Polymodal Transient Receptor Potential Vanilloid (TRPV) Ion Channels in Chondrogenic Cells

Mature and developing chondrocytes exist in a microenvironment where mechanical load, changes of temperature, osmolarity and acidic pH may influence cellular metabolism. Polymodal Transient Receptor Potential Vanilloid (TRPV) receptors are environmental sensors mediating responses through activation of linked intracellular signalling pathways. In chondrogenic high density cultures established from limb buds of chicken and mouse embryos, we identified TRPV1, TRPV2, TRPV3, TRPV4 and TRPV6 mRNA expression with RT-PCR. In both cultures, a switch in the expression pattern of TRPVs was observed during cartilage formation. The inhibition of TRPVs with the non-selective calcium channel blocker ruthenium red diminished chondrogenesis and caused significant inhibition of proliferation. Incubating cell cultures at 41 °C elevated the expression of TRPV1, and increased cartilage matrix production. When chondrogenic cells were exposed to mechanical load at the time of their differentiation into matrix producing chondrocytes, we detected increased mRNA levels of TRPV3. Our results demonstrate that developing chondrocytes express a full palette of TRPV channels and the switch in the expression pattern suggests differentiation stage-dependent roles of TRPVs during cartilage formation. As TRPV1 and TRPV3 expression was altered by thermal and mechanical stimuli, respectively, these are candidate channels that contribute to the transduction of environmental stimuli in chondrogenic cells.     

Analysis of fumonisin mycotoxins with capillary electrophoresis – mass spectrometry

ABSTRACT

This paper demonstrates the development of an analytical method based on CE coupled to ESI-MS for the identification and quantification of fumonisin mycotoxins. Separation and detection parameters (pH of background electrolyte (BGE), organic modifier content, sheath liquid (SL) composition, MS mode and nebuliser pressure) were optimised. Ammonium formate/ammonia (pH = 9.5) with 10% ACN modifier was found the most suitable BGE. Positive mode MS was used for detection by scanning the m/z range of 400–1200. Separation was highly affected by the nebuliser pressure, a 25% improvement in peak resolution was achieved by applying the optimised parameters. The ‘dilute and shoot’ approach was applied to overcome disturbing effects caused by the matrix of fungi supernatant samples. The available sample volume affected the reproducibility of the measurements greatly: the scattering of peak intensities were between 4 and 11 RSD% instead of 27–195 RSD% for fumonisin B₁ and fumonisin B₂ when the available volume was ~200 µL instead of ~20 µL. Quantitative determinations were carried out in Fusarium verticillioides and Fusarium proliferatum culture supernatant (raw) and mycelium (cleaned up) samples. The optimised method enabled the detection of 11 fumonisins in Fusarium proliferatum inoculated rice samples; 2 of them were quantified based on external calibration and 4 other compounds with fumonisin-like formulas were detected.     

Biodegradable zinc-based materials with a polymer coating designed for biomedical applications

Over the last decades, biodegradable metals have gained popularity for biomedical applications due to their ability to assist in tissue healing. These materials degrade in vivo, while the corrosion products formed are either absorbed or excreted by the body, and no further surgical intervention is required for removal. Intensive research has been carried out mainly on degradable biomaterials based on Mg and Fe. In recent years, zinc-based degradable biomaterials have been explored by the biomedical community for their intrinsic physiological relevance, desirable biocompatibility, intermediate degradation rate, tuneable mechanical properties and pro-regeneration properties. Since pure Zn does not exhibit sufficient mechanical properties for orthopedic applications, various Zn alloys with better properties are being developed. In this work, the combined effect of minor Fe addition to Zn and a polyethyleneglycol (PEG) coating on the surface morphology, degradation, cytotoxicity and mechanical properties of Zn-based materials was studied. There are several studies regarding the influence of the production of Zn alloys, but the effect of polymer coating on the properties of Zn-based materials has not been reported yet. A positive effect of Fe addition and polymer coating on the degradation rate and mechanical properties was observed. However, a reduction in biocompatibility was also detected.     

