Study of apoptosis-like features in platelets following aspirin treatment.

<p>Mitochondrial transmembrane potential (red/green ratio) (A), PS exposure (PE-annexin V binding) (B) and ROS generation (C) were studied in control platelets, as well as in cells pre-treated with aspirin as indicated. In (A), CCCP (mitochondrial protonophore) has been employed as the positive control. Data are representative of five different experiments and expressed as mean±SD. (*p<0.05 as compared to ethanol-pretreated resting platelets).</p

Aspirin affects lifespan and phagocytic uptake of platelets (A), Platelet count in control as well as aspirin-administered mice on different days.

<p>(B), Proportion of biotinylated platelets (%) in peripheral blood sample drawn from ethanol (vehicle) or aspirin (10 and 15 mg/kg) pre-administered mice 0, 24, 48, 72, and 96 h after administration of NHS-biotin. t_1/2 (h) represents platelet half-life in hours. (C) and (D), phagocytic uptake of platelets by autologous macrophages. Flow cytometry (C) and epifluorescence microscopy (D) of macrophages co-incubated with calcein-labeled platelets pretreated either with aspirin (5 mM) or ethanol (control). Scale bars, 10 µm. Data are representative of five different experiments.</p

Aspirin Delimits Platelet Life Span by Proteasomal Inhibition

<div><p>Aspirin is widely used in clinical settings as an anti-inflammatory and anti-platelet drug due its inhibitory effect on cyclooxygenase activity. Although the drug has long been considered to be an effective and safe therapeutic regime against inflammatory and cardiovascular disorders, consequences of its cyclooxygenase-independent attributes on platelets, the key players in thrombogenesis, beg serious investigation. In this report we explored the effect of aspirin on platelet lifespan in murine model and its possible cytotoxicity against human platelets <i>in vitro</i>. Aspirin administration in mice led to significant reduction in half-life of circulating platelets, indicative of enhanced rate of platelet clearance. Aspirin-treated human platelets were found to be phagocytosed more efficiently by macrophages, associated with attenuation in platelet proteasomal activity and upregulation of conformationally active Bax, which were consistent with enhanced platelet apoptosis. Although the dosage of aspirin administered in mice was higher than the therapeutic regimen against cardiovascular events, it is comparable with the recommended anti-inflammatory prescription. Thus, above observations provide cautionary framework to critically re-evaluate prophylactic and therapeutic dosage regime of aspirin in systemic inflammatory as well as cardiovascular ailments.</p></div

Study of proteosome and caspase-3 activities in aspirin-treated platelets (A), Western blots showing expression level of active Bax in platelets pretreated with ethanol, aspirin, ABT737, epoxomicin, PSI and bortezomib, as indicated (upper panel) normalized against β-actin (lower panel).

<p>(B), Quantitative representation of active Bax levels in platelet whole cell lysates determined by densitometry of Western blots. (C), caspase-3 activity from the extent of cleavage of fluorigenic substrate AC-DEVD-AMC. (D), Assay of proteasome enzymatic activity in platelets pretreated with ethanol, PSI (proteasome inhibitor) (10 µM) and aspirin. Data are representative of five different experiments and expressed as mean±SD. (*p<0.05 as compared to ethanol-pretreated resting platelets).</p

CNT Induced β‑Phase in Polylactide: Unique Crystallization, Biodegradation, and Biocompatibility

The effect of multi-walled carbon nanotube (MWCNT) on the crystal structure, unique crystallization, mechanical behavior, enzymatic degradation, and significant improvement in biocompatibility of polylactide (PLA) nanohybrid has been reported. Functionalization of carbon nanotube using stearyl alcohol has been carried out and has been confirmed through FTIR and Raman spectroscopy. PLA nanohybrids have been synthesized using functionalized and neat MWCNT through solution route, and the improved level of dispersion of MWCNT has been achieved in PLA matrix. High-magnification transmission electron microscope images indicate the unique adsorption of PLA chain leading to the crystallization of β-phase structure on the surface of the functionalized MWCNT against the usual crystallized α-form of pure PLA. The presence of β phase in nanohybrids has been confirmed through electron diffraction pattern, differential scanning calorimetry thermograms, and X-ray diffraction patterns. The improved and diverse mechanical, thermal properties, and crystallization kinetics have been explored with the special emphasis on the relaxation behavior of β phase in dynamic mechanical analysis. The cause of these developments has been appraised from the interaction point of view as calculated from the interaction parameter (χ) using melting-point depression technique. The rate of biodegradation has been studied in detail with plausible mechanism in Proteinase K enzyme media showing their specificity and tuning of biodegradation rate followed by their optimization. For biomedical applications, the effect of pure polymer and nanohybrids on circulating blood cells has been evaluated in detail, and the hemocompatible nature of the nanohybrids has been revealed, suppressing the cellular toxicity of MWCNT

