Asymptotic analysis of a family of non-local functionals on sets

We study the asymptotic behavior of a family of functionals which penalize a short-range interaction of convolution type between a finite perimeter set and its complement. We first compute the pointwise limit and we obtain a lower estimate on more regulars sets. Finally, some examples are discussed

Properties of graphene-related materials controlling the thermal conductivity of their polymer nanocomposites

Different types of graphene-related materials (GRM) are industrially available and have been exploited for thermal conductivity enhancement in polymers. These include materials with very different features, in terms of thickness, lateral size and composition, especially concerning the oxygen to carbon ratio and the possible presence of surface functionalization. Due to the variability of GRM properties, the differences in polymer nanocomposites preparation methods and the microstructures obtained, a large scatter of thermal conductivity performance is found in literature. However, detailed correlations between GRM-based nanocomposites features, including nanoplatelets thickness and size, defectiveness, composition and dispersion, with their thermal conductivity remain mostly undefined. In the present paper, the thermal conductivity of GRM-based polymer nanocomposites, prepared by melt polymerization of cyclic polybutylene terephtalate oligomers and exploiting 13 different GRM grades, was investigated. The selected GRM, covering a wide range of specific surface area, size and defectiveness, secure a sound basis for the understanding of the effect of GRM properties on the thermal conductivity of their relevant polymer nanocomposites. Indeed, the obtained thermal conductivity appeares to depend on the interplay between the above GRM feature. In particular, the combination of low GRM defectiveness and high filler percolation density was found to maximize the thermal conductivity of nanocomposites

Effect of polyphenolic compounds on the proteolytic activities of constitutive and immuno-proteasomes

The effect of several polyphenols on the 20S proteasomes, both the constitutive and the LMP proteasomes, isolated from bovine tissues, has been investigated. Polyphenolic compounds show many biological activities such as antiviral, antibacterial, antifungal, anti-inflammatory, antimutagenic, and antiallergic activities. However, the molecular mechanism underlying these effects has not been identified. It is well established that polyphenols possess inhibitory activities on several enzymes and among them the 20S proteasome. In the present work, the ChT-L, BrAAP, PGPH, and T-L activities of the isolated constitutive and immuno-proteasomes were assayed in order to get an overall information on the polyphenols binding to the complexes. The effects of the polyphenols on the proteasomal activities were analyzed, taking into account the different subunits composition of the two complexes. Furthermore the same activities were measured on whole extracts from cancer cells exposed to EGCG and gallic acid, evaluating, also, their antioxidant action under oxidative stress. EGCG and gallic acid are able to affect the 20S proteasomes functionality, depending on the complex subunit composition and, in cell extracts, they behave both as antioxidants and proteasome effectors

20S proteasome mediated degradation of DHFR: implications in neurodegenerative disorders

The 20S proteasome is responsible for the degradation of protein substrates implicated in the onset and progression of neurodegenerative disorders, such as a-synuclein and tau protein. Here we show that the 20S proteasome isolated from bovine brain directly hydrolyzes, in vitro, the dihydrofolate reductase (DHFR), demonstrated to be involved in the pathogenesis of neurodegenerative diseases. Furthermore, the DHFR susceptibility to proteolysis is enhanced by oxidative conditions induced by peroxynitrite, mimicking the oxidative environment typical of these disorders. The results obtained suggest that the folate metabolism may be impaired by an increased degradation of DHFR, mediated by the 20S proteasome

50 Hz Extremely Low Frequency Electromagnetic Fields Enhance Protein Carbonyl Groups Content in Cancer Cells: Effects on Proteasomal Systems

Electromagnetic fields are an assessed cause of prolonging free radicals lifespan. This study was carried out to investigate the influence of extremely low frequency electromagnetic fields on protein oxidation and on the 20S proteasome functionality, the complex responsible for the degradation of oxidized proteins. Caco 2 cells were exposed, for 24–72 hours, to 1 mT, 50 Hz electromagnetic fields. The treatment induced a time-dependent increase both in cell growth and in protein oxidation, more evident in the presence of TPA, while no changes in cell viability were detected. Exposing the cells to 50 Hz electromagnetic fields caused a global activation of the 20S proteasome catalytic components, particularly evident at 72 hours exposure and in the presence of TPA. The finding that EGCG, a natural antioxidant compound, counteracted the field-related pro-oxidant effects demonstrates that the increased proteasome activity was due to an enhancement in intracellular free radicals

Acid-Stable Serine Proteinase Inhibitors in the Urine of Alzheimer Disease Subjects

A comparative study of the levels of acid-stable proteinase inhibitors (kallikrein and trypsin inhibitors) in the urine of healthy and Alzheimer subjects, of both sexes, has been performed. A preliminary characterization of the purified inhibitors indicates that the urinary antitryptic activity is accounted for by the presence of the well known Urinary Trypsin Inhibitor (UTI) while an apparently new molecule appears to be responsible for the anti kallikrein activity. The urinary levels of kallikrein inhibitors are very similar in healthy and sick subjects while the levels of trypsin inhibitors appear significatively increased in Alzheimer subjects of both sexes. The data presented here support the hypothesis that unpaired proteolytic processes could be involved in the pathogenesis of Alzheimer's disease and suggest that the levels of urinary acid-stable inhibitors may prove to be useful markers of the disease

A yeast strain associated to Anopheles mosquitoes produces a toxin able to kill malaria parasites

BACKGROUND: Malaria control strategies are focusing on new approaches, such as the symbiotic control, which consists in the use of microbial symbionts to prevent parasite development in the mosquito gut and to block the transmission of the infection to humans. Several microbes, bacteria and fungi, have been proposed for malaria or other mosquito-borne diseases control strategies. Among these, the yeast Wickerhamomyces anomalus has been recently isolated from the gut of Anopheles mosquitoes, where it releases a natural antimicrobial toxin. Interestingly, many environmental strains of W. anomalus exert a wide anti-bacterial/fungal activity and some of these 'killer' yeasts are already used in industrial applications as food and feed bio-preservation agents. Since a few studies showed that W. anomalus killer strains have antimicrobial effects also against protozoan parasites, the possible anti-plasmodial activity of the yeast was investigated. METHODS: A yeast killer toxin (KT), purified through combined chromatographic techniques from a W. anomalus strain isolated from the malaria vector Anopheles stephensi, was tested as an effector molecule to target the sporogonic stages of the rodent malaria parasite Plasmodium berghei, in vitro. Giemsa staining was used to detect morphological damages in zygotes/ookinetes after treatment with the KT. Furthermore, the possible mechanism of action of the KT was investigated pre-incubating the protein with castanospermine, an inhibitor of β-glucanase activity. RESULTS: A strong anti-plasmodial effect was observed when the P. berghei sporogonic stages were treated with KT, obtaining an inhibition percentage up to around 90 %. Microscopy analysis revealed several ookinete alterations at morphological and structural level, suggesting the direct implication of the KT-enzymatic activity. Moreover, evidences of the reduction of KT activity upon treatment with castanospermine propose a β-glucanase-mediated activity. CONCLUSION: The results showed the in vitro killing efficacy of a protein produced by a mosquito strain of W. anomalus against malaria parasites. Further studies are required to test the KT activity against the sporogonic stages in vivo, nevertheless this work opens new perspectives for the possible use of killer strains in innovative strategies to impede the development of the malaria parasite in mosquito vectors by the means of microbial symbionts