Elaboration of small‐diameter vascular prostheses—Selection of appropriate sterilisation method

The aim of study is the elaboration of semi‐biodegradable, multilayered tubular structures as substitutes for the reconstruction of small diameter vascular prostheses (<6 mm). The inert external layer of the prostheses will be fabricated via the melt electrospinning of poly (l ‐lactide‐co‐glycolide) (PLGA). The middle layer will be constructed from polypropylene (PP); the first prototype will be produced via melt electrospinning and the second using the melt blowing technique. The general aim of this stage of the research is the selection of a sterilisation technique that is appropriate for semi‐biodegradable, multilayered tubular structures. For this purpose, single tubular structures created via the melt electrospinning of PLGA or PP and melt blown tubular structures of PP were elaborated. The influence of steam, ethylene‐oxide (EO), and radiation sterilisation techniques on the elaborated microstructure of tubular structures was analyzed during this study. The effect of each sterilisation technique was evaluated using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy analysis (SEM/EDS). The changes in average molecular weight (M_w) and crystallinity index (CI) of the PLGA tubular structures after EO and steam sterilisation were evaluated. The EO and steam sterilisation resulted in the complete destruction of PLGA tubular structures. Only the radiation sterilisation (accelerated electrons) did not influence on PLGA tubular structures morphology as well as thermal and chemical properties. FTIR and SEM/EDS analysis indicated that no changes in the chemical properties of PP tubular structures after each sterilisation occurred. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40812.     

Curcumin and Its New Derivatives: Correlation between Cytotoxicity against Breast Cancer Cell Lines,Degradation of PTP1B Phosphatase and ROS Generation

Breast cancer is the most common cancer of women—it affects more than 2 million women worldwide. PTP1B phosphatase can be one of the possible targets for new drugs in breast cancer therapy. In this paper, we present new curcumin derivatives featuring a 4-piperidone ring as PTP1B inhibitors and ROS inducers. We performed cytotoxicity analysis for twelve curcumin derivatives against breast cancer MCF-7 and MDA-MB-231 cell lines and the human keratinocyte HaCaT cell line. Furthermore, because curcumin is a known antioxidant, we assessed antioxidant effects in its derivatives. For the most potent cytotoxic compounds, we determined intracellular ROS and PTP1B phosphatase levels. Moreover, for curcumin and its derivatives, we performed real-time microscopy to observe the photosensitizing effect. Finally, computational analysis was performed for the curcumin derivatives with an inhibitory effect against PTP1B phosphatase to assess the potential binding mode of new inhibitors within the allosteric site of the enzyme. We observed that two tested compounds are better anticancer agents than curcumin. Moreover, we suggest that blocking the -OH group in phenolic compounds causes an increase in the cytotoxicity effect, even at a low concentration. Furthermore, due to this modification, a higher level of ROS is induced, which correlates with a lower level of PTP1B.     

The Potential of Asiatic Acid in the Reversion of Cyclophosphamide-Induced Hemorrhagic Cystitis in Rats

The purpose of this study was to determine if asiatic acid may act efficiently in the model of cyclophosphamide (CYP)-induced cystitis in rats. We performed experiments after administration of CYP (single dose 200 mg/kg, intraperitoneally), asiatic acid (30 mg/kg/day for 14 consecutive days, by oral gavage), or CYP plus asiatic acid, during which conscious cystometry, measurements of urothelium thickness and bladder edema, as well as selected biomarkers analyses were conducted. In rats that received asiatic acid together with CYP, a drop in bladder basal pressure, detrusor overactivity index, non-voiding contraction amplitude, non-voiding contraction frequency, and the area under the pressure curve were observed, when compared to the CYP group. Furthermore, a significant increase in threshold pressure, voided volume, intercontraction interval, bladder compliance, and volume threshold to elicit NVC were found in that group accordingly. Administration of the asiatic acid successfully restored concentrations of biomarkers both in bladder urothelium (BDNF, CGRP, OCT-3, IL-1β, IL-6, NGF, nitrotyrosine, malondialdehyde, TNF-α, SV2A, SNAP23, SNAP25, PAC-1, ORM1, occludin, IGFBP-3, HB-EGF, T–H protein, Z01, and HPX) and detrusor muscle (Rho kinase and VAChT) in CYP-treated rats. Finally, asiatic acid significantly decreased urothelium thickness and bladder oedema. Asiatic acid proved to be a potent and effective drug in the rat model of CYP-induced cystitis.     

