Spontaneous Aggregation Research Articles

FEATURES OF HAEMOSTASIS IN DIFFERENT TYPES OF 24 HOURS DAY'S PROFILE OF BLOOD PRESSURE IN HYPERTENSIVE PATIENTS OF DIFFERENT AGE GROUPS

Relevance. The phenomenon of non-dipper (insufficient nocturnal decrease in blood pressure) has prognostic significance for increasing the risk of complications of arterial hypertension - myocardial infarction, stroke. To date, there are only isolated reports of platelet hemostasis in this category of individuals. Therefore, it is important to find out the peculiarities of state of platelet aggregation depending on circadian rhythm of blood pressure (BP).
 Objective is to identify the baseline level of platelet and plasma hemostasis at different 24 hours day's blood pressure profiles in middle-aged and elderly hypertensive patients.
 Materials and methods. Subjects (n=90) are divided into 3 groups. Group 1 (n=30) included middle-aged hypertensive patients (45-59 years), group 2 (n=30) − elderly hypertensive (60-74 years) patients. Patients are divided into two subgroups in each of these groups, 15 people in each: subgroup dipper (D) − with adequate nocturnal blood pressure reduction (10-20 %) and subgroup non-dipper (ND) − with insufficient nocturnal blood pressure reduction (<10 %). The control group (n = 30) consisted of 15 patients without arterial hypertension for each of the examined groups. 
 The state of spontaneous and induced platelet aggregation was determined. Adenosine diphosphate (1´10-5 mM/L) and adrenaline (1 µg/mL) were used as aggregation inducers on SOLAR AP-2110 optical aggregometer. The following parameters of aggregatograms were calculated: amplitude of spontaneous and induced aggregation (AA, %); time of maximal aggregation (TMA, min.); slope of aggregation (SA, %/min.). The state of plasma hemostasis was determined on hemocoagulometer Amelung KC 1A. The following parameters were determined to assess state of plasma hemostasis: fibrinogen (FG, g/L), antithrombin III (AT-III, %), fibrinolysis (min.).
 Results. The increase in induced platelet aggregation activity was found in middle-aged hypertensive patients. In subgroup D AA was 1,9 times and in subgroup ND – 2,3 times higher than the norm; the rate of SA increased by 105,5 % and 112 %, respectively. In subgroup ND compared with subgroup D AA was higher by 21 % and SA − by 3,2 %.
 In elderly hypertensive patients, the rate of spontaneous aggregation AA is 1,7 times higher in subgroup ND compared with subgroup D (4,2±1,6 % vs. 2,5±0,2 %). In the ND subgroup AA rate is 68 % higher than in the control. Indicators of induced platelet aggregation were also higher in subgroup ND compared with subgroup D: AA with induction of ADP – 74,7±25,1 % vs. 51,4±22,2 %; TMA with adrenaline induction – 8,2±2,6 minutes against 5,7±2,5 minutes, respectively. There was the significant reduction in TMA with adrenaline-induced aggregation by 30,5 % in subgroup D compared with the control also.
 Fibrinolysis activity in middle-aged hypertensive patients in subgroup D was slowed down by 36,1% compared with the control group: fibrinolysis was 215,0±49,7 minutes while 158,0±5,7 minutes in the control group.
 Conclusions. Platelet hemostasis changes with age in the direction of increasing the aggregation properties of platelets in hypertensive patients. More pronounced changes were found in patients with insufficient reduction of blood pressure at night. In elderly patients, the most significant changes are determined by adrenaline-induced aggregation compared with middle-aged patients.

CRISPR/Cas9-mediated genetic correction reverses spinocerebellar ataxia 3 disease-associated phenotypes in differentiated cerebellar neurons

