Inadequate antioxidant protection in preterm babies: possible cause for hyperbilirubinemia

Many illnesses in pre-term infants are thought to be related to the action of reactive oxygen species and it is conceivable that the oxidants play a certain role in the etiopathogenesis of unconjugated hy- perbilirubinemia. We hypothesized that an important factor in the mechanism of oxidative injury in hyperbilirubinemic infants on the first day of life would be increased oxidative stress in relation to antioxidants. For this aim, 43 pre-term infants as well as full-term healthy reference group (A=50) were subjected in the present study. Additionally, pre-terms were divided in: healthy pre-terms (B=25) and hyperbilirubinemic pre-terms (C=18). Perinatal variables (gestational age, birth weight and Apgar score) were recorded, and erythrocyte superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity and selenium (Se) levels were measured in umbilical cord blood, immediately after the delivery. The obtained results indicate strikingly lower antioxidant capacity of pre-term infants; they showed significantly lower SOD and GPx activity and Se level, compared to the full-term infants (p<0,001, for all). In the hyperbilirubinemic group, GPx activity and Se levels were found to be significantly lower than those in healthy pre-terms (p<0.001, for both), while SOD showed highly increased enzyme activity (p<0.001). Alterations in enzyme activities were accompanied by a simultaneous significant increase in the bilirubin level (p<0.001). In conclusion, disequilibrium between SOD and GPx activity ratio may represent a marker of oxidative stress in cells of premature infants. Aditionally, this inadequacy of the protection, may cause erythrocyte haemolysis, resulting with hyperbilirubinaemia

Electrophoretic Deposition of Biocompatible and Bioactive Hydroxyapatite-Based Coatings on Titanium

Current trends in biomaterials science address the issue of integrating artificial materials as orthopedic or dental implants with biological materials, e.g., patients' bone tissue. Problems arise due to the simple fact that any surface that promotes biointegration and facilitates osteointegration may also provide a good platform for the rapid growth of bacterial colonies. Infected implant surfaces easily lead to biofilm formation that poses a major healthcare concern since it could have destructive effects and ultimately endanger the patients' life. As of late, research has centered on designing coatings that would eliminate possible infection but neglected to aid bone mineralization. Other strategies yielded surfaces that could promote osseointegration but failed to prevent microbial susceptibility. Needless to say, in order to assure prolonged implant functionality, both coating functions are indispensable and should be addressed simultaneously. This review summarizes progress in designing multifunctional implant coatings that serve as carriers of antibacterial agents with the primary intention of inhibiting bacterial growth on the implant-tissue interface, while still promoting osseointegration

On the second order statistics of N-Hop FSO communications over N-gamma-gamma turbulence induced fading channels

The paper explores N-hop FSO communications assisted by amplify-and-forward relays (AFRs) over N-gamma-gamma (N-gg) turbulence induced (TI) fading channels. We model TI fading signal as the product of independent but not necessarily identically distributed (i.n.i.d) N number of gg random processes (RPs) in order to address N-hop AFR FSO communications in moderate to strong TI fading conditions. The closed form statistical measures such as: probability density function (PDF), cumulative distribution function (CDF), average level crossing rate (LCR) and average fade duration (AFD) approximated by general Laplace integration formula (LIF) and exponential LIF are derived. The CDF and AFD derived expressions are in terms of finite sums and valid only for an integer value of the parameter related to small-scale atmospheric cells in the first link of N-hop AFR FSO system. The numerical examples for moderate to strong TI fading conditions as well as for various number of hops for the proposed N-hop AFR FSO systems are presented and discussed. Moreover, LIF approximate numerical results are compared with numerical results evaluated from exact integral expressions for the observed system model parameters.Caslav Stefanovic would like to acknowledge CONEX-Plus project. The CONEX-Plus has received research funding from UC3M and the European Unio's Horizon 2020 programme under the Marie Sklodowska-Curie grant agreement No 801538. The authors would like also to acknowledge the COST Action 16220

Electrophoretic deposition and thermal treatment of boehmite coatings on titanium

An aqueous boehmite sol was prepared by the peptization of Al(OH)3. The electrophoretic deposition of boehmite coatings on titanium from the aqueous sol was performed at a constant voltage (from 1.0 to 10 V) and for a constant deposition time (from 10 to 30 min). Increasing the applied voltage and deposition time increased the mass of the boehmite coating. It was shown that boehmite coatings of maximum thickness, low porosity and good adhesion can be formed at lower deposition voltages and longer deposition times. The boehmite powder, obtained by drying the prepared aqueous sol, and the boehmite coatings were thermally treated at 1000 °C and 1300 °C with a holding period of 1 h at the maximum temperature. X-Ray diffraction analysis of the thermally treated samples confirmed the existence of g-Al2O3 and a-Al2O3 phases, respectively, while scanning electron microscopy revealed the graininess of the structure of the a-Al2O3 coatings treated at 1300 °C, indicating a significantly lower sintering temperature of the boehmite coating obtained by electrophoretic deposition

