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Glioblastoma multiforme (GBM) is the most lethal primary brain tumor in adults, characterized by a highly invasive nature and therapy resistance. Combination of menadione and ascorbic acid (AA+MD) exerts strong ROS-mediated anti-GBM activity in vitro. The objective of this study was to improve AA+MD anti-GBM potential by modulating the activity of Akt and c-Jun N-terminal kinase (JNK), molecules with an important role in GBM development. The effects of Akt and JNK modulation on AA+MD toxicity in U251 human glioblastoma cells were assessed by cell viability assays, flow cytometry, RNA interference and plasmid overexpression, and immunoblot analysis. The AA+MD induced severe oxidative stress, an early increase in Akt phosphorylation followed by its strong inhibition, persistent JNK activation, and U251 cell death. Small molecule Akt kinase inhibitor 10-DEBC enhanced, while pharmacological and genetic Akt activation decreased, AA+MD-induced toxicity. The U251 cell death potentiation by 10-DEBC correlated with an increase in the combination-induced autophagic flux and was abolished by genetic autophagy silencing. Additionally, pharmacological JNK inhibitor SP600125 augmented combination toxicity toward U251 cells, an effect linked with increased ROS accumulation. These results indicate that small Akt and JNK kinase inhibitors significantly enhance AA+MD anti-GBM effects by autophagy potentiation and amplifying deleterious ROS levels. [ABSTRACT FROM AUTHOR]

Introduction: The accumulation of alpha-synuclein (ASYN) in susceptible neurons is considered to be a major contributing factor in pathogenesis of Parkinson's disease. Although ASYN was considered as an intracellular protein, recent data suggest that it can be detected extracellularly. Autophagy plays an important role in ASYN degradation; therefore, impairment of autophagy could be an important contributor to ASYN accumulation. ATG (autophagy-related genes) proteins function at several physiologically continuous steps in autophagy, and ATG7 is considered as essential in autophagosome formation and maturation. Aim: The aim of this study was to investigate the role of autophagy in neurotoxicity, caused by extracellular ASYN. Material and methods: All experiments were conducted in all-trans retinoic acid-differentiated human neuroblastoma SH-SY5Y cells, that were exposed to extracellular ASYN. The presence of extracellular ASYN and the expression of autophagy markers, beclin-1 and LC3-II, were monitored using immunoblotting. Transfection, with small interfering RNA (siRNA), was used to knock down ATG7 gene. Cell viability was assessed using crystal violet dye exclusion assay. Results: Extracellular ASYN caused significant loss of viability in differentiated SH-SY5Y cells, accompanied by the increase in expression of beclin-1 and in conversion of LC3-I to autophagosome-associated LC3-II. The RNA interference-mediated knock-down of ATG7 increased the sensitivity of SH-SY5Y cells to the extracellular ASYN-induced toxicity. Conclusion: Extracellular ASYN caused loss of viability in differentiated SH-SY5Y cells accompanied by autophagy induction. Having in mind that inhibition of autophagy, through ATG7 knock-down increased cell death, we can conclude that autophagy could have a protective role in the harmful effect of extracellular ASYN.

Segmented polyurethanes based on poly(dimethylsiloxane), currently used for biomedical applications, have sub-optimal biocompatibility which reduces their efficacy. Improving the endothelial cell attachment and blood-contacting properties of PDMS-based copolymers would substantially improve their clinical applications. We have studied the surface properties and in vitro biocompatibility of two series of segmented poly(urethane-dimethylsiloxane)s (SPU-PDMS) based on hydroxypropyl- and hydroxyethoxypropyl- terminated PDMS with potential applications in blood-contacting medical devices. SPU-PDMS copolymers were characterized by contact angle measurements, surface free energy determination (calculated using the van Oss-Chaudhury-Good and Owens-Wendt methods), and atomic force microscopy. The biocompatibility of copolymers was evaluated using an endothelial EA.hy926 cell line by direct contact assay, before and after pre-treatment of copolymers with multicomponent protein mixture, as well as by a competitive blood-protein adsorption assay. The obtained results suggested good blood compatibility of synthesized copolymers. All copolymers exhibited good resistance to fibrinogen adsorption and all favored albumin adsorption. Copolymers based on hydroxyethoxypropyl-PDMS had lower hydrophobicity, higher surface free energy, and better microphase separation in comparison with hydroxypropyl-PDMS-based copolymers, which promoted better endothelial cell attachment and growth on the surface of these polymers as compared to hydroxypropyl-PDMS-based copolymers. The results showed that SPU-PDMS copolymers display good surface properties, depending on the type of soft PDMS segments, which can be tailored for biomedical application requirements such as biomedical devices for short- and long-term uses. [Projekat Ministarstva nauke Republike Srbije, br. 172062]

