Research on groundwater residence times is essential for evaluating groundwater abstraction rates and aquifer vulnerabilities, and hence, for sustainable water resources management. Naturally occurring radionuclides are suitable tools for related investigations. While the applicability of several long-lived radionuclides for the investigation of long-term processes has been demonstrated frequently, tracer-based approaches for studying residence times of less than one year have not been fully exploited. That is due to the rather small number of applicable radionuclides that show adequately short half-lives. A promising approach for investigating sub-yearly residence times applies radioactive Sulphur (35S). Radio-Sulphur is naturally produced by high-energy cosmic radiation in the upper atmosphere from where it is transferred with precipitation to the groundwater. As soon as the meteoric water enters the subsurface its 35S activity concentration decreases with an 87.4-day half-life. This makes 35S suitable for investigating sub-yearly groundwater residence times. However, the low 35S activities in natural waters require sulphate pre-concentration for 35S detection by means of liquid scintillation counting. This is done by sulphate extraction from large water samples with anion-exchange resins or/and precipitation as BaSO4. The resulting samples are usually associated with background interferences and quenching. The presented experiments aim at (i) optimizing the sample preparation procedure by simplifying the pre-concentration of sulphate to make it applicable for field sampling and at (ii) reducing quench and background during measurement. We will discuss the different sample preparation methods and lessons learned for the detection and quantification of 35S pre-concentrated from natural water samples that contain a wide range of SO42− concentrations.
Due to its short half-life (87 days), naturally occurring radio-sulfur (35S) is applicable as aqueous environmental tracer for investigating groundwater residence times shorter than one year. Being a pure β-decaying radionuclide, 35S is detected straightforwardly by means of liquid scintillation counting (LSC). The rather low 35S activities in natural waters require (i) a careful sample preparation aiming at extracting 35SO42- from large-volume water samples (ca. 20 L) resulting in samples ready for LSC measurement and (ii) an optimal device-specific setup of the LSC to maximize the 35S signal-to-noise-ratio. A few publications that discuss approaches for sample preparation and device-specific LSC setup optimization are available. This paper presents a summarizing step-by-step instruction for both optimized sample preparation and LSC setup. For practical reasons, two different sample preparation approaches are presented, one for samples with low total sulphate inventories (up to 350 mg) and one for samples with elevated total sulphate inventories (350-1500 mg). LSC setup optimization aiming at the measurement of the two resulting types of samples is described for three LSC devices, namely Quantulus GCT, TriCarb 3170 TR/SL, and Quantulus LB 1220.
Cosmogenic radio-sulphur (35S) is applicable as aqueous environmental tracer for investigating sub-yearly groundwater residence times. For the purpose 35SO4 has to be extracted from large-volume water samples (ca. 20 l) and measured by liquid scintillation counting (LSC). Publications that discuss sample preparation approaches focus on waters with low or moderate sulphate concentrations based on sulphate extraction using an ion-exchange resin. However, sulphate extraction by ion-exchange is not feasible for water samples that contain total sulphate loads of over about 1500 mg. Our paper presents an approach for the preparation of water samples with sulphate loads of up to 6000 mg based on BaSO4 precipitation directly from the sample. The key challenge of this approach is the co-precipitation of interfering natural radionuclides (226Ra, short-lived progeny of 222Rn, 210Pb + progeny, 32/33P), which complicates LSC measurement of 35S. Two options are discussed to allow either pre-precipitating the unwanted radionuclides before, or keeping them in solution during Ba35SO4 precipitation.
