Fibrin-polyurethane composites for articular cartilage tissue engineering: a preliminary analysis

In this study we investigated the use of a fibrin hydrogel to improve the potential of a polyurethane (PU) scaffold-based system for articular cartilage tissue engineering. PU-only ("no-fibrin") and PU-fibrin ("fibrin") composites were cultured for up to 28 days and analyzed for DNA content, glycosaminoglycan (GAG) content, type II collagen content, GAG release, and gene expression of aggrecan, collagen I, and collagen II. The use of fibrin allowed for higher viable cell-seeding efficiency (10% higher DNA content on day 2 in fibrin versus no-fibrin composites) and more even cell distribution on seeding, a more than 3-fold increase in the percentage of newly synthesized GAG retained in the constructs, and 2- to 6-fold higher levels of type II collagen and aggrecan gene expression through day 14. Addition of aprotinin to the medium inhibited fibrin degradation, most noticeably in the center of the constructs, but had little effect on biochemical composition or gene expression. Short-term mechanical compression (0-10% sinusoidal strain at 0.1 Hz for 1 h, applied twice daily for 3 days) doubled the rate of GAG release from the constructs, but had little effect on gene expression, regardless of the presence of fibrin. Although further work is needed to optimize this system, the addition of fibrin hydrogel to encapsulate cells in the stiff, macroporous PU scaffold is a step forward in our approach to articular cartilage tissue engineering.     

Biodegradable polyurethanes for implants. II. In vitro degradation and calcification of materials from poly(epsilon-caprolactone)-poly(ethylene oxide) diols and various chain extenders

Linear, biodegradable, aliphatic polyurethanes with various degrees of hydrophilicity were synthesized in bulk at 50-100 degrees C. The ratios between the hydrophilic and hydrophobic segments were 0:100, 30:70, 40:60, 50:50, and 70:30, respectively. The hydrophilic segment consisted of poly(ethylene oxide) (PEO) diol (molecular weight = 600 or 2000) or the poly(ethylene-propylene-ethylene oxide) (PEO-PPO-PEO) diol Pluronic F-68 (molecular weight = 8000). The hydrophobic segment was made of poly(epsilon-caprolactone) diol (molecular weight = 530, 1250, or 2000). The chain extenders were 1,4-butane diol and 2-amino-1-butanol. The diisocyanate was aliphatic hexamethylene diisocyanate. The polymers absorbed water in an amount that increased with the increasing content of the PEO segment in the polymer chain. The total amount of absorbed water did not exceed 2% for the poly(ester urethane)s and was as high as 212% for some poly(ester ether urethane)s that behaved in water like hydrogels. The polymers were subjected to in vitro degradation at 37 +/- 0.1 degrees C in phosphate buffer solutions for up to 76 weeks. The poly(ester urethane)s showed 1-2% mass loss at 48 weeks and 1.1-3.8% mass loss at 76 weeks. The poly(ester ether urethane)s manifested 1.6-76% mass loss at 48 weeks and 1.6-96% mass loss at 76 weeks. The increasing content and molecular weight of the PEO segment enhanced the rate of mass loss. Similar relations were also observed for polyurethanes from PEO-PPO-PEO (Pluronic) diols. Materials obtained with 2-amino-1-butanol as the chain extender degraded at a slower rate than similar materials synthesized with 1,4-butane diol. All the materials already manifested a progressive decrease in the molecular weight in the first month of in vitro aging. The rate of molecular weight loss was higher for poly(ester ether urethane)s than for poly(ester urethane)s. For poly(ester ether urethane)s, the rate of molecular weight loss was higher for materials containing Pluronic than for those containing PEO segments. All polymers calcified in vitro. The susceptibility to calcification increased with material hydrophilicity. The progressive deposition of calcium salt on the film surfaces resulted in the formation of large crystal aggregates, the structure of which depended on the chemical composition of the calcified material. Needle-like aggregates, resembling brushite, formed on the hydrophobic polyurethane, and plate-like crystals formed on the highly hydrophilic material. The calcium-to-phosphorus atomic ratio of the crystals growing on the samples was dependent on the chemical composition of the material and varied from 0.94 to 1.55.     

