Identification of xanthones as selective killers of cancer cells overexpressing the ABC transporter MRP1

Multidrug‐resistance protein 1 (MRP1) belongs to the ATP‐binding cassette (ABC) transporter family. MRP1 mediates MDR (multidrug resistance) by causing drug efflux either by conjugation to glutathione (GSH) or by co‐transport with free GSH (without covalent bonding between the drug and GSH). We recently reported that the calcium channel blocker verapamil can activate massive GSH efflux in MRP1‐overexpressing cells, leading to cell death through apoptosis. However, clinical use of verapamil is hampered by its cardiotoxicity. Then, in the search for compounds that act similarly to verapamil, but without major side effects, we investigated xanthones. Herein we show that xanthones induce apoptosis among resistant cells overexpressing MRP1 similarly to the verapamil effect. Among the xanthones studied, 1,3‐dihydroxy‐6‐methoxyxanthone was identified as the most active derivative, able to specifically kill cells transfected with human MRP1 with even greater potency than verapamil. Under the same conditions, the active xanthones have no toxic effect on control (sensitive) cells. Xanthones could therefore be considered as new potential anticancer agents for the selective treatment of MRP1‐positive tumors.     

Production of bacteriocin‐like inhibitory substances (BLIS) by Bifidobacterium lactis using whey as a substrate

The objective of this work was to evaluate the production of bacteriocin‐like inhibitory substances (BLIS) by Bifidobacterium animalis subsp. lactis in whey supplemented with yeast extract, inulin, Tween‐80 or l ‐cysteine. Cell growth, acidification, glucose and lactose consumption as well as BLIS production were measured during fermentations carried out in shake flasks. The best additive for both cell growth and BLIS production was shown to be yeast extract, which gave the highest concentrations of biomass (9.9 log cfu/mL) and BLIS (800 AU/mL). In a bench‐scale fermentor, B. lactis growth and BLIS production were between 6% and 25% higher than in flasks depending on the conditions assayed.     

Bacteriocin production by Lactobacillus plantarum ST16Pa in supplemented whey powder formulations

Whey, the main by-product of the dairy industry, is frequently disposed of in the environment without any treatment due to the high cost of this process. Alternatively, whey can be used as a medium to culture lactic acid bacteria and produce value-added products such as bacteriocins. In this work, we attempted to improve bacteriocin production by Lactobacillus plantarum ST16Pa in a whey powder formulation supplemented with additional sources of carbon, nitrogen, and vitamin B₁₂ at different levels and varying the agitation intensity according to a Plackett–Burman experimental design. Only the addition of tryptone positively influenced the production of this bacteriocin. The results allowed us to identify a supplemented whey formulation, comprising 150 g/L of whey total solids plus 10 g/L of tryptone and soybean extract, whose fermentation by Lb. plantarum ST16Pa in shake flasks under agitation at 150 rpm led to a cell-free supernatant with an antimicrobial activity against Listeria innocua 6a CLIST 2865 (inhibition zone of 13.23 mm) close to that previously obtained in de Man, Rogosa and Sharpe medium by other authors. These results are significant considering that the same strain cultured in cheese whey did not previously display any antimicrobial activity.     

Growth and acidification performance of probiotics in pure culture and co-culture with Streptococcus thermophilus: The effect of inulin

Inulin was used as a prebiotic to improve the quality and consistency of skim milk fermented by co-cultures and pure cultures of Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus bulgaricus and Bifidobacterium lactis with Streptococcus thermophilus. We compared, either in the presence or absence of 4 g inulin/100 g, the results of the main kinetic parameters, specifically the generation time (t_g), the maximum acidification rate (V_max), and the times to reach V_max (t_max), to attain pH 5.0 (t_pH5.0) and to complete the fermentation (t_pH4.5). Post-acidification, lactic acid formation and cell counts were also determined and compared, either 1 day after the fermentation was complete or after 7 day storage at 4 °C. In general, inulin addition to the milk increased in co-cultures V_max, decreased t_max, t_g and t_pH4.5, favored post-acidification, exerted a bifidogenic effect, and preserved almost intact cell viability during storage. In addition, S. thermophilus was shown to stimulate the metabolism of the other lactic bacteria. Contrary to co-cultures, most of the effects in pure cultures were not statistically significant. The most important aspect of this paper is the use of the generation time as a tool to investigate the microbial response to inulin addition.     

G‐protein alpha subunits distribution in the cyprid of Balanus amphitrite (=Amphibalanus amphitrite) (Cirripedia,Crustacea)

The acorn barnacle Balanus amphitrite is a marine crustacean with six nauplius and one cyprid larval stages and a sessile adult, that represent one of the main constituents of sea biofouling. The cyprid is the last larval stage, specialized for settlement, and the study of its biology is interesting also in the frame of antifouling strategies. In this study, a novel approach to the neurobiology of B. amphitrite cyprid has undertaken, studying immunohistochemically the distribution of some G‐protein α subunits (Gαs, Gαo Gαi, and Gαq) on B. amphitrite cyprid. Gαs‐like immunoreactivity was observed in the intestinal mucosa, oral cone, epithelial cells along the outer face of the mantle and thorax; Gαo into the fibers of the neuropile of the central nervous system; Gαi in oil cells, epithelial cells, and limbs and thorax muscles; Gαq was not detected. The results suggest the involvement of the G‐protein α subunits in different tissues and functions that seem to be in agreement with the distribution of the ones from the same class of G‐proteins in vertebrates. Microsc. Res. Tech., 2012. © 2012 Wiley Periodicals, Inc.     

Large‐Eddy Simulation of Oil‐Water Annular Flow in Eccentric Vertical Pipes

One of the difficulties related to oil exploration is transporting heavy oil since its high viscosity causes high‐pressure drop and energy consumption. In order to save energy, the core annular flow (CAF) can be applied where a two‐phase annular flow occurs, with peripheral water flowing offering a reduction in energy expenditure. The multiphase flow was studied experimentally in a simple purpose‐built unit. To theoretically handle the CAF, computational fluid dynamics simulations were done with the commercial package Ansys Fluent. The flow was considered turbulent, isothermal, incompressible, and 3D, and both stationary and transient cases were evaluated. The volume‐of‐fluid model was adopted for the multiphase system, and water/oil interface and turbulence phenomena were well predicted.     

Kinetics and Isotherms of Mercury Biosorption by Dry Biomass of Arthrospira (Spirulina) platensis

Inorganic mercury was effectively removed from water solutions by means of dry biomass of Arthrospira (Spirulina) platensis as biosorbent. The results obtained at defined pH and biomass concentration as well as variable Hg concentrations were used to estimate biosorption kinetics and isotherm parameters. Biosorption kinetics was best described by the pseudo-first-order model of Lagergren that allowed estimating an average specific rate constant as high as 0.044 min⁻¹, while the Dubinin and Radushkevich model was the best fitting isotherm. Hg biosorption seemed to occur via physisorption. Considering the wide dissemination of A. platensis and its easy cultivation, these results point to its biomass as a low-cost biosorbent to treat Hg-contaminated waters.