Development of an impedance based biosensor for studies of spheroids formation

Three-dimensional (3D) multicellular spheroids are exceptional in vitro cell models for their ability to accurately mimic real cell-cell interaction processes. However, the challenges in producing well-defined spheroids with controlled size together with the deficiency of techniques to monitor them significantly restrict their use. Herein, a novel device to study spheroid formation in real time is presented. By exploiting electrochemical impedance spectroscopy, a multi-electrode array (MEA) attached to a calcium alginate scaffold is able to monitor the behaviour of 36 different hydrogel wells. The scaffold contains inverted shape pyramidal microwells, which guide the aggregation of cells into spheroids with controlled dimensions. Preliminar studies on calcium alginate, optimisation of fabrication strategy are shown, together with testing of the device in the presence and the absence of the hydrogel. Lastly, the device was tested for its intended aim, i.e. to monitor the formation of a spheroid, proving its potential as an impedance biosensor.

On The Distinct Molecular Architectures Of Dipping- And Spray-lbl Films Containing Lipid Vesicles.

The introduction of spraying procedures to fabricate layer-by-layer (LbL) films has brought new possibilities for the control of molecular architectures and for making the LbL technique compliant with industrial processes. In this study we show that significantly distinct architectures are produced for dipping and spray-LbL films of the same components, which included DODAB/DPPG vesicles. The films differed notably in their thickness and stratified nature. The electrical response of the two types of films to aqueous solutions containing erythrosin was also different. With multidimensional projections we showed that the impedance for the DODAB/DPPG spray-LbL film is more sensitive to changes in concentration, being therefore more promising as sensing units. Furthermore, with surface-enhanced Raman scattering (SERS) we could ascribe the high sensitivity of the LbL films to adsorption of erythrosin.

Corrosion Kinetics And Topography Analysis Of Ti-6al-4v Alloy Subjected To Different Mouthwash Solutions.

This study evaluated the corrosion kinetics and surface topography of Ti-6Al-4V alloy exposed to mouthwash solutions (0.12% chlorhexidine digluconate, 0.053% cetylpyridinium chloride and 3% hydrogen peroxide) compared to artificial saliva (pH6.5) (control). Twenty Ti-6Al-4V alloy disks were used and divided into 4 groups (n=5). For the electrochemical assay, standard tests as open circuit potential and electrochemical impedance spectroscopy (EIS) were applied at baseline, 7 and 14days after immersion in the solutions. Scanning electron microscopy, atomic force microscopy and profilometry (average roughness - Ra) were used for surface characterization. Total weight loss of disks was calculated. Data were analyzed by ANOVA and Bonferroni's test (α=0.05). Hydrogen peroxide generated the lowest polarization resistance (Rp) values for all periods (P<0.05). For the capacitance (Cdl), similar results were observed among groups at baseline (P=0.098). For the 7 and 14-day periods, hydrogen peroxide promoted the highest Cdl values (P<0.0001). Hydrogen peroxide promoted expressive superficial changes and greater Ra values than the others (P<0.0001). It could be concluded that solutions containing cetylpyridinium chloride and chlorhexidine digluconate might be the mouthwashes of choice during the post-operatory period of dental implants. However, hydrogen peroxide is counter-indicated in these situations. Further studies evaluating the dynamics of these solutions (tribocorrosion) and immersing the disks in daily cycles (two or three times a day) to mimic a clinical situation closest to the application of mouthwashes in the oral cavity are warranted to prove our results.

Endocytosis Of Tight Junctions Caveolin Nitrosylation Dependent Is Improved By Cocoa Via Opioid Receptor On Rpe Cells In Diabetic Conditions.

