Magnetically responsive composite polymer scaffolds have good potential for a variety of biomedical applications. In this work, electrospun composite scaffolds made of polyhydroxybutyrate (PHB) and magnetite (Fe 3 O 4 ) particles (MPs) were studied before and after degradation in either PBS or a lipase solution. MPs of different sizes with high saturation magnetization were synthesized by the coprecipitation method followed by coating with citric acid (CA). Nanosized MPs were prone to magnetite−maghemite phase transformation during scaffold fabrication, as revealed by Raman spectroscopy; however, for CA-functionalized nanoparticles, the main phase was found to be magnetite, with some traces of maghemite. Submicron MPs were resistant to the magnetite−maghemite phase transformation. MPs did not significantly affect the morphology and diameter of PHB fibers. The scaffolds containing CA-coated MPs lost 0.3 or 0.2% of mass in the lipase solution and PBS, respectively, whereas scaffolds doped with unmodified MPs showed no mass changes after 1 month of incubation in either medium. In all electrospun scaffolds, no alterations of the fiber morphology were observed. Possible mechanisms of the crystalline-lamellar-structure changes in hybrid PHB/Fe 3 O 4 scaffolds during hydrolytic and enzymatic degradation are proposed. It was revealed that particle size and particle surface functionalization affect the mechanical properties of the hybrid scaffolds. The addition of unmodified MPs increased scaffolds' ultimate strength but reduced elongation at break after the biodegradation, whereas simultaneous increases in both parameters were observed for composite scaffolds doped with CA-coated MPs. The highest saturation magnetization�higher than that published in the literature�was registered for composite PHB scaffolds doped with submicron MPs. All PHB scaffolds proved to be biocompatible, and the ones doped with nanosized MPs yielded faster proliferation of rat mesenchymal stem cells. In addition, all electrospun scaffolds were able to support angiogenesis in vivo at 30 days after implantation in Wistar rats.
The main purpose of the review article is to assess the contributions of telomere length and telomerase activity to the cardiac function at different stages of development and clarify their role in cardiac disorders. It has been shown that the telomerase complex and telomeres are of great importance in many periods of ontogenesis due to the regulation of the proliferative capacity of heart cells. The review article also discusses the problems of heart regeneration and the identification of possible causes of dysfunction of telomeres and telomerase.
We studied the protective effect of bioregulators isolated from the liver and blood serum of mammals under conditions of manifest fibrosis. Fibrosis was induced by CCl4 administration for 30 days and then, the liver was cultured in a roller organotypic culture for 30 days in the presence of bioregulators. Hepatoprotective effect of bioregulators was evaluated on histological sections of the liver at different terms of culturing. Experiments with roller organotypic culture of the liver isolated from animals with in vivo CCl4-induced fibrosis demonstrated the protective effect of bioregulator of the liver origin, while bioregulator isolated from the blood was ineffective.
The different effects on animals of the thrombolytic protease complex of the new producer S. strictum 203 were studied. The tests of acute toxicity, immunotoxicity and allergenicity should conclude that the studied proteolytic complex is safe for medical usage. For the intravenous and the intraperitoneal routes of administration, the maximum tolerated dose and the median lethal dose were not determined.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.