Protein adsorption, attachment, growth and activity of primary rat osteoblasts on polylactide membranes with defined surface characteristics

The adsorption of proteins and growth and activity of primary rat osteoblasts cultured for 1, 2 and 3 weeks on nonporous and porous resorbable poly(L/DL-lactide) 80/20% membranes with defined surface characteristics were investigated. The growth and activity of cells were estimated from the measurements of DNA, alkaline phosphatase activity and the total amount of protein in the cell lysate. The cell morphology was assessed from scanning electron microscopy and rhodamine staining. The protein adsorption to the membrane surface was assessed from the amide I peak at 1640-1660 cm(-1) and the amide II peak at 1540-1560 cm(-1) in the attenuated total reflection infrared spectra. The relative amount of proteins adsorbed on the nonporous and porous membranes was comparable. The cells growing on the nonporous and porous membranes maintained the phenotype and revealed morphology typical for osteoblasts. The mineralized noduli were larger in size on the porous membranes. The number of cells, the amount of DNA, the alkaline phosphatase activity, and the total amount of protein increased with time of the experiment and were higher for the porous membranes than for the nonporous ones.     

Research on the Release of Dangerous Compounds from the BTEX and PAHs Groups in Industrial Casting Conditions

The assessment of the harmfulness of moulding and core sands is mainly based on investigations of compositions of gases emitted by liquid casting alloys during the mould pouring. The results of investigations of moulding sands obtained under industrial conditions are presented in this paper. A unique research stand was designed and built for this aim. It allowed us to determine emissions of gases at individual stages of casting a mass up to 50 kg. This approach enables simulation of foundry conditions. Moulding sands bound by organic binders (phenol-formaldehyde; furan), inorganic binders and green sand, were subjected to investigations. The composition of gases that evolved during the individual stages, pouring, cooling and knocking out, was tested each time, and the contents of Polycyclic Aromatic Hydrocarbons (PAHs) and benzene, toluene, ethylbenzene, and xylenes (BETX) were analysed. Investigations indicated that the emission of gases from sands with inorganic binders is negligible when compared with the emission of gases from sands with organic binders. The emission of gases from green sand is placed in the middle of the scale. As an example: the sand with furan resin emitted 84 mg of BTEX (in recalculation for 1 kg of sand) while from sands with inorganic binders there was a maximum of 2.2 mg (for 1 kg of sand). In the case of sands with inorganic binders, MI and MC sands indicated comparable and very low emissions of gases from the PAHs group, at the level of 0.018 mg and 0.019 mg for 1 kg of sand, respectively. The higher emission of PAHs from MG sand is the result of its different way of hardening (a binder was of an organic character) than of sands MI and MC.     

Favorable four‐yr outcome after renal transplantation in a patient with complement factor H antibody and CFHR1/CFHR3 gene mutation‐associated HUS

aHUS is a clinical challenge for successful renal transplantation. Case report: A 14‐yr‐old girl lost her kidneys at the age of 7, due to CFH antibodies and CFH‐related protein (CFHR1/CFHR3) homozygous deletion‐associated aHUS. CFH, CFI, and MCP gene mutations were excluded. The patient was a candidate for renal transplantation despite persistent presence of CFH antibodies (up to 539 AU/mL). Treatment with MMF, IVIG, and repeated PF (n = 8) was introduced while being placed on urgent waiting list. Three years after aHUS onset, the patient underwent the deceased donor renal transplantation “under cover” of PF, as PF was performed directly prior to surgery and, then, PFs were repeated up to overall 14 sessions. Quadruple immunosuppression (basiliximab + tacrolimus + MMF + prednisolone) was used. Moderate symptoms of aHUS (hemolysis, low platelets, and low C3) were present within first seven days post‐transplant and then normalized with PF therapy. The patient remained stable during four yr of further follow‐up after transplantation. Conclusion: Specific pre‐ and post‐transplant management allowed successful renal transplantation in a CFH antibody‐positive patient.     

Analysis of the Abrasive-Type Influence on the Effectiveness of Rotary Cleaning of Machine Parts with Complex Geometric Features

This work presents the analysis of functional relationships between fraction size of abrasives and geometric parameters of surfaces after rotary cleaning. The influence of an abrasive type on the effectiveness of rotary cleaning of machine parts with complex geometric features was determined as well. The process of mechanical cleaning, using a rotational method, of clutch springs was performed in the proprietary device for rotational cleaning, which was followed by the computer-aided analysis of the obtained results. The research process was carried out using abrasive materials such as grinding stone, sand, basalt, glass, and fine gravel, and the test samples were clutch springs after eight years of operation. Based on calculated three-dimensional (3D) roughness values of the cleaned samples’ surfaces, qualitative classification of abrasives was determined. The most effective material turned out to be fine gravel, while the worst results were related to basalt usage.     

