Tannase from Aspergillus melleus improves the antioxidant activity of green tea: purification and biochemical characterisation

Tannase is an inducible enzyme used extensively in food, feed, pharmaceutical and chemical industries. In this study, tannase production and its biochemical properties were evaluated. From 42 Aspergillus strains analysed for potential tannase selection, Aspergillus melleus yielded the best results. Production was analysed using a complete factorial planning of 2³. Maximum activity (452.55 U mL^?1) was obtained in the optimal conditions of substrate (5.0 g), initial moisture (60%), tannic acid (2%) and 48 h of fermentation. The molecular weight of the purified enzyme was estimated as 69.52 kDa; its optimum temperature and pH were 40 °C and 5.5, respectively. Regarding the chemical effectors used, tannase was inhibited by ZnCl₂, ZnSO₄, Triton X‐100 and SDS. The addition of tannase to green tea improved its antioxidant potential by approximately 85% when compared to the control. The present results suggest that tannase may be used as an adjuvant to increase the antioxidant potential of green tea.     

Clitocybe alexandri extract induces cell cycle arrest and apoptosis in a lung cancer cell line: Identification of phenolic acids with cytotoxic potential

Mushrooms are a possible rich source of biologically active compounds with the potential for drug discovery. The aim of this work was to gain further insight into the cytotoxicity mechanism of action of Clitocybe alexandri ethanolic extract against a lung cancer cell line (NCI-H460 cells). The effects on cell cycle profile and levels of apoptosis were evaluated by flow cytometry, and the effect on the expression levels of proteins related to cellular apoptosis was also investigated by Western blot. The extract was characterised regarding its phenolic composition by HPLC-DAD, and the identified compounds were studied regarding their growth inhibitory activity, by sulforhodamine B (SRB) assay. The effect of individual or combined compounds on viable cell number was also evaluated using the Trypan blue exclusion assay. It was observed that the C. alexandri extract induced an S-phase cell cycle arrest and increased the percentage of apoptotic cells. In addition, treatment with the GI₅₀ concentration (concentration that was able to cause 50% of cell growth inhibition; 24.8 μg/ml) for 48 h caused an increase in the levels of wt. p53, cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase (PARP). The main components identified in this extract were protocatechuic, p-hydroxybenzoic and cinnamic acids. Cinnamic acid was found to be the most potent compound regarding cell growth inhibition. Nevertheless, it was verified that the concomitant use of the individual compounds provided the strongest decrease in viable cell number. Overall, evidence was found for alterations in cell cycle and apoptosis, involving p53 and caspase-3. Furthermore, our data suggests that the phenolic acids identified in the extract are at least partially responsible for the cytotoxicity induced by this mushroom extract.     

Improvement of the Molar Tube Bond Durability with Preheated Orthodontic Adhesive

This study aimed to evaluate the effect of preheated orthodontic adhesives and thermal cycling on the bond strength of molar tubes. One hundred sixty molar tubes were bonded to acid-etched bovine incisors using a conventional orthodontic adhesive (Transbond XT), two microhybrid (Wave and Permaflo), and a nanofilled (Filtek Z350) flowable composite resins, at room temperature or preheated at 60°C. Transbond XT primer and Single Bond 2 adhesive system were used in association with Transbond XT and the flowable composites, respectively. The specimens were stored in water (37°C) for 24 h, and half of the sample was subjected to thermal cycling for 6000 cycles. Ashear bond strength (SBS) test was performed, followed by the appraisal of the adhesive Remnant Index (ARI). Three-way analysis of variance (ANOVA) and the Tukey test were performed at a significance level of 95% (P < .05). Samples bonded with preheated adhesives showed higher SBS regardless of the aging method. Only samples bonded with preheated conventional orthodontic adhesive maintained their bond strength after thermal cycling for 6000 cycles. Preheating orthodontic adhesives improved the bond strength of molar tubes, but only the preheated conventional orthodontic adhesive was capable of maintaining bond strength after thermal cycling.     

