Cyclopropenes as Chemical Reporters for Dual Bioorthogonal and Orthogonal Metabolic Labeling of DNA.

Dual bioorthogonal labeling enables the investigation and understanding of interactions in the biological environment that are not accessible by a single label. However, applying two bioorthogonal reactions in the same environment remains challenging due to cross-reactivity. We developed a pair of differently modified 2'-deoxynucleosides that solved this issue for dual and orthogonal labeling of DNA. Inverse-electron demand Diels-Alder and photoclick reactions were combined to attach two different fluorogenic labels to genomic DNA in cells. Using a small synthetic library of 1- and 3-methylcyclopropenyl-modified 2'-deoxynucleosides, two 2'-deoxyuridines were identified to be the fastest-reacting ones for each of the two bioorthogonal reactions. Their orthogonal reactivity could be evidenced in vitro. Primer extension experiments were performed with both 2'-deoxyuridines investigating their replication properties as substitutes for thymidine and evaluating subsequent labeling reactions on the DNA level. Finally, dual, orthogonal and metabolic fluorescent labeling of genomic DNA was demonstrated in HeLa cells. An experimental procedure was developed combining intracellular transport and metabolic DNA incorporation of the two 2'-deoxyuridines with the subsequent dual bioorthogonal labeling using a fluorogenic cyanine-styryl tetrazine and a fluorogenic pyrene-tetrazole. These results are fundamental for advanced metabolic labeling strategies for nucleic acids in the future, especially for live cell experiments.

Influence of Cannabinoid Receptor Deficiency on Parameters Involved in Blood Glucose Regulation in Mice.

Cannabinoids are known to influence hormone secretion of pancreatic islets via G protein­coupled cannabinoid receptor type 1 and 2 (CB1 and CB2). The present study was designed to further investigate the impact of cannabinoid receptors on the parameters involved in insulin secretion and blood glucose recognition. To this end, CB1 and CB2 receptor knockout mice (10-12 week old, both sexes) were characterised at basal state and compared to wild-type mice. The elimination of cannabinoid receptor signalling resulted in alterations of blood glucose concentrations, body weights and insulin levels. Changes were dependent on the deleted receptor type and on the sex. Analyses at mRNA and protein levels provided evidence for the impact of cannabinoid receptor deficiency on the glucose sensing apparatus in the pancreas. Both receptor knockout mouse lines showed decreased mRNA and protein amounts of glucose transporters Glut1 and Glut2, combined with alterations in immunostaining. In addition, pancreatic glucokinase expression was elevated and immunohistochemical labelling was modified in the pancreatic islets. Taken together, CB1 and CB2 signalling pathways seem to influence glucose sensing in ß-cells by affecting glucose transporters and glucokinase. These alterations were more pronounced in CB2 knockout mice, resulting in higher blood glucose and lower plasma insulin levels.

Metabolic labelling of DNA in cells by means of the "photoclick" reaction triggered by visible light.

Two pyrene-tetrazole conjugates were synthesized as photoreactive chromophores that allow for the first time the combination of metabolic labelling of DNA in cells and subsequent bioorthogonal "photoclick" modification triggered by visible light. Two strained alkenes and three alkene-modified nucleosides were used as reactive counterparts and revealed no major differences in their "photoclick" reactivity. This is a significant advantage because it allows 5-vinyl-2'-deoxyuridine to be applied as the smallest possible alkene-modified nucleoside for metabolic labelling of DNA in cells. Both pyrene-tetrazole conjugates show fluorogenicity during the "photoclick" reactions, which is a second advantage for cellular imaging. Living HeLa cells were incubated with 5-vinyl-2'-deoxyuridine for 48 h to ensure one cell division. After fixation, the newly synthesized genomic DNA was successfully labelled by irradiation with visible light at 405 nm and 450 nm. This method is an attractive tool for the visualization of genomic DNA in cells with full spatiotemporal control by the use of visible light as a reaction trigger.

Long-term trends in the prescription of antidiabetic drugs: real-world evidence from the Diabetes Registry Tyrol 2012-2018.

INTRODUCTION: Prescription patterns of antidiabetic drugs in the period from 2012 to 2018 were investigated based on the Diabetes Registry Tyrol. To validate the findings, we compared the numbers with trends of different national registries conducted in a comparable period of time. RESEARCH DESIGN AND METHODS: Medication data, prescription patterns, age groups, antidiabetic therapies and quality parameters (hemoglobin A1c, body mass index, complications) of 10 875 patients with type 2 diabetes from 2012 to 2018 were retrospectively assessed and descriptively analyzed. The changes were assessed using a time series analysis with linear regression and prescription trends were plotted over time. RESULTS: Sodium/glucose cotransporter 2 inhibitors (SGLT-2i) showed a significant increase in prescription from 2012 to 2018 (p<0.001), as well as metformin (p=0.002), gliptins (p=0.013) and glucagon-like peptide-1 agonists (GLP-1a) (p=0.017). Significant reduction in sulfonylurea prescriptions (p<0.001) was observed. Metformin was the most frequently prescribed antidiabetic drug (51.3%), followed by insulin/analogs (34.6%), gliptins (28.2%), SGLT-2i (11.7%), sulfonylurea (9.1%), glitazones (3.7%), GLP-1a (2.8%) and glucosidase inhibitors (0.4%). CONCLUSIONS: In this long-term, real-world study on prescription changes in the Diabetes Registry Tyrol, we observed significant increase in SGLT-2i, metformin, gliptins and GLP-1a prescriptions. In contrast prescriptions for sulfonylureas declined significantly. Changes were consistent over the years 2012-2018. Changes in prescription patterns occurred even before the publication of international and national guidelines. Thus, physicians change their prescription practice not only based on published guidelines, but even earlier on publication of cardiovascular outcome trials.