Oligomer Concentration Research Articles

Elevated concentrations of amyloid-β oligomers and their proapoptotic effects on age-related cataract.

Recently, amyloid-β oligomers (AβOs) have been studied as the primary pathogenic substances in Alzheimer's disease (AD). Our previous study revealed that the Aβ expression level is closely related to ARC progression. Here, we demonstrated that the accumulation of AβOs in the lens epithelium of age-related cataract (ARC) patients increased during ARC progression and that this alteration was consistent with the changes in mitochondrial function, oxidative stress, and cellular apoptosis. Invitro, human lens epithelial cells (HLECs) treated with AβOs exhibited Ca2+ dyshomeostasis, impaired mitochondrial function, elevated oxidative stress levels, and increased apoptosis. Moreover, the proapoptotic effect of AβOs was alleviated after the uptake of mitochondrial Ca2+ was inhibited. These results establish that AβOs may promote HLEC apoptosis by inducing mitochondrial Ca2+ overload, thus preliminarily revealing the possible association between the accumulation of AβOs and other pathological processes in ARC.

Dynamics of waste proteins in brain tissue: Numerical insights into Alzheimer's risk factors.

Over the past few decades, research has indicated that the buildup of waste proteins, like amyloid-β (Aβ), in the brain's interstitial spaces is linked to neurodegenerative diseases like Alzheimer's, but the details of how such proteins are removed from the brain are not well understood. We have developed a numerical model to investigate the aggregation and clearance mechanisms of Aβ in the interstitial spaces of the brain. The model describes the volume-averaged transport of Aβ in a segment of the brain interstitium modeled as a porous medium, oriented between the perivascular space (fluid-filled channel surrounding a blood vessel) of a penetrating arteriole and that of a venule. Our numerical approach solves N coupled advection-diffusion-aggregation equations that model the production, aggregation, fragmentation, and clearance of N species of Aβ. We simulate N=50 species to investigate the oligomer-size dependence of clearance and aggregation. We introduce a timescale plot that helps predict Aβ buildup for different neurological conditions. We show that a sudden increase in monomer concentration, as occurs in conditions like traumatic brain injury, leads to significant plaque formation, which can qualitatively be predicted using the timescale plot. Our results also indicate that impaired protein clearance (as occurs with aging) and fragmentation are both mechanisms that sustain large intermediate oligomer concentrations. Our results provide novel insight into several known risk factors for Alzheimer's disease and cognitive decline, and we introduce a unique framing of Aβ dynamics as a competition between different timescales associated with production rates, aggregation rates, and clearance conditions.

IAPP - oligomerisation levels in plasma of people with type 2 diabetes

Islet amyloid polypeptide (IAPP) is co-secreted with insulin from pancreatic ß-cells. Its oligomerisation is regarded as disease driving force in type 2 diabetes (T2D) pathology. Up to now, IAPP oligomers have been detected in affected tissues. IAPP oligomer concentrations in blood have not been analysed so far. Using the IAPP single-oligomer-sensitive and monomer-insensitive surface-based fluorescence intensity distribution analysis (sFIDA) technology, levels of IAPP oligomers in blood plasma from healthy controls and people with T2D in different disease stages where determined. Subsequently, the level of IAPP oligomerisation was introduced as the ratio between the IAPP oligomers determined with sFIDA and the total IAPP concentration determined with ELISA. Highest oligomerisation levels were detected in plasma of people with T2D without late complication and without insulin therapy. Their levels stand out significantly from the control group. Healthy controls presented with the lowest oligomerisation levels in plasma. In people with T2D without complications, IAPP oligomerisation levels correlated with disease duration. The results clearly demonstrate that IAPP oligomerisation in insulin-naïve patients correlates with duration of T2D. Although a correlation per se does not identify, which is cause and what is consequence, this result supports the hypothesis that IAPP aggregation is the driving factor of T2D development and progression. The alternative and conventional hypothesis explains development of T2D with increasing insulin resistance causing exhaustion of pancreatic ß-cells due to over-secretion of insulin, and thus IAPP, too, resulting in subsequent IAPP aggregation and fibril deposition in the pancreas. Further experiments and comparative analyses with primary tissues are warranted.