Adverse anticholinergic drug reactions are common, yet evidence on how to reduce exposure to anticholinergic activity and reliably measure successful deprescribing is still scant. This study proposes an algorithm-based approach to evaluate and reduce anticholinergic load, and reports the results of its pilot testing. Based on published evidence and expert opinion, a list of 85 anticholinergic drugs and 21 algorithms for reducing anticholinergic load, e.g., by recommending alternative drugs with lower risk, were developed. An accompanying test battery was assembled by focusing on instruments that sensitively reflect anticholinergic load and may be sensitive to depict changes (Neuropsychological Assessment Battery to measure memory and attention, validated assessments for constipation, urinary symptoms, and xerostomia, as well as blood biomarkers). The approach was pilot-tested in a geriatric rehabilitation unit, with clinician feedback as the primary outcome and characterization of anticholinergic symptoms as the secondary outcome. The intervention was delivered by a pharmacist and a clinical pharmacologist who used the algorithms to generate personalized recommendation letters. We included a total of 20 patients, 13 with anticholinergic drugs and 7 without. Recommendations were made for 22 drugs in nine patients from the intervention group, of which seven letters (78
BACKGROUND:Despite substantial progress made in the past decades, the pathogenesis of sporadic Alzheimer disease (sAD) and related biological markers of the disease are still controversially discussed. Cerebrospinal fluid and functional brain imaging markers have been established to support the clinical diagnosis of sAD. Yet, due to the invasiveness of such diagnostics, less burdensome markers have been increasingly investigated in the past years. Among such markers, extracellular vesicles may yield promise in (early) diagnostics and treatment monitoring in sAD.MATERIALS AND METHODS:In this pilot study, we collected the blood plasma of 18 patients with sAD and compared the proteome of extracted extracellular vesicles with the proteome of 11 age-matched healthy controls. The resulting proteomes were characterized by Gene Ontology terms and between-group statistics.RESULTS:Ten distinct proteins were found to significantly differ between sAD patients and controls (P<0.05, False Discovery Rate, corrected). These proteins included distinct immunoglobulins, fibronectin, and apolipoproteins.CONCLUSIONS:These findings lend further support for exosomal changes in neurodegenerative disorders, and particularly in sAD. Further proteomic research could decisively advance our knowledge of sAD pathophysiology as much as it could foster the development of clinically meaningful biomarkers.
Supplementary Figures 1-16 from Danger Signaling Protein HMGB1 Induces a Distinct Form of Cell Death Accompanied by Formation of Giant Mitochondria
Patients with sepsis-associated delirium (SAD) show severe neurological impairment, often require an intensive care unit (ICU) stay and have a high risk of mortality. Hence, useful biomarkers for early detection of SAD are urgently needed. Extracellular vesicles (EVs) and their cargo are known to maintain normal physiology but also have been linked to numerous disease states. Here, we sought to identify differentially expressed proteins in plasma EVs from SAD patients as potential biomarkers for SAD. Plasma EVs from 11 SAD patients and 11 age-matched septic patients without delirium (non-SAD) were isolated by differential centrifugation, characterized by nanoparticle tracking analysis, transmission electron microscopy and Western blot analysis. Differential EV protein expression was determined by mass spectrometry and the resulting proteomes were characterized by Gene Ontology term and between-group statistics. As preliminary results because of the small group size, five distinct proteins showed significantly different expression pattern between SAD and non-SAD patients (p ≤ 0.05). In SAD patients, upregulated proteins included paraoxonase-1 (PON1), thrombospondin 1 (THBS1), and full fibrinogen gamma chain (FGG), whereas downregulated proteins comprised immunoglobulin (IgHV3) and complement subcomponent (C1QC). Thus, plasma EVs of SAD patients show significant changes in the expression of distinct proteins involved in immune system regulation and blood coagulation as well as in lipid metabolism in this pilot study. They might be a potential indicator for to the pathogenesis of SAD and thus warrant further examination as potential biomarkers, but further research is needed to expand on these findings in longitudinal study designs with larger samples and comprehensive polymodal data collection.
Supplementary Tables 1-2 from High Frequency of LMAN1 Abnormalities in Colorectal Tumors with Microsatellite Instability
Supplementary Methods from Danger Signaling Protein HMGB1 Induces a Distinct Form of Cell Death Accompanied by Formation of Giant Mitochondria
Mammalian galectins have no signal peptide, and it is not known what would happen if a galectin is directed to take the classical export route. The corresponding engineering of galectin-specific cDNA will answer questions on the fate of a signal peptide-bearing protein variant after its entry into the endoplasmic reticulum (ER). Affinity chromatography and mass-spectrometric analysis of occupancy of potential N-glycosylation sites for the galectin, binding and functional assays with cells as well as subcellular fractionation by density gradient ultracentrifugation and immunocytochemical colocalization with ER/Golgi markers report on aspects of the consequences of letting a galectin enter new territory. Applying these methods will help to clarify why galectins are leaderless and thus produced by free ribosomes.
