Sprachbildung in digitalen verstehensorientierten Lerneinheiten zum Operationsverständnis

Während Plattformen und Lerneinheiten zum Aufbau und adaptivem Training von Rechenfertigkeiten bereits breit etabliert sind (vgl. kritische Analyse von Thurm, 2020), müssen verstehensorientierte digitale Lerneinheiten erst forschungsbasiert entwickelt werden. Divomath ist ein Design-Research- Projekt, das dieses Ziel für die Klassen 3-6 verfolgt. Am Beispielmodul S1 zum Divisionsverständnis (Kl. 5) zeigt dieser Kurzbeitrag, wie dabei auch fachbezogene Sprachbildung zu berücksichtigen ist

HIV reverse transcriptase: Structural interpretation of drug resistant genetic variants from India

The reverse transcriptase (RT) enzyme is the prime target of nucleoside/ nucleotide (NRTI) and non-nucleoside (NNRTI) reverse transcriptase inhibitors. Here we investigate the structural basis of effects of drug-resistance mutations in clade C RT using three-dimensional structural modeling. Apropos the expectation was for unique mechanisms in clade C based on interactions with amino acids of p66 subunit in RT molecule. 3-D structures of RT with mutations found in sequences from 2 treatment naïve, 8 failed and one reference clade C have been modeled and analyzed. Models were generated by computational mutation of available crystal structures of drug bound homologous RT. Energy minimization of the models and the structural analyses were carried out using standard methods. Mutations at positions 75,101,118,190,230,238 and 318 known to confer drug resistance were investigated. Different mutations produced different effects such as alteration of geometry of the drugbinding pocket, structural changes at the site of entry of the drug (into the active site), repositioning the template bases or by discriminating the inhibitors from their natural substrates. For the mutations analyzed, NRTI resistance was mediated mainly by the ability to discriminate between inhibitors and natural substrate, whereas, NNRTI resistance affected either the drug entry or the geometry of the active site. Our analysis suggests that different mutations result in different structural effects affecting the ability of a given drug to bind to the RT. Our studies will help in the development of newer drugs taking into account the presence of these mutations and the structural basis of drug resistance

Improvement of cutaneous inflammation and panniculitis in patients with dermatomyositis by the Janus kinase inhibitor baricitinib

Dear Editor, Dermatomyositis (DM) is a rare autoimmune disease with cutaneous and systemic involvement significantly impairing quality of life. Current treatment options are unspecific and often induce only partial remission, especially in DM‐associated panniculitis. The pathogenesis of the disease is fairly unknown; however, induction of type I interferon (IFN) and its IFN‐stimulated genes (ISGs) was discovered in patients’ blood, muscle and skin.1 Inhibiting the activation of Janus kinase (JAK)‐transmitting signals of the type I IFN receptor is a valuable therapeutic option, and the efficacy of the JAK1 and JAK2 inhibitor baricitinib was reported in eight patients with juvenile DM and in two patients with adult DM.2–6 The prominent type I IFN signature in DM prompted us to treat three patients with classic adult DM with the JAK inhibitor baricitinib.1 Patient 1 had experienced a recurrent disease course for 25 years. She had previously received immunosuppressive therapy and intravenous immunoglobulin (IVIG). Partial remission was achieved with low‐dose prednisolone (5 mg per day), methotrexate, hydroxychloroquine and adalimumab. Nevertheless, she presented with a new disease flare with violaceous erythema prone to the face, décolleté, neck and periungual area, but normal muscle enzymes (Figure 1a). The therapy with methotrexate and adalimumab was terminated due to an increase in liver enzymes. Thereafter, tofacitinib was started but was not well tolerated because of lactose intolerance in the patient. Therefore, the therapy was changed to baricitinib 4 mg daily. The neck, facial and periungual erythema completely regressed within 5 months of treatment (Figure 1a)

Urinary Excretion of Mercapturic Acids of the Rodent Carcinogen Methyleugenol after a Single Meal of Basil Pesto: A Controlled Exposure Study in Humans

Methyleugenol (ME), found in numerous plants and spices, is a rodent carcinogen and is classified as “possibly carcinogenic to humans”. The hypothesis of a carcinogenic risk for humans is supported by the observation of ME-derived DNA adducts in almost all human liver and lung samples examined. Therefore, a risk assessment of ME is needed. Unfortunately, biomarkers of exposure for epidemiological studies are not yet available. We hereby present the first detection of N-acetyl-l-cysteine conjugates (mercapturic acids) of ME in human urine samples after consumption of a popular ME-containing meal, pasta with basil pesto. We synthesized mercapturic acid conjugates of ME, identified the major product as N-acetyl-S-[3′-(3,4-dimethoxyphenyl)allyl]-l-cysteine (E-3′-MEMA), and developed methods for its extraction and LC–MS/MS quantification in human urine. For conducting an exposure study in humans, a basil cultivar with a suitable ME content was grown for the preparation of basil pesto. A defined meal containing 100 g of basil pesto, corresponding to 1.7 mg ME, was served to 12 participants, who collected the complete urine at defined time intervals for 48 h. Using d6-E-3′-MEMA as an internal standard for LC–MS/MS quantification, we were able to detect E-3′-MEMA in urine samples of all participants collected after the ME-containing meal. Excretion was maximal between 2 and 6 h after the meal and was completed within about 12 h (concentrations below the limit of detection). Excreted amounts were only between 1 and 85 ppm of the ME intake, indicating that the ultimate genotoxicant, 1′-sulfooxy-ME, is formed to a subordinate extent or is not efficiently detoxified by glutathione conjugation and subsequent conversion to mercapturic acids. Both explanations may apply cumulatively, with the ubiquitous detection of ME DNA adducts in human lung and liver specimens arguing against an extremely low formation of 1′-sulfooxy-ME. Taken together, we hereby present the first noninvasive human biomarker reflecting an internal exposure toward reactive ME species

