Mechanosignaling-related angiocrine factors drive osteoblastic phenotype in response to zirconia.

BACKGROUND: The growing use of zirconia as a ceramic material in dentistry is attributed to its biocompatibility, mechanical properties, esthetic appearance, and reduced bacterial adhesion. These favorable properties make ceramic materials a viable alternative to commonly used titanium alloys. Mimicking the physiological properties of blood flow, particularly the mechanosignaling in endothelial cells (ECs), is crucial for enhancing our understanding of their role in the response to zirconia exposure. METHODS: In this study, EC cultures were subjected to shear stress while being exposed to zirconia for up to 3 days. The conditioned medium obtained from these cultures was then used to expose osteoblasts for a duration of 7 days. To investigate the effects of zirconia on osteoblasts, we examined the expression of genes associated with osteoblast differentiation, including Runx2, Osterix, bone sialoprotein, and osteocalcin genes. Additionally, we assessed the impact of mechanosignaling-related angiocrine factors on extracellular matrix (ECM) remodeling by measuring the activities of matrix metalloproteinases 2 and 9 (MMP2 and MMP9) during the acquisition of the osteogenic phenotype, which precedes mineralization. RESULTS: Our data revealed that mechanosignaling-related angiocrine factors play a crucial role in promoting an osteoblastic phenotype in response to zirconia exposure. Specifically, exposed osteoblasts exhibited significantly higher expression levels of genes associated with osteoblast differentiation, such as Runx2, Osterix, bone sialoprotein, and osteocalcin genes. Furthermore, the activities of MMP2 and MMP9, which are involved in ECM remodeling, were modulated by mechanosignaling-related angiocrine factors. This modulation is likely an initial event preceding the mineralization phase. CONCLUSION: Based on our findings, we propose that mechanosignaling drives the release of angiocrine factors capable of modulating the osteogenic phenotype at the biointerface with zirconia. This process creates a microenvironment that promotes wound healing and osseointegration. Moreover, these results highlight the importance of considering the mechanosignaling of endothelial cells in the modulation of bone healing and osseointegration in the context of blood vessel effects. Our data provide new insights and open avenues for further investigation into the influence of mechanosignaling on bone healing and the osseointegration of dental devices.

Heavy Metal Accumulation in the Intestinal Tapeworm Proteocephalus macrophallus Infecting the Butterfly Peacock Bass (Cichla ocellaris), from Southeastern Brazil.

Here we evaluate the potential of heavy metal accumulation of Proteocephalus macrophallus parasitizing the Butterfly Peacock Bass (Cichla ocellaris). A total of 19 fish specimens were collected. From the hosts, samples of intestine, liver, muscle, and parasites were taken. Heavy metal concentrations (Al, As, Ba, Cd, Cr, Fe, Hg, Mg, Mn, Ni, Pb, Ti, and Zn) were obtained using Atomic Absorption Spectrometry. All analyzed elements was found in higher concentrations in the parasites comparing to its host tissues. The bioconcentration factors were higher in the intestine, varying between 5.91 (Ti) to 8.00 (Ba), followed by the muscle, 1.88 (Mg) to 6.39 (Zn), and liver, 1.67 (Al) to 2.02 (Ba). These results show that at the infection site heavy metal concentrations are reduced, since the elements are absorbed directly from the intestinal wall by the parasites. In general, P. macrophallus presents a reasonable capacity of metal accumulation comparing to its hosts.

The ultra-sonication of minerals in swine feed.