The effect of applied current density on the surface morphology of deposited calcium phosphate coatings on titanium

Electrochemical deposition of calcium phosphate coatings on titanium was performed galvanostatically from the aqueous solution of Ca(NO3)(2) and NH4H2PO4 with the current densities between 5.0 and 10 mA cm(-2), for different deposition times, at room temperature. The coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results showed that dicalcium phosphate dihydrate (DCPD), brushite (CaHPO4 center dot 2H(2)O) coatings were deposited. The influence of applied current density and the deposition time on the phase composition, crystallite domain size and the morphology of brushite coatings were investigated. It was shown that brushite coating of the greatest mass was obtained for the longest deposition time, while the increase in current density over 7 mA cm(-2) does not affect significantly the mass of brushite coatings. The finest crystallites, with the smallest crystallite domain size of 15.6nm, were deposited at the current density of 9.0 mA cm(-2). Brushite coatings were fully converted to hydroxyapatite in simulated body fluid (SBF) which was confirmed by XRD and SEM. The crystallite domain size of HA coatings is controlled by applied current density for brushite coatings deposition: crystallization of HA at more porous brushite coatings, deposited at higher current density, caused the formation of smaller crystallites of hydroxyapatite

Electrochemical synthesis and characterization of hydroxyapatite powders

Electrochemical synthesis of hydroxyapatite powders was performed galvanostatically from homogeneous solution of Na(2)H(2)EDTA center dot 2H(2)O, NaH2PO4 and CaCl2 at a concentration relationship Ca/EDTA/PO43- of 0.25/0.25/0.15 M at current densities of 137 and 207 mA cm(-2) and pH values of 9.0 and 12.0. The hydroxyapatite powders were characterized by X-ray diffraction, size distribution measurements, transmission electron microscopy, scanning electron microscopy and thermogravimetric and differential thermal analysis. The influence of the electrochemical synthesis parameters, e.g. applied current density and pH value, on the phase composition, crystallite size, morphology and thermal characteristics of hydroxyapatite powders were investigated. (c) 2008 Elsevier B.V. All rights reserved

The Current Density on Electrosynthesis of Hydroxyapatite with Bipolar Membrane

Synthesis of hydroxyapatite by electrochemical method was has been successfully done. The novelty of this research is used of the bipolar membrane to separate electrolysis chamber. The bipolar membrane is used to keep the cations still around the cathode and react to form hydroxyapatite. The aim of this paper was to compare the current density on electrosynthesis of hydroxyapatite with and without bipolar membrane and the effect of current density on electrosynthesis. The electrosynthesis was performed at 2 hours at 400 to 600 mA/cm2 at room temperature. The bigger the current density, the more pure HA formed. The electrosynthesis of hydroxyapatite with bipolar membrane more effective than without bipolar membrane. The formation of HA is very effective in the cathode chamber. HA can be formed at low current density. In electrosynthesis with the bipolar membrane, particles of HA are nanosheet flower-like. The nanosheet flower-like HA growth at 1.6 A to 2 A

Electrodeposited hydroxyapatite thin films modified by ion beam irradiation

Surface modification of hydroxyapatite (HA) thin films electrodeposited on titanium was conducted by ion implantation, using nitrogen and argon ions at different constant fluences of 1x10(15), 1x10(16) and 1x10(17) ions/cm(2). SEM and XRD analysis, as well as SRIM calculation, were used to monitor the changes induced by ion bombardment. In the case of HA film implanted with N(4+) ions, the unit cell parameters and unit cell volume increase with increasing nitrogen ion fluences. Similarly, the unit cell parameters and unit cell volume increase after Ar(6+) ions irradiation to a 1x10(15) ions/cm(2). At higher fluences, the unit cell parameters and unit cell volume decrease when argon ion fluences increase to 1x10(16) and 1x10(17) ions/cm(2). These structural changes are consequence of different mechanism of energy transfer of nitrogen and argon ions to HA film. For nitrogen ion irradiation electron energy loss is predominant, while for argon ion irradiation nuclear energy transfer to HA film prevails

The chitosan-based bioactive composite coating on titanium

This paper describes a promising electrophoretic deposition (EPD) approach for developing composite coatings based on chitosan with the additional components of hydroxyapatite, graphene, and gentamicin on titanium substrate. Bioactive properties were investigated in vitro by immersing the coatings in simulated body fluid (SBF) at 37 degrees C. The newly formed biomimetic layer on the top of the deposited chitosan-based coatings on Ti was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and electrochemical measurements, while coatings' bioactivity was proved by alkaline phosphatase activity assay in MRC-5 and L929 tested cell lines. The biocompatibility towards MRC-5 and L929 cell lines was investigated by dye exclusion test (DET) implying the non-cytotoxic effect of coatings. Gentamicin release studies were monitored during 21-day by high-performance liquid chromatography coupled with mass spectrometry, indicating rapid release of gentamicin (approximate to 40%) in the first 48 h and more than 60% after 14 days