Polyurethane-Grafted Chitosan as New Biomaterials for Controlled Drug Delivery

The present investigation focuses on the grafting of chitosan (CHT) with diisocyanate terminated polyurethane. Solid state ¹³C NMR spectroscopy confirms the grafting reaction and the degree of substitution (DS) was calculated from the deconvoluted area of the corresponding NMR peak. Solubility studies, swelling behavior and contact angle measurements support the hydrophobic chemical modification on CHT molecules and higher DS leads to the cross-linking of CHT molecules having polyurethane bridges resulting insolubility and regulated swelling in the graft copolymer. Molecular relaxations phenomena due to the constraint associated with the grafting have been revealed using spin–lattice relaxation tine (<i>T</i>₁) and shifting of peak position in tan δ curve toward lower temperature in dynamic mechanical measurement at constant frequency indicating flexible nature of graft copolymers as compared to pure CHT. The sustained drug delivery has been achieved using graft copolymers vis-à-vis pure CHT following the Fickian diffusion behavior (<i>n</i> ≤ 0.45) and the release rate can be tuned by altering the DS. In depth biocompatibility studies through platelet aggregation, platelet adhesion, reactive oxygen species of the developed graft copolymers, and <i>in vitro</i> hemolysis assay and cell viability have been performed to understand its potential use in biomedical applications and compared the improved properties with respect to pure CHT. Hence, bio- and hemocompatible CHT graft copolymers have been developed with the capability of controlled and sustained drug release

Supplemental Material, Supplementary_File - Chemical modification of nitrile rubber in the latex stage by functionalizing phosphorylated cardanol prepolymer: A bio-based plasticizer and a renewable resource

<p>Supplemental Material, Supplementary_File for Chemical modification of nitrile rubber in the latex stage by functionalizing phosphorylated cardanol prepolymer: A bio-based plasticizer and a renewable resource by Satyajit Samantarai, Ahindra Nag, Nitesh Singh, Debabrata Dash, Amit Basak, Golok B. Nando and Narayan Ch Das in Journal of Elastomers & Plastics</p

Amine-Modified Graphene: Thrombo-Protective Safer Alternative to Graphene Oxide for Biomedical Applications

Graphene and its derivatives have attracted significant research interest based on their application potential in different fields including biomedicine. However, recent reports from our laboratory and elsewhere have pointed to serious toxic effects of this nanomaterial on cells and organisms. Graphene oxide (GO) was found to be highly thrombogenic in mouse and evoked strong aggregatory response in human platelets. As platelets play a central role in hemostasis and thrombus formation, thrombotoxicity of GO potentially limits its biomedical applications. Surface chemistry of nanomaterials is a critical determinant of biocompatibility, and thus differentially functionalized nanomaterials exhibit varied cellular toxicity. Amine-modified carbon nanotubes have recently been shown to possess cytoprotective action, which was not exhibited by their relatively toxic carboxylated counterparts. We, therefore, evaluated the effect of amine modification of graphene on platelet reactivity. Remarkably, our results revealed for the first time that amine-modified graphene (G-NH₂) had absolutely no stimulatory effect on human platelets nor did it induce pulmonary thromboembolism in mice following intravenous administration. Further, it did not evoke lysis of erythrocytes, another major cellular component in blood. These findings contrasted strikingly the observations with GO and reduced GO (RGO). We conclude that G-NH₂ is not endowed with thrombotoxic property unlike other commonly investigated graphene derivatives and is thus potentially safe for <i>in vivo</i> biomedical applications