Biodegradable Polyurethane Elastomers for Biomedical Applications – Synthesis Methods and Properties

Biodegradable polyurethane elastomers (BioEPUR) are becoming increasingly important as biomaterials because they have excellent chemical, physico-mechanical and biological properties. This review presents the recent developments on BioEPUR and their potential applications in the biomedical and pharmaceutical fields. The aim of this work is to present an overview of the various methods of synthesis and properties of biomedical BioEPUR. Polyurethanes-based aliphatic or cycloaliphatic diisocyanates and polyesters, poly(ester-carbonate)s or copolymers of heterocyclic monomers were discussed.     

Polycationic star polymers with hyperbranched cores for gene delivery

Core-shell type stars synthesized via atom transfer radical polymerization were used for the delivery of nucleic acids. The interior of the stars consisted of hyperbranched poly(arylene oxindole), while the arms were composed of poly(N,N-dimethylaminoethyl methacrylate). The length of the star arms varied in degree of polymerization (DP) from 14 to 98. The hydrodynamic radius of the structures measured in water indicated the presence of small aggregates, while isolated stars ranging in size from 14 to 29 nm were seen in organic solvent. The phase transition temperatures of the stars in water, measured in basic conditions, were shifted to lower values with increasing DP of the arms. Stable polyplexes of stars with plasmid DNA were formed. Their size varied from 300 nm to 400 nm, depending upon the DP of arms. The zeta potential of the polyplexes was positive, which facilitated their cellular uptake. The DP of the arms influenced the transfection efficiency of HT-1080 cells, demonstrating that stars are promising candidates for synthetic gene vectors.     

Effect of the sintering temperature on microstructure and properties of Al2O3–Cu–Ni hybrid composites obtained by PPS

In the present research, the influence of sintering temperature on the microstructure and properties of Al₂O₃–Cu–Ni hybrid composites prepared by the Pulse Plasma Sintering (PPS) technique were described. In this research, three temperatures have been selected: 1250°C, 1300°C, and 1350°C. SEM observations were carried out to determine the distribution of the metallic phase in the composite depending on the sintering temperature. The conducted experiments and microscopic observations enabled a better understanding of the phenomena occurring between the ceramic matrix and metallic phase in the obtained materials. The mechanical properties like a hardness and fracture toughness were measured. The technology applied allowed us to obtain ceramic-metal composites with a homogeneous microstructure. It was found that the sintering temperature influences the selected physical and mechanical properties of the composites produced. It was found that samples produced at 1300°C are characterized by the highest relative density and the mechanical properties.     

Bacteriophages vB_Sen-TO17 and vB_Sen-E22, Newly Isolated Viruses from Chicken Feces,Specific for Several Salmonella enterica Strains

Two newly discovered bacteriophages, isolated from chicken feces and infecting Salmonella enterica strains, are described in this report. These phages have been named vB_Sen-TO17 and vB_Sen-E22, and we present their molecular and functional characterization. Both studied viruses are able to infect several S. enterica strains and develop lytically, but their specific host ranges differ significantly. Electron microscopic analyses of virions have been performed, and full genome sequences were determined and characterized, along with molecular phylogenetic studies. Genomes of vB_Sen-TO17 (ds DNA of 41,658 bp) and vB_Sen-E22 (dsDNA of 108,987 bp) are devoid of homologs of any known or putative gene coding for toxins or any other proteins potentially deleterious for eukaryotic cells. Both phages adsorbed efficiently (>95% adsorbed virions) within 10 min at 42 °C (resembling chicken body temperature) on cells of most tested host strains. Kinetics of lytic development of vB_Sen-TO17 and vB_Sen-E22, determined in one-step growth experiments, indicated that development is complete within 30–40 min at 42 °C, whereas burst sizes vary from 9 to 79 progeny phages per cell for vB_Sen-TO17 and from 18 to 64 for vB_Sen-E22, depending on the host strain. Virions of both phages were relatively stable (from several percent to almost 100% survivability) under various conditions, including acidic and alkaline pH values (from 3 to 12), temperatures from −80 °C to 60 °C, 70% ethanol, chloroform, and 10% DMSO. These characteristics of vB_Sen-TO17 and vB_Sen-E22 indicate that these phages might be considered in further studies on phage therapy, particularly in attempts to eliminate S. enterica from chicken intestine.     

