507 research outputs found
In the shadow of the church: the building of mosques in early medieval Syria
No full textIn his book In the Shadow of the Church: The Building of Mosques in Early Medieval Syria Mattia Guidetti examines the establishment of Muslim religious architecture within the Christian context in which it first appeared in the Syrian region, contributing to the debate on the transformation of late antique society to a Muslim one. He scrutinizes the slow process of conversion to Islam of the most important town centers by looking at religious places of both communities between the seventh and the eleventh century. The author assesses the relevancy of churches by analyzing the location of mosques and by researching phenomena of transfer of marble material from churches to mosques
Antimicrobial activity of gallium compounds on ESKAPE pathogens
No full textESKAPE bacteria are a major cause of multidrug-resistant infections, and new drugs are urgently needed to combat these pathogens. Given the importance of iron in bacterial physiology and pathogenicity, iron uptake and metabolism have become attractive targets for the development of new antibacterial drugs. In this scenario, the FDA-approved iron mimetic metal Gallium [Ga(III)] has been successfully repurposed as an antimicrobial drug. Ga(III) disrupts ferric iron-dependent metabolic pathways, thereby inhibiting microbial growth. This work provides the first comparative assessment of the antibacterial activity of Ga(NO3)3 (GaN), Ga(III)-maltolate (GaM), and Ga(III)-protoporphyrin IX (GaPPIX), belonging to the first-, second- and third-generation of Ga(III) formulations, respectively, on ESKAPE species, including reference strains and multidrug-resistant (MDR) clinical isolates. In addition to the standard culture medium Mueller Hinton broth (MHB), iron-depleted MHB (DMHB) and RPMI-1640 supplemented with 10% human serum (HS) (RPMI-HS) were also included in Ga(III)-susceptibility tests, because of their different nutrient and iron contents. All ESKAPE species were resistant to all Ga(III) compounds in MHB and DMHB (MIC > 32 μM), except Staphylococcus aureus and Acinetobacter baumannii, which were susceptible to GaPPIX. Conversely, the antibacterial activity of GaN and GaM was very evident in RPMI-HS, in which the low iron content and the presence of HS better mimic the in vivo environment. In RPMI-HS about 50% of the strains were sensitive (MIC < 32) to GaN and GaM, both compounds showing a similar spectrum of activity, although GaM was more effective than GaN. In contrast, GaPPIX lost its antibacterial activity in RPMI-HS likely due to the presence of albumin, which binds GaPPIX and counteracts its inhibitory effect. We also demonstrated that the presence of multiple heme-uptake systems strongly influences GaPPIX susceptibility in A. baumannii. Interestingly, GaN and GaM showed only a bacteriostatic effect, whereas GaPPIX exerted a bactericidal activity on susceptible strains. Altogether, our findings raise hope for the future development of Ga(III)-based compounds in the treatment of infections caused by multidrug-resistant ESKAPE pathogens
Geometrical-optics approach to increase the accuracy in LED-based photometers for point-of-care testing
No full textA geometrical-optics approach is proposed to increase the accuracy in photometric measurements, using a point-of-care testing (POCT) LED-based sensor. Due to stray-light effects, the measurement accuracy depends on the dimension of the CMOS area, where the radiation is detected. We propose two image processing approaches and evaluate the influence of the sensor area. In addition, we demonstrate that with the same measurement, both absorption coefficient and refractive index can be determined, measuring the beam attenuation and the spot-size enlargement due to ray refraction
Geometrical-optics approach to measure the optical density of bacterial cultures using a LED-based photometer
No full textisolated from Danish pig farms
No full textNeomycin is the first-choice antibiotic for the treatment of porcine enteritis caused by enterotoxigenic Escherichia coli. Resistance to this aminoglycoside is on the rise after the increased use of neomycin due to the ban on zinc oxide. We identified the neomycin resistance determinants and plasmid contents in a historical collection of 128 neomycin-resistant clinical E. coli isolates from Danish pig farms. All isolates were characterized by whole-genome sequencing and antimicrobial susceptibility testing, followed by conjugation experiments and long-read sequencing of eight selected representative strains. We detected 35 sequence types (STs) with ST100 being the most prevalent lineage (38.3%). Neomycin resistance was associated with two resistance genes, namely aph(3')-Ia and aph(3')-Ib, which were identified in 93% and 7% of the isolates, respectively. The aph(3')-Ia was found on different large conjugative plasmids belonging to IncI1α, which was present in 67.2% of the strains, on IncHI1, IncHI2, and IncN, as well as on a multicopy ColRNAI plasmid. All these plasmids except ColRNAI carried genes encoding resistance to other antimicrobials or heavy metals, highlighting the risk of co-selection. The aph(3')-Ib gene occurred on a 19 kb chimeric, mobilizable plasmid that contained elements tracing back its origin to distantly related genera. While aph(3')-Ia was flanked by either Tn903 or Tn4352 derivatives, no clear association was observed between