13C2]-Acetaldehyde promotes unequivocal formation of 1,N2-propano-2'-deoxyguanosine in human cells

Acetaldehyde is an environmentally widespread genotoxic aldehyde present in tobacco smoke, vehicle exhaust and several food products. Endogenously, acetaldehyde is produced by the metabolic oxidation of ethanol by hepatic NAD-dependent alcohol dehydrogenase and during threonine catabolism. The formation of DNA adducts has been regarded as a critical factor in the mechanisms of acetaldehyde mutagenicity and carcinogenesis. Acetaldehyde reacts with 2'-deoxyguanosine in DNA to form primarily N(2)-ethylidene-2'-deoxyguanosine. The subsequent reaction of N(2)-ethylidenedGuo with another molecule of acetaldehyde gives rise to 1,N(2)-propano-2'-deoxyguanosine (1,N(2)-propanodGuo), an adduct also found as a product of the crotonaldehyde reaction with dGuo. However, adducts resulting from the reaction of more than one molecule of acetaldehyde in vivo are still controversial. In this study, the unequivocal formation of 1,N(2)-propanodGuo by acetaldehyde was assessed in human cells via treatment with [(13)C(2)]-acetaldehyde. Detection of labeled 1,N(2)-propanodGuo was performed by HPLC/MS/MS. Upon acetaldehyde exposure (703 μM), increased levels of both 1,N(2)-etheno-2'-deoxyguanosine (1,N(2)-εdGuo), which is produced from α,β-unsaturated aldehydes formed during the lipid peroxidation process, and 1,N(2)-propanodGuo were observed. The unequivocal formation of 1,N(2)-propanodGuo in cells exposed to this aldehyde can be used to elucidate the mechanisms associated with acetaldehyde exposure and cancer risk.     

Effect of aqueous and ethanolic extracts from pinhão coats on the properties of corn and pinhão starches

Journal of Thermal Analysis and Calorimetry - The Araucaria angustifolia seed, named pinhão, has a high content of carbohydrates, and it is considered an unconventional starch source. Its...     

Expanding the applicability of magnetic ionic liquids for multiclass determination in biological matrices based on dispersive liquid–liquid microextraction and HPLC with diode array detector analysis

Monitoring biological samples at trace levels of chemicals from anthropogenic actions such as pesticides, pharmaceuticals, and hormones has become a very important subject. This work describes a method for the determination of eight compounds of different chemical classes in human urine samples. Dispersive liquid–liquid microextraction based on magnetic ionic liquids was used as the sample preparation procedure. The main parameters of the method, such as sample dilution, type, and volume of disperser solvent, amount of magnetic ionic liquids, extraction time, and pH were optimized by univariate and multivariate procedures. Validation was performed using a urine sample of a male volunteer in order to obtain a calibration curve and the main analytical parameters of merit such as limits of detection and quantification. Values varied from 3.0 to 7.5 µg/L and from 10 to 25 µg/L, respectively. Satisfactory precisions of 21% for intraday (n = 3) and 16% for interday (n = 9) were achieved. Accuracy was evaluated by relative recovery assays using different urine samples and ranged from 75 to 130%. Robustness was assured by the Lenth method. The validated procedure was applied to five urine samples from different volunteers and the hormone estrone was found in one sample.     

Immobilization of Candida antarctica lipase B on the surface of modified sol–gel matrix

The use of modified sol–gel matrix to immobilize the enzyme Candida antartica lipase B (CALB) was investigated. Free hydroxyl groups on the matrix surface were exploited to covalently immobilize the enzyme. Based from the results, incorporating hydrophobic sol–gel precursor (ethyltrimethoxysilane) enhanced enzyme activity. An enzyme activity of 192.02 U/g beads with 80.88 % attachment was obtained. At alkaline pH, immobilization yield of enzyme increased. The attachment of enzyme on the surface of the matrix was confirmed by scanning electron microscope images. Covalently immobilized CALB on sol–gel supports has higher thermal stability with 2.7 times higher half-life compared to soluble enzymes at 60 °C. This enzyme immobilization system retains the enzyme residual activity even for repetitive use. Hence, the immobilization approach developed recommends its further application.     

Determination of residual oil in diesel oil by spectrofluorimetric and chemometric analysis

Multivariate calibration (PLS), principal components analysis (PCA) and linear discriminant analysis (LDA), associated to synchronous spectrofluorimetry, were used to identify and quantify non-transesterified residual vegetable oil in diesel oil with the addition of 2% of biodiesel (B2). The addition of residual oil, one of the easiest ways of adultering fuel, damages engines and leads to tax evasion. Using this method, the samples of diesel oil, B2, and B2 contaminated with residual oil were classified correctly and separated into three well-defined groups. The quantification of residual oil in B2 was carried out in the 0-25% (w/w) band, RMSEC and RMSEP values ranging from 0.26 to 0.48% (w/w) and 1.6-2.6% (w/w), respectively. The method is highly sensitive and efficient to identify and quantify this type of adulterant in which 100% of the samples were correctly classified and the average relative error was approximately 4% in the range 0.5-25% (w/w).     