AbstractThe neurodegenerative disease spinocerebellar ataxia type 3 (SCA3; also called Machado-Joseph disease, MJD) is a trinucleotide repeat disorder caused by expansion of the CAG repeats in the ATXN3 gene. Here, we applied a CRISPR/Cas9-mediated approach using homologous recombination to achieve a one-step genetic correction in SCA3-specific induced pluripotent stem cells (iPSCs). The genetic correction reversed disease-associated phenotypes during cerebellar region-specific differentiation. In addition, we observed spontaneous ataxin-3 aggregates specifically in mature cerebellar neurons differentiated from SCA3 iPSCs rather than in SCA3 pan-neurons, SCA3 iPSCs or neural stem cells, suggesting that SCA3 iPSC-derived disease-specific and region-specific cerebellar neurons can provide unique cellular models for studying SCA3 pathogenesis in vitro. Importantly, the genetically corrected cerebellar neurons did not display typical SCA3 aggregates, suggesting that genetic correction can subsequently reverse SCA3 disease progression. Our strategy can be applied to other trinucleotide repeat disorders to facilitate disease modeling, mechanistic studies and drug discovery.

Smartphone-based automated estimation of plasma creatinine from finger-pricked blood on a paper strip via single-user step sample-to-result integration

Measuring creatininelevels in blood plasma is one of the most commonly used means of routine monitoring of renal function. Point-of-care devicesfor creatinine level estimation potentially allow rapid measurement, facilitating continuous monitoring of vulnerable patients. However, a majority of such devices currently available is constrained by several factors such as lack of simplicity in fabrication and operation (including plasma separation), a limited regime of efficacy, compromised reagent stability, and elevated costs. Here, we report the invention of a simple-to-fabricate and easy-to-use paper strip for rapid evaluation of plasma creatinine levels (ranging from 0.1 to 15 mg dL-1) in an integrated single-step process. For the testing, one drop of whole blood is first dripped onto the calcium salt-functionalized sample pad of the strip. Subsequently, blood plasma separation occurs due to spontaneous aggregation of red blood cells (RBCs) in the presence of calcium ions. The plasma spontaneously traverses into the reaction zone of the test-strip via capillary action where it reacts with previously dispensed alkaline picrate reagent, resulting in a colorimetric signal. Smartphone-interfaced imaging and image analytics of the reaction spot renders the dissemination of the test result in a turn-around time of about 2–3 min, without necessitating additional device interfacing. High efficacy of performance is established by validating with the results obtained from laboratory-benchmarked biochemical auto-analyzer, exhibiting an accuracy of 94%, and the coefficient of variation ranging from 0.64 to 6.4%. Suitability of use in extreme resource-limited settings is established by favorable stability of the reagents outside controlled laboratory ambience and engagement of unskilled personnel to execute the testing procedure with uncompromised accuracy.

Monodispersed ZnO nanoink and ultra-smooth large-area ZnO films for high performance and stable organic solar cells

In the organic solar cells (OSCs), zinc oxide nanoparticles (ZnO NPs) have been widely used to fabricate electron transporting layer (ETL). However, spontaneous aggregation of NPs and film surface defects are two issues that limit the application of ZnO NPs in the printed photovoltaics. To simultaneously solve the two problems, the ZnO nanoinks were modified with a 2-(2-methoxyethoxy) acetic acid (MEA) solution, in which a monodispersed nanoink was obtained, and no aggregation occurred after 18 months of storage at room temperature. Meanwhile, the ZnO:MEA ETL had fewer surface hydroxyl groups defects because of Lewis acid-base interactions. The monodispersibility and passivated surface defects ensured an ultra-smooth ZnO film, leading to an improved device performance, longer lifetime, and higher thickness tolerance. As a result, an efficiency of 15.84% was achieved for the 1 cm2 PM6:Y6 ZnO:MEA ETL-based OSCs, and the T 80 lifetime was also increased to 6600 h. The thickness of ZnO:MEA ETL could be increased to 225 nm with less performance degradation. ZnO:MEA NPs were dispersed well in alcohols with high boiling points, which ensured a high-quality slot-die coated film. The ZnO:MEA ETL also has a unique advantage in flexible organic OSCs, with enhanced bending resistance during 10000 times bending. These properties demonstrated the great potential of ZnO:MEA nanoinks in the printed electronics.