Characteristics and competitive mechanisms of polycondensation and cyclization induced by end‐groups in polyamide 6 melt

AbstractPolycondensation and ring‐formation reactions are the main factors that cause instability in the molecular structure of commercial polyamide 6 (PA6) during melting. In this study, the mechanisms and interactions of the ring‐formation and polycondensation reactions induced by various factors were thoroughly investigated. The findings suggest that the average molecular weight of PA6 increased by 20.4% during melting. The total monomer and oligomer content increased by 79.2%, and the ring‐forming reaction was promoted with an increase in temperature. Moreover, a high concentration of the end‐amino in PA6 promoted the ring‐forming reaction, whereas similar concentrations of the end‐amino and end‐carboxyl groups were more conducive to the polycondensation reaction. In short, the nitrogen atoms in the end‐amino group on the PA6 molecular chain attack the carbonyl carbon at different sites, including the carbonyl carbon in the amide bond and the carbonyl carbon in the end‐carboxyl group, which is the key to the strength of the ring‐formation and polycondensation reactions.

GUANIDINE-CONTAINING ALIPHATIC OLIGOMERS WITH BACTERICIDAL ACTIVITY

A method for the synthesis of reactive aliphatic guanidine oligomers (GO) of different MM by the reaction of oligomeric oxyalkylaliphatic diepoxide with guanidine by varying the ratio of the starting components with subsequent neutralization of the obtained product with hydrochloric acid was developed. A characteristic feature of the structure of the obtained GO oligomers is their amphiphilicity, with the presence of hydroxy-containing guanidine fragments both at the ends and inside the chain. The obtained oligomers are reactive to further chemical transformations. The chemical structure of GO was characterized by FTIR and 1H-NMR spectroscopy, molecular weight was determined by liquid chromatography and titration data. The bactericidal properties of aliphatic guanidine oligomers against a number of gram-positive (Micrococcus luteus, Rhodococcus erythropolis, Rhodococcus rubber, Bacillus megaterium, Bacillus subtilis, Bacillus cereus) and gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Serratia marcescen), depending on the MW of GO were investigated. The minimum inhibitory concentration of aliphatic guanidine oligomers against the studied bacterial strains was determined. It has been shown that the oligomer with the highest content of guanidine fragments has the greatest bactericidal activity and, accordingly, the lowest minimum inhibitory concentration against gram-positive and gram-negative bacteria. The reactive guanidine oligomers obtained by analogy with polyhexamethylene guanidine chloride can be recommended as substances with biocidal and fungicidal properties. In addition, the inherent reactivity of the synthesized GO makes them promising for obtaining various new types of polymers and composites based on them.

Measuring Erosion of Biodegradable Polymers in Brimonidine Drug Delivery Implants by Quantitative Proton NMR Spectroscopy (q-HNMR)

Erosion of biodegradable polymeric excipients, such as polylactic acid (PLA) and polylactic-co-glycolic acid (PLGA), is generally characterized by microbalance for the remaining mass of PLA and/or PLGA and Gel Permeation Chromatography (GPC) for molecular weight (MW) decrease. For polymer erosion studies of intravitreal sustained release brimonidine implants, however, both microbalance and GPC present several challenges. Mass loss measurement by microbalance does not have specificity for excipient polymers and drug substances. Accuracy of the remaining mass by weighing could also be low due to sample mass loss through retrieval-drying steps, especially at later drug release (DR) time points. When measuring the decrease of polymer MW by GPC, trace amounts of polymeric degradants (oligomers and/or monomers) trapped inside the implants during DR tests may not be measurable due to sensitivity limitations of the GPC detector and column MW range. Previous efforts to measure remained PLGA weight of dexamethasone micro-implants using qNMR with external calibration have been performed, however, these measurements do not account for chemical structure changes (i.e. LA to GA ratio changes from time zero) of PLGA implants during drug release tests. Here, a qNMR method with an internal standard was developed to monitor the following changes in micro-implants during drug release tests: 1. The remaining overall PLA/PLGA mass. 2. The remaining lactic acid (LA), glycolic acid (GA) unit and PLGA's lauryl ester end group percentages. 3. The trace content of PLA/PLGA oligomers as degradants retained in the implants. Unlike microbalance analysis, qNMR has both specificity for drug substance, excipient polymer, and accuracy due to minimal implant loss during sample preparation. Compared to the overall PLA/PLGA remaining mass generally monitored in erosion studies, the percentage of remaining LA, GA, and the ester end group provide more information about the microstructure change (such as hydrophobicity) of PLA/PLGA. Additionally, the qNMR method can complement GPC methods by measuring the change of remaining PLA and PLGA oligomer concentrations in brimonidine implants, with tenfold less sample and no MW cutoff. The qNMR method can be used as a sensitive tool for both polymer excipient characterization and kinetics studies of brimonidine implant erosion.