High prevalence of drug-resistance mutations in Plasmodium falciparum and Plasmodium vivax in southern Ethiopia

BACKGROUND: In Ethiopia, malaria is caused by both Plasmodium falciparum and Plasmodium vivax. Drug resistance of P. falciparum to sulfadoxine-pyrimethamine (SP) and chloroquine (CQ) is frequent and intense in some areas. METHODS: In 100 patients with uncomplicated malaria from Dilla, southern Ethiopia, P. falciparum dhfr and dhps mutations as well as P. vivax dhfr polymorphisms associated with resistance to SP and P. falciparum pfcrt and pfmdr1 mutations conferring CQ resistance were assessed. RESULTS: P. falciparum and P. vivax were observed in 69% and 31% of the patients, respectively. Pfdhfr triple mutations and pfdhfr/pfdhps quintuple mutations occurred in 87% and 86% of P. falciparum isolates, respectively. Pfcrt T76 was seen in all and pfmdr1 Y86 in 81% of P. falciparum. The P. vivax dhfr core mutations N117 and R58 were present in 94% and 74%, respectively. CONCLUSION: These data point to an extraordinarily high frequency of drug-resistance mutations in both P. falciparum and P. vivax in southern Ethiopia, and strongly support that both SP and CQ are inadequate drugs for this region

Fbxl17 is rearranged in breast cancer and loss of its activity leads to increased global O -GlcNAcylation

Funder: Wildy Fellowship Department of PathologyFunder: Addenbrooke's Charitable Trust, Cambridge University Hospitals; doi: http://dx.doi.org/10.13039/501100002927Funder: The Mark FoundationAbstract: In cancer, many genes are mutated by genome rearrangement, but our understanding of the functional consequences of this remains rudimentary. Here we report the F-box protein encoded by FBXL17 is disrupted in the region of the gene that encodes its substrate-binding leucine rich repeat (LRR) domain. Truncating Fbxl17 LRRs impaired its association with the other SCF holoenzyme subunits Skp1, Cul1 and Rbx1, and decreased ubiquitination activity. Loss of the LRRs also differentially affected Fbxl17 binding to its targets. Thus, genomic rearrangements in FBXL17 are likely to disrupt SCFFbxl17-regulated networks in cancer cells. To investigate the functional effect of these rearrangements, we performed a yeast two-hybrid screen to identify Fbxl17-interacting proteins. Among the 37 binding partners Uap1, an enzyme involved in O-GlcNAcylation of proteins was identified most frequently. We demonstrate that Fbxl17 binds to UAP1 directly and inhibits its phosphorylation, which we propose regulates UAP1 activity. Knockdown of Fbxl17 expression elevated O-GlcNAcylation in breast cancer cells, arguing for a functional role for Fbxl17 in this metabolic pathway

DNA methylation patterns in CD4+ T-cells separate psoriasis patients from healthy controls, and skin psoriasis from psoriatic arthritis

BackgroundPsoriasis is an autoimmune/inflammatory disorder primarily affecting the skin. Chronic joint inflammation triggers the diagnosis of psoriatic arthritis (PsA) in approximately one-third of psoriasis patients. Although joint disease typically follows the onset of skin psoriasis, in around 15% of cases it is the initial presentation, which can result in diagnostic delays. The pathophysiological mechanisms underlying psoriasis and PsA are not yet fully understood, but there is evidence pointing towards epigenetic dysregulation involving CD4+ and CD8+ T-cells.ObjectivesThe aim of this study was to investigate disease-associated DNA methylation patterns in CD4+ T-cells from psoriasis and PsA patients that may represent potential diagnostic and/or prognostic biomarkers.MethodsPBMCs were collected from 12 patients with chronic plaque psoriasis and 8 PsA patients, and 8 healthy controls. CD4+ T-cells were separated through FACS sorting, and DNA methylation profiling was performed (Illumina EPIC850K arrays). Bioinformatic analyses, including gene ontology (GO) and KEGG pathway analysis, were performed using R. To identify genes under the control of interferon (IFN), the Interferome database was consulted, and DNA Methylation Scores were calculated.ResultsNumbers and proportions of CD4+ T-cell subsets (naïve, central memory, effector memory, CD45RA re-expressing effector memory cells) did not vary between controls, skin psoriasis and PsA patients. 883 differentially methylated positions (DMPs) affecting 548 genes were identified between controls and “all” psoriasis patients. Principal component and partial least-squares discriminant analysis separated controls from skin psoriasis and PsA patients. GO analysis considering promoter DMPs delivered hypermethylation of genes involved in “regulation of wound healing, spreading of epidermal cells”, “negative regulation of cell-substrate junction organization” and “negative regulation of focal adhesion assembly”. Comparing controls and “all” psoriasis, a majority of DMPs mapped to IFN-related genes (69.2%). Notably, DNA methylation profiles also distinguished skin psoriasis from PsA patients (2,949 DMPs/1,084 genes) through genes affecting “cAMP-dependent protein kinase inhibitor activity” and “cAMP-dependent protein kinase regulator activity”. Treatment with cytokine inhibitors (IL-17/TNF) corrected DNA methylation patterns of IL-17/TNF-associated genes, and methylation scores correlated with skin disease activity scores (PASI).ConclusionDNA methylation profiles in CD4+ T-cells discriminate between skin psoriasis and PsA. DNA methylation signatures may be applied for quantification of disease activity and patient stratification towards individualized treatment