Nitrogen Dissolution in Liquid Ga and Fe: Comprehensive Ab Initio Analysis,Relevance for Crystallization of GaN

The dissolution of molecular nitrogen in Ga and Fe was investigated by ab initio calculations and some complementary experiments. It was found that the N bonding inside these solvents is fundamentally different. For Ga, it is between Ga4s and Ga4p and N2p states whereas for Fe this is by N2p to Fe4s, Fe4p and Fe3d states. Accordingly, the energy of dissolution of N2 for arbitrarily chosen starting atomic configurations was 0.535 eV/mol and −0.299 eV/mol for Ga and Fe, respectively. For configurations optimized with molecular dynamics, the difference between the corresponding energy values, 1.107 eV/mol and 0.003 eV/mol, was similarly large. Full thermodynamic analysis of chemical potential was made employing entropy-derived terms in a Debye picture. The entropy-dependent terms were obtained via a normal conditions path to avoid singularity of ideal gas entropy at zero K. Nitrogen solubility as a function of temperature and N2 pressure was evaluated, being much higher for Fe than for Ga. For T=1800 K and p=104 bar, the N concentration in Ga was 3×10−3 at. fr. whereas for Fe, it was 9×10−2 at. fr. in very good agreement with experimental data. It indicates that liquid Fe could be a prospective solvent for GaN crystallization from metallic solutions.     

Anti- and pro-oxidant potential of lettuce (Lactuca sativa L.) biofortified with iodine by KIO3, 5-iodo- and 3,5-diiodosalicylic acid in human gastrointestinal cancer cell lines

Vegetables are particularly rich sources of micronutrients and phytochemicals such as polyphenols and vitamins. These plant-derived bioactive compounds provide antitumor and antioxidant properties due to their capacity to interact with reactive oxygen species (ROS). The objective of this study was to determine the effect of iodine biofortification (potassium iodate/KIO₃/, 5-iodosalicylic acid/5-ISA/, and 3,5-diiodosalicylic acid/3,5-diISA/) on the antioxidant activity of lettuce (Lactuca sativa L. capitata) cv. ‘Melodion’. In this work, HPLC analysis was used to identify polyphenolic compounds while the antioxidant activity of iodine-enriched vegetables was determined by using DPPH, ABTS and FRAP methods. The content of the water-soluble vitamins was analyzed by using the LC-MS/MS technique. The impact of extracts from iodine-biofortified lettuce on production of reactive oxygen species (ROS) in gastrointestinal cancer cells was also evaluated. The results from this research indicate that application of iodine compounds improves the antioxidant potential of lettuce by increasing the concentration of some vitamins, antioxidant enzymes and polyphenolic compounds in the enriched plants. Moreover, the study has shown that iodine-biofortified lettuce induces production of ROS in cancer cells, resulting in an anticancer effect by the induction of programmed cancer cell death.

Vegetables are particularly rich sources of micronutrients and phytochemicals such as polyphenols and vitamins.     

Znaczenie modyfikacji epigenetycznych w patogenezie białaczek

Relations between genetic alterations and different types of leukemia lead to understanding that leukemogenesis is a mainly genetic-based phenomenon. However recently role of factors of epigenetic nature is highlighted in research on oncogenic transformation. Epigenetic regulation is defined as heritable patterns that are not related to DNA sequence. There are three major forms of epigenetic regulation: DNA methylation, histone modifications – methylation and acetylation – and regulation through small non-coding RNAs. Epigenetic regulation is important in development of different types of leukemia. Changes in DNA methylation patterns as well as in histone methylation and acetylation were detected in samples from patients with leukemia. In addition different profiles of miRNA, one subtype of noncoding RNAs, were associated with this disease. What is more, alteration in activity of enzymes involved in regulation of DNA and histone modification can also be detected in leukemic cells. Current knowledge of epigenetic regulation allows for better diagnostic of leukemia and better understanding of mechanism involved in its therapy. It also allowed for development of new forms of therapies targeted specifically on mechanisms involved in epigenetic regulation.