Effects of efflux pumps on antifungal activity of chitosan against Candida albicans

ABSTRACT Background Antifungal resistance is a major problem, commonly caused by drug-efflux pump overexpression. To evaluate if chitosan could be effective in drug-resistant Candida infections, we investigated the effects of efflux pumps on antifungal activity of chitosan. Materials and Methods The minimal fungicidal concentration (MFC) of oligomer (7–9 kD) and polymer (900–1,000 kD) chitosan against Saccharomyces cerevisiae and Candida albicans were evaluated by broth and agar dilution methods. The MFCs of S. cerevisiae with single deletion of efflux pump genes, with deletion of seven efflux pumps (AD∆), and AD∆ overexpressing C. albicans efflux pump genes (CDR1, CDR2 and MDR1) were determined. C. albicans with homozygous deletions of CDR1 and of CDR2 were generated using CRISPR-Cas9 system and tested for chitosan susceptibility. Results While deleting any individual efflux pump genes had no effect on chitosan susceptibility, simultaneous deletion of multiple pumps (in AD∆) increased sensitivity to both types of chitosan. Interestingly, the overexpression of CDR1, CDR2 or MDR1 in AD∆ barely affected its sensitivity. Moreover, C. albicans with homozygous deletions of CDR1 and/or CDR2 showed similar sensitivity to wildtype. Conclusion Thus, C. albicans susceptibility to chitosan was not affected by drug-efflux pumps. Chitosan may be a promising antifungal agent against pump-overexpressing azole-resistant C. albicans.

Spatiotemporal X-Ray Imaging of Neat and Viscosified CO2 in Displacement of Brine-Saturated Porous Media

Summary CO2 storage in saline aquifers may contribute to a 90% share in preventing emissions to the atmosphere. Due to low CO2 viscosity at the subsurface often found in supercritical (sc) conditions, the injected CO2 may spread quickly at the formation top and increase the probability of leakage. This work relates to improved CO2 storage in saline aquifers by effective viscosification of the sc-CO2 at very low concentrations of engineered oligomers and the effectiveness of slug injection of viscosified CO2 (vis-CO2). We present the results from X-ray computed tomography (CT) imaging to advance the understanding of two-phase CO2-brine flow in porous media and firmly establish the transport mechanisms. X-ray CT imaging of displacement experiments is conducted to quantify the in-situ sc-CO2 saturation spatiotemporally. In neat CO2 injection, gravity override and adverse mobility ratio may result in early breakthrough and low sweep efficiency. We find cumulative brine production from the fraction collector to be lower than X-ray CT imaging at 2 pore volume (PV) injection. The difference between the two is attributed to the solubility of the produced water in the produced CO2 at atmospheric pressure. We show that when the solubility is accounted for, there is a good agreement between direct measurements and in-situ saturation results. There are three reports (two by the same group) that oligomers of 1-decene (O1D) with six repeat units may have marginal CO2 viscosification. The majority of published work by other groups shows that O1D with six repeat units and higher are effective CO2 viscosifiers. In the past, we have demonstrated the effectiveness of an O1D in the displacement of brine by CO2 at a concentration of 1.5 wt%. The effectiveness is examined and identified by three different methods. In this work, we show that the same oligomer is effective at a low concentration of 0.6 wt%. The oligomer slows the breakthrough by 1.6 times and improves the brine production by 34% in the horizontal orientation. X-ray CT imaging results reveal that such a large effect may be from the increase in the interfacial elasticity. We also show that there is no need for continuous injection of the oligomer. A slug of 0.3 PV injection (PVI) of vis-CO2 followed by neat CO2 injection has the same effectiveness as the continuous injection of the vis-CO2. In this work, we also demonstrate the effectiveness of a new engineered molecule at 0.3 wt% that may increase residual trapping by about 35%. The combination of mobility control and residual brine saturation reduction is expected to improve CO2 storage by effective viscosification with low concentrations of oligomers.