aph(3')-Ib and mobile genetic elements. In conclusion, the spread of neomycin resistance in porcine clinical E. coli is driven by two resistance determinants located on distinct plasmid scaffolds circulating within a highly diverse population dominated by ST100. IMPORTANCE Neomycin is the first-choice antibiotic for the management of Escherichia coli enteritis in pigs. This work shows that aph(3')-Ia and to a lesser extent aph(3')-Ib are responsible for the spread of neomycin resistance that has been recently observed among pig clinical isolates and elucidates the mechanisms of dissemination of these two resistance determinants. The aph(3')-Ia gene is located on different conjugative plasmid scaffolds and is associated with two distinct transposable elements (Tn903 and Tn4352) that contributed to its spread. The diffusion of aph(3')-Ib is mediated by a small non-conjugative, mobilizable chimeric plasmid that likely derived from distantly related members of the Pseudomonadota phylum and was not associated with any detectable mobile genetic element. Although the spread of neomycin resistance is largely attributable to horizontal transfer, both resistance determinants have been acquired by a predominant lineage (ST100) associated with enterotoxigenic E. coli, which accounted for approximately one-third of the strains
RESVERATROL-INDUCED AUTOPHAGY CONTRIBUTES TO THE INHIBITION OF EPSTEIN BARR VIRUS REPLICATION IN BURKITT’S LYMPHOMA CELLS
No full textRESVERATROL-INDUCED AUTOPHAGY CONTRIBUTES TO THE INHIBITION OF EPSTEIN BARR VIRUS REPLICATION IN BURKITT’S LYMPHOMA CELLS
De Leo Alessandra (a), Colavita Francesca (a), Arena Giuseppe (b), Mattia Elena (a)
(a) Dip. di Scienze di Sanità Pubblica e Malattie Infettive “Sanarelli”, Univ. di Roma “Sapienza”
(b) Casa Sollievo della Sofferenza Hospital, CSS-Mendel Institute, Roma
Presenting author: De Leo Alessandra, [email protected]
We have previously examined the antiviral activity of resveratrol on the replication of Epstein Barr Virus (EBV), the etiologic agent of infectious mononucleosis and associated with several types of malignancies of epithelial and lymphoid origin.
In a cellular context that allows in vitro EBV activation and lytic cycle progression through mechanisms closely resembling those that in vivo initiate and enable productive infection, we found that RV inhibited EBV lytic genes expression and the production of viral particles in a dose-dependent manner
The microbial community of a biofilm lining the wall of a pristine cave in Western New Guinea
No full textCave microbes are organised in complex ecological networks and have developed survival strategies involving
the production and release of a large variety of secondary metabolites, including antibiotic-like compounds. In
this study, the structure and the metabolic features of a biofilm-like microbial community lining the walls of a
pristine karst cavity (the Yumugi river cave) located in a remote region of the Western New Guinea were
investigated. 16S rRNA and shotgun sequence analyses highlighted the prevalence of chemoorganotrophic phyla
(Proteobacteria, Actinobacteria, Firmicutes and Acidobacteria), consistent with metabolic predictions inferred from
the cave metagenome analysis. Few clinically relevant antimicrobial resistance genes were detected. A culturebased
approach allowed the isolation of some heterotrophic members of the bacterial community, and antimicrobial
susceptibility testing revealed an overall high level of resistance to different antimicrobials classes.
Isolates presumptively representing new uncharacterized members of genus Pseudomonas displayed interesting
antibiotic properties against Gram-positive indicator strains. Our work supports the hypothesis that caves
represent a reservoir for new bacterial species and drug discovery research
A Highly Sensitive Luminescent Biosensor for the Microvolumetric Detection of the Pseudomonas aeruginosa Siderophore Pyochelin
No full textThe pyochelin (PCH) siderophore produced by the pathogenic bacterium Pseudomonas aeruginosa is an important virulence factor, acting as a growth promoter during infection. While strong evidence exists for PCH production in vivo, PCH quantification in biological samples is problematic due to analytical complexity, requiring extraction from large volumes and time-consuming purification steps. Here, the construction of a bioluminescent whole cell-based biosensor, which allows rapid, sensitive, and single-step PCH quantification in biological samples, is reported. The biosensor was engineered by fusing the promoter of the PCH biosynthetic gene pchE to the luxCDABE operon, and the resulting construct was inserted into the chromosome of the ΔpvdAΔpchDΔfpvA siderophore-null P. aeruginosa mutant. A bioassay was setup in a 96-well microplate format, enabling the contemporary screening of several samples in a few hours. A linear response was observed for up to 40 nM PCH, with a lower detection limit of 1.64 ± 0.26 nM PCH. Different parameters were considered to calibrate the biosensor, and a detailed step-by-step operation protocol, including troubleshooting specific problems that can arise during sample preparation, was established to achieve rapid, sensitive, and specific PCH quantification in both P. aeruginosa culture supernatants and biological samples. The biosensor was implemented as a screening tool to detect PCH-producing P. aeruginosa strains on a solid medium
Does Independence Affect Regulatory