Sometimes simple is not best: The complex γδ T cell interaction with tumour needs depth

Sometimes simple is not best: The complex γδ T cell interaction with tumour needs depth

Self-assembly of a photoluminescent metal-organic cage and its spontaneous aggregation in dilute solutions enabling time-dependent emission enhancement

Self-assembly of a photoluminescent metal-organic cage and its spontaneous aggregation in dilute solutions enabling time-dependent emission enhancement

Reference range for ADAMTS13 antigen, activity and anti-ADAMTS13 antibody in the healthy adult Singapore population

ADAMTS13 (a disintegrin-like and metalloproteinase with a thrombospondin Type 1 motif, member 13) plays a fundamental role in the regulation of haemostasis and thrombosis. Its deficiency leads to an accumulation of ultra-large von Willebrand multimers, inducing spontaneous platelet aggregation, thrombosis in the microvasculature, and thrombotic thrombocytopenic purpura (TTP), a condition with 90% mortality when left untreated. Prompt quantification of ADAMTS13 antigen, activity and autoantibody plays a crucial role in the diagnosis and management of TTP and can help differentiate it from other thrombotic microangiopathies (TMAs). Reference ranges for ADAMTS13 are generally derived from Caucasian patients. Given that polymorphism in the ADAMTS13 gene can be associated with variable ADAMTS13 levels, we aimed to establish the first reference range in Singapore and provide a crucial laboratory test for institutions here and elsewhere. 150 healthy voluntary donors (75 men, 75 women) aged 21-60 years, with an ethnic mix mirroring Singapore's population profile, were recruited. ADAMTS13 antigen, activity and autoantibody levels were measured using the fluorescence resonance energy transfer-vWF73 and enzyme-linked immunosorbent assay methodologies. Levels (activity 0.65-1.79 IU/mL, antigen 0.36-1.17 IU/mL, autoantibody 1.4-12.5 U/mL) were not statistically different between the genders and various age groups. TTP and TMAs are encountered in a wide range of specialties. The availability of new assays in Singapore will aid clinicians in the timely management of these conditions. Standardising reference ranges established for Singapore against World Health Organization standards allows harmonisation of measurements between laboratories and for future research collaborations.

Deciphering the Effect of Lysine Acetylation on the Misfolding and Aggregation of Human Tau Fragment 171IPAKTPPAPK180 Using Molecular Dynamic Simulation and the Markov State Model.

The formation of neurofibrillary tangles (NFT) with β-sheet-rich structure caused by abnormal aggregation of misfolded microtubule-associated protein Tau is a hallmark of tauopathies, including Alzheimer’s Disease. It has been reported that acetylation, especially K174 located in the proline-rich region, can largely promote Tau aggregation. So far, the mechanism of the abnormal acetylation of Tau that affects its misfolding and aggregation is still unclear. Therefore, revealing the effect of acetylation on Tau aggregation could help elucidate the pathogenic mechanism of tauopathies. In this study, molecular dynamics simulation combined with multiple computational analytical methods were performed to reveal the effect of K174 acetylation on the spontaneous aggregation of Tau peptide 171IPAKTPPAPK180, and the dimerization mechanism as an early stage of the spontaneous aggregation was further specifically analyzed by Markov state model (MSM) analysis. The results showed that both the actual acetylation and the mutation mimicking the acetylated state at K174 induced the aggregation of the studied Tau fragment; however, the effect of actual acetylation on the aggregation was more pronounced. In addition, acetylated K174 plays a major contributing role in forming and stabilizing the antiparallel β-sheet dimer by forming several hydrogen bonds and side chain van der Waals interactions with residues I171, P172, A173 and T175 of the corresponding chain. In brief, this study uncovered the underlying mechanism of Tau peptide aggregation in response to the lysine K174 acetylation, which can deepen our understanding on the pathogenesis of tauopathies.

