Investigation of different bleaching conditions on the amount of elutable substances from nano-hybrid composites

Objectives

To analyse the influence of irradiation time, aging before bleaching, and bleaching technique (home bleaching vs. in-office bleaching) on the amount of elutable substances from modern nano-hybrid resin-based composites (RBCs).

Methods

Specimens (n = 5) of three nano-hybrid RBCs (Venus^® Diamond, Tetric EvoCeram^® and Filtek™ Supreme XTE) were irradiated for 5, 10, 20 and 40 s. The degree of conversion (DC) was measured in real-time with Fourier transform infrared spectroscopy (FTIR). Specimens were bleached either directly after irradiation or after aging (1.5 or 6 month in distilled water at 37 °C) with Opalescence^® PF15% for 6 h (simulation of home bleaching) or PF35% for 0.5 h (simulation of in-office bleaching) and incubated in ethanol/water (3:1) at 37 °C for 7 d. The eluates were analyzed by gas chromatography/mass spectrometry. Unbleached specimens at the above mentioned irradiation times were used as controls.

Results

Bleaching increases the amount of elutable substances. This amount is generally stronger influenced by aging than by polymerization time or concentration of the gel. 2-Hydroxyethyl methacrylate was found in amounts up to 334.14 (106.91) μmol/l (Tetric EvoCeram^®, irradiation time 5 s; bleaching with 15% CP) as a destruction product. Diethoyxdimethylsilane was found in all eluates from bleached specimens, but not in the control groups. This substance may be formed by oxidation of 3-methacryloxy-propyltrimethoxysilane, indicating that the bond between inorganic filler and organic matrix might be weakened after bleaching.

Significance

Bleaching gels might alter the physical properties of resin-based composites, especially at low irradiation times and fresh placed restorations.     

Dynamics of the circadian blood pressure profiles after renal transplantation

BACKGROUND: Abnormalities of diurnal blood pressure (BP) rhythm ("nondipping") are well-described in dialysis patients, and have prognostic importance. It is controversial whether successful renal transplantation (RTx) improves diurnal BP rhythm. To date, no study has attempted to define and model the evolution of diurnal BP rhythm profiles from dialysis to engraftment, focusing on the immediate (4-6 weeks) and medium-term (>1 year) postengraftment periods. METHODS: To test if kidney transplantation normalizes the BP profile, ambulatory blood pressure monitoring (ABPM) was performed in 20 living related transplants (age, 30.3+/-5.1 years; 11 males, on dialysis for 25.6 months) 1 month preRTx and repeated 1 month and >1 year (ABPM3) after successful RTx. Dipping was defined as a sleep-to-awake ratio>0.92 (for systolic BP) and >0.90 (for diastolic BP). RESULTS: PreRTx only 15% patients were dippers. At 1 month postRTx (creatinine clearance, 65.8 ml/min), all patients were complete nondippers. However, after >1 year postRTx (creatinine clearance, 70.4 ml/min), 40% were now dippers. Most importantly, overall, 30% of the patients improved significantly their circadian rhythm (35.3% of the initial preRTx nondippers). Despite successful renal transplantation, 55% patients maintained unchanged their nondipping profile throughout all three ABPM recordings. The only determinants of "long-term" postRTx circadian rhythm are the contemporary level of the renal function and the baseline, dialysis dipping profile: SBP3 sleep-to-awake ratio is related with serum creatinine3 (r=0.58, P=0.001), creatinine clearance (r=-0.41, P=0.036) and SBP1 sleep-to-awake ratio (r=0.48, P=0.034); similarly DBP3 sleep-to-awake ratio is related with serum creatinine3 (r=0.63, P=0.001), creatinine clearance (r=-0.471, P=0.036) and SBP1 sleep-to-awake ratio (r=0.53, P=0.016). In all, 57% of the variance in dipping status can be attributed and explained by the contribution of renal function and initial circadian variability. CONCLUSIONS: Half of the nondipper dialysis patients maintain a permanently abnormal circadian rhythm, despite successful RTx. In the short term, RTx is associated with a highly abnormal diurnal profile, exclusively related to ciclosporin dose and levels. However, in the longer term, renal transplantation leads to a significant improvement of the circadian blood pressure profile, influenced by the renal function level and by the pretransplantation dipping profile.     

