The aim of the presented study was preparation, analysis of properties, and in vitro characterization of porous shape-memory scaffolds, designed for large bone defects treatment using minimally invasive surgery approach. Biodegradable terpolymers of l-lactide/glycolide/trimethylene carbonate (LA/GL/TMC) and l-lactide/glycolide/ε-caprolactone (LA/GL/Cap) were selected for formulation of these scaffolds. Basic parameters of shape memory behavior (i.e. recovery ratio, recovery time) and changes in morphology (SEM, average porosity) and properties (surface topography, water contact angle, compressive strength) during shape memory cycle were characterized. The scaffolds preserved good mechanical properties (compressive strength about 0.7 to 0.9 MPa) and high porosity (more than 80%) both in initial shape as well as after return from compressed shape. Then the scaffolds in temporary shape were inserted into the model defect of bone tissue at 37°C. After 12 min the defect was filled completely as a result of shape recovery process induced by body temperature. The scaffold obtained from LA/GL/TMC terpolymer was found the most prospective for the planned application thanks to its appropriate recovery time, high recovery ratio (more than 90%), and cytocompatibility in contact with human osteoblasts and chondrocytes.
Betulin (BT) is a natural pentacyclic lupane-type triterpene exhibiting anticancer activity. Betulin derivatives bearing propynoyloxy and phosphate groups were prepared in an effort to improve the availability and efficacy of the drug. In this study, a comparative assessment of the in vitro anticancer activity of betulin and its four derivatives was carried out using two human breast cancer cell lines: SK-BR-3 and MCF-7. In both studied cell lines, 30-diethoxyphosphoryl-28-propynoylbetulin (compound 4) turned out to be the most powerful inhibitor of growth and inducer of cellular death. Detailed examination of that derivative pertained to the mechanisms underlying its anticancer action. Treatment with compound 4 decreased DNA synthesis and up-regulated p21WAF1/Cip1 mRNA and protein levels in both cell lines. On the other hand, that derivative caused a significant increase in cell death, as evidenced by increased lactate dehydrogenase (LDH) release and ethidium homodimer uptake. Shortly after the compound addition, an increased generation of reactive oxygen species and loss of mitochondrial membrane potential were detected. The activation of caspase-3 and fragmentation of genomic DNA suggested an apoptotic type of cell death. However, analysis of cellular morphology did not reveal any nuclear features typical of apoptosis. Despite necrosis-like morphology, dead cells exhibited activation of the cascade of caspases. These observations have led to the conclusion that compound 4 pushed cells to undergo a form of necrotic-like regulated cell demise.
The search for safe and effective anticancer therapies is one of the major challenges of the 21st century. The ineffective treatment of cancers, classified as civilization diseases, contributes to a decreased quality of life, health loss, and premature mortality in oncological patients. Many natural phytochemicals have anticancer potential. Pentacyclic triterpenoids, characterized by six- and five-membered ring structures, are one of the largest class of natural metabolites sourced from the plant kingdom. Among the known natural triterpenoids, we can distinguish lupane-, oleanane-, and ursane-types. Pentacyclic triterpenoids are known to have many biological activities, e.g., anti-inflammatory, antibacterial, hepatoprotective, immunomodulatory, antioxidant, and anticancer properties. Unfortunately, they are also characterized by poor water solubility and, hence, low bioavailability. These pharmacological properties may be improved by both introducing some modifications to their native structures and developing novel delivery systems based on the latest nanotechnological achievements. The development of nanocarrier-delivery systems is aimed at increasing the transport capacity of bioactive compounds by enhancing their solubility, bioavailability, stability in vivo and ensuring tumor-targeting while their toxicity and risk of side effects are significantly reduced. Nanocarriers may vary in sizes, constituents, shapes, and surface properties, all of which affect the ultimate efficacy and safety of a given anticancer therapy, as presented in this review. The presented results demonstrate the high antitumor potential of systems for delivery of pentacyclic triterpenoids.
To study the secretory products and the proliferation of cells of the human respiratory surface epithelium, we established a miniorgan-culture system of bronchial tissue. Biopsies of large airways were grown on agar-coated dishes immersed in a serum-enriched medium. As determined by light and transmission electron microscopy, between 1 and 3 weeks, the organ cultures were covered by a differentiated epithelium consisting of secretory, ciliated, and basal cells. Immunohistochemistry, using antibodies to mucin and lysozyme, and lectin histochemistry revealed both mucous and serous secretory cells in the epithelium. Cell proliferation was studied in situ using antibodies to proliferating cell nuclear antigen (PCNA) and Ki-67. Whereas at the time of explantation the proliferation was low (2.5+/-1.7% of the epithelial cells were PCNA-positive, 1.7+/-0.6 were Ki-67-positive), at 24 h of cultivation, 30.4+/-5.1% or 25.2+/-4.9% of the epithelial cells were labeled with antibodies to PCNA or Ki-67. After 7 days, the number of dividing cells was low again. The results show that the organ-culture system of human respiratory surface epithelium produces a differentiated epithelium that is useful in the study of secretory processes, differentiation, and proliferation.
The paper presents a synthesis of poly(l-lactide) with bacteriostatic properties. This polymer was obtained by ring-opening polymerization of the lactide initiated by selected low-toxic zinc complexes, Zn[(acac)(L)H2O], where L represents N-(pyridin-4-ylmethylene) tryptophan or N-(2-pyridin-4-ylethylidene) phenylalanine. These complexes were obtained by reaction of Zn[(acac)2 H2O] and Schiff bases, , the products of the condensation of amino acids and 4-pyridinecarboxaldehyde. The composition, structure, and geometry of the synthesized complexes were determined by NMR and FTIR spectroscopy, elemental analysis, and molecular modeling. Both complexes showed the geometry of a distorted trigonal bipyramid. The antibacterial and antifungal activities of both complexes were found to be much stronger than those of the primary Schiff bases. The present study showed a higher efficiency of polymerization when initiated by the obtained zinc complexes than when initiated by the zinc(II) acetylacetonate complex. The synthesized polylactide showed antibacterial properties, especially the product obtained by polymerization initiated by a zinc(II) complex with a ligand based on l-phenylalanine. The polylactide showed a particularly strong antimicrobial effect against Pseudomonas aeruginosa, Staphylococcus aureus, and Aspergillus brasiliensis. At the same time, this polymer does not exhibit fibroblast cytotoxicity.
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