Development and validation of a liquid chromatographic/tandem mass spectrometric method for determination of tetracycline in human plasma: application to bioequivalence study

A fast, sensitive, and specific liquid chromatographic/tandem mass spectrometric method was developed and validated for determination of tetracycline in human plasma. Tetracycline and oxytetracycline [internal standard (IS)] were extracted from the plasma by protein precipitation. The mobile phase consisted of acetonitrile-formic acid 0.1% (48 + 52, v/v), run at a flow rate of 1 ml/min (split 1:5). Detection was performed by positive electrospray ionization in multiple reaction monitoring mode, monitoring the transitions 444.8 > 410.0 and 461.0 > 426.0 for tetracycline and IS, respectively. The analysis was performed in 3.5 min and the method was linear in the plasma concentration range of 50-6000 ng/mL. The mean extraction recoveries for tetracycline and IS from plasma were 92.14 and 94.04%, respectively. Method validation investigated parameters such as the linearity, precision, accuracy, specificity, and stability, giving results within the acceptable range. The proposed method was successfully applied for determination of tetracycline in human plasma samples to support bioequivalence studies.     

Control of properties of nanocomposites bio-based collagen and cellulose nanocrystals

Collagen is an important biomaterial because it has many applications in the biomedical sector. However, the high hydrophilicity of collagen (COL) leads to easy swelling. Thus, controlling this property is highly desirable. In this work, cellulose nanocrystals (CNCs) dispersed in glycerol (GLI) were incorporated in the matrix collagen to tailor the hydrophilicity and mechanical properties. Study of the hydrophilicity of the bio-based nanocomposite was evaluated by contact angle measurement and thermogravimetric analysis. Mechanical analyses showed that CNCs are excellent reinforcing fillers to the collagen matrix. Synchrotron small-angle X-ray scattering was employed to investigate the nanostructures of COL/GLI/CNC nanocomposites and CNC water dispersion. CNC in concentrations up to 1 wt% presents an intermediate shape between a rod and a plane with a 9.34-nm radius of gyration (R _g). Bio-based nanocomposites present two different structural levels with two types of particles with very different R _gs. At the intermediate power-law regime, a large-scale mass fractal aggregate is observed. In the high-power-law regime, it is observed scattering from primary particles smaller than 1 nm. As the CNC concentration increases, the original particle distorts from a rod to a plate. The cytotoxicity assay indicates that the collagen and nanocomposites did not affect the cell viability of rat calvarial cells in vitro.     

Ultrastructural localization of Trypanosoma cruzi lysosomes by aryl sulphatase cytochemistry

Lysosomes of trypanosomatid protozoa are poorly known. In this work we have cytochemically detected the lysosomal enzyme aryl sulphatase in the trypanosomatids Trypanosoma cruzi and Crithidia fasciculata, by using p-nitrocatecholsulphate as substrate. Positive reaction was located exclusively inside membrane-bound cytoplasmic vesicles distributed throughout the cell body. Electron-dense reaction was either dispersed homogeneously through the vesicular matrix or located at the vesicle periphery, apposed to the membrane, with fine granular deposits occasionally found at the vesicular matrix. Trypomastigote and epimastigote forms of T. cruzi lacked electron-dense deposits at the plasma membrane, thus indicating that aryl sulphatase was not secreted to the environment. Furthermore, no positive reaction was detected in epimastigote reservosomes, which are organelles considered as pre-lysosomal compartments. Thus, our data show that reservosomes and lysosomes are organelles that can be distinguished by the cytochemical localization of aryl sulphatase in T. cruzi epimastigotes and trypomastigotes. Positive reaction in cytoplasmic vesicles of C. fasciculata choanomastigotes confirmed the specificity of the reaction for lysosomes in other trypanosomatid species.     

Effects of therapeutic pulsed ultrasound and dimethylsulfoxide phonophoresis on oxidative stress parameters after injury induced by eccentric exercise

Introduction

The aim of the study was to evaluate the effects of TPU together with DMSO on oxidative stress parameters after eccentric exercise.

Methods

Thirty and six animals were divided in control; eccentric exercise (EE); EE + saline gel 0.9%; EE + TPU 0.8 W/cm²; EE + DMSO gel; EE + TPU + DMSO gel and submitted to one 90-min downhill run (1.0 km h⁻¹). TPU was used 2, 12, 24, 46 h after exercise session and 48 h after the animals were killed and the gastrocnemius muscles were surgically removed. Production of superoxide anion, creatine kinase (CK) levels, lipoperoxidation, carbonylation, and antioxidants enzymes were analyzed.

Results

Showed that TPU and gel-DMSO improved muscle healing. Moreover, superoxide anion production, TBARS level and protein carbonyls levels, superoxide dismutase and catalase activity were all decreased in the group TPU plus gel-DMSO.

Discussion

Our results show that DMSO is effective in the reduction of the muscular lesion and in the oxidative stress after eccentric exercise only when used with TPU.     

Higher Order Coherent Pairs

In this paper, we study necessary and sufficient conditions for the relation $$\begin{array}{@{}l}P_n^{{[r]}}(x) + a_{n-1,r} P_{n-1}^{{[r]}}(x)= R_{n-r}(x) + b_{n-1,r} R_{n-r-1}(x),\\[5pt]\quad a_{n-1,r}\neq0,\ n\geq r+1,\end{array}$$ where {P _n (x)} _n??0 and {R _n (x)} _n??0 are two sequences of monic orthogonal polynomials with respect to the quasi-definite linear functionals $\mathcal{U},\mathcal{V}$ , respectively, or associated with two positive Borel measures ?? ₀,?? ₁ supported on the real line. We deduce the connection with Sobolev orthogonal polynomials, the relations between these functionals as well as their corresponding formal Stieltjes series. As sake of example, we find the coherent pairs when one of the linear functionals is classical.