A sample preparation method based on ultrasound assisted-extraction (UAE) of Ca, Mg and P from swine feed has been described. The experiment was performed to cover the variables influencing the sonication process and, the method validation using standard reference material. Final solutions obtained upon sonication were analyzed by flame atomic absorption spectrometry (for Ca and Mg) and by UV-vis spectrophotometry (for P). The best conditions for metal extraction were as follows: sample mass: 100 mg in 20 mL 0.10 mol/L HCl, a particle size: <60 µm, sonication time: 5 cycles of 10 s and ultrasound power: 102 W. The UAE method was applied in digestibility assays in different piglet feeds and their results showed that it is highly comparable (P > 0.05) to the other methods used for such purposes, as block digestion, and offered a Ca, Mg and P method of quantification limit of 10.6, 12.4 and 14 mg/kg, respectively. The major advantages of the UAE method compared to other methods are the high treatment rate, low reagent usage in the extracts and, it does not generate toxic residues that might negatively affect human health and the environment, accompanied by good precision and accuracy.

Determination of the Mercury Fraction Linked to Protein of Muscle and Liver Tissue of Tucunaré (Cichla spp.) from the Amazon Region of Brazil.

This study used metalloproteomic techniques to characterize mercury (Hg)-bound proteins in the muscle and liver tissue of Tucunaré (Cichla spp.) collected at the Jirau Hydroelectric Power Plant in Madeira River Basin, Brazil. The proteome of the muscle and liver tissue was obtained after two steps of fractional precipitation and separating the proteins by 2-D polyacrylamide gel electrophoresis. Hg was identified and quantified in the protein spots by graphite furnace atomic absorption spectrometry after acid mineralization in an ultrasound bath. Hg with a molecular weight <20 kDa and a concentration between 13.30 and 33.40 mg g(-1) was found in the protein spots. These protein spots were characterized by electrospray ionization tandem mass spectrometry after trypsin digestion. From a total of 12 analyzed spots, seven proteins showing Hg biomarker characteristics were identified: parvalbumin and its isoforms, ubiquitin-40S ribosomal protein S27a, zinc (Zn) finger and BTB domain-containing protein 24, and dual-specificity protein phosphatase 22-B.

Blood and seminal plasma concentrations of selenium, zinc and testosterone and their relationship to sperm quality and testicular biometry in domestic cats.

The aim of this study was to assess seminal plasma (SP) and serum concentrations of zinc (Zn), selenium (Se) and testosterone (T) in domestic cats and determine whether these are related to sperm quality and testicular biometry. Six tomcats were collected using an artificial vagina and sperm analysis included motility by CASA, morphology, plasma membrane integrity, and sperm count. Serum and SP were submitted to total T concentration determination using a solid-phase radioimmunoassay technique while Zn and Se were measured by atomic absorption spectroscopy. Serum T concentrations were greater compared to SP concentrations, but both values were significantly correlated. Se concentrations were higher in serum, whereas SP had greater Zn values. Concentrations of Se, Zn and T were not correlated with each other either in serum or SP. Negative correlations were detected between Se concentrations in SP and total sperm head defects, and between Se concentrations in serum and VAP, VSL, STR, and LIN. Serum concentrations of Zn were negatively correlated with total abnormal sperm and midpiece defects and positively related to progressive motility. Both serum and SP concentrations of T had no relationship with sperm quality. Concentrations of Se exhibited a negative correlation with total testicular weight, whereas T concentrations in SP and serum were correlated with total testicular volume and weight. In conclusion, both Se and Zn concentrations in serum were correlated to sperm quality variables in the domestic cat, thus, making these potential candidates for fertility markers.

Ultrasound-assisted extraction of Na and K from swine feed and its application in a digestibility assay: a green analytical procedure.

The study is aimed to evaluate the efficiency of ultrasound-assisted extraction (UAE) as a simple strategy focused on sample preparation for metal determination in biological samples. The extraction of sodium and potassium extraction was carried out from swine feed followed by determination of the concentration of these metals by flame atomic emission spectrometry (FAES). The experiment was performed to cover the study of the variables influencing the extraction process and its optimal conditions (sample mass, particle size, acid concentration, sonication time and ultrasound power); the determination of these analytical characteristics and method validation using certified reference material; and the analysis of pre-starter diets. The optimal conditions established conditions were as follows: mass: 100mg, particle size:<60 µm, acid concentration: 0.10 mol L(-1) HCl, sonication time: 50s and ultrasound power: 102 W. The proposed method (UAE) was applied in digestibility assays of those nutrients present in different piglet pre-starter feeds and their results proved to be compatible with those obtained from mineralized samples (P<0.05). The ultrasound extraction method was demonstrated to be an excellent alternative for handless sampling and operational costs and the method also has the advantage of does not generating toxic residues that may negatively affect human health and contaminate the environment.