Galectin-4 (Gal4) has been suggested to function as a tumor suppressor in colorectal cancer (CRC). In order to systematically explore its function in CRC, we established a CRC cell line where Gal4 expression can be regulated via the doxycycline (dox)-inducible expression of a single copy wildtype LGALS4 transgene generated by recombinase-mediated cassette exchange (RMCE). Using this model and applying in-depth proteomic and phosphoproteomic analyses, we systematically screened for intracellular changes induced by Gal4 expression. Overall, 3083 cellular proteins and 2071 phosphosites were identified and quantified, of which 1603 could be matched and normalized to their protein expression levels. A bioinformatic analysis revealed that most of the regulated proteins and phosphosites can be localized in the nucleus and are categorized as nucleic acid-binding proteins. The top candidates whose expression was modulated by Gal4 are PURB, MAPKAPK3, BTF3 and BCAR1, while the prime candidates with altered phosphorylation included ZBTB7A, FOXK1, PURB and CK2beta. In order to validate the (phospho)proteomic data, we confirmed these candidates by a radiometric metabolic-labelling and immunoprecipitation strategy. All candidates exert functions in the transcriptional or translational control, indicating that Gal4 might be involved in these processes by affecting the expression or activity of these proteins.
A code is defined by the nature of the symbols, which are used to generate information‐storing combinations (e. g. oligo‐ and polymers). Like nucleic acids and proteins, oligo‐ and polysaccharides are ubiquitous, and they are a biochemical platform for establishing molecular messages. Of note, the letters of the sugar code system (third alphabet of life) excel in coding capacity by making an unsurpassed versatility for isomer (code word) formation possible by variability in anomery and linkage position of the glycosidic bond, ring size and branching. The enzymatic machinery for glycan biosynthesis (writers) realizes this enormous potential for building a large vocabulary. It includes possibilities for dynamic editing/erasing as known from nucleic acids and proteins. Matching the glycome diversity, a large panel of sugar receptors (lectins) has developed based on more than a dozen folds. Lectins ‘read’ the glycan‐encoded information. Hydrogen/coordination bonding and ionic pairing together with stacking and C−H/π‐interactions as well as modes of spatial glycan presentation underlie the selectivity and specificity of glycan‐lectin recognition. Modular design of lectins together with glycan display and the nature of the cognate glycoconjugate account for the large number of post‐binding events. They give an entry to the glycan vocabulary its functional, often context‐dependent meaning(s), hereby building the dictionary of the sugar code.
Rocaglates are natural compounds that have been extensively studied for their ability to inhibit translation initiation. Rocaglates represent promising drug candidates for tumor treatment due to their growth-inhibitory effects on neoplastic cells. In contrast to natural rocaglates, synthetic analogues of rocaglates have been less comprehensively characterized, but were also shown to have similar effects on the process of protein translation. Here, we demonstrate an enhanced growth-inhibitory effect of synthetic rocaglates when combined with glucose anti-metabolite 2-deoxy-D-glucose (2DG) in different cancer cell lines. Moreover, we unravel a new aspect in the mechanism of action of synthetic rocaglates involving reduction of glucose uptake mediated by downregulation or abrogation of glucose transporter GLUT-1 expression. Importantly, cells with genetically induced resistance to synthetic rocaglates showed substantially less pronounced treatment effect on glucose metabolism and did not demonstrate GLUT-1 downregulation, pointing at the crucial role of this mechanism for the anti-tumor activity of the synthetic rocaglates. Transcriptome profiling revealed glycolysis as one of the major pathways differentially regulated in sensitive and resistant cells. Analysis of synthetic rocaglate efficacy in a 3D tissue context with a co-culture of tumor and normal cells demonstrated a selective effect on tumor cells and substantiated the mechanistic observations obtained in cancer cell lines. Increased glucose uptake and metabolism is a universal feature across different tumor types. Therefore, targeting this feature by synthetic rocaglates could represent a promising direction for exploitation of rocaglates in novel anti-tumor therapies.
Wild-type lectins have distinct types of modular design. As a step to explain the physiological importance of their special status, hypothesis-driven protein engineering is used to generate variants. Concerning adhesion/growth-regulatory galectins, non-covalently associated homodimers are commonly encountered in vertebrates. The homodimeric galectin-7 (Gal-7) is a multifunctional context-dependent modulator. Since the possibility of conversion from the homodimer to hybrids with other galectin domains, i.e. from Gal-1 and Gal-3, has recently been discovered, we designed Gal-7-based constructs, i.e. stable (covalently linked) homo- and heterodimers. They were produced and purified by affinity chromatography, and the sugar-binding activity of each lectin unit proven by calorimetry. Inspection of profiles of binding of labeled galectins to an array-like platform with various cell types, i.e. sections of murine epididymis and jejunum, and impact on neuroblastoma cell proliferation revealed no major difference between natural and artificial (stable) homodimers. When analyzing heterodimers, acquisition of altered properties was seen. Remarkably, binding properties and activity as effector can depend on the order of arrangement of lectin domains (from N- to C-termini) and on the linker length. After dissociation of the homodimer, the Gal-7 domain can build new functionally active hybrids with other partners. This study provides a clear direction for research on defining the full range of Gal-7 functionality and offers the perspective of testing applications for engineered heterodimers.
