Polyazetidine-based immobilization of redox proteins for electron-transfer-based biosensors

A highly stable functional composite film was prepared using polyazetidine prepolymer (PAP) with peroxidase from horseradish (HRP) and/or glucose oxidase (GOx). The good permeability of the PAP layer to classical electrochemical mediators, as evaluated by the determination of the diffusion coefficient of different redox molecules, is of great importance in view of the use of PAP as an immobilizing agent in second-generation biosensor development. Cyclic voltammetry of the HRP-PAP layer on a glassy carbon electrode (GCE) showed a pair of stable and quasi-reversible peaks for the HRP-Fe((III))/Fe((II)) redox couple at about -370 mV vs. Ag/AgCl electrode in pH 6.5 phosphate buffer. The electrochemical reaction of HRP entrapped in the PAP film exhibited a surface-controlled electrode process. This film and the successive modifications (HRP-PAP self-assembled monolayer (SAM) modified Au electrode) were used as a biological catalyst (hydrogen peroxide transducers) for glucose biosensors, after coupling to GOx. Both HRP/GOx-PAP and HRP/GOx-PAP SAM third generation biosensors were prepared and characterized. The use of PAP as immobilizing agent offers a biocompatible micro-environment for confining the enzyme and foreshadows the great potentiality of this immobilizing agent not only in theoretical studies on protein direct electron transfer but also from an applications point of view in the development of second- and third-generation biosensors.     

Potential of Ginkgo biloba L. leaves in the management of hyperglycemia and hypertension using in vitro models

Leaves from four different Ginkgo biloba L. trees (1 and 2 – females; 3 and 4 – males), grown at the same conditions, were collected during a period of 5 months (from June to October, 2007). Water and 12% ethanol extracts were analyzed for total phenolics content, antioxidant activity, phenolic profile, and the potential in vitro inhibitory effects on α-amylase, α-glucosidase, and Angiotensin I-Converting Enzyme (ACE) enzymes related to the management of diabetes and hypertension. The results indicated a significant difference among the trees in all functional benefits evaluated in the leaf extracts and also found important seasonal variation related to the same functional parameters. In general, the aqueous extracts had higher total phenolic content than the ethanolic extracts. Also, no correlation was found between total phenolics and antioxidant activity. In relation to the ACE inhibition, only ethanolic extracts had inhibitory activity.     

Ozonation strategies to reduce sludge production of a seafood industry WWTP

In this work, several alternatives related to the application of ozone in different streams of a seafood industry WWTP were evaluated to minimize the production of waste sludge. The WWTP was composed of two coagulation-flocculation units and a biological unit and generated around of 6550 kg/d of sludge. Ozone was applied to sludge coming from flotation units (110 g TSS/L) at doses up to 0.03 g O(3)/g TSS during batch tests, no solids solubilization being observed. Ozone doses ranging from 0.007 to 0.02 g O(3)/g TSS were also applied to the raw wastewater in a bubble column reaching a 6.8% of TSS removal for the highest ozone dose. Finally, the effect of the pre-ozonation (0.05 g O(3)/g TSS) of wastewater coming from the first flotation unit was tested in two activated sludge systems during 70 days. Ozonation caused a reduction of the observed yield coefficient of biomass from 0.14 to 0.07g TSS/g COD(Tremoved) and a slight improvement of COD removal efficiencies. On the basis of the capacity for ozone production available in the industry, a maximum reduction of sludge generated by the WWTP of 7.5% could be expected.     

Genotoxic activity of <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> essential oil in <Emphasis Type="Italic">Aspergillus nidulans</Emphasis> diploid cells

Eucalyptus globulus essential oil was evaluated for its genotoxic potential using a somatic segregation assay and a diploid strain of the fungus Aspergillus nidulans, heterozygous for nutritional and conidia color markers. The main compounds of the current essential oil sample were eucalyptol (49.0 %), α-pinene (8.9), β-pinene (1.5), globulol (6.9), α-eudesmol (1.12), spathulenol (1.42), γ-cadinene (1.45), trans-β-elemenone (1.23) and aromandendrene (2.3), totaling 74 % of oil. Oil at 0.12 and 0.25 μL/mL was found to increase the mitotic instability of the original diploid strain and the number of diploid mitotic recombinants of A. nidulans. The genotoxicity of the oil was associated with the induction of mitotic crossing-over or with oil-broken chromosomes.     

Molecular diversity and transferability of the tetracycline resistance gene <Emphasis Type="Italic">tet</Emphasis>(M), carried on Tn<Emphasis Type="Italic">916-1545</Emphasis> family transposons,in enterococci from a total food chain

In the present study, 20 enterococci belonging to the species Enterococcus faecalis (12 strains), Enterococcus faecium (4), Enterococcus durans (2), Enterococcus hirae (1) and Enterococcus mundtii (1) and originating from a total production chain of swine meat commodities were analysed to investigate the diversity of their tetracycline resistance gene tet(M). PCR–RFLP and sequence analysis showed that the tet(M) gene of most strains can be correlated with the Tn916 transposon. Conversely, tet(M) of six E. faecalis and the E. hirae strain, all isolated from pig faecal samples, may be associated with previously undescribed members of the Tn916-1545 transposon family. In vitro filter conjugation trials showed the ability of 50% of the enterococcal strains, including E. mundtii, to transfer the tet(M) gene (and the associated Tn916 and new transposons) to E. faecalis or Listeria innocua recipient strains. tet(M) gene transfer to L. innocua recipient was also directly observed in meat food products. Collectively, these sequence and conjugation data indicate that various transposons can be responsible of the spread of tetracycline resistance in enterococci and validate the opinion that Enterococcus species are important sources of antibiotic resistance genes for potentially pathogenic bacteria occurring in the food chain. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Brazilian mothers' beliefs, attitudes and practices related to child weight status and early feeding within the context of nutrition transition

