended to the putative pockets of class II Eb and E* molecules, and allowed, together with sequence information of previously Identified natural ligands of Eb and E5 molecules, a prediction of their respective motifs. The information obtained by this study should be useful to identify putative class II E epltopes in proteins and to design peptides for blocking class II E molecule

Modulation of the Major Histocompatibility Complex Class II–Associated Peptide Repertoire by Human Histocompatibility Leukocyte Antigen (Hla)-Do

Antigen presentation by major histocompatibility complex class II molecules is essential for antibody production and T cell activation. For most class II alleles, peptide binding depends on the catalytic action of human histocompatibility leukocyte antigens (HLA)-DM. HLA-DO is selectively expressed in B cells and impedes the activity of DM, yet its physiological role remains unclear. Cell surface iodination assays and mass spectrometry of major histocompatibility complex class II–eluted peptides show that DO affects the antigenic peptide repertoire of class II. DO generates both quantitative and qualitative differences, and inhibits presentation of large-sized peptides. DO function was investigated under various pH conditions in in vitro peptide exchange assays and in antigen presentation assays using DO− and DO+ transfectant cell lines as antigen-presenting cells, in which effective acidification of the endocytic pathway was prevented with bafilomycin A1, an inhibitor of vacuolar ATPases. DO effectively inhibits antigen presentation of peptides that are loaded onto class II in endosomal compartments that are not very acidic. Thus, DO appears to be a unique, cell type–specific modulator mastering the class II–mediated immune response induced by B cells. DO may serve to increase the threshold for nonspecific B cell activation, restricting class II–peptide binding to late endosomal compartments, thereby affecting the peptide repertoire

Intravenous Ferric Carboxymaltose in Patients with Type 2 Diabetes Mellitus and Iron Deficiency: CLEVER Trial Study Design and Protocol

INTRODUCTION HbA1c is the gold standard for glycemic control in pre-diabetes and diabetes. However, its validity has been questioned, especially in the presence of imbalanced iron homeostasis. The CLEVER trial aims to evaluate the relationship between iron deficiency and HbA1c (a biomarker for the diagnosis and therapeutic monitoring of type 2 diabetes) in a randomized, placebo-controlled, multicenter clinical trial. METHODS The CLEVER (intravenous ferric CarboxymaLtosE for improVement of mEtabolic parameters in type 2 diabetes patients with iRon deficiency) trial is a randomized, single-blind, proof-of-concept study with two treatment arms. 140 men and women diagnosed with type 2 diabetes and iron deficiency will receive either placebo or ferric carboxymaltose (500 or 1000 mg) as intravenous infusions. The primary outcome measure is the change in HbA1c level between baseline and after 12 weeks of treatment. Secondary endpoints include change of iron status and metabolic markers as well as treatment safety and tolerability. Furthermore, the potential clinical improvement in quality of life and the reliability of HbA1c measurement in patients with type 2 diabetes and iron deficiency will be investigated. RESULTS Both excessive iron and iron deficiency are associated with metabolic disorders; excessive iron is a risk factor for the development of diabetes, whereas iron deficiency is associated with obesity and insulin resistance. It has been suggested that iron increases insulin secretion in pancreatic beta-cells. CLEVER is the first study to investigate the hypothesis that intravenous substitution with ferric carboxymaltose reduces HbA1c levels in patients with type 2 diabetes and iron deficiency, thereby improving metabolic status and quality of life

Correction to: Intravenous Ferric Carboxymaltose in Patients with Type 2 Diabetes Mellitus and Iron Deficiency: CLEVER Trial Study Design and Protocol

In the original publication, the text in Table 2 stated 'Hypersensitivity to the active substance, to Ferinject, or to any of its excipients'

Interaction between HLA-DM and HLA-DR involves regions that undergo conformational changes at lysosomal pH

Antigenic peptide loading of major histocompatibility complex class II molecules is enhanced by lysosomal pH and catalyzed by the HLA-DM molecule. The physical mechanism behind the catalytic activity of DM was investigated by using time-resolved fluorescence anisotropy (TRFA) and fluorescence binding studies with the dye 8-anilino-1-naphthalenesulfonic acid (ANS). We demonstrate that the conformations of both HLA-DM and HLA-DR3, irrespective of the composition of bound peptide, are pH sensitive. Both complexes reversibly expose more nonpolar regions upon protonation. Interaction of DM with DR shields these hydrophobic domains from the aqueous environment, leading to stabilization of the DM and DR conformations. At lysosomal pH, the uncovering of additional hydrophobic patches leads to a more extensive DM–DR association. We propose that DM catalyzes class II peptide loading by stabilizing the low-pH conformation of DR, favoring peptide exchange. The DM–DR association involves a larger hydrophobic surface area with DR/class II-associated invariant chain peptides (CLIP) than with stable DR/peptide complexes, explaining the preferred association of DM with the former. The data support a release mechanism of DM from the DM–DR complex through reduction of the interactive surface, upon binding of class II molecules with antigenic peptide or upon neutralization of the DM–DR complex at the cell surface

Effect of a Sodium and Calcium DL- β

Background. Ketone body therapy and supplementation are of high interest for several medical and nutritional fields. The intake of ketone bodies is often discussed in relation to rare metabolic diseases, such as multiple acyl-CoA dehydrogenase deficiency (MADD), that have no alternatives for treatment. Case reports showed positive results of therapy using ketone bodies. The number of ketone body salts offered on the wellness market is increasing steadily. More information on the kinetics of intake, safety, and tolerance of these products is needed. Methods. In a one-dose kinetic study, six healthy subjects received an intervention (0.5 g/kg bw) using a commercially available ketone body supplement. The supplement contained a mixture of sodium and calcium D-/L-β-hydroxybutyrate (βHB) as well as food additives. The blood samples drawn in the study were tested for concentrations of D-βHB, glucose, and electrolytes, and blood gas analyses were done. Data on sensory evaluation and observed side effects of the supplement were collected. The product also went through chemical food analysis. Results. The supplement led to a significant increase of D-βHB concentration in blood 2.5 and 3 h after oral intake (p=0.033;  p=0.043). The first significant effect was measured after 2 h with a mean value of 0.598 ± 0.300 mmol/L at the peak, which was recorded at 2.5 h. Changes in serum electrolytes and BGA were largely unremarkable. Taking the supplement was not without side effects. One subject dropped out due to gastrointestinal symptoms and two others reported similar but milder problems. Conclusions. Intake of a combination of calcium and sodium D-/L-βHB salt shows a slow resorption with a moderate increase of D-βHB in serum levels. An influence of βHB salts on acid-base balance could not be excluded by this one-dose study. Excessive regular consumption without medical observation is not free of adverse effects. The tested product can therefore not be recommended unconditionally

Beratungsselbstverständnis(se)

Sickendiek U. Beratungsselbstverständnis(se). In: Grüneberg T, Blaich I, Egerer J, et al., eds. Handbuch Studienberatung Band 1. Bielefeld: wbv Publikationen; 2021: 30-38

Supervision

Walpuski VJ, von Blanckenburg C. Supervision. In: Grüneberg T, Blaich I, Egerer J, et al., eds. Handbuch Studienberatung. Berufliche Orientierung und Beratung für akademische Bildungswege. Vol 2. Bielefeld: wbv media; 2021: 954-959