Levels of copper in Nile tilapia from Brazil.

The purpose of this work was to determine the concentration of copper in samples of farmed Nile tilapia (Oreochromis niloticus L.) fillets purchased in the city of Botucatu (São Paulo, Brazil) and in fillet and liver samples of Tilapia fed diets supplemented with different concentrations of Cu from the Laboratory of Aquatic Organism Nutrition/FMVZ-UNESP (Botucatu, Brazil). The fillet samples were prepared by lyophilisation and cryogenic grinding into particles smaller than 60 µm, and copper was extracted ultrasonically using 0.10 mol l(-1) HCl as extraction solution. Copper determination was performed by graphite furnace atomic absorption spectrometry (GFAAS) with optimised temperatures of drying, pyrolysis, atomisation and cleaning. Palladium nitrate was injected into the samples as a chemical modifier and tungsten as a permanent modifier. Copper concentrations of 0.70-1.60 mg kg(-1) were found, which are in line with Brazilian regulations. The accuracy and precision of the copper concentrations determined in this study were evaluated using certified standard Lake Michigan fish tissue (NIST SRM 1947).

Analytical approach to the metallomic of Nile tilapia (Oreochromis niloticus) liver tissue by SRXRF and FAAS after 2D-PAGE separation: Preliminary results.

An investigation was made into calcium, iron and zinc in protein spots in samples of Nile tilapia (Oreochromis niloticus) liver tissue obtained after protein separation by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and subsequent qualitative and quantitative evaluation by synchrotron radiation X-ray fluorescence (SRXRF) and Flame Atomic Absorption Spectrometry (FAAS). An analysis of the fluorescence spectra indicated the presence of calcium, iron and zinc in 12, 6 and 8 liver protein spots, respectively. The metal ions found were distributed mainly in proteins with a molar mass of less than 40.00 kDa and more than 12.00 kDa, with pI in the range of 4.70-9.40. The only exception was a spot presenting protein with a molar mass of 10.10 kDa. In addition to calcium, iron and zinc, sulfur and phosphorus - which are non-metals that may be part of the protein structure, were also detected. After microwave-assisted acid mineralization of the proteins spots, a FAAS estimation of the concentration of calcium, iron and zinc ions bound to these proteins indicated a range of 1.08-5.80 mg g(-1), 2.02-8.03 mg g(-1) and 1.60-8.55 mg g(-1), respectively.

Sediment grain size distribution and heavy metals determination in a dam on the Paraná River at Ilha Solteira, Brazil.

This paper reports on a preliminary evaluation of the grain size distribution of cadmium, lead and copper in sediment from Catarina Beach, Ilha Solteira, in the state of São Paulo, Brazil. Surface sediments were fractionated with <63 microm nylon sieves and subjected to three digestion procedures: the proposed open digestion, the standard USEPA-3050B and closed digestion in a Teflon tube. The metals were determined by atomic absorption spectrometry. The results of the three procedures showed no significant differences. The 309 mg Kg1 concentration of copper found at the P3 sampling point exceeded the PEL (probable effect level) value of 197 mg Kg1, which represents an environmental hazard to aquatic organisms. The sediments organic matter content determined by the loss on ignition was 6.8, 1.7 and 0.6% in the P3, P1 and P2 samples, respectively. The distribution of metal concentrations in sieved sediment followed the order P3 < P2 < P1 thereby suggesting an interaction with organic matter.

Determination of selenium by GFAAS in slurries of fish feces to estimate the bioavailability of this micronutrient in feed used in pisciculture.