With the rapid pace of the nutrition transition worldwide, understanding influences of child feeding practices within a context characterized by the co-existence of overweight and undernutrition in the same population has increasing importance. This qualitative study describes Brazilian mothers' child feeding practices and their perceptions of their association with child weight status and explores the role of socioeconomic, cultural and organizational factors on these relationships. Forty-one women enrolled in the Family Health/Community Health Workers Programme were selected from rural, urban, coastal and indigenous areas in Ceara State, north-east Brazil, to participate in four focus group discussions. Content analysis identified fourteen emergent themes showing mothers' child feeding practices in this setting were influenced by economic resources, mothers' immediate social support networks (e.g. neighbours and family members) and participation in nutrition assistance programmes. Child malnutrition was the most common nutritional concern; nevertheless, mothers were aware of the negative health consequences of obesity but misunderstood its causes (e.g. foods filled with fat would make a person fat; others thought that birth control pills and stimulants given to children were causes of obesity); several reported their own struggles with overweight. Food assistance programmes emerged as an important influence on children's dietary adequacy, especially among mothers describing dire economic situations. The findings have implications for targeting food assistance as well as health and nutrition education strategies in low-income families undergoing the nutrition transition in north-east Brazil.     

Succinate is the controller of O<Stack><Subscript>2</Subscript><Superscript>−</Superscript></Stack>/H<Subscript>2</Subscript>O<Subscript>2</Subscript> release at mitochondrial complex I : negative modulation by malate,positive by cyanide

Mitochondrial production of H₂O₂ is low with NAD substrates (glutamate/pyruvate, 3 and 2 mM) (G/P) and increases over ten times upon further addition of succinate, with the formation of a sigmoidal curve (semimaximal value at 290 μM, maximal H₂O₂ production at 600 μM succinate). Malate counteracts rapidly the succinate induced increased H₂O₂ release and moves the succinate dependent H₂O₂ production curve to the right. Nitric oxide (NO) and carbon monoxide (CO) are cytochrome c oxidase inhibitors which increase mitochondrial ROS production. Cyanide (CN⁻) was used to mimic NO and CO. In the presence of G/P and succinate (300 μM), CN⁻ progressively increased the H₂O₂ release rate, starting at 1.5 μM. The succinate dependent H₂O₂ production curve was moved to the left by 30 μM CN⁻. The V_max was little modified. We conclude that succinate is the controller of mitochondrial H₂O₂ production, modulated by malate and CN⁻. We propose that succinate promotes an interaction between Complex II and Complex I, which activates O₂⁻ production.     

Synthesis, characterization and deepening in the comprehension of the biological action mechanisms of a new nickel complex with antiproliferative activity

Thiosemicarbazones are versatile organic compounds that present considerable pharmaceutical interest because of a wide range of properties. In our laboratory we synthesised some new metal-complexes with thiosemicarbazones derived from natural aldehydes which showed peculiar biological activities. In particular, a nickel complex [Ni(S-tcitr)₂] (S-tcitr = S-citronellalthiosemicarbazonate) was observed to induce an antiproliferative effect on U937, a human histiocytic lymphoma cell line, at low concentrations (IC₅₀ = 14.4 μM). Therefore, we decided to study the interactions of this molecule with various cellular components and to characterise the induced apoptotic pathway. Results showed that [Ni(S-tcitr)₂] causes programmed cell death via down-regulation of Bcl-2, alteration of mitochondrial membrane potential and caspase-3 activity, regardless of p53 function. The metal complex is not active on G₀ cells (i.e. fresh leukocytes) but is able to induce perturbation of the cell cycle on stimulated lymphocytes and U937 cells, in which a G₂/M block was detected. It reaches the nucleus where it induces, at low concentrations (2.5-5.0 μM), DNA damage, which could be partially ascribed to oxidative stress. [Ni(S-tcitr)₂] is moreover able to strongly reduce the telomerase activity. Although the biological target of this metal complex is still unknown, the reported data suggest that [Ni(S-tcitr)₂] could be a good model for the synthesis of new metal thiosemicarbazones with specific biological activity.     

Phenolic glycosides from Cucumis melo var. inodorus seeds

A new phenolic glycoside (E)-4-hydroxycinnamyl alcohol 4-O-(2′-O-β-d-apiofuranosyl)(1″ → 2′)-β-d-glucopyranoside (1) was isolated and identified from Cucumis melo seeds together with benzyl O-β-d-glucopyranoside (2), 3,29-O-dibenzoylmultiflor-8-en-3α,7β,29-triol (3) and 3-O-p-amino-benzoyl-29-O-benzoylmultiflor-8-en-3α,7β,29-triol (4). Their structures were elucidated by extensive NMR experiments including ¹H–¹H (COSY, TOCSY, ROESY) and ¹H–¹³C (HSQC and HMBC) spectroscopy and chemical evidence. The multiflorane triterpene esters were identified as new melon constituents.