Effects of Amyloid Beta (Aβ) Oligomers on Blood-Brain Barrier Using a 3D Microfluidic Vasculature-on-a-Chip Model.

The disruption of the blood-brain barrier (BBB) in Alzheimer's Disease (AD) is largely influenced by amyloid beta (Aβ). In this study, we developed a high-throughput microfluidic BBB model devoid of a physical membrane, featuring endothelial cells interacting with an extracellular matrix (ECM). This paper focuses on the impact of varying concentrations of Aβ1-42 oligomers on BBB dysfunction by treating them in the luminal. Our findings reveal a pronounced accumulation of Aβ1-42 oligomers at the BBB, resulting in the disruption of tight junctions and subsequent leakage evidenced by a barrier integrity assay. Additionally, cytotoxicity assessments indicate a concentration-dependent increase in cell death in response to Aβ1-42 oligomers (LC50 ~ 1 μM). This study underscores the utility of our membrane-free vascular chip in elucidating the dysfunction induced by Aβ with respect to the BBB.

One-pot in situ bulk polymerization of triblock copolymer PCL-b-PA6-b-PCL based on PA6 by using tetraphenyl tin

The preparation of polyesteramides (PEAs) with regular block structure has long been a challenge, owing to the occurrence of the ester-amide exchange during the polymerization at high tempereture. In this work, we report a simple and green method to prepare polyamide 6 (PA6) based triblock PEA whose structure is poly(ε-caprolactone)-block-PA6-block-poly(ε-caprolactone) (PCL-b-PA6-b-PCL) using tetraphenyl tin as catalyst without solvent. The first segment PA6 was synthesized via cationic ring-opening polymerization (ROP) of ε-caprolactam (CPL), later, ROP of ε-caprolactone (CL) was involved to extend polycaprolactone (PCL) segments by using tetraphenyl tin as catalyst. By varying the proportion of CPL and CL, series PA6-based PEAs was prepared and characterized by gel permeation chromatography, 1H, DOSY, and 13C NMR. The results showed that PEA containing more proportion of CL presented a higher molecular weight with narrow polydisperse index. In particular, the lower water absorption and lower oligomers content infers that the PEA could have a prospective application in processing precision electronic devices.

Single-step fabrication of liquid gallium nanoparticles via capillary interaction for dynamic structural colours

Incorporating structural coloured materials in flexible and stretchable elastomeric substrates requires numerous steps that compromise their scalability and economic viability for prospective applications in visual sensors and displays. Here we describe a one-step approach for fabricating plasmonic Ga nanostructures embedded in a polydimethylsiloxane substrate exhibiting tunable chromaticity, in response to mechanical stimuli. The process exploits the capillary interactions between uncrosslinked oligomeric chains of the substrate and Ga metal deposited by thermal evaporation, as elucidated by a theoretical model that we developed. By tuning the oligomer content in polydimethylsiloxane, we attain a range of colours covering a substantial gamut in CIE (Commission Internationale de l’Éclairage) coordinates. This mechanochromic flexible substrate shows reversible response to external mechanical stimuli for ~80,000 cycles. We showcase the capabilities of our processing technique by presenting prototypes of reflective displays and sensors for monitoring body parts, smart bandages and the capacity of the nanostructured film to map force in real time.