Comparative analysis of hemostasis system state indicators in severe COVID-19

Introduction. Clinical experience in managing patients with a new coronavirus infection caused by the SARS-CoV-2 allowed to identify specific hemostasis disorders, and enables to introduce the concept of COVID-associated coagulopathy. The aim of the study was to assess the direction of coagulogram parameter changes, whole blood clotting parameters and characteristics of platelet and plasma hemostasis in patients with severe COVID-19. Materials and methods. The parameters of the hemostasis system were assessed using venous blood of 12 patients with severe COVID-19 and 16 healthy volunteers. The whole blood clotting process was investigated by low-frequency piezothromboelastography. The platelet count and indicators of spontaneous and ADP-induced platelet aggregation were estimated with the help of a laser platelet aggregation analyzer. Fibrinolytic activity of plasma, plasminogen activity, content of fibrinogen, D-dimer, PTT, APTT, PTI and INR were assessed. Results. An increased level of fibrinogen, a 6-fold increased D-dimer level, and increased PTT were found in patients with severe COVID-19. The patient platelets count was reduced by 51 % (p <0.05), spontaneous platelet aggregation remained at nearly normal level. Almost complete inhibition of ADP-induced platelet reactivity and inhibition of XIIa-dependent fibrinolysis was revealed, despite an increased by 19.3 % (p <0.05) plasminogen activity. Parameters of the whole blood coagulation process pointed a pronounced activation of platelet hemostasis, a significant intensification of the polymerization stage of clot formation and an increased intensity of clot lysis and retraction. Conclusion. The significant increase of D-dimer level and paradoxical inhibition of plasma fibrinolytic activity revealed by test of XIIa-dependent fibrinolysis (in contrast to the increased intensity of clot lysis when assessing the coagulation of whole blood) indicate the complex pathogenic mechanisms of coagulopathy caused by SARS-CoV-2 infection, and the involvement of blood cells and the vascular wall in the process of pathological thrombus formation.

Взаимосвязь числа и агрегационной способности тромбоцитов с процессом перекисного окисления липидов у больных хроническим гепатитом С

The purpose — to determine the role of the relationship between the number and aggregation capacity of platelets (Tr) with the process of lipid peroxidation (POL) in the natural course of chronic hepatitis C (HCV). Material and methods. 332 patients with HCV were observed, divided into three groups according to the phases of disseminated intravascular coagulation and the number of Tr: the first group — the hypercoagulation phase (Tr > 330 x 109/l, n = 22); the second — the transition phase (Tr from 330 to 200 x 109/L, n = 132); the third — hypocoagulation (Tr < 200 x 109/L, n = 178). The vascular-platelet link of hemostasis was evaluated by the number and degree of maximum amplitude (MA) of spontaneous Tr aggregation. The POL process was studied by medium-weight molecules (MSM), malonic dialdehyde (MDA), and enzymes — superoxide dismutase (SOD), reduced (VG) and oxidized (OG) glutathione. Results. The decrease in the number of Trs against the background of prolonged infection with the hepatitis C virus was accompanied by a decrease in the antioxidant potential, an increase in the intensity of lipoperoxidation and an increase in the ability of Tr to aggregate, especially pronounced in the phase of hypocoagulation. Correlations were revealed: the numbers Tr showed inverse correlation with the levels of SOD, MSM, MDA, OG and direct correlation with VG; MA of spontaneous aggregation Tr showed direct correlation with MSM, MDA, SOD, OG and inverse correlation with VG. Conclusions. Changes in the number and aggregation ability of Tr, the level of POL products in the course of the natural course of HCV, in parallel with the ALT enzyme, reflect the activity of the infectious process. The number and MA of spontaneous Tr aggregation in patients with natural HCV with exacerbation of the disease correlate with a reduced antioxidant potential and increased intensity of lipoperoxidation. The natural course of HCV is characterized by a multidirectional change in the AOS enzymes – an increase in the SOD level and a decrease in the amount of reduced glutathione with a simultaneous increase in the oxidized one.

Study on Axial Compressive Behaviour of Spontaneous Combustion Gangue Coarse Aggregate Concrete Confined with Frp Tube

Study on Axial Compressive Behaviour of Spontaneous Combustion Gangue Coarse Aggregate Concrete Confined with Frp Tube

Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particles.

