Detection and Quantification of 41 Antibiotic Residues in Gilthead Sea Bream (<Emphasis Type=Italic>Sparus aurata</Emphasis>) From Aquaculture Origin,Using a Multiclass and Multi-residue UHPLC-MS/MS Method

Aquaculture is one of the worldwide strategic development fields, and its importance is evident in its significant worldwide growth in the last decades. This growth is associated with the implementation of intensive and semi-intensive production methods, with the use of antibiotics in order to prevent the emergence and spread of infectious diseases in fish. This practice constitutes a real public health problem, not only due to the presence of antimicrobial residues in edible tissues, which can cause allergic reactions in hypersensitive individuals, but also due to the emergence of bacterial resistance. Consequently, the Regulatory Agencies have established maximum residue limits (MRL_s). In the present study, a validated multiclass multi-residue ultra-high-performance liquid chromatography coupled with mass spectrometry in tandem methodology was used for the determination of 41 antibiotics from seven different classes—sulfonamides, trimethoprim, tetracyclines, macrolides, quinolones, penicillins and chloramphenicol—in 29 samples of gilthead sea bream of aquaculture origin, purchased in Portugal. The analysed samples showed that, in eight of them, antibiotic residues were present, three being of doxycycline—antibiotic for which no MRL is established—that was detected in concentrations ranging from 0.35 to 0.61 μg kg^?1. Other antibiotics were also detected and quantified and their concentrations were below the MRL established by the European legislation.     

Rhodium catalyzed hydroformylation of kaurane derivatives: A route to new diterpenes with potential bioactivity

Kaurenic and grandiflorenic acids are naturally occurring diterpenes whose biological activity has been described. Both acids contain an exocyclic methylenic double bond that allows further functionalization on their structure. In an attempt to expand the number of derivatives of these two natural products, we have undertaken a study on the hydroformylation of the methyl esters of the two acids and the trimethylsilyl ether of kaurenol. These substrates have been hydroformylated by using unmodified Rh catalysts, as well as Rh/PPh₃ and Rh/tris-(o-t-butylphenyl)phosphite catalytic systems at 100 °C and 20 bar of CO/H₂ (1:1). For the three substrates, the two Rh catalysts modified with P-donor ligands, produced high conversions and chemo- and regioselectivities in the diastereoisomeric pair of linear aldehydes. In all cases, the stereoselectivity observed is strongly dependent of the system used, being the most diastereoselective the least hindered unmodified Rh/CO catalyst. A correlation between the higher diastereoselectivity and the faster β-elimination of the metal-alkyl intermediate observed in the unmodified system is discussed.     

Evaluation of in vitro cytotoxicity,biocompatibility, and changes in the expression of apoptosis regulatory proteins induced by cerium oxide nanocrystals

Abstract

Cerium oxide nanocrystals (CeO₂-NCs) exhibit superoxide dismutase and catalase mimetic activities. Based on these catalytic activities, CeO₂-NCs have been suggested to have the potential to treat various diseases. The crystalline size of these materials is an important factor that influences the performance of CeO₂-NCs. Previous reports have shown that several metal-based nanocrystals, including CeO₂-NCs, can induce cytotoxicity in cancer cells. However, the underlying mechanisms have remained unclear. To characterize the anticancer activities of CeO₂-NCs, several assays related to the mechanism of cytotoxicity and induction of apoptosis has been performed. Here, we have carried out a systematic study to characterize CeO₂-NCs phase purity (X-ray diffraction), morphology (electron microscopy), and optical features (optical absorption, Raman scattering, and photoluminescence) to better establish their potential as anticancer drugs. Our study revealed anticancer effects of CeO₂-NCs in HT29 and SW620 colorectal cancer cell lines with half-maximal inhibitory concentration (IC₅₀) values of 2.26 and 121.18 μg ml^–1, respectively. Reductions in cell viability indicated the cytotoxic potential of CeO₂-NCs in HT29 cells based on inverted and florescence microscopy assessments. The mechanism of cytotoxicity confirmed by estimating possible changes in the expression levels of Bcl2, BclxL, Bax, PARP, cytochrome c, and β-actin (control) proteins in HT29 cells. Down-regulation of Bcl2 and BclxL and up-regulation of Bax, PARP, and cytochrome c proteins suggested the significant involvement of CeO₂-NCs exposure in the induction of apoptosis. Furthermore, biocompatibility assay showed minimum effect of CeO₂-NCs on human red blood cells.     

Effects of chemical agents on physical properties and structure of primary pulp chamber dentin

This study evaluated the effects of chemical agents on the physical properties and structure of primary pulp chamber dentin using surface roughness, microhardness tests, and scanning electron microscopy (SEM). Twenty‐five primary teeth were sectioned exposing the pulp chamber and were divided into five groups (n = 5): NT, no treatment; SH1, 1% sodium hypochlorite (NaOCl); SH1U, 1% NaOCl + Endo‐PTC^®; SH1E, 1% NaOCl + 17% EDTA; and E, 17% EDTA. After dentin treatment, the specimens were submitted to roughness, microhardness testing, and SEM analysis. Roughness and microhardness data were submitted to one‐way ANOVA and Tukey's test (P < 0.05). The SH1E group showed the highest roughness, followed by the E group (P < 0.05) when compared with the NT, SH1, and SH1U groups. Microhardness values of SH1 and SH1U showed no significant difference as compared to the NT (control) group (P > 0.05). Microhardness values could not be obtained in the EDTA groups (SH1E and E). The presence of intertubular dentin with opened dentin tubules was observed in the NT, SH1, and SH1U groups. SH1E showed eroded and disorganized dentin with few opened tubules and the intertubular/peritubular dentin was partially removed. Considering the physical and structural approaches and the chemical agents studied, it can be concluded that NaOCl and NaOCl associated with Endo‐PTC^® were the agents that promoted the smallest changes in surface roughness, microhardness, and structure of the pulp chamber dentin of primary teeth. Microsc. Res. Tech. 77:52–56, 2014. © 2013 Wiley Periodicals, Inc.     

