Humic-mineral interactions modulated by pH conditions in bauxite residues – Implications in stable aggregate formation

SummaryWe studied the effect of GPIIb/IIIa-inhibitors on platelet activation with flow cytometry in vitro. Citrated whole blood was incubated with increasing concentrations of three different GPIIb/IIIa-inhibitors (c7E3, DMP728, XJ757), then thrombin or ADP were added and after 1 min the sample was fixed. Samples without c7E3 but with 0.1 U/ml thrombin had a decrease in platelet count. Samples with increasing concentrations of c7E3 had a lesser or no decrease in platelet count. The two other inhibitors (DMP 725, XJ757) gave similar results. GPIIb/IIIa-inhibitors prevent aggregate formation and more single platelets remain in the blood sample. The agonist-induced decrease in platelet count correlates closely with the concentration of the GPIIb/IIIa inhibitor and receptor occupancy. This correlation may be used as a simple measure for inhibitor activity in whole blood.

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Glycoproteins IIb and IIIa and Platelet Thrombospondin in a Liposome Model of Platelet Aggregation

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661529 ◽

1986 ◽

Vol 55 (02) ◽

pp. 240-245 ◽

Cited By ~ 11

Author(s):

M E Rybak

Keyword(s):

Platelet Aggregation ◽

Direct Evidence ◽

Phospholipid Vesicles ◽

Aggregate Formation ◽

Membrane Glycoproteins ◽

Protein Orientation ◽

Phosphatidylcholine Liposomes ◽

Calcium Dependent ◽

Lentil Lectin ◽

Complete Reversal

SummaryPlatelet membrane glycoproteins IIb and IIIa and platelet thrombospondin were incorporated onto phosphatidylcholine liposomes, by freeze thawing and sonication. Protein orientation on the liposomes was confirmed by susceptibility to neuraminidase cleavage and binding to lentil lectin-Sepharose (GPIIb-IIIa liposomes) and to heparin-Sepharose (thrombospondin liposomes). Glycoproteins Ilb-IIIa bound 125I-fibrinogen with Kd of 7.5 × 10™7M. Binding was reversible and calcium-dependent. Ilb-IIIa liposomes underwent fibrinogen-dependent aggregation in the presence of 10 mM CaCl2. Maximal aggregate formation was observed with a combination of IIb-IIIa liposomes and thrombospondin liposomes. This aggregation was partially inhibited by preincubation with monoclonal antibodies to the IIb-IIIa complex. Addition of EDTA caused complete reversal of aggregates. Thrombospondin liposomes also underwent fibrinogen and calcium dependent aggregation, however, this aggregation was less than that observed with the GPIIb-IIIa liposomes. Maximal aggregate formation was observed with a mixture of IIb-IIIa liposomes and thrombospondin liposomes. These studies demonstrate that GPIIb-IIIa and thrombospondin can be incorporated into phospholipid vesicles with preservation of function. Direct evidence is provided to demonstrate that glycoprotein lib and Ilia and fibrinogen are sufficient for platelet aggregation and to demonstrate that thrombospondin may also contribute to platelet aggregation.

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In Vitro Elucidation of the Folding Intermediates and Aggregate Formation of Hemoglobin Induced by Acetonitrile: A Multispectroscopic Approach

Protein and Peptide Letters ◽

10.2174/0929866523666160831154706 ◽

2016 ◽

Vol 23 (10) ◽

pp. 884-891 ◽

Cited By ~ 3

Author(s):

Mohammad Furkan ◽

Asim Rizvi ◽

Mohammad Afsar ◽

Mohammad Rehan Ajmal ◽

Rizwan H. Khan ◽

...

Keyword(s):

Aggregate Formation ◽

Folding Intermediates

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Fibronectin regulates anoikis resistance via cell aggregate formation

Cancer Letters ◽

10.1016/j.canlet.2021.03.011 ◽

2021 ◽

Author(s):

Hyeong-jun Han ◽

Jee Young Sung ◽

Su-Hyeon Kim ◽

Un-Jung Yun ◽

Hyeryeong Kim ◽

...

Keyword(s):

Cell Aggregate ◽

Aggregate Formation ◽

Anoikis Resistance

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Adsorption of p-Arsanilic Acid on Iron (Hydr)oxides and Its Implications for Contamination in Soils

Minerals ◽

10.3390/min11020105 ◽

2021 ◽

Vol 11 (2) ◽

pp. 105

Author(s):

Yifan Yang ◽

Shiyong Tao ◽

Zhichun Dong ◽

Jing Xu ◽

Xiang Zhang ◽

...