Suspensions of active Brownian particles (ABPs) undergo motility-induced phase separation (MIPS) over a wide range of mean density and activity strength, which implies the spontaneous aggregation of particles due to the persistence of their direction of motion, even in the absence of an explicit attraction. Both similarities and qualitative differences have been obtained when the MIPS is analysed in the same terms as a liquid-gas phase coexistence in an equilibrium attractive system. Negative values of the mechanical surface tension have been reported, from the total forces across the interface, while stable fluctuations of the interfacial line could be interpreted as a positive capillary surface tension; in equilibrium liquid surfaces, these two magnitudes are equal. We present here the analysis of 2D-ABP interfaces in terms of the intrinsic density and force profiles, calculated with the particle distance to the instantaneous interfacial line. Our results provide new insight into the origin of MIPS from the local rectification of the random active force on the particles near the interface. As has been reported, this effect acts as an external potential that produces a pressure gradient across the interface, such that the mechanical surface tension of the MIPS cannot be described as that of equilibrium coexisting phases; however, our analysis shows that most of that effect comes from the tightly caged particles at the dense (inner) side of the MIPS interface, rather than from the free moving particles at the outer side that collide with the dense cluster. Moreover, a clear correlation appears between the decay of the hexatic order parameter at the dense slab and the end of the MIPS as the strength of the active force is lowered. We show that, using the strong active forces required for MIPS, the interfacial structure and properties are very similar for ABPs with purely repulsive interactions (the Weeks-Chandler-Andersen-Lennard-Jones (WCA-LJ) model truncated at its minimum) and when the interaction includes a range of the LJ attractive force.

Construction of TiO2 microsphere through different titanium precursors via a green pathway

TiO2 microspheres (TMCS) with superior dispersity and uniform particle size (size distribution vary from 1 µm to 3 µm) were synthesized by using of different titanium precursors through a sol–gel method. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) were employed to study the morphology and microstructure. Moreover, by Brunauer-Emmett-Teller (BET) test, the specific surface area of TMCS were about 200 m2/g. In addition, Raman spectroscopy (Raman), X-ray diffraction (XRD) and X–ray photo-electron spectroscopy (XPS) were applied to investigate the phase composition and existing state of TMCS. Furthermore, its photocatalytic activity was estimated by observing the degradation efficiency of Rhodamine (RhB). Remarkably, the degradation efficiency is 98 % after 30 min and the photocatalytic degradation rate remained almost unchanged in five successive cycles, indicating that TMCS were stable and suitable for removing RhB in water. Finally, the probable formation mechanism of TMCS was studied. The spontaneous aggregation of TiO2 nanoparticles lead to the formation of TMCS which would be promoted to combine with others to form mesoporous TMCS by temperature. Therefore, this work provides an encouraging pathway for controlling the morphology of TiO2 and showing potential application in wastewater treatment.

Study on the microscopic aggregation behavior of lignite molecules in water

Molecular simulation is a reliable tool for studying the self-aggregation behavior of lignite molecules in a solution. To explore how the molecular structure of lignite influences its aggregation behavior, 13C NMR analysis was first performed to construct its molecular structure. Molecular simulation results show that the extreme regions of the electrostatic potential on the lignite surface mainly appear near the polar functional groups. In a solution, the hydrogen bonding and van der Waals interactions between lignite and water molecules will hinder the self-aggregation of the former ones. The self-aggregation process of lignite molecules can be divided into three stages: Brownian (random) motion, agglomeration, and structural adjustment. Driven by the Lennard-Jones and electrostatic potentials, the lignite molecules gradually aggregate to form a cluster. This process will destroy the hydration film on the lignite surface, ultimately decreasing the number of hydrogen bonds and changing the orientation of the water molecules. Increasing the number of lignite molecules will help their spontaneous aggregation. This work reveals the self-aggregation process of lignite molecules and helps to understand their aggregation behavior in solution. This work provides theoretical guidance for solving the flocculation settlement of slime water.

Spontaneous Platelet Aggregation in Blood Is Mediated by FcγRIIA Stimulation of Bruton's Tyrosine Kinase.

