Multifunctionalized CMCht/PAMAM dendrimer nanoparticles modulate the cellular uptake by astrocytes and oligodendrocytes in primary cultures of glial cells

The efficiency of the treatments involving CNS disorders is commonly diminished by the toxicity, reduced stability and lack of targeting of the administered neuroactive compounds. In this study, we have successfully multifunctionalized CMCht/PAMAM dendrimer nanoparticles by coupling the CD11b antibody and loading MP into the nanoparticles. The modification of the new antibody-conjugated nanoparticles was confirmed by S-TEM observation and (1) H NMR and FTIR spectroscopy. Cytotoxicity assays revealed that the conjugates did not affect the viability of both primary cultures of glial and microglial cells. Trace analyses of FITC-labelled nanoparticles revealed that the uptake of antibody-conjugated nanoparticles was conserved in microglial cells but significantly decreased in astrocytes and oligodendrocytes. Thus, this study demonstrates that antibody conjugation contributes to a modulation of the internalization of these nanocarriers by different cell types, which might be of relevance for specific targeting of CNS cell populations.     

Study of the volatile compounds produced by Debaryomyces hansenii NRRL Y-7426 during the fermentation of detoxified concentrated distilled grape marc hemicellulosic hydrolysates

The volatile compounds produced by Debaryomyces hansenii NRRL Y-7426 during the fermentation of detoxified concentrated distilled grape marc hemicellulosic hydrolysates was analysed by GC?CMS. Thirty-five compounds corresponding to ten groups of volatile compounds: terpenes, higher alcohols, C₆ alcohols, aldehydes, volatile acids, acetates, ethyl esters, volatile phenols, sulphur compounds and hydrocarbons were identified. The supplementation with commercial nutrients increased the concentration of 2-phenylethanol, a commercial flavour and fragrance compound, with a rose-like odour, employed in cosmetics and food industries; and other positive compounds to the aroma such as terpenes and ethyl esters. Non-supplemented media produced the highest content in higher alcohols, volatile acids, sulphur compounds and in the majority of hydrocarbons detected, meanwhile supplementation with vinasses hardly produced volatile compounds. Only four volatile compounds contributed directly to the aroma according to the OAVs values higher than 1. Finally, a PCA analysis allowed accounting for 100?% of the variance.     

DNA methylation-independent reversion of gemcitabine resistance by hydralazine in cervical cancer cells

Background

Down regulation of genes coding for nucleoside transporters and drug metabolism responsible for uptake and metabolic activation of the nucleoside gemcitabine is related with acquired tumor resistance against this agent. Hydralazine has been shown to reverse doxorubicin resistance in a model of breast cancer. Here we wanted to investigate whether epigenetic mechanisms are responsible for acquiring resistance to gemcitabine and if hydralazine could restore gemcitabine sensitivity in cervical cancer cells.

Methodology/Principal Findings

The cervical cancer cell line CaLo cell line was cultured in the presence of increasing concentrations of gemcitabine. Down-regulation of hENT1 & dCK genes was observed in the resistant cells (CaLoGR) which was not associated with promoter methylation. Treatment with hydralazine reversed gemcitabine resistance and led to hENT1 and dCK gene reactivation in a DNA promoter methylation-independent manner. No changes in HDAC total activity nor in H3 and H4 acetylation at these promoters were observed. ChIP analysis showed H3K9m2 at hENT1 and dCK gene promoters which correlated with hyper-expression of G9A histone methyltransferase at RNA and protein level in the resistant cells. Hydralazine inhibited G9A methyltransferase activity in vitro and depletion of the G9A gene by iRNA restored gemcitabine sensitivity.

Conclusions/Significance

Our results demonstrate that acquired gemcitabine resistance is associated with DNA promoter methylation-independent hENT1 and dCK gene down-regulation and hyper-expression of G9A methyltransferase. Hydralazine reverts gemcitabine resistance in cervical cancer cells via inhibition of G9A histone methyltransferase.     

