Expanded LUXendin Color Palette for GLP1R Detection and Visualization In Vitro and In Vivo

The glucagon-like peptide-1 receptor (GLP1R) is expressed in peripheral tissues and the brain, where it exerts pleiotropic actions on metabolic and inflammatory processes. Detection and visualization of GLP1R remains challenging, partly due to a lack of validated reagents. Previously, we generated LUXendins, antagonistic red and far-red fluorescent probes for specific labeling of GLP1R in live and fixed cells/tissues. We now extend this concept to the green and near-infrared color ranges by synthesizing and testing LUXendin492, LUXendin551, LUXendin615, and LUXendin762. All four probes brightly and specifically label GLP1R in cells and pancreatic islets. Further, LUXendin551 acts as a chemical beta cell reporter in preclinical rodent models, while LUXendin762 allows noninvasive imaging, highlighting differentially accessible GLP1R populations. We thus expand the color palette of LUXendins to seven different spectra, opening up a range of experiments using wide-field microscopy available in most labs through super-resolution imaging and whole animal imaging. With this, we expect that LUXendins will continue to generate novel and specific insights into GLP1R biology.

Sulfonated red and far-red rhodamines to visualize SNAP- and Halo-tagged cell surface proteins

The (in)ability to permeate membranes is a key feature of chemical biology probes that defines their suitability for specific applications. Here we report sulfonated rhodamines that endow xanthene dyes with cellular impermeability for analysis of surface proteins. We fuse charged sulfonates to red and far-red dyes to obtain Sulfo549 and Sulfo646, respectively, and further link these to benzylguanine and choloralkane substrates for SNAP-tag and Halo-tag labelling. Sulfonated rhodamine-conjugated fluorophores maintain desirable photophysical properties, such as brightness and photostability. While transfected cells with a nuclear localized SNAP-tag remain unlabelled, extracellular exposed tags can be cleanly visualized. By multiplexing with a permeable rhodamine, we are able to differentiate extra- and intracellular SNAP- and Halo-tags, including those installed on the glucagon-like peptide-1 receptor, a prototypical class B G protein-coupled receptor. Sulfo549 and Sulfo646 also labelled transfected neurons derived from induced pluripotent stem cells (iPSCs), allowing STED nanoscopy of the axonal membrane. Together, this work provides a new avenue for rendering dyes impermeable for exclusive extracellular visualization via self-labelling protein tags. We anticipate that Sulfo549, Sulfo646 and their congeners will be useful for a number of cell biology applications where labelling of intracellular sites interferes with accurate surface protein analysis.

Sulfonated rhodamine dyes allow SNAP- and Halo-tag labelling of cell surface protein fusions. A far-red version can be used for STED nanoscopy.

Surrogate Cerebrospinal Fluid Biomarkers for Assessing the Efficacy of Gene Therapy in Hurler Syndrome

Mucopolysaccharidosis type I (MPS I) is caused by a deficiency of the lysosomal hydroxylase alpha-l-iduronidase (IDUA). The resulting accumulation of dermatan and heparan sulfate induces intellectual disabilities and pre-mature death, and only a few treatment options are available. In a previous study, we demonstrated the feasibility, safety, and efficacy of gene therapy by injecting recombinant adeno-associated viral vector serotype (AAV)2/5-IDUA into the brain of a canine model of MPS I. We report on a quantitative proteomic analysis of control dogs and untreated dogs with MPS I cerebrospinal fluid (CSF) that had been collected throughout the study in the MPS I dogs. Mass spectrometry (MS) analysis identified numerous proteins present at altered levels in MPS I CSF samples. Quantitative immunoblotting, performed on CSF from healthy controls, untreated MPS I dogs, and MPS I dogs early treated and late treated by gene therapy, confirmed the MS data for a subset of proteins with higher abundance (neuronal pentraxin 1, chitinase 3-like 1, monocyte differentiation antigen CD14, and insulin-like growth factor-binding protein 2). Scoring of the results shows that the expression levels of these proteins are close to those of the control group for dogs that underwent gene therapy early in life but not for older treated animals. Our results disclose four novel predictive biomarker candidates that might be valuable in monitoring the course of the neurological disease in MPS patients at diagnosis, during clinical follow-up, and after treatment.

