Mobile phase modifier effects in multimodal cation exchange chromatography

This study examines protein adsorption behavior and the effects of mobile phase modifiers in multimodal chromatographic systems. Chromatography results with a diverse protein library indicate that multimodal and ion exchange resins have markedly different protein binding behavior and selectivity. NMR results corroborate the stronger binding observed for the multimodal system and provide insight into the structural basis for the observed binding behavior. Protein-binding affinity and selectivity in multimodal and ion exchange systems are then examined using a variety of mobile phase modifiers. Arginine and guanidine are found to have dramatic effects on protein adsorption, yielding changes in selectivity in both chromatographic systems. While sodium caprylate leads to slightly weaker chromatographic retention for most proteins, certain proteins exhibit significant losses in retention in both systems. The presence of a competitive binding mechanism between the multimodal ligand and sodium caprylate for binding to ubiquitin is confirmed using STD NMR. Polyol mobile phase modifiers are shown to result in increased retention for weakly bound proteins and decreased retention for strongly bound proteins, indicating that the overall retention behavior is determined by a balance between changes in electrostatic and hydrophobic interactions. This work provides an improved understanding of protein adsorption and mobile phase modifier effects in multimodal chromatographic systems and sets the stage for future work to develop more selective protein separation systems.     

Binding affinities of vascular endothelial growth factor (VEGF) for heparin-derived oligosaccharides

Heparin and HS (heparan sulfate) exert their wide range of biological activities by interacting with extracellular protein ligands. Among these important protein ligands are various angiogenic growth factors and cytokines. HS binding to VEGF (vascular endothelial growth factor) regulates multiple aspects of vascular development and function through its specific interaction with HS. Many studies have focused on HS-derived or HS-mimicking structures for the characterization of VEGF165 interaction with HS. Using a heparinase 1-prepared small library of heparin-derived oligosaccharides ranging from hexasaccharide to octadecasaccharide, we systematically investigated the heparin-specific structural features required for VEGF binding. We report the apparent affinities for the association between the heparin-derived oligosaccharides with both VEGF165 and VEGF55, a peptide construct encompassing exclusively the heparin-binding domain of VEGF165. An octasaccharide was the minimum size of oligosaccharide within the library to efficiently bind to both forms of VEGF and a tetradecasaccharide displayed an effective binding affinity to VEGF165 comparable to unfractionated heparin. The range of relative apparent binding affinities among VEGF and the panel of heparin-derived oligosaccharides demonstrate that the VEGF binding affinity likely depends on the specific structural features of these oligosaccharides, including their degree of sulfation, sugar-ring stereochemistry and conformation. Notably, the unique 3-O-sulfo group found within the specific antithrombin binding site of heparin is not required for VEGF165 binding. These findings afford new insight into the inherent kinetics and affinities for VEGF association with heparin and heparin-derived oligosaccharides with key residue-specific modifications and may potentially benefit the future design of oligosaccharide-based anti-angiogenesis drugs.     

5-Thienyltryptamine derivatives as serotonin 5-HT1B/1D receptor agonists: potential treatments for migraine

A series of 5-(2- or 3-thienyl)tryptamine derivatives (9) has been synthesized and shown to be potent and selective 5-HT1D versus 5-HT1B receptor agonists and, therefore, potential treatments for migraine.     

Increases in alpha4* but not alpha3*/alpha6* nicotinic receptor sites and function in the primate striatum following chronic oral nicotine treatment

Knowledge of the effects of chronic nicotine is critical considering its widespread use in tobacco products and smoking cessation therapies. Although nicotine is well known to up-regulate alpha4* nAChR sites and function in the cortex, its actions in the striatum are uncertain because of the presence of multiple subtypes with potentially opposing effects. We therefore investigated the effect of long-term nicotine treatment on nAChR sites and function in the primate striatum, which offers the advantage of similar proportions of alpha3*/alpha6* and alpha4* nAChRs. Nicotine was given in drinking water, which resembles smoking in its intermittent but chronic delivery. Plasma nicotine and cotinine levels were similar to smokers. Chronic nicotine treatment (> 6 months) enhanced alpha4* nAChR-evoked [(3)H]dopamine release in striatal subregions, with an overall pattern of increase throughout the striatum when normalized to uptake. This increase correlated with elevated striatal alpha4* nAChRs. Under the same conditions, striatal alpha3*/alpha6* nAChR sites and function were decreased or unchanged. These divergent actions of chronic nicotine treatment on alpha4* versus alpha6* nAChRs, as well as effects on dopamine uptake, allow for a complex control of striatal activity to maintain dopaminergic function. Such knowledge is important for understanding nicotine dependence and the consequences of nicotine administration for the treatment of neurological disorders.     