Acute effect of CyA A (Neoral) on large artery hemodynamics in renal transplant patients

BACKGROUND: CyA A (CyA) may induce intrarenal vasoconstriction, endothelial dysfunction, and hypertension. There are only two contradictory reports describing the acute effect of CyA on renal resistances measured by color Doppler flowmetry. Therefore, we studied the acute influence of oral CyA on arterial haemodynamics by assessing simultaneous changes in blood pressure, applanation tonometry-derived pulse wave analysis and duplex ultrasound-derived intrarenal resistance indices. METHODS: Augmentation index (AIx) (difference between the first and second systolic peak on the aortic pressure waveform divided by the pulse pressure = AIx) was determined from contour analysis of arterial waveforms recorded by applanation tonometry using the AtCor device in 18 live-related renal transplants (11 females/7 males, age = 32.0 +/- 8.1 years, transplantation duration = 17.5 +/- 16.1 months, and mean serum creatinine = 133 +/- 70 micromol/L). All studies were performed just before (C0), and 2 hours after (C2) the oral administration of CyA. At the same C0 and C2 moments the resistive index (RI) = (peak systolic frequency shift - minimum diastolic frequency shift)/peak systolic frequency shift, and pulsatility index (PI) = (peak systolic frequency shift - minimum diastolic frequency shift)/mean frequency shift were calculated from Doppler recorded waveforms. RESULTS: Blood pressure and heart rate did not differ significantly at C0 and at C2 serum levels: 134.3/82.9 vs. 128.1/80.0 mm Hg and 72.0 vs. 71.0 beats/min, respectively, despite a marked increase in whole blood concentration (CyA(C0)= 90.8 +/- 45.9 vs. CyA(C2)= 547.4 +/- 251.3 ng/mL) (P= 0.05). Mean AIx fell significantly from 17.2 +/- 13.8 to 12.9 +/- 14.2 (P < 0.0001). There was no correlation between the extent (expressed as absolute or relative change) of the measured alteration in AIx and total administered CyA dose, or increment in blood level between C0 and C2. In support, the intake of CyA did not induce a significant increase in Doppler resistance (RI(C0)= 0.68 +/- 0.08 vs. RI(C2)= 0.70 +/- 0.09) and pulsatility indices (PI(C0)= 1.32 +/- 0.31 vs. PI(C2)= 1.33 +/- 0.28). Finally, three patients were studied twice (>1 week): one under two levels of creatinine, one with no antihypertensives, and a third receiving verapamil initially. All these maintained a significant decrease in AIx at C2 from C0 supporting the reproducibility of the phenomenon. CONCLUSION: We demonstrate that Neoral CyA acutely improves large arterial compliance function and does not induce an acute rise in intrarenal resistance in stable renal transplant subjects with normal renal function. We speculate that there may be an effect of vitamin E, the diluent vehicle in which CyA is carried (1000 IU/100 mg CyA), shown to improve endothelial function.     

The monitoring of the accumulation of protoporphyrin IX in Walker tumours by subcutaneous administration of delta-aminolevulinic acid

Photodynamic therapy with protoporphyrin IX induced by delta-aminolevulinic acid (ALA) is mainly applied for the treatment of human superficial skin cancer. In this paper we present our study on photodynamic therapy (PDT) of the implanted Walker tumours using subcutaneous administration of ALA to improve the availability of ALA in the skin. We determined the accumulation and localization of protoporphyrin IX (PpIX) after subcutaneous administration of different concentrations of ALA in a physiological saline solutions, using fluorescence imaging technique. The results obtained indicate that PpIX accumulation depends on the concentration of ALA. The temporal behavior of PpIX fluorescence has shown a clear demarcation of tumoural zone depending on the post-administration time and the administrated concentration of the ALA solution. Further studies are needed to confirm these encouraging results and to define the PDT protocols using subcutaneous administration of ALA solution     

Valorization of Polypropylene Waste in the Production of New Materials with Adequate Mechanical and Thermal Properties for Environmental Protection

Innovative composites based on polypropylene waste impurified cu HDPE (PPW) combined with two thermoplastic block-copolymers, namely styrene-butadiene-styrene (SBSBC) and styrene-isoprene-styrene (SISBC) block-copolymers, and up to 10 wt% nano-clay, were obtained by melt blending. SBSBC and SISBC with almost the same content of polystyrene (30 wt%) were synthesized by anionic sequential polymerization and used as compatibilizers for PPW. Optical microscopy evaluation of the PPW composites showed that the n-clay was encapsulated into the elastomer. Addition of n-clay, together with SBSBC or SISBC, increased the interphase surface of the components in the PPW composites and enhanced the superficial area/volume ratio, which led to a recycled material with improved performance. The data resulting from differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), mechanical evaluation, and dynamic mechanical analysis (DMA) revealed that PPW reinforcement with n-clay and styrene-diene block-copolymers allows the obtaining of composites with favorable mechanical and thermal properties, and excellent impact strength for potential engineering applications.     