Keyword(s):

Iron Oxides ◽

Organic Matter Content ◽

Feed Additives ◽

Unit Surface Area ◽

Potential Hazard ◽

Order Kinetic ◽

Positive Correlation ◽

Arsanilic Acid ◽

Organic Arsenic ◽

Ph Conditions

Because of the diversification of industries in developing cities, the phenomenon of the simultaneous contamination of various kinds of pollutants is becoming common, and the environmental process of pollutants in multi-contaminated environmental mediums has attracted attention in recent years. In this study, p-arsanilic acid (ASA), a kind of organic arsenic feed additive that contains the arsenic group in a chemical structure, is used as a typical contaminant to investigate its adsorption on iron oxides and its implication for contaminated soils. The adsorption kinetics on all solids can be fitted to the pseudo-second-order kinetic model well. At the same mass dosage conditions, the adsorption amount per unit surface area on iron oxides follows the order α-FeOOH > γ-Fe2O3 > α-Fe2O3, which is significantly higher than that for actual soil, because of the lower content of iron oxides in actual soil. Lower pH conditions favor ASA adsorption, while higher pH conditions inhibit its adsorption as a result of the electrostatic repulsion and weakened hydrophobic interaction. The presence of phosphate also inhibits ASA adsorption because of the competitive effect. Correlations between the amount of ASA adsorption in actual soil and the Fe2O3 content, total phosphorus content, arsenic content, and organic matter content of actual soil are also investigated in this work, and a moderate positive correlation (R2 = 0.630), strong negative correlation (R2 = 0.734), insignificant positive correlation (R2 = 0.099), and no correlation (R2 = 0.006) are found, respectively. These findings would help evaluate the potential hazard of the usage of organic arsenic feed additives, as well as further the understanding of the geochemical processes of contaminants in complicated mediums.

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Emulsion Formation and Stabilizing Properties of Olive Oil Cake Crude Extracts

Processes ◽

10.3390/pr9040633 ◽

2021 ◽

Vol 9 (4) ◽

pp. 633

Author(s):

Firdaous Fainassi ◽

Noamane Taarji ◽

Fatiha Benkhalti ◽

Abdellatif Hafidi ◽

Marcos A. Neves ◽

...

Keyword(s):

Olive Oil ◽

Ethanol Extract ◽

Active Components ◽

Oil In Water ◽

Surface Active ◽

Ph Conditions ◽

Oil Water ◽

Surface Active Compounds ◽

Ionizable Groups ◽

Emulsifying Ability

The surface-active and emulsifying properties of crude aqueous ethanolic extracts from untreated olive oil cake (OOC) were investigated. OOC extracts contained important concentrations of surface-active components including proteins, saponins and polyphenols (1.2–2.8%, 7.8–9.5% and 0.7–4.5% (w/w), respectively) and reduced the interfacial tension by up to 46% (14.0 ± 0.2 mN m−1) at the oil–water interface. The emulsifying ability of OOC extracts was not correlated, however, with their interfacial activity or surface-active composition. Eighty percent aqueous ethanol extract produced the most stable oil-in-water (O/W) emulsions by high-pressure homogenization. The emulsions had average volume mean droplet diameters of approximately 0.4 µm and negative ζ-potentials of about -45 mV, and were stable for up to 1 month of storage at 5, 25 and 50 °C. They were sensitive, however, to acidic pH conditions (<5) and NaCl addition (≥25 mM), indicating that the main stabilization mechanism is electrostatic due to the presence of surface-active compounds with ionizable groups, such as saponins.

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Characterization of design grammar of peptides for regulating liquid droplets and aggregates of FUS

Scientific Reports ◽

10.1038/s41598-021-86098-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kiyoto Kamagata ◽

Rika Chiba ◽

Ichiro Kawahata ◽

Nanako Iwaki ◽

Saori Kanbayashi ◽

...

Keyword(s):

Amino Acid ◽

Electrostatic Interactions ◽

Amyloid Fibrils ◽

Droplet Formation ◽

Liquid Droplets ◽

Proof Of Concept ◽

Aggregate Formation ◽

Fused In Sarcoma ◽

Dynamics Simulations

AbstractLiquid droplets of aggregation-prone proteins, which become hydrogels or form amyloid fibrils, are a potential target for drug discovery. In this study, we proposed an experiment-guided protocol for characterizing the design grammar of peptides that can regulate droplet formation and aggregation. The protocol essentially involves investigation of 19 amino acid additives and polymerization of the identified amino acids. As a proof of concept, we applied this protocol to fused in sarcoma (FUS). First, we evaluated 19 amino acid additives for an FUS solution and identified Arg and Tyr as suppressors of droplet formation. Molecular dynamics simulations suggested that the Arg additive interacts with specific residues of FUS, thereby inhibiting the cation–π and electrostatic interactions between the FUS molecules. Second, we observed that Arg polymers promote FUS droplet formation, unlike Arg monomers, by bridging the FUS molecules. Third, we found that the Arg additive suppressed solid aggregate formation of FUS, while Arg polymer enhanced it. Finally, we observed that amyloid-forming peptides induced the conversion of FUS droplets to solid aggregates of FUS. The developed protocol could be used for the primary design of peptides controlling liquid droplets and aggregates of proteins.

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