Forcing term discretization techniques in the external field‐to‐MTL coupling problems

In this paper, two, under certain conditions, equivalent models of electromagnetic plane wave coupling to multiconductor transmission lines (MTLs) are described. The ‘frequency‐to‐time domain’ (FTD) model incorporates the effect of the impinging electromagnetic waves by means of distributed voltage and current sources whose expressions are found through mathematical approximations made in the frequency domain followed by a transformation to the time domain. The approximations were made in order to gain an advantage in computation time in the discrete FTD (DFTD) model. In contrast to this approach, the same distributed sources of the ‘approximate analytic’ (AA) model are derived by directly evaluating the corresponding integral formulas. It is shown that, although the same second‐order‐accurate discretization technique has been employed to create both the DFTD and the discrete AA (DAA) models, the simulation results are not the same. In the case of the DFTD model, significant numerical error can be seen in the simulation results, whereas the DAA model does not show such a behaviour. It is shown that time averaging of the forcing terms in the DFTD model helps to reduce the numerical errors significantly at no extra computational cost. Copyright © 2001 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.     

The relationship between the α-tocopherol content of the yolk and its accumulation in the tissues of the newly hatched chick

The effect of a range of concentrations of α-tocopherol in the initial yolk on the subsequent levels of this vitamin in the tissues of the newly hatched chick was investigated. Four batches of fertile eggs (Ross 1 broiler-breeder type) with mean yolk α-tocopherol concentrations (μg g⁻¹ yolk) of 60·8, 155·3, 272·2 and 376·6 were incubated and the levels of the vitamin in the liver, brain, heart and kidney of the resultant chicks were measured. The liver of the day-old chick contained far higher levels of the vitamin than were found in the other tissues studied. The concentration of α-tocopherol in the liver was directly proportional to the initial level of this vitamin in the yolk. The concentrations of α-tocopherol in the brain were only about 1% of the corresponding liver values but were also directly proportional to the levels initially present in the yolk. The concentrations of α-tocopherol exhibited by the heart and kidney were affected by the initial yolk values but the response was not linear over the range of yolk α-tocopherol concentrations studied. The results indicate that the initial concentration of α-tocopherol in the yolk has a profound effect on the subsequent levels of this vitamin in the tissues of the chick. In a separate experiment, the changes in the concentration of α-tocopherol in the liver were studied over the first 9 days after hatching. The vitamin was found to be rapidly depleted from the liver after hatching. © 1997 SCI.     

Mechanical and rheological properties of multicomponent polypropylene blends

Polypropylene (PP) compositions containing CaCO₃ filler, EPDM (ethylene-propylene-ethylidenenorbornene) elastomer, and a non-reactive surfactant were investigated in the mixing chamber of a plastograph. Rheological properties were determined from the registered torque (M) vs. time and temperature (T) vs. time curves, while tensile characteristics of the blends were measured on compression molded plates. The homogenization process can be followed with the aid of 1 n M vs. 1/T diagrams. In the first few minutes of the mixing, beside homogenization, a significant breaking down of the elastomer takes place, and the size of the particles attains an equilibrium value. Dispersion time increases with increasing amount of EPDM and surface active-agent. Morphological investigations indicate the presence of a continuous PP phase containing dispersed CaCO₃ and elastomer particles. The rheological and tensile characteristics are seemingly determined by the total amount of additives, which imply that the elastomer and the filler has the same effect on the properties of the composite. Separation of the effects proved, however, that the effect of the two components are dissimilar, the filler exerts a larger influence on the investigated properties.     