Quantifying and explaining accessibility with application to the 2009 H1N1 vaccination campaign

Accessibility and equity across populations are important measures in public health. This paper is specifically concerned with potential spatial accessibility, or the opportunity to receive care as moderated by geographic factors, and with horizontal equity, or fairness across populations regardless of need. Both accessibility and equity were goals of the 2009 vaccination campaign for the novel H1N1a influenza virus, including during the period when demand for vaccine exceeded supply. Distribution system design can influence equity and accessibility at the local level. We develop a general methodology that integrates optimization, game theory, and spatial statistics to measure potential spatial accessibility across a network, where we quantify spatial accessibility by travel distance and scarcity. We estimate and make inference on local (census-tract level) associations between accessibility and geographic, socioeconomic, and health care infrastructure factors to identify potential inequities in vaccine accessibility during the 2009 H1N1 vaccination campaign in the U.S. We find that there were inequities in access to vaccine at the local level and that these were associated with factors including population density and health care infrastructure. Our methodology for measuring and explaining accessibility leads to policy recommendations for federal, state, and local public health officials. The spatial-specific results inform the development of equitable distribution plans for future public health efforts.     

Toxicity of pamam‐coated gold nanoparticles in different unicellular models

Polyamidoamine (PAMAM) dendrimers are used for many pharmaceutical and biomedical applications. However, the toxicological risks of several PAMAM‐based compounds are still not fully evaluated, despite evidences of PAMAM deleterious effects on biological membranes, leading to toxicity. In this report, we investigated the toxicity of generation 0 PAMAM‐coated gold nanoparticles (AuG0 NPs) in four different models to determine how different cellular systems are affected by PAMAM‐coated NPs. Toxicity was evaluated in two mammalian cell lines, Neuro 2A and Vero, in the green alga Chlamydomonas reinhardtii and the bacteria Vibrio fischeri. AuG0 NP treatments reduced cell metabolic activity in algal and bacterial cells, measured by esterase enzymatic activity (C. reinhardtii) and luminescence emission (V. fischeri). EC50 value after 30 min of treatment was similar in both organisms, with 0.114 and 0.167 mg mL^?1 for C. reinhardtii and V. fischeri, respectively. On the other hand, AuG0 NPs induced no change of mitochondrial activity in mammalian cells after 24 h of treatment to up to 0.4 mg mL^?1 AuG0 NPs. Change in the absorption spectra of AuG0 NP in the mammalian cell culture media may indicate an alteration of NP properties that contributed to the low toxicity of AuG0 NPs in mammalian cells. For a safe development of PAMAM‐based nanomaterials, the difference of sensitivity between mammalian and microbial cells, as well as the modulation of NPs toxicity by medium properties, should be taken into account when designing PAMAM NPs for applications that may lead to their introduction in the environment. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 328–336, 2014.     

Co-encapsulation of dexamethasone 21-acetate and SPIONs into biodegradable polymeric microparticles designed for intra-articular delivery

Objective: Intra-articular drug delivery systems still suffer from too short-lasting effects. Magnetic particles retained in the joint using an external magnetic field might prolong the local release of an anti-inflammatory drug. For the purpose, superparamagnetic iron oxide nanoparticles (SPIONs) and dexamethasone 21-acetate (DXM) were co-encapsulated into biodegradable microparticles.

Methods: Poly(D,L-lactide-co-glycolide) microparticles embedding both SPIONs and DXM were prepared by a double emulsion technique. The formulation was optimized in two steps, a screening design and a full factorial design, aiming at 10-μm particle diameter and high DXM encapsulation efficacy.

Results: The most significant parameters were the polymer concentration, the stirring speed during solvent extraction and the extractive volume. Increasing the polymer concentration from 200 to 300 mg ml^?1, both the microparticle mean diameter and the DXM encapsulation efficacy increased up to 12 μm and 90%, respectively. The microparticles could be retained with an external magnet of 0.8 T placed at 3 mm. Faster DXM release was obtained for smaller microparticles.

Conclusion: The experimental set-up offered the tools for tailoring a formulation with magnetic retention properties and DXM release patterns corresponding to the required specifications for intra-articular administration.