Efficient production of copolymerized PA6-based polymer fibers: Oligomer control and direct melt spinning

Synthesis of PA6-based polyester amides (PEAs) is the one of main way to expand the application of PA6. Due to the residual oligomers in the polymer matrix, PEAs are also difficult to achieve directly melt spinning similar to PA6. In this work, the molecular structure designable PEA synthesis method proposed in our previous work was further investigated to control the oligomer content control by end-amino shielding at open-loop stages and efficient de-volatilization at polycondensation stages. The effect of the molecular weight of PA6 segments on oligomer formation was also investigated. The results show that the oligomers, caprolactam, and cyclic dimer contents of PEAs are reduced to 2 wt%, 0.38–0.76 wt%, and 0.2–0.3 wt%, which is lower 75%, 85%, and 50% compared to industrially produced PA6, respectively. It indicates that the molecular weight of PA6 segments, in addition to affecting the physicochemical properties, can also thermodynamically enable regulation of the type of oligomer generated. By adjusting the chain segment structure and controlling the reaction conditions, all PEAs can be directly melting spinning (1200 m/min) and maintains good physical and chemical properties. At the same time, the substantial reduction in oligomers means that PEAs can completely eliminate post-processing such as hydrothermal extraction, fiber production time is shortened from more than 40 h (PA6) to less than 15 h and resource consumption is reduced by more than 30%. This oligomer control method is also applicable to functional PA6, which lays the foundation for efficient and sustainable industrial production of copolymerized PA6 functional fibers on a large scale.

Occurrence and distribution of trisiloxane ethoxylates in citrus orchard soils in China: Analytical challenges

Trisiloxane ethoxylates (TSEOn) are widely used as agricultural surfactants due to their significant synergism with the active ingredients of pesticides, generally, including three typical end groups which are hydroxyl (TSEOn-H), methoxy (TSEOn-CH3), and acetoxy (TSEOn-COCH3), respectively. However, the potential ecotoxicological and endocrine-disrupting risks of TSEOn congeners have recently attracted ever-growing concern. Above all, there is limited research on the concentration levels of TSEOn in agroecosystems. This study, simultaneous analysis of 39 TSEOn oligomers in citrus orchard soils in China was implemented by the modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The method detection limits (MDLs) and the method quantification limits (MQLs) for TSEOn were 0.003–0.07 μg/kg and 0.01–0.20 μg/kg, respectively. The recoveries for TSEOn oligomers in soils ranged from 81 % ∼ 106 % with related standard deviations (RSDs) < 7 %. This newly developed UPLC-MS/MS method with high sensitivity and stability allows us to successfully trace the occurrence of TSEOn congeners in the citrus orchard soils from 3 provinces and 1 municipality in China. The detected concentrations of TSEOn-H oligomers in the sampled soils ranged from 0.02 to 0.288 μg/kg (dry weight). The congener profiles of TSEOn-H were dominated by TSEOn-H (n = 6– 8) in the soils. Additionally, the total concentrations of TSEOn-H congeners (ΣTSEOn-H) in the soils were in the range of 0.03 to 1.49 μg/kg. A comparison of ΣTSEOn-H distribution among the different citrus orchard soils indicated a higher level of ΣTSEOn-H in the soil samples collected from Zhejiang Province. Notably, TSEOn-CH3 or TSEOn-COCH3 oligomers were not detected in the tested soils. To the best of our knowledge, this is the first report on the occurrence and distribution of TSEOn congeners in agricultural soils.

Natural rubber – Increasing diversity of an irreplaceable renewable resource

This paper discusses the importance of introducing domestic natural rubber production and presents the rediscovery of a rubber-producing species, Scorzonera tau-saghyz or “mountain gum”, originally discovered in 1929 on the Karatau mountains in Kazakhstan. This plant could potentially also be cultivated in the U.S. In this exploratory work, roots (2–5 years old) were harvested on June 16, 2021 from wild strands in the Karatau mountains, Kumantas ridge, and Saraba, Kazakhstan, and processed at the Ohio State University. The rubber extraction method was based on an indigenous method in Kazakhstan to make natural chewing gum. Water extraction followed by purification yielded 16.2 wt% rubber from the dry roots, in comparison with 4–8 wt% from most rubber dandelion (Taraxacum kok-saghyz) plants, also a potential domestic rubber producing plant. High-resolution size exclusion chromatography was used to analyze rubber samples. The molecular weights and gel and oligomer contents were very similar to the rubber from Hevea brasiliensis, the current commercial source of natural rubber. More detailed investigations of this very interesting rubber-producing plant are in progress.