Retinal pigment epithelium cells, along with tight junction (TJ) proteins, constitute the outer blood retinal barrier (BRB). Contradictory findings suggest a role for the outer BRB in the pathogenesis of diabetic retinopathy (DR). The aim of this study was to investigate whether the mechanisms involved in these alterations are sensitive to nitrosative stress, and if cocoa or epicatechin (EC) protects from this damage under diabetic (DM) milieu conditions. Cells of a human RPE line (ARPE-19) were exposed to high-glucose (HG) conditions for 24 hours in the presence or absence of cocoa powder containing 0.5% or 60.5% polyphenol (low-polyphenol cocoa [LPC] and high-polyphenol cocoa [HPC], respectively). Exposure to HG decreased claudin-1 and occludin TJ expressions and increased extracellular matrix accumulation (ECM), whereas levels of TNF-α and inducible nitric oxide synthase (iNOS) were upregulated, accompanied by increased nitric oxide levels. This nitrosative stress resulted in S-nitrosylation of caveolin-1 (CAV-1), which in turn increased CAV-1 traffic and its interactions with claudin-1 and occludin. This cascade was inhibited by treatment with HPC or EC through δ-opioid receptor (DOR) binding and stimulation, thereby decreasing TNF-α-induced iNOS upregulation and CAV-1 endocytosis. The TJ functions were restored, leading to prevention of paracellular permeability, restoration of resistance of the ARPE-19 monolayer, and decreased ECM accumulation. The detrimental effects on TJs in ARPE-19 cells exposed to DM milieu occur through a CAV-1 S-nitrosylation-dependent endocytosis mechanism. High-polyphenol cocoa or EC exerts protective effects through DOR stimulation.

Interações sociais em aulas de educação fisica

Universidade Estadual de Campinas . Faculdade de Educação Física

Estado nutricional e qualidade de vida de escolares de 7 a 10 anos de idade de municípios da Região Metropolitana de Campinas

Universidade Estadual de Campinas. Faculdade de Educação Física

Inter-relações de turistas e moradores : um olhar atraves das manifestações corporais no Carnaval de Ouro Preto

Universidade Estadual de Campinas. Faculdade de Educação Física

Lazer e grupos sociais ; : concepções e metodo

Universidade Estadual de Campinas . Faculdade de Educação Física

A motricidade como base para a aprendizagem : o estudo de um caso pela reorganização neurofuncional

Universidade Estadual de Campinas . Faculdade de Educação Física

Estado nutricional e composição corporal de crianças do ensino fundamental do municipio de Vinhedo - SP

Universidade Estadual de Campinas . Faculdade de Educação Física

Characterization of the interdependency between residues that bind the substrate in a β-glycosidase

The manner by which effects of simultaneous mutations combine to change enzymatic activity is not easily predictable because these effects are not always additive in a linear manner. Hence, the characterization of the effects of simultaneous mutations of amino acid residues that bind the substrate can make a significant contribution to the understanding of the substrate specificity of enzymes. In the β-glycosidase from Spodoptera frugiperda (Sfβgly), both residues Q39 and E451 interact with the substrate and this is essential for defining substrate specificity. Double mutants of Sfβgly (A451E39, S451E39 and S451N39) were prepared by site-directed mutagenesis, expressed in bacteria and purified using affinity chromatography. These enzymes were characterized using p-nitrophenyl β-galactoside and p-nitrophenyl β-fucoside as substrates. The k cat/Km ratio for single and double mutants of Sfβgly containing site-directed mutations at positions Q39 and E451 was used to demonstrate that the effect on the free energy of ES‡ (enzyme-transition state complex) of the double mutations (∆∆G‡xy) is not the sum of the effects resulting from the single mutations (∆∆G‡x and ∆∆G‡y). This difference in ∆∆G‡ indicates that the effects of the single mutations partially overlap. Hence, this common effect counts only once in ∆∆G‡xy. Crystallographic data on β-glycosidases reveal the presence of a bidentate hydrogen bond involving residues Q39 and E451 and the same hydroxyl group of the substrate. Therefore, both thermodynamic and crystallographic data suggest that residues Q39 and E451 exert a mutual influence on their respective interactions with the substrate.