Quantitative Evaluation of Different Protein Fractions of Cerebrospinal Fluid Using 18O Labeling

Molecular analysis of cerebrospinal fluid (CSF) provides comprehensive information on physiological and pathological processes related to the brain. In particular, proteomic studies give insights into the pathogenesis of many brain diseases which still pose diagnostic and therapeutic challenges. The identification of reliable biomarkers is an important step to meet these challenges. Mass spectrometry is an essential proteomic tool, not only for highly sensitive identification of proteins and posttranslational modifications, but also for their reliable quantification. Here, ¹⁸O labeling of tryptic peptides was employed to qualitative and quantitative analyses of protein fractions obtained by depletion of highly abundant proteins from cerebrospinal fluid. It was found that the execution of the investigated depletion protocols may cause the loss of potential protein biomarkers of neurological diseases.

Fatal outcome of a hyperinfection syndrome despite successful eradication of Strongyloides with subcutaneous ivermectin

We report the case of a 77-year-old man who developed a Strongyloides hyperinfection syndrome following immunosuppressive therapy more than 60 years after he moved away from an area endemic for Strongyloides stercoralis. Successful eradication of the nematode was achieved with an off label subcutaneous formulation of ivermectin. However, the patient subsequently died from acute respiratory distress syndrome (ARDS). Despite a high wormload in the stool and sputum of the patient and delayed infection control measures in the hospital, testing of the medical staff revealed a very low risk of Strongyloides transmission among healthcare workers.

Optimization of force constants with an Urey-Bradley force field avoiding normal mode crossings

We present a method that simplifies the refinement of force constants in normal mode calculations and makes the results more reliable. The method avoids normal mode crossings by constraining the force constants during refinement. It was tested with pyrrole, imidazole, benzene, pyridine, pyrimidine, aniline and adenine using a Urey-Bradley force field. The global error of the frequency fit for these molecules was 0.61%. The method reproduced with fewer parameters the accuracy of similar calculations of the single ring aromatic compounds. It improved the accuracy and isotopic shifts of previous empirical calculations of adenine by 40%. The C-C and C-N stretchings differed by less than 7% from the values of force constant-bond length empirical relations.

Effect on fertility of female mice of the transfer of lymphocytes from females previously immunized with mouse spermatozoa

To examine the influence of cellular immunity to spermatozoa on the fertility of inbred mice, leucocytes were transferred from other female mice that had been immunized with spermatozoa. Both syngeneic and allogeneic systems were investigatd. The cellular immune reaction was estimated using a footpad swelling test before and after the cell transfer. There was a significant increase of the paw thickness and a statistically significant reduction in fertility only for C3H mice immunized with C57BL spermatozoa.

Beitrag zur Morphologie der myometrialen und dezidualen Arterien bei normalen Schwangerschaften, EPH-Gestosen und mütterlichem Diabetes mellitus

127 specimens, obtained by different methods from the myometrium and the placental bed after parturition, are investigated histologically. This material includes normal pregnancies as well as cases of maternal diabetes with and without hypertension and cases of hypertension in EPH-gestosis. The different parts of the arterial system (spiral arteries, basal arteries, radial arteries) are separately investigated. Physiologically, the pregnancy induces changes in the wall of the decidual arteries and possibly in the distal part of the radial arteries. The fibromuscular layer including the elastic fibers were destructed and replaced by fibrin and connective tissue. For this reason, in these parts of arteries it is very difficult to separate pathological from physiological changes. Maternal hypertension produces in myometrial, basal and decidual arteries (myometrial part) a thickening of the arterial wall. This thickening is caused in arteries with normal structure by hypertrophy of the media, in the spiral arteries by intimal processes (edematous reaction of the intima, deposition of foam cells) and fibrinoid necrosis of the arterial wall. The cases of maternal diabetes without hypertension are characterized by an increase of fibrin deposits in the wall of the distal part of the spiral artery. In the proximal part of the spiral artery we have found in two cases without hypertension some foam cells in the wall. Myometrial arteries show particularly thickening of the wall and narrowing of the arterial lumen, less frequently intimal swelling and groups of foam cells. In diabetes mellitus, complicated by hypertension, we could find changes in the proximal part of the spiral artery and in the basal arteries. This alterations correspond with the changes in cases of hypertension without diabetes. In the myometrial arteries the pathological processes are the same as in cases of diabetes without hypertension. A significant increase of pathological processes by the diabetes mellitus alone exists only in the myometrial arteries. Besides, in the small arterial vessels of the myometrium in diabetes occurs a proliferative angiolopathy, involving cases of White classes D and F only. We could demonstrate the so-called ‘acute atherosis’ in a small number of cases in the myometrial part of the spiral artery and in the distal part of the radial artery, too. It concerns especially cases of maternal hypertension, more seldom cases of normal pregnancy and diabetic pregnancy without hypertension.