Improvement of biocompatibility of high molecular weight poly-3-hydroxybutyrate by blending with its functionalized oligomers

Oligomers of poly-3-hydroxybutyrate (PHB) were prepared by aminolysis of high molecular weight PHB with ethylenediamine and 1,4-diaminobutane. Polymer-oligomer blends (10, 30, and 50% content of the oligomers) were prepared as films by solution casting. As the content of oligomers increased, a gradual increase in the hydrophilicity of the polymer surface was observed, resulting reflected in the water contact angle decrease from 84° to 72–76°. In addition, a moderate decrease in elongation at break, Young's modulus, and tensile strength for the blends were observed as more oligomer was added to the film. Finally, the viability of NIH-3T3 mouse fibroblasts was higher compared to intact PHB when growing in non-prepared polymer/oligomer mixtures. These findings confirm the benefits of the introduction of a hydrophilic functionalized oligomer into the PHB matrix in terms of improving the biocompatibility of the resulting polymer/oligomer blends.

Characterization of Polyhexamethylene Guanidine Oligomers in Solutions and Aerosols Emitted during Humidifier Use

The behavior of polyhexamethylene guanidine (PHMG), the causative agent of many humidifier-induced lung diseases, is not well known because of its various oligomer structures and analytical difficulties. The aim of this study was to identify different PHMG oligomer types both in solution and aerosols and to estimate the airborne concentration of oligomers during humidifier use. Three products containing PHMG as the main component were diluted to the manufacturer’s recommended concentration (6.5 ppm) or the worst-case concentration (65 ppm or 125 ppm). Samples were qualitatively and quantitatively analyzed with liquid chromatography-quadrupole time-of-flight (LC-qToF) mass spectrometry in the diluted solution and in the air at 0.5 m and 1 m. The LC-qToF data were processed using UNIFI software to characterize the PHMG structure. For all products in both the humidifier solution and air, the linear type was predominant over the branched/cyclic structure, but each product had different characteristics. The linear structure in the Oxy product, the main product of lung diseases, accounted for 90.6%, while that of the Scunder and BOC Sciences’ products accounted for 78.6% and 75.8%, respectively. The concentration of the oligomer in air for the Oxy product was estimated to be 35.89 and 390.96 μg/m3 at 6.5 and 65 ppm, respectively. Most of the oligomers in the solution were found in air at a short distance (0.5 m), with a negligible concentration beyond 1 m. Oligomers with 1–7 monomer units were identified in the humidifier solution, whereas mainly monomers, dimers, and trimers were identified in the air. The results of this study will facilitate further investigations of the mechanisms of lung disease by identifying the behaviors and forms of PHMG in the air, along with previously revealed toxicity results.

Oligomer composition and content in regenerated PA6 fiber and its effect on properties

AbstractThe preparation process from waste fibers to regenerated fibers is an environmental significance work. In this work, liquid chromatography/time‐of‐flight mass spectrometry, advanced polymer chromatography/multi‐angle laser‐light‐scattering/refractive index detector, and two‐dimensional wide‐angle X‐ray diffractometry were employed to characterize the polycaprolactam(PA6) fibers above oligomers composition and content, molecular weight and distribution, crystallization and orientation, and analyzing the changes in mechanical properties. The total content of oligomers in physical and chemical regenerated PA6 fiber is 2.084 wt% and 1.812 wt%, individually, which is higher than that in waste PA6 fiber. And the oligomer content of C1–C4 (cyclic monomer, cyclic dimer, cyclic trimer, and cyclic tetramer) in the regenerated PA6 fiber is higher than that of waste PA6 fiber. The regenerated PA6 fiber sample contains more low‐molecular‐weight substances, making it easier to form crystal nuclei and crystallize. During the dyeing process of the regenerated PA6 fiber, the γ crystal transformed into α crystal. The tensile strength of physical and chemical regenerated PA6 fiber is lower than that of waste PA6 fiber. And after dyeing, the oligomers content of regenerated PA6 fiber is significantly decreased, especially in C1–C4 oligomer. However, the crystalliniy and orientation of regenerated PA6 fibers were improved, which also leads to the fracture strength increased by about 20% compared to undyed fibers.