Effect of Acute Sprint Exercise on Myokines and Food Intake Hormones in Young Healthy Men

Physical exercise is known to influence hormonal mediators of appetite, but the effect of short-term maximal intensity exercise on plasma levels of appetite hormones and cytokines has been little studied. We investigated the effect of a 30 s Wingate Test, followed by a postprandial period, on appetite sensations, food intake, and appetite hormones. Twenty-six physically active young males rated their subjective feelings of hunger, prospective food consumption, and fatigue on visual analogue scales at baseline, after exercise was completed, and during the postprandial period. Blood samples were obtained for the measurement of nesfatin-1, ghrelin, leptin, insulin, pancreatic polypeptide (PP), human growth factor (hGH) and cytokine interleukin-6 (IL-6), irisin and plasma lactate concentrations, at 30 min before exercise, immediately (210 s) after exercise, and 30 min following a meal and at corresponding times in control sedentary males without ad libitum meal intake, respectively. Appetite perceptions and food intake were decreased in response to exercise. Plasma levels of irisin, IL-6, lactate, nesfatin-1 and ghrelin was increased after exercise and then it was returned to postprandial/control period in both groups. A significant rise in plasma insulin, hGH and PP levels after exercise was observed while meal intake potentiated this response. In conclusion, an acute short-term fatiguing exercise can transiently suppress hunger sensations and food intake in humans. We postulate that this physiological response involves exercise-induced alterations in plasma hormones and the release of myokines such as irisin and IL-6, and supports the notion of existence of the skeletal muscle–brain–gut axis. Nevertheless, the detailed relationship between acute exercise releasing myokines, appetite sensations and impairment of this axis leading to several diseases should be further examined.     

The Characteristics of the Superconducting and Magnetic Phases in the Polycrystalline Samples of Ruthenocuprates of Nominal Compositions RuSr2GdCu2O8, Ru0.98Sr2GdCu2O8 and Ru0.5Sr2GdCu2.5O8−δ

The temperature dependencies of the resistivity for the superconducting ruthenocuprates of nominal compositions RuSr₂GdCu₂O₈, Ru_0.98Sr₂GdCu₂O₈ and Ru_0.5Sr₂GdCu_2.5O_8?δ were examined for the magnetic field dependent characteristics of the superconducting transitions. The effect of the insignificant diminishing of the Ru/Cu ratio in parent RuSr₂GdCu₂O₈ was confirmed as relevant for the stabilisation of the superconducting phase. Noted differences in the compared characteristics are interpreted for possible inhomogeneous nucleation of the superconducting phase in the parent ruthenocuprate. The phase anisotropy in RuSr₂GdCu₂O₈ and Ru_0.98Sr₂GdCu₂O₈, in presence of the compounds Ru magnetism, appears to be a cause of a significant softening of the H _c2(T) phase line. An anomalous lowering of the magnetoresistivity was observed in the approx. 10 K range above the onset of the superconducting transition, which may suggest the presence of enhanced superconducting fluctuations in the samples. The positive magnetic field shift of the temperatures, which limit the magnetoresistivity and the specific heat signatures of the magnetic ordered state of the Ru sublattice, suggests probing the influence of the ferromagnetic Ru interactions in an effective metallic-like conduction channel present in the samples. Superconducting characteristics of the Ru_0.5Sr₂GdCu_2.5O_8?δ reveal a significant contribution of the Gd paramagnetic signal at low temperatures, interpreted for the presence of a significant anisotropy of the superconducting phase. It is concluded that the Ru–Cu substituted phases of ruthenocuprates may present an opportunity to investigate the effectively anisotropic superconducting phase despite its comparatively high T _c in the compounds related to the 123-type cuprate superconductor.     

Relaxation processes and intermolecular interactions in PVME hydrogels in sub-zero temperatures: Glass transition and pre-melting of ice

The phase transition observed by various methods in poly(vinyl methyl ether)/water systems at around 18 °C has been assigned by some investigators to the pre-melting of water and by others to a glass transition of the polymer. In this study, broadband dielectric spectroscopy and temperature modulated differential scanning calorimetry were used to identify this transition in radiationally crosslinked poly(vinyl methyl ether) hydrogels, as well as to analyse sub-zero relaxation processes in such a three-phase (polymer/ice/liquid water) system. The process at 18 °C was related to the pre-melting of water induced by the segmental motions of the polymer; however, it was seen to be one transition due to the cooperative motions of both compounds. The atypical (two regimes) temperature dependence of the segmental motion process was observed and was related to confinement of the polymer chains between ice clusters below approximately ?24 °C; furthermore, the main dielectric process of hexagonal ice was identified and a Maxwell-Wagner effect was observed.