Molecular phylogeny of diplomonads and enteromonads based on SSU rRNA,alpha-tubulin and HSP90 genes: Implications for the evolutionary history of the double karyomastigont of diplomonads

Background  

Fornicata is a relatively recently established group of protists that includes the diplokaryotic diplomonads (which have two similar nuclei per cell), and the monokaryotic enteromonads, retortamonads and Carpediemonas, with the more typical one nucleus per cell. The monophyly of the group was confirmed by molecular phylogenetic studies, but neither the internal phylogeny nor its position on the eukaryotic tree has been clearly resolved.     

Statins but not fibrates improve the atherogenic to anti-atherogenic lipoprotein particle ratio: a randomized crossover study

Background  

Prior studies suggested low density lipoprotein particle (LDLP) size is a predictor of atherosclerosis. Knowledge of effects of lipid lowering drugs on lipoprotein subclasses is useful. We treated subjects with hyperlipidemia sequentially with statins and fibrates, the 2 main classes of lipid lowering therapy and studied changes in NMR lipoprotein subclasses.     

Mapping global cropland and field size

A new 1 km global IIASA‐IFPRI cropland percentage map for the baseline year 2005 has been developed which integrates a number of individual cropland maps at global to regional to national scales. The individual map products include existing global land cover maps such as GlobCover 2005 and MODIS v.5, regional maps such as AFRICOVER and national maps from mapping agencies and other organizations. The different products are ranked at the national level using crowdsourced data from Geo‐Wiki to create a map that reflects the likelihood of cropland. Calibration with national and subnational crop statistics was then undertaken to distribute the cropland within each country and subnational unit. The new IIASA‐IFPRI cropland product has been validated using very high‐resolution satellite imagery via Geo‐Wiki and has an overall accuracy of 82.4%. It has also been compared with the EarthStat cropland product and shows a lower root mean square error on an independent data set collected from Geo‐Wiki. The first ever global field size map was produced at the same resolution as the IIASA‐IFPRI cropland map based on interpolation of field size data collected via a Geo‐Wiki crowdsourcing campaign. A validation exercise of the global field size map revealed satisfactory agreement with control data, particularly given the relatively modest size of the field size data set used to create the map. Both are critical inputs to global agricultural monitoring in the frame of GEOGLAM and will serve the global land modelling and integrated assessment community, in particular for improving land use models that require baseline cropland information. These products are freely available for downloading from the http://cropland.geo-wiki.org website.     

Biochemical genetics of glucosinolate modification in Arabidopsis and Brassica

Fine mapping of the glucosinolate biosynthesis gene OHP, which regulates the conversion of 3-methylsulphinylpropyl to 3-hydroxypropyl glucosinolate, in an Arabidopsis thaliana Columbia × Landsberg erecta RI line population positioned the gene within 54 kb of DNA on chromosome IV. Sequence data identified a family of genes encoding 2-oxoglutarate-dependent dioxygenases in this region. A probe based on these genes co-segregated with ALK in Brassica oleracea,a gene regulating the synthesis of alkenyl glucosinolates. The reactions catalysed by the OHP and ALK enzymes utilise similar substrates and may have a common mechanism. Thus, these dioxygenases are prime candidates for controlling the side chain modification of glucosinolates. Received: 12 May 2000 / Accepted: 29 May 2000     

Ancestral SARS-CoV-2, but not Omicron,replicates less efficiently in primary pediatric nasal epithelial cells

Children typically experience more mild symptoms of Coronavirus Disease 2019 (COVID-19) when compared to adults. There is a strong body of evidence that children are also less susceptible to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection with the ancestral viral isolate. However, the emergence of SARS-CoV-2 variants of concern (VOCs) has been associated with an increased number of pediatric infections. Whether this is the result of widespread adult vaccination or fundamental changes in the biology of SARS-CoV-2 remain to be determined. Here, we use primary nasal epithelial cells (NECs) from children and adults, differentiated at an air–liquid interface to show that the ancestral SARS-CoV-2 replicates to significantly lower titers in the NECs of children compared to those of adults. This was associated with a heightened antiviral response to SARS-CoV-2 in the NECs of children. Importantly, the Delta variant also replicated to significantly lower titers in the NECs of children. This trend was markedly less pronounced in the case of Omicron. It is also striking to note that, at least in terms of viral RNA, Omicron replicated better in pediatric NECs compared to both Delta and the ancestral virus. Taken together, these data show that the nasal epithelium of children supports lower infection and replication of ancestral SARS-CoV-2, although this may be changing as the virus evolves.

Children typically experience more mild symptoms of COVID-19 when compared to adults; why is this? This study uses nasal epithelial cells from children and adults to show that the ancestral SARS-CoV-2 and Delta, but not the Omicron variant, replicate less efficiently in pediatric nasal epithelial cells.