Serum Glycome as a Diagnostic and Prognostic Factor in Gestational Diabetes Mellitus.

Gestational diabetes mellitus (GDM) is a risk factor for both mother and fetus/neonate during and after the pregnancy. Inconsistent protocols and cumbersome screening procedures warrant the search for new and easily accessible biomarkers. We investigated a potential of serum N-glycome to differentiate between healthy pregnant women (n = 49) and women with GDM (n = 53) using a lectin-based microarray and studied the correlation between the obtained data and parameters of glucose and lipid metabolism. Four out of 15 lectins used were able to detect the differences between the control and GDM groups in fucosylation, terminal galactose/N-acetylglucosamine (Gal/GlcNAc), presence of Galα1,4Galβ1,4Glc (Gb3 antigen), and terminal α2,3-sialylation with AUC values above 60%. An increase in the Gb3 antigen and α2,3-sialylation correlated positively with GDM, whereas the amount of fucosylated glycans correlated negatively with the content of terminal Gal/GlcNAc. The content of GlcNAc oligomers correlated with the highest number of blood analytes, indices, and demographic characteristics, but failed to discriminate between the groups. The presence of terminal Gal residues correlated positively with the glucose levels and negatively with the LDL levels in the non-GDM group only. The results suggest fucosylation, terminal galactosylation, and the presence of Gb3 antigen as prediction markers of GDM.

Diameter-Dependent Competitive Adsorption of Sodium Dodecyl Sulfate and Single-Stranded DNA on Carbon Nanotubes.

The equilibrium compositions of coatings on single-wall carbon nanotubes were spectroscopically deduced for samples dispersed in dilute sodium dodecyl sulfate (SDS) and then exposed to low concentrations of ssDNA oligomers. With all studied oligomers, displacement of the SDS tended to occur at lower ssDNA concentrations for smaller diameter nanotubes than for larger diameter ones. However, the behavior varied significantly with oligomer. For example, the diameter dependence was steeper for (TAT)4 than for (ATT)4, suggesting that interstrand head-to-tail hydrogen bonding interactions play a role in SWCNT wrapping. Concentrations of ssDNA in the range of several μg/mL displace SDS from nanotubes dispersed in 1500 μg/mL SDS solutions. This effect allows the use of coating exchange to prepare ssDNA dispersions with minimal oligomer costs. Another demonstrated use exploits the structure-dependent relative coating affinities in a simple filtration method for the diameter enrichment of SWCNT mixtures.

The role of glial cells in neuroinflammation in the context of Alzheimer’s disease

AbstractBackgroundAlzheimer’s disease (AD) is the world’s leading form of dementia. The pathogenesis of AD includes increased brain levels of β‐amyloid peptide oligomers (AβOs), neurotoxins associated with AD. The increase in oligomer concentration is neurotoxic and causes, among the damages, synapse loss, mitochondrial dysfunction and impairment of proteostasis mechanisms. Neuroinflammation, notably the activation of microglia and astrocytes to pro‐inflammatory states, has been associated with the pathogenesis of several neurodegenerative diseases. The current work aimed to evaluate the neuroprotective role of microglia in the context of the pathophysiology of AD.MethodThis study aims to investigate potential modulations in morphology and function of glial cells in experimental models of Alzheimer’s disease (AD), evaluating (1) the in vitro activation of microglia and astrocytes promoted by AβOs, and (2) in vivo microglia and/or astrocytic activation in mice receiving intracerebroventricular (icv) administration of AβOs. Expression of cytokines and glial markers were analyzed by RT PCR and Immunocytochemistry.ResultPreliminary results suggest an increase in glial activation markers, such as GFAP and F4/80, and complement immune system markers such as C1q, 7 days after icv infusion of AβOs. No significant differences were observed in the expression of TNF‐α. Immunocytochemical analyzes suggest greater nuclear factor‐KB translocation in microglial cells treated with AβOs compared to vehicle.ConclusionResults are consistent with an important role of glial cells in the pathogenesis of AD, with glial activity altered and activated in both in vitro and in vivo models. In the face of chronic processes, these cells can remain in an activated state, releasing cytokines, complement components and chemokines, which may contribute to the production and accumulation of Aβ and further exacerbate pathology.