High platelet reactivity leading to spontaneous platelet aggregation (SPA) is a hallmark of cardiovascular diseases; however, the mechanism underlying SPA remains obscure. Platelet aggregation in stirred hirudin-anticoagulated blood was measured by multiple electrode aggregometry (MEA) for 10 min. SPA started after a delay of 2–3 min. In our cohort of healthy blood donors (n = 118), nine donors (8%) with high SPA (>250 AU*min) were detected. Pre-incubation of blood with two different antibodies against the platelet Fc-receptor (anti-FcγRIIA, CD32a) significantly reduced high SPA by 86%. High but not normal SPA was dose-dependently and significantly reduced by blocking Fc of human IgG with a specific antibody. SPA was completely abrogated by blood pre-incubation with the reversible Btk-inhibitor (BTKi) fenebrutinib (50 nM), and 3 h after intake of the irreversible BTKi ibrutinib (280 mg) by healthy volunteers. Increased SPA was associated with higher platelet GPVI reactivity. Anti-platelet factor 4 (PF4)/polyanion IgG complexes were excluded as activators of the platelet Fc-receptor. Our results indicate that high SPA in blood is due to platelet FcγRIIA stimulation by unidentified IgG complexes and mediated by Btk activation. The relevance of our findings for SPA as possible risk factor of cardiovascular diseases and pathogenic factor contributing to certain autoimmune diseases is discussed.

Veronetta: prove di geografia sociale

This paper reports the case of one district of Verona, precisely Veronetta, located near the historical center of the town, that shows broad sociospatial dynamics. Given its territorial history, the compresence of attraction and repulsion factors as well as the recent pushes exerted by movements carried out by active citizenship (such as the spontaneous aggregation in a social street, the subsidiarity pacts, or the community cinema project), Veronetta reveals all the richness and criticality of a portion of the town looking for a definition of its meaning in the wider context of the urban area.

Pathogenetic therapy of vascular-platelet hemostasis disorders in canine acute spontaneous babesiosis

The article presents the results of a study of the vascular-platelet hemostasis disorders processes in complications of canine acute spontaneous babesiosis, as well as a clinical trial of plasma substitute infusion for the purpose of identified disorders pathogenetic therapy. It was found that acute spontaneous Babesiosis is accompanied by complications in the form of subcompensated shock and a thrombogenic link of disseminated intravascular coagulation syndrome (DIC). This determines the potential risk of complications with a cautious prognosis. The basis for the diagnosis of complications is the establishment of the following changes: a significant deficit in the volume of circulating blood (a decrease in the hematocrit value, the volume of circulating plasma, the volume of circulating red blood cells, the specific volume of circulating blood), as well as significant changes in the functioning of the vascular-platelet link of hemostasis – thrombocytopenia against the background of an increase in the spontaneous aggregation ability of platelets and red blood cells, an increase in the wetting index of the vascular wall, which determines the thrombogenic state, and pronounced thrombocytopenia indicates the consumption of these shaped elements in blood clots. The described changes indicate the development of subcompensated shock and the thrombogenic component of DIC syndrome. Given the prognostic danger of established complications, there is a need for pathogenetic therapy of severe conditions. Infusions of plasma substitute solutions have been proposed to eliminate shock phenomena and the thrombogenic state of disseminated intravascular coagulation syndrome. A clinical trial of intravenous administration of Rheosorbylact solution and a mixture of Rheosorbylact with Dipyridamole was conducted in a comparative aspect. It is shown that a mixture of Rheosorbylact 100 ml and Dipyridamole solution 0.5 % 4 ml in the form of infusions at a dose of 5 ml/kg of animal body weight per day for 3 days can bring hemodynamic parameters and parameters of vascular-platelet hemostasis to physiological ones within 48 hours compared to an infusion of Rheosorbylact solution in its pure form. The synergy of the crystalloid solution of Rheosorbylact and the disaggregating vasodilator Dipyridamole enhances the disaggregating effect of both drugs, and the crystalloid solution itself is able to restore the lost volume of circulating blood.

High glucose removes natural anti-α-galactoside and anti-β-glucoside antibody immune complexes adhering to surface O-glycoproteins of normal platelets and enhances platelet aggregation.