Determinação de ácido acéttico em amostra de vinagre adulterada com ácido clorídrico - um experimento integrado de titulação potenciométrica e condutométrica

The determination of acetic acid in vinegar adulterated sample using simultaneous potentiometric and condutometric titrations was used as an example of integrated experiment in instrumental analysis. An Excel® spreadsheet, which allows the entry of simultaneous data and the construction of the superimposed experimental curves (condutometric, potentiometric, first and second derivative potentiometric curve and, distribution diagrama of the acetic species as function of pH), was used as powerful tool to discuss the fundamental concepts involved in each technique and choose the best of them to quantify, without mutual interference, H3CCOOH and HCl in vinegar adulterated sample.

Electronic conduction and electrocatalysis by supramolecular tetraruthenated copper porphyrazine films

A new tetraruthenated copper(II)-tetra(3,4-pyridyl)porphyrazine species, [CuTRPyPz]4+, has been synthesized and fully characterized by means of analytical, spectroscopic and electrochemical techniques. This À-conjugated system contrasts with the related meso-tetrapyridylporphyrins by exhibiting strong electronic interaction between the coordinated peripheral complexes and the central ring. Based on favorable À-stacking and electrostatic interactions, layer-by-layer assembled films were successfully generated from the appropriate combination of [CuTRPyPz]4+ with copper(II)-tetrasulfonated phtalocyanine, [CuTSPc]4-. Their conducting and electrocatalytic properties were investigated by means of impedance spectroscopy and rotating disc voltammetry, exhibiting metallic behavior near the Ru(III/II) redox potential, as well as enhanced catalytic activity for the oxidation of nitrite and sulphite ions.

Clonal relationship among atypical enteropathogenic Escherichia coli strains isolated from different animal species and humans

Forty-nine typical and atypical enteropathogenic Escherichia coli (EPEC) strains belonging to different serotypes and isolated from humans, pets (cats and dogs), farm animals (bovines, sheep, and rabbits), and wild animals (monkeys) were investigated for virulence markers and clonal similarity by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The virulence markers analyzed revealed that atypical EPEC strains isolated from animals have the potential to cause diarrhea in humans. A close clonal relationship between human and animal isolates was found by MLST and PFGE. These results indicate that these animals act as atypical EPEC reservoirs and may represent sources of infection for humans. Since humans also act as a reservoir of atypical EPEC strains, the cycle of mutual infection of atypical EPEC between animals and humans, mainly pets and their owners, cannot be ruled out since the transmission dynamics between the reservoirs are not yet clearly understood.

Metabolic syndrome and dietary components are associated with coronary artery disease risk score in free-living adults: a cross-sectional study

Background: Coronary artery disease (CAD) is among the main causes of death in developed countries, and diet and lifestyle can influence CAD incidence. Objective: To evaluate the association of coronary artery disease risk score with dietary, anthropometric and biochemical components in adults clinically selected for a lifestyle modification program. Methods: 362 adults (96 men, 266 women, 53.9 +/- 9.4 years) fulfilled the inclusion criteria by presenting all the required data. The Framingham score was calculated and the IV Brazilian Guideline on Dyslipidemia and Prevention of Atherosclerosis was adopted for classification of the CAD risks. Anthropometric assessments included waist circumference (WC), body fat and calculated BMI (kg/m(2)) and muscle-mass index (MMI kg/m(2)). Dietary intake was estimated through 24 h dietary recall. Fasting blood was used for biochemical analysis. Metabolic Syndrome (MS) was diagnosed using NCEP-ATPIII (2001) criteria. Logistic regression was used to determine the odds of CAD risks according to the altered components of MS, dietary, anthropometric, and biochemical components. Results: For a sample with a BMI 28.5 +/- 5.0 kg/m(2) the association with lower risk (<10% CAD) were lower age (<60 years old), and plasma values of uric acid. The presence of MS within low, intermediary, and high CAD risk categories was 30.8%, 55.5%, and 69.8%, respectively. The independent risk factors associated with CAD risk score was MS and uric acid, and the protective factors were recommended intake of saturated fat and fiber and muscle mass index. Conclusion: Recommended intake of saturated fat and dietary fiber, together with proper muscle mass, are inversely associated with CAD risk score. On the other hand, the presence of MS and high plasma uric acid are associated with CAD risk score.