Human macrophage galactose-type lectin (hMGL, HML, CD301, CLEC10A), a C-type lectin expressed by dendritic cells and macrophages, is a receptor for N-acetylgalactosamine α-linked to serine/threonine residues (Tn antigen, CD175) and its α2,6-sialylated derivative (sTn, CD175s). Because these two epitopes are among malignant cell glycan displays, particularly when presented by mucin-1 (MUC1), assessing the influence of the site and frequency of glycosylation on lectin recognition will identify determinants governing this interplay. Thus, chemical synthesis of the tandem-repeat O-glycan acceptor region of MUC1 and site-specific threonine glycosylation in all permutations were carried out. Isothermal titration calorimetry (ITC) analysis of the binding of hMGL to this library of MUC1 glycopeptides revealed an enthalpy-driven process and an affinity enhancement of an order of magnitude with an increasing glycan count from 6–8 μM for monoglycosylated peptides to 0.6 μM for triglycosylated peptide. ITC measurements performed in D2O permitted further exploration of the solvation dynamics during binding. A shift in enthalpy–entropy compensation and contact position-specific effects with the likely involvement of the peptide surroundings were detected. KinITC analysis revealed a prolonged lifetime of the lectin–glycan complex with increasing glycan valency and with a change in the solvent to D2O.
The article “Proinflammatory Extracellular Vesicle-Mediated Signaling Contributes to the Induction of Neuroinflammation in Animal Models of Endotoxemia and Peripheral Surgical Stress”, written by F. Fricke, J. Gebert, J. Kopitz and K. Plaschke, was originally published electronically on the publisher’s internet portal on 18 June 2020 without open access. With the author(s)’ decision to opt for Open Choice the copyright of the article changed on 27 May 2021 to © The Author(s) 2020 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0 .
Glycosylation is the most prevalent and varied form of post-translational protein modifications. Protein glycosylation regulates multiple cellular functions, including protein folding, cell adhesion, molecular trafficking and clearance, receptor activation, signal transduction, and endocytosis. In particular, membrane proteins are frequently highly glycosylated, which is both linked to physiological processes and of high relevance in various disease mechanisms. The cellular glycome is increasingly considered to be a therapeutic target. Here we describe a new strategy to compare membrane glycoproteomes, thereby identifying proteins with altered glycan structures and the respective glycosites. The workflow started with an optimized procedure for the digestion of membrane proteins followed by the lectin-based isolation of glycopeptides. Since alterations in the glycan part of a glycopeptide cause mass alterations, analytical size exclusion chromatography was applied to detect these mass shifts. N-glycosidase treatment combined with nanoUPLC-coupled mass spectrometry identified the altered glycoproteins and respective glycosites. The methodology was established using the colon cancer cell line CX1, which was treated with 2-deoxy-glucose—a modulator of N-glycosylation. The described methodology is not restricted to cell culture, as it can also be adapted to tissue samples or body fluids. Altogether, it is a useful module in various experimental settings that target glycan functions.
The small 3-O-sulfated galactose head group of sulfatides, an abundant glycosphingolipid class, poses the (sphinx-like) riddle on involvement of glycan bridging by tissue lectins (sugar code). First, synthesis of head group derivatives for functionalization of amphiphilic dendrimers is performed. Aggregation of resulting (biomimetic) vesicles, alone or in combination with lactose, demonstrates bridging by a tissue lectin (galectin-4). Physiologically, this can stabilize glycolipid-rich microdomains (rafts) and associate sulfatide-rich regions with specific glycoproteins. Further testing documents importance of heterobivalency and linker length. Structurally, sulfatide recognition by galectin-8 is shown to involve sphingosine's OH group as substitute for the 3'-hydroxyl of glucose of lactose. These discoveries underscore functionality of this small determinant on bio-membranes intracellularly and on the cell surface. Moreover, they provide a role model to examine counterreceptor capacity of more complex glycans of gly-cosphingolipids and to start their bottom-up glycotope surface programming.