Human natural anti-α-galactoside (anti-Gal) and anti-β-glucoside (ABG) antibodies were previously reported to recognize the serine- and threonine-rich peptide sequences (STPS) of albumin-associated O-glycoproteins (AOP1 and AOP2) as surrogate antigens, forming anti-Gal/ABG-AOP1/AOP2-albumin triplet immune complexes in plasma. Since antibodies in these triplets still possessed unoccupied binding sites, the presence of triplets on human platelets that abound in surface O-glycoproteins was examined. Upon treatment with α-galactosides and β-glucosides, normal platelets freshly isolated from young healthy individuals released triplets identical with plasma triplets according to ELISA results. The resulting denuded platelets, unless pre-treated with fibrinogen or the O-glycan-binding lectin jacalin, recaptured these sugar-extracted triplets in the absence of antibody-specific sugars, suggesting that the triplet antibodies recognized the STPS of O-glycosylated receptors on platelets. Molecular weight of the dominant jacalin-binding subunit on triplet-free platelet membrane was 116 kDa, close to the ~120 kDa reported for the IIb subunit of the most abundant fibrinogen-binding platelet O-glycoprotein, GPIIb/IIIa. Denuded, but not native, platelets underwent slow spontaneous aggregation and rapid ADP-mediated GPIIb/IIIa-dependent aggregation according to spectrophotometric assay. Pre-treatment of denuded platelets with jacalin significantly reduced their ADP-mediated aggregation. Amyloid β (Aβ-42 monomer) was reported to bind triplet O-glycoproteins through their STPS but not to albumin or the antibodies. This peptide bound to the triplets on normal platelets and to surface membrane O-glycoproteins on denuded platelets, suggesting that the surface O-glycoproteins on the normal platelets were engaged and masked by the triplets. The ABG-specific sugar glucose denuded the platelets at concentrations typically reached in diabetic sera, since anti-Gal specific or ABG-specific sugar released the triplets of both the antibodies from the platelets. In conclusion, the present study offered rationale for the presence of anti-Gal/ABG-O-glycoprotein-albumin triplets on normal platelets, for the role of triplets in platelet physiology amidst circulating platelet-activating factors such as ADP, and for platelet vulnerability during diabetes.

Positive response to surfactants on the interfacial behavior and aggregation stability of Fab fragments from yolk immunoglobulin

The antigen binding fragment (Fab) is pepsin-digested product from egg yolk immunoglobulin (IgY), which shows lower immunogenicity and higher antibacterial activity. However, it limited the application of Fab due to the spontaneous adsorption and aggregation at the air-liquid interface. The present work is to investigate the effect of surfactants polysorbate 20 (PS20), poloxamer 188 (P188), and polyethylene glycol (PEG) on the aggregation stability of Fab of IgY. The results confirmed the positive role of surfactants in improving Fab stability. PS20 could effectively prevent the generation of Fab aggregates (DLS and light-obscuration analysis). It could also distinctly increase the internal hydrophobicity level, fortify the surface charge by altering the molecular conformational characteristics of Fab. The results of CLSM and surface tension demonstrated that P188 and PEG were co-adsorbed with Fab at the air-liquid interface and inhibited the formation of aggregation. PS20 competitively adsorbed in the gap between Fab molecules to inhibit the formation of aggregates. These findings would give an in-depth understanding of protein aggregation behavior influenced by surfactants and provide a theoretical basis for the development of functional food based on Fab active fragments.

Proliferation of Tau 304-380 Fragment Aggregates through Autocatalytic Secondary Nucleation.

The self-assembly of the protein tau into neurofibrillary tangles is one of the hallmarks of Alzheimer’s disease and related tauopathies. Still, the molecular mechanism of tau aggregation is largely unknown. This problem may be addressed by systematically obtaining reproducible in vitro kinetics measurements under quiescent conditions in the absence of triggering substances. Here, we implement this strategy by developing protocols for obtaining an ultrapure tau fragment (residues 304–380 of tau441) and for performing spontaneous aggregation assays with reproducible kinetics under quiescent conditions. We are thus able to identify the mechanism of fibril formation of the tau 304–380 fragment at physiological pH using fluorescence spectroscopy and mass spectrometry. We find that primary nucleation is slow, and that secondary processes dominate the aggregation process once the initial aggregates are formed. Moreover, our results further show that secondary nucleation of monomers on fibril surfaces dominates over fragmentation of fibrils. Using separate isotopes in monomers and fibrils, through mass spectroscopy measurements, we verify the isotope composition of the intermediate oligomeric species, which reveals that these small aggregates are generated from monomer through secondary nucleation. Our results provide a framework for understanding the processes leading to tau aggregation in disease and for selecting possible tau forms as targets in the development of therapeutic interventions in Alzheimer’s disease.