Molecular architecture and biophysical properties of phospholipids during thermal adaptation in fish: An experimental and model study

Phospholipids from livers of carps (Cyprinus carpio L.) adapted to winter (5°C) and summer (25°C) temperatures were isolated, and the fatty acid composition of total phospholipids, as well as molecular species composition of diacyl phosphatidylcholines and ethanolamines, were determined. Order parameter of 5-doxyl stearic acid and steady-state fluorescence anisotropy of different anthroyloxy fatty acids—[2-, 12(N-9-anthroyloxy)stearic acid and 16(N-9-anthroyloxy)palmitic acid—embedded in native and synthetic (16∶0/16∶0, 16∶0/22∶6, 18∶0/22∶6, 18∶1/22∶6, 20∶4/20∶4, 22∶6/22∶6 phosphatidylcholines and 16∶0/18∶1, 18∶1/22∶6 phosphatidylethanolamines) phospholipid vesicles was also determined between −30 and 30°C and 5 and 30°C, respectively. There is an accumulation of 1-monoenoic, 2-polyenoic diacyl phosphatidylcholine and ethanolamine with a concomitant reduction of 1-stearoyl,2-docosahexaenoyl species in the cold-adapted state. Despite a 30% accumulation of long-chain polyunsaturated fatty acids in phospholipids in cold, there is only a 5°C downshift in the solid-gel to liquid-crystalline phase transition temperature (−8 vs. −13°C). Vesicles from total phospholipids of cold-adapted fish proved to be more disordered in all segments than from the warmadapted ones when assayed using 2,12-(N-9-anthroyloxy)stearic and 16-(N-9-anthroyloxy)palmitic acid. Vesicles made from purified phosphatidylcholines showed the same pattern, but they were more disordered than the corresponding total phospholipids. This could be modelled using mixed phospholipid vesicles made of synthetic 16∶0/22∶6 phosphatidylcholine (75%) and either 18∶1/22∶6 phosphatidylethanolamine (25%) vs. 16∶0/18∶1 phosphatidylethanolamine (25%) and comparison of the anisotropy parameters of 100% 16∶0/22∶6 and 100% 18∶1/22∶6 phosphatidylcholine vesicles. Mixing either 16∶0/18∶1 (25%) or 18∶1/22∶6 (25%) phosphatidylethanolamines to 18∶0/22∶6 (75%) phosphatidylcholine shifted down or up, respectively, the transition temperature of vesicles compared to 100% 18∶0/22∶6 vesicles assayed by electron spin resonance spectroscopy using 5-doxylstearic acid. It is concluded that it is not the gross amount of long-chain polyunsaturated fatty acids in phospholipids, but rather their specific combination withcis Δ9 monounsaturated fatty acids in the positionsn-1, especially in phosphatidylethanolamines, that is important in determining the physical properties of biomembranes in relation to adaptational temperature.     

Manufacturing and testing of long basalt fiber reinforced thermoplastic matrix composites

In this work, long basalt fiber reinforced composites were investigated and compared with short basalt fiber reinforced compounds. The results show that long fiber reinforced thermoplastic composites are particularly advantageous in the respects of dynamic mechanical properties and injection molding shrinkage. The fiber orientation in long basalt fiber reinforced products fundamentally differs from short basalt fiber reinforced ones. This results in more isotropic molding shrinkage in case of long basalt fiber reinforced composites. The main advantage of the used long fiber thermoplastic technology is that the special long fiber reinforced pellet can be processed by most conventional injection molding machines. During extrusion compounding the fibers in the compound containing 30 wt% fibers are fragmented to an average length of 0.48 mm (typical of short fiber reinforced thermoplastic compounds), this length decreases further during injection molding to 0.20 mm. Contrarily using long fiber reinforced pellets and cautious injection molding parameters, an average fiber length of 1.8 mm can be achieved with a conventional injection molding machine, which increased the average length/diameter ratio from 14 to 130. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Effect of salts on the binding of some environmental pollutants to corn protein zein studied by HPLC

The strength and the character of the binding of 14 organic solvents to the corn protein zein in distilled water and in various salt solutions were determined by preparing zein-coated carbon stationary phase and by measuring the retention characteristics of solvents on a high-performance liquid chromatographic column filled with this stationary phase. The relationship between the physicochemical parameters and binding characteristics of solvents was elucidated by principal component analysis. It was established that various interactive forces are involved in the binding of solvent to the protein, suggesting a mixed binding mechanism. Binding characteristics are equally influenced by the molecular hydrophobicity and by the polarity parameters of the solvent. Coordination numbers, ionization, and lattice energies of the monovalent cations significantly influenced the various aspects of the binding of organic solvents to zein.