An analysis of the machinability of ASTM grades 2 and 3 austempered ductile iron

The main goal of this work is to perform an analysis of the machinability of two ASTM grades of ADI, namely 2 and 3. The samples used in this work were cast and austempered according to ASTM standards for the production of grade 2 (G2) and grade 3 (G3) ADI. Characterization was accomplished through tensile and hardness tests, metallography and X-ray diffraction. Machinability was evaluated by analyzing tool life, cutting forces, surface finish and chip characteristics in turning operations. A quick-stop test was also performed in order to verify some mechanical processes during the chip formation and to analyze the shear plane angle. Tool life when machining G2 was 33% lower than G3 (18 min against 26 min), although the latter is a harder material. Abrasion and adhesion were the wear mechanisms observed through SEM images, whereas in other cast irons mainly abrasion is observed. Cutting forces measurements showed that the value of K_c1,1 decreased 19%, from 1448 to 1175 N/mm², for G2 as the depth of cut increased from 2 to 5 mm at a cutting speed of 80 m/min and 18%, from 1501 to 1236 N/mm², for G3. Surface roughness measurements proved that a smoother surface is obtained for both alloys at f = 0.10 mm/rev when using an insert with nose radius 1.6 mm instead of smaller radii. Both alloys presented similar surface quality. All chips observed were segmented.     

Characterizing inorganic crystals grown on organic self‐assembled bilayers with scanning probe and electron microscopies

Combined microscopy techniques are used to establish the usability of phosphonic acid layers as promoters of hydroxyapatite (HAp) growth. Using spread coating, octadecylphosphonic acid (OPA) self‐assembled bilayers are delivered to the thin natural oxide layer of a titanium film surface with no prior treatment. These bilayers aggregate two major advantages of phosphonic moieties to titanium surfaces: nucleation of hydroxyapatite crystals from ionic solution and affinity for both titanium oxide surface and HAp crystals. The functionalized substrates and bare titanium (control) samples are immersed in an aqueous solution containing calcium and phosphorus ions. Over a 4‐week immersion time, OPA‐functionalized substrates present numerous large agglomerates of inorganic crystals, in contrast to control samples, with no significant amount of deposits. Initial sample characterization was performed with atomic force microscopy (AFM). Compositional and structural characterization of these agglomerates (using TEM, EDS, and electron diffraction), revealed that they are indeed HAp, the main component of the inorganic bone matrix. Microsc. Res. Tech. 76:1278–1283, 2013. © 2013 Wiley Periodicals, Inc.     

High‐fat diet based on trienantin has no adverse metabolic effects in rats

The present study was designed to evaluate the metabolic effects of a high‐fat diet based on trienantin, an uncommon medium‐odd‐chain triacylglycerol. Male Wistar rats (33.37 ± 5.69 g) (n = 3×10) were maintained for 6 weeks on a control diet (7 g soya oil/100 g) or a high‐fat diet based on trienantin (40 g margarine, 4 g soya oil and 25.79 g trienantin/100 g), or a high‐fat diet based on soya oil (40 g margarine and 29.79 g soya oil/100 g). The serum lipid profile, hepatic function and injury markers, and renal function and injury markers were determined. Samples of liver, stomach, kidney and small intestine were collected for histological analysis. The animals fed the high‐fat diet based on trienantin exhibited a lower body weight gain in relation to the control group, between the second and fifth week of the experiment. There were no differences amongst the biochemical markers of the three groups (p ≥0.05). Lipid infiltration of the hepatocytes was detected in a similar manner in all groups (p ≥0.05). These data demonstrate that the high‐fat diet based on trienantin did not promote adverse metabolic effects under the conditions of this study. This could serve as a reference parameter in the evaluation of the safety of its therapeutic application.     