Chemiluminescence of the Fenton reaction and a dihydroxybenzene-driven Fenton reaction

A dihydroxybenzenes(DHB)-driven Fenton reaction was found to be more efficient than a simple Fenton reaction based on OH radical and activated species production. The reason for this enhanced reactivity by [Fe DHB] complexes is not well understood, but results suggest that it may be explained by the formation of oxidation species different from those formed during the classic Fenton reactions. In previous work, greater concentrations, and more sustained production of OH over time were observed in DHB driven Fenton reactions versus neat Fenton and Fenton-like reactions. In this work, chemiluminescence (CL) was monitored, and compared to OH production kinetics. The CL of the DHB-driven Fenton reaction was shorter than that for sustained production of OH. CL appears to have been caused by excited Fe(IV) species stabilized by the DHB ligands initially formed in the reaction. Formation of this species would have to have occurred by the reaction between OH and Fe(III) in a DHB complex.     

Lrig1 is an estrogen-regulated growth suppressor and correlates with longer relapse-free survival in ERα-positive breast cancer

Lrig1 is the founding member of the Lrig family and has been implicated in the negative regulation of several oncogenic receptor tyrosine kinases including ErbB2. Lrig1 is expressed at low levels in several cancer types but is overexpressed in some prostate and colorectal tumors. Given this heterogeneity, whether Lrig1 functions to suppress or promote tumor growth remains a critical question. Previously, we found that Lrig1 was poorly expressed in ErbB2-positive breast cancer, suggesting that Lrig1 has a growth-inhibitory role in this tumor type. However, breast cancer is a complex disease, with ErbB2-positive tumors accounting for just 25% of all breast cancers. To gain a better understanding of the role of Lrig1 in breast cancer, we examined its expression in estrogen receptor α (ERα)-positive disease which accounts for the majority of breast cancers. We find that Lrig1 is expressed at significantly higher levels in ERα-positive disease than in ERα-negative disease. Our study provides a molecular rationale for Lrig1 enrichment in ERα-positive disease by showing that Lrig1 is a target of ERα. Estrogen stimulates Lrig1 accumulation and disruption of this induction enhances estrogen-dependent tumor cell growth, suggesting that Lrig1 functions as an estrogen-regulated growth suppressor. In addition, we find that Lrig1 expression correlates with prolonged relapse-free survival in ERα-positive breast cancer, identifying Lrig1 as a new prognostic marker in this setting. Finally, we show that ErbB2 activation antagonizes ERα-driven Lrig1 expression, providing a mechanistic explanation for Lrig1 loss in ErbB2-positive breast cancer. This work provides strong evidence for a growth-inhibitory role for Lrig1 in breast cancer.     

Pore formation by a Bax-derived peptide: effect on the line tension of the membrane probed by AFM

Bax is a critical regulator of physiological cell death that increases the permeability of the outer mitochondrial membrane and facilitates the release of the so-called apoptotic factors during apoptosis. The molecular mechanism of action is unknown, but it probably involves the formation of partially lipidic pores induced by Bax. To investigate the interaction of Bax with lipid membranes and the physical changes underlying the formation of Bax pores, we used an active peptide derived from helix 5 of this protein (Bax-alpha5) that is able to induce Bax-like pores in lipid bilayers. We report the decrease of line tension due to peptide binding both at the domain interface in phase-separated lipid bilayers and at the pore edge in atomic force microscopy film-rupture experiments. Such a decrease in line tension may be a general strategy of pore-forming peptides and proteins, as it affects the energetics of the pore and stabilizes the open state.     

Plasmon Features of Coinage Metal Nanoparticles Supported on Zeolites

The plasmonic features in the optical response of coinage metal nanoparticles supported on different type of zeolites were studied. The shifts in the plasmon frequency were analyzed for Cu, Ag, and Au nanoparticles in mordenite, β-zeolite, and Y-zeolite. It was shown experimentally that the resonance energy is sensitive both to type of zeolite structure and counter-cation of zeolite, as well as to annealing temperature and chemical composition of zeolite, their SiO₂/Al₂O₃ molar ratio. A theoretical framework was employed to identify physical mechanism for this sensitivity. Within a simple model, the width of the absorption window identified in the imaginary part of the bulk dielectric function of the different metals was seen to play the important role in establishing the range of the plasmon energies available. In terms of an effective dielectric function, the composite medium was fully described by the complex dielectric function of the metal involved, the dissipation-free dielectric function of the zeolite matrix, and the filling fraction which relates the volume of metal inclusions as a fraction of the total sample volume. The sensitivity of the optical spectra is understood in terms of variations in both the dielectric response of the zeolite matrix as well as nanoparticle size.