In Situ Imaging of Barnacle (Balanus amphitrite) Cyprid Cement Using Confocal Raman Microscopy

Barnacles are a model for research on permanent underwater adhesion and the wider process of marine biofouling. A detailed understanding of the permanent adhesive secreted by the cypris larva for permanent settlement, the so-called cyprid cement, has potential to lead to novel antifouling solutions. There is a need for micro-analytical chemical in situ methods to gain more insight into the process of adhesion and the chemical composition of the cement. In this study, the applicability of confocal Raman microscopy for imaging the cyprid cement beneath permanently attached juvenile barnacles (Balanus amphitrite) was explored. Based on acquired area scans Raman images for characteristic chemical functional groups were obtained. In addition to showing the morphology of the attachment apparatus, the images provided information on chemical composition, in particular the hydration state of the cement, and demonstrated the potential of this method for in situ studies of adhesion at the micro-scale.     

Isolation and genetic identification of spore-forming bacteria associated with concentrated-milk processing in Nebraska

Spore-forming bacteria are heat-resistant microorganisms capable of surviving and germinating in milk after pasteurization. They have been reported to affect the quality of dairy products by the production of enzymes (lipolytic and proteolytic) under low-temperature conditions in fluid milk, and have become a limiting factor for milk powder in reaching some selective markets. The objective of this research was to isolate and identify the population of spore-forming bacteria (psychrotrophic and thermophilic strains) associated with concentrated milk processing in Nebraska. During 2 seasons, in-process milk samples from a commercial plant (raw, pasteurized, and concentrated) were collected and heat-treated (80°C/12 min) to recover only spore-formers. Samples were spread-plated using standard methods agar and incubated at 32°C to enumerate mesophilic spore counts. Heat-treated samples were also stored at 7°C and 55°C to recover spore-formers that had the ability to grow under those temperature conditions. Isolates obtained from incubation or storage conditions were identified using molecular techniques (16S or rpoB sequencing). Based on the identification of the isolates and their relatedness, strains found in raw, pasteurized, and concentrated milk were determined to be similar. Paenibacillus spp. were associated with both raw and concentrated milk. Due to their known ability to cause spoilage under refrigeration, this shows the potential risk associated with the transferring of these problematic organisms into other dairy products. Other Bacillus species found in concentrated milk included Bacillus clausii, Bacillus subtilis, Lysinibacillus sp., Bacillus safensis, Bacillus licheniformis, Bacillus sonorensis, and Brevibacillus sp., with the last 3 organisms being capable of growing at thermophilic temperatures. These strains can also be translocated to other dairy products, such as milk powder, representing a quality problem. The results of this research highlight the importance of understanding spore-formers associated with the processing of condensed milk, which then may allow for specific interventions to be applied to control these microorganisms in this processing chain. To our knowledge, this is the first study evaluating spore-formers associated with concentrated milk in the United States.     

An acoustic wave sensor for the hydrophilic fluoride

A new acoustic wave sensor to detect and quantify fluoride, one of the most hydrophilic anions, is proposed. Meso-octamethylcalix[4]pyrrole (OMCP) and seven of its derivatives were evaluated as piezoelectric quartz crystal coatings. Some of these sensors experienced appreciable coating leaching under a water flow, while others did show a very small sensitivity to fluoride. As the OMCP-naphthoquinone sensor was very sensitive to fluoride and did not lose a significant amount (α = 0.05) of coating during eight weeks, it was selected among all the others. A piezoelectric crystal coated with an amount of OMCP-naphthoquinone that produced a frequency decrease of 22 kHz showed a linear calibration range that extended up to 80 mg L⁻¹, within which sensitivity to fluoride was 0.45 Hz L mg⁻¹_, and was able to detect fluoride at the concentration of 3.66 mg L⁻¹. This sensor was used to determine fluoride in commercial fluoride tablets, and the result found was not statistically different (α = 0.05) from the value provided by the manufacturer.     

Reduction of fumonisin B₁ in corn grits by twin-screw extrusion

Abstract: This study was designed to investigate the fate of fumonisins in flaking corn grits during twin‐screw extrusion by measuring fumonisin B₁ (FB₁) and its analogs with a mass balance approach. Food grade corn grits and 2 batches of grits contaminated with FB₁ at 10 and 50 μg/g by Fusarium verticillioides M‐2552 were processed with or without glucose supplementation (10%, w/w) with a twin‐screw extruder. Extrusion reduced FB₁ in contaminated grits by 64% to 72% without glucose and 89% to 94% with added glucose. In addition, extrusion alone resulted in 26% to 73% reduction in the levels of fumonisin B₂ and fumonisin B₃, while levels of both mycotoxins were reduced by >89% in extruded corn grits containing 10% glucose. Mass balance analysis showed that 38% to 46% of the FB₁ species detected in corn extruded with glucose was N‐(deoxy‐D‐fructos‐1‐yl)‐FB₁, while 23% to 37% of FB₁ species detected in extruded corn grits with and without added glucose was bound to the matrix. It was also found that the hydrolyzed form of FB₁ was a minor species in extruded corn grits with or without added glucose, representing <15% of the total FB₁ species present. Less than 46% of FB₁ originally present in corn grits could be detected in the fumonisin analogues measured in this study. Research is needed to identify the reaction products resulting from extrusion processing of fumonisin‐contaminated corn products. Practical Application: Twin‐screw extrusion is widely used in food industry for its versatility. This technology may reduce the level of fumonisins in corn particularly with added glucose.