Oxidative Stress as an Underlying Contributor in the Development of Chronic Complications in Diabetes Mellitus

The high prevalence of diabetes mellitus and its increasing incidence worldwide, coupled with several complications observed in its carriers, have become a public health issue of great relevance. Chronic hyperglycemia is the main feature of such a disease, being considered the responsible for the establishment of micro and macrovascular complications observed in diabetes. Several efforts have been directed in order to better comprehend the pathophysiological mechanisms involved in the course of this endocrine disease. Recently, numerous authors have suggested that excess generation of highly reactive oxygen and nitrogen species is a key component in the development of complications invoked by hyperglycemia. Overproduction and/or insufficient removal of these reactive species result in vascular dysfunction, damage to cellular proteins, membrane lipids and nucleic acids, leading different research groups to search for biomarkers which would be capable of a proper and accurate measurement of the oxidative stress (OS) in diabetic patients, especially in the presence of chronic complications. In the face of this scenario, the present review briefly addresses the role of hyperglycemia in OS, considering basic mechanisms and their effects in diabetes mellitus, describes some of the more commonly used biomarkers of oxidative/nitrosative damage and includes selected examples of studies which evaluated OS biomarkers in patients with diabetes, pointing to the relevance of such biological components in general oxidative stress status of diabetes mellitus carriers.     

Erbium photoluminescence response related to nanoscale heterogeneities in sol-gel silicates

Sol-gel glassy films of the SiO2-TiO2-PO2.5-ErO2.5 system containing nanocrystallites of ErPO4, were obtained through suitable heat treatments. Variations in the shape and intensity of the Er3+ photoluminescent signal around 1500 nm were linked to the nature of the host environment of the active ions; the specific features of the photoluminescent emission spectrum of the erbium 4I13/2 metastable level were interpreted in terms of structural changes in the glassy films. The photoluminescent spectrum was found to be sensitive to the order (crystalline) or disorder (amorphous) of the Er3+ ions neighbour within the glassy matrix. An amorphous environment led to a broadening of Er3+ PL emission band while a crystalline one was responsible for a drastic photoluminescent bandwidth narrowing. The presence of nanoscale heterogeneities caused a drastic photoluminescence intensity decrease. Changes in the shape of the decay curve of fluorescence lifetime were found also structurally dependent on volumetric defects, occurrence of phase separation and Er3+-Er3+ clustering effects as well.     

High‐Throughput Topographic,Mechanical, and Biological Screening of Multilayer Films Containing Mussel‐Inspired Biopolymers

A high‐content screening method to characterize multifunctional multilayer films that combine mechanical adhesion and favorable biological response is reported. Distinct combinations of nanostructured films are produced using layer‐by‐layer methodology and their morphological, physicochemical, and biological properties are analyzed in a single microarray chip. Inspired by the composition of the adhesive proteins in mussels, thin films containing dopamine‐modified hyaluronic acid are studied. Flat biomimetic superhydrophobic patterned chips produced by a bench‐top methodology are used for the build‐up of arrays of multilayer films. The wettability contrasts imprinted onto the chips are allowed to produce individual, position controlled, multilayer films in the wettable regions. The flat configuration of the chip permits to perform a series of nondestructive measurements directly on the individual spots. In situ adhesion properties are directly measured in each spot, showing that nanostructured films richer in dopamine promote the adhesion. In vitro tests show an enhanced cell adhesion for the films with more catechol groups. The advantages presented by this platform include ability to control the uniformity and size of the multilayers films, its suitability to be used as a new low cost toolbox and for high‐content cellular screening, and capability for monitoring in situ a variety of distinct material properties.     

Solvent composition and rheology of starch–DMSO–water solutions

The rheology of starch–DMSO–water solutions was studied as a function of water content and temperature. A correlation between flow regime, temperature, and water content was presented so as to characterize amylose conformation change in a novel way. Rheological behavior was characterized using an empirical equation to classify fluids under study as Newtonian, pseudoplastic, or dilatant. The temperature effect was analyzed through the determination of the apparent activation energy and preexponential constant. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1285–1290, 2001