Background: Dietary intake influence changes in fatty acids (FA) profiles in liver which plays a central role in fatty acid metabolism, triacylglycerol synthesis and energy homeostasis. We investigated the effects of 4-weeks treatment with milk- and fish-based diet, on plasma biochemical parameters and FA composition of liver phospholipids (PL) in rats of both sexes. Methods: Adult, 4 months old, Wistar rats of both sexes, were fed with different types of diets: standard, milk-based and fish-based, during 4 weeks. Analytical characterization of different foods was done. Biochemical parameters in plasma were determined. Fatty acid composition was analyzed by gas-chromatography. Statistical significance of FA levels was tested with two-way analysis of variance (ANOVA) using the sex of animals and treatment (type of diet) as factors on logarithmic or trigonometric transformed data. Results: Our results showed that both, milk- and fish-based diet, changed the composition and ratio of rat liver phospholipids FA, in gender-specific manner. Initially present sex differences appear to be dietary modulated. Although, applied diets changed the ratio of total saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), and effects were gender specific. Milk-based diet lowered SFA and elevated MUFA in males and increased PUFA in females vs. standard diet. The same diet decreased n-3, increased n-6 and n-6/n-3 ratio in males. Fish-based diet increased n-3, decreased n-6 and n-6/n-3 ratio vs. standard and milk-based diet in females. However, the ratio of individual FA in liver PL was also dietary-influenced, but with gender specific manner. While in females fish-based diet decreased AA (arachidonic acid) increased level of EPA (eicosapentaenoic acid), DPA (docosapentaenoic acid) and DHA (docosahexaenoic acid), the same diet elevated only DHA levels in males. Conclusion: Gender related variations in FA composition of rat liver PL were observed, and results have shown that those initial differences could be significantly modulated by the type of diet. Furthermore, the modulatory effects of milk- and fish-based diets on liver phospholipids FA profiles appeared to be sex-specific. [ABSTRACT FROM AUTHOR]

We investigated the ability of graphene quantum dot (GQD) nanoparticles to protect SH-SY5Y human neuroblastoma cells from oxidative/nitrosative stress induced by iron-nitrosyl complex sodium nitroprusside (SNP). GQD reduced SNP cytotoxicity by preventing mitochondrial depolarization, caspase-2 activation, and subsequent apoptotic death. Although GQD diminished the levels of nitric oxide (NO) in SNP-exposed cells, NO scavengers displayed only a slight protective effect, suggesting that NO quenching was not the main protective mechanism of GQD. GQD also reduced SNP-triggered increase in the intracellular levels of hydroxyl radical (•OH), superoxide anion (O 2 •−), and lipid peroxidation. Nonselective antioxidants, •OH scavenging, and iron chelators, but not superoxide dismutase, mimicked GQD cytoprotective activity, indicating that GQD protect cells by neutralizing •OH generated in the presence of SNP-released iron. Cellular internalization of GQD was required for optimal protection, since a removal of extracellular GQD by extensive washing only partly diminished their protective effect. Moreover, GQD cooperated with SNP to induce autophagy, as confirmed by the inhibition of autophagy-limiting Akt/PRAS40/mTOR signaling and increase in autophagy gene transcription, protein levels of proautophagic beclin-1 and LC3-II, formation of autophagic vesicles, and degradation of autophagic target p62. The antioxidant activity of GQD was not involved in autophagy induction, as antioxidants N -acetylcysteine and dimethyl sulfoxide failed to stimulate autophagy in SNP-exposed cells. Pharmacological inhibitors of early (wortmannin, 3-methyladenine) or late stages of autophagy (NH 4 Cl) efficiently reduced the protective effect of GQD. Therefore, the ability of GQD to prevent the in vitro neurotoxicity of SNP depends on both •OH/NO scavenging and induction of cytoprotective autophagy. [Display omitted] • Graphene quantum dots (GQD) protect SH-SY5Y cells from sodium nitroprusside (SNP). • GQD inhibit SNP-induced apoptotic death of SH-SY5Y neuronal cells. • Quenching of NO and.•OH contributes to GQD-mediated protection from SNP toxicity • GQD induce autophagy associated with reduced Akt/mTOR signaling. • GQD-induced autophagy is cytoprotective independently of their antioxidant activity. [ABSTRACT FROM AUTHOR]

• Novel PU network nanocomposites containing embedded MSNs are successfully prepared. • The addition of MSNs improves surface, thermal and mechanical properties of PUs. • Materials exhibit promising traits for application as coatings for medical devices. Novel polyurethane nanocomposite (PUN) materials containing different surface-functionalized mesoporous silica nanoparticles (MSNs) were prepared by in situ polymerization methodology. Polyurethane network was formed from poly(dimethylsiloxane)-based macrodiol (PDMS), 4,4′-methylenediphenyldiisocyanate (MDI), and hyperbranched polyester of the second pseudo-generation (BH-20; used as crosslinking agent). PU and PU/MSN nanocomposites contained equal ratios of soft PDMS and hard MDI-BH-20 segments. Non-functionalized and surface-functionalized (with 3-(trihydroxysilyl)propyl methylphosphonate (FOMSN) and 2-[methoxy(polyethyleneoxy)6−9propyl]trimethoxysilane (PEGMSN)) MSNs were used as the nanofillers at a concentration of 1 wt%. Prepared materials were characterized by Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analyses (DMTA), nanoindentation, equilibrium swelling and water absorption measurements. Characteristics of the prepared PUNs when in contact with a biological environment were assessed through testing their biocompatibility, protein adsorption and adhesion of endothelial cells. The favourable influence of MSNs on the physico-chemical and biological characteristics of these novel PUN materials was identified, which evidences their vast applicability potential as coatings for medical devices and implants. [ABSTRACT FROM AUTHOR]