This paper presents a simple, fast and sensitive method to determine selenium in samples of feces and of fish feed by graphite furnace atomic absorption spectrometry (GFAAS) through the direct introduction of slurries of the samples into the spectrometer's graphite tube. The limits of detection (LOD) and quantification (LOQ) calculated for 20 readings of the blank of the standard slurries (0.50% m/v of feces or feed devoid of selenium) were 0.31 microg l(-1) and 1.03 microg l(-1), respectively, for the standard feces slurries and 0.35 microg l(-1) and 1.16 microg l(-1), respectively, for the standard feed slurries. The proposed method was applied in studies of bioavailability of selenium in different fish feeds and the results proved consistent with that obtained from samples mineralized by acid digestion using the microwave oven.

A solid paraffin-based carbon paste electrode modified with 2-aminothiazole organofunctionalized silica for differential pulse adsorptive stripping analysis of nickel in ethanol fuel.

A solid paraffin-based carbon paste electrode modified with 2-aminothiazole organofunctionalized silica (SiAt-SPCPE) was applied to Ni(2+) determination in commercial ethanol fuel samples. The proposed method comprised four steps: (1) Ni(2+) preconcentration at open circuit potential directly in the ethanol fuel sample, (2) transference of the electrode to an electrochemical cell containing DMG, (3) differential pulse voltammogram registering and (4) surface regeneration by polishing the electrode. The proposed method combines the high Ni(2+) adsorption capacity presented by 2-aminothiazole organofunctionalized silica with the electrochemical properties of the Ni(DMG)(2) complex, whose electrochemical reduction provides the analytical signal. All experimental parameters involved in the proposed method were optimized. Using a preconcentration time of 20 min, it was obtained a linear range from 7.5 x 10(-9) to 1.0 x 10(-6) mol L(-1) with detection limit of 2.0 x 10(-9) mol L(-1). Recovery values between 96.5 and 102.4% were obtained for commercial samples spiked with 1.0 micromol L(-1) Ni(2+) and the developed electrode was totally stable in ethanolic solutions. The contents of Ni(2+) found in the commercial samples using the proposed method were compared to those obtained by graphite furnace atomic absorption spectroscopy by using the F- and t-test. Neither the F- nor t-values exceeded the critical values at 95% confidence level, confirming that there are not statistical differences between the results obtained by both methods. These results indicate that the developed electrode can be successfully employed to reliable Ni(2+) determination in commercial ethanol fuel samples without any sample pretreatment or dilution step.

Copper determination in ethanol fuel by differential pulse anodic stripping voltammetry at a solid paraffin-based carbon paste electrode modified with 2-aminothiazole organofunctionalized silica.

Solid paraffin-based carbon paste electrodes modified with 2-aminothiazole organofunctionalized silica have been applied to the anodic stripping determination of copper ions in ethanol fuel samples without any sample treatment. The proposed method comprised four steps: (1) copper ions preconcentration at open circuit potential directly in the ethanol fuel sample; (2) exchange of the solution and immediate cathodic reduction of the absorbate at controlled potential; (3) differential pulse anodic stripping voltammetry; (4) electrochemical surface regeneration by applying a positive potential in acid media. Factors affecting the preconcentration, reduction and stripping steps were investigated and the optimum conditions were employed to develop the analytical procedure. Using a preconcentration time of 20min and reduction time of 120s at -0.3V versus Ag/AgCl(sat) a linear range from 7.5x10(-8) to 2.5x10(-6)mol L(-1) with detection limit of 3.1x10(-8)mol L(-1) was obtained. Interference studies have shown a decrease in the interference effect according to the sequence: Ni>Zn>Cd>Pb>Fe. However, the interference effects of these ions have not forbidden the application of the proposed method. Recovery values between 98.8 and 102.3% were obtained for synthetic samples spiked with known amounts of Cu(2+) and interfering metallic ions. The developed electrode was successfully applied to the determination of Cu(2+) in commercial ethanol fuel samples. The results were compared to those obtained by flame atomic absorption spectroscopy by using the F-test and t-test. Neither F-value nor t-value have exceeded the critical values at 95% confidence level, confirming that there are no significant differences between the results obtained by both methods.

Studies on the adsorption and kinetics of photodegradation of a model compound for heterogeneous photocatalysis onto TiO(2).

An investigation was made on the adsorption and kinetics of photodegradation of potassium hydrogenphthalate in an aqueous suspension of TiO(2). Two models, Langmuir and Freundlich, were used to describe the adsorption process and the model proposed by Langmuir-Hinshelwood (L-H) was employed to describe the kinetics of the photodecomposition reactions of hydrogenphthalate. The results of the adsorptions were fitted to the models proposed by Langmuir and Freundlich. Adsorption was found to be a function of the temperature, with adsorption capacity increasing from 2.4 to 4.5 mg/g when the temperature rose from 20 to 30 degrees C. The kinetic model indicates that the rate constant, k, of the first order reaction, is high in the 10.0 to 100 mg/l interval, which is coherent with the low value of the adsorption constant, K. The results fitted to the L-H model led to an equation that, within the range of concentrations studied here, theoretically allows one to evaluate the photodegradation rate.

Determination of chromium by GFAAS in slurries of fish feces to estimate the apparent digestibility of nutrients in feed used in pisciculture.

This paper presents a simple, fast and sensitive method to determine chromic oxide (used as a biological marker of fish feed) in samples of fish feces by GFAAS through the direct introduction of slurries of the samples into the spectrometer's graphite tube. The standard samples of feces and of fish feed containing 0.10-1.00mgkg(-1) of Cr(2)O(3) were pre-frozen for 1min in liquid nitrogen and then ground a cryogenic mill for 2min, which reduced the samples' grain size to less than 60mum. The standard slurries were prepared by mixing 20mg of standard samples of fish feed or feces with 1mL of a solution containing 0.05% (v/v) of Triton X-100 and 0.50% (v/v) of suprapure HNO(3) directly in the spectrometer's automatic sampling glass. The final concentrations of Cr(2)O(3) present in the standard slurries were 2, 4, 8, 16 and 20mugL(-1). After sonicating the mixture for 20s, 10muL of standard slurries were injected into the graphite tube, whose internal wall was lined with a metallic palladium film that acted as a permanent chemical modifier. The limits of detection (LOD) and quantification (LOQ) calculated for 20 readings of the blank of the standard slurries (2%, m/v of feces or feed devoid of minerals) were 0.81 and 2.70mugL(-1) of Cr(2)O(3) for the standard feces slurries, 0.84 and 2.83mugL(-1) of Cr(2)O(3) for the standard feed slurries. The proposed method was applied in studies of nutrient digestibility of different fish feeds and its results proved compatible with the results obtained from samples pre-mineralized by acid digestion.

Determination of cadmium in river water samples by flame AAS after on-line preconcentration in mini-column packed with 2-aminothiazole-modified silica gel.

A rapid and sensitive method was developed to determine trace levels of Cd2+ ions in an aqueous medium by flame atomic absorption spectrometry, using on-line preconcentration in a mini-column packed with 100 mg of 2-aminothiazol modified silica gel (SiAT). The Cd2+ ions were sorbed at pH 5.0. The preconcentrated Cd2+ ions were directly eluted from the column to the spectrometer's nebulizer-burner system using 100 microL of 2 mol L(-1) hydrochloric acid. A retention efficiency of over 95% was achieved. The enrichment factor (calculated as the ratio of slopes of the calibration graphs) obtained with preconcentrations in a mini-column packed with SiAT (A = -1.3 x 10(-3) + 1.8 x 10(-3)[Cd2+]) and without preconcentrations (A = 4 x 10(-5) + 3.5 x 10(-5)[Cd2+]), was 51 and the detection limit calculated was 0.38 microg L(-1). The preconcentration procedure was applied to determine trace levels of Cd in river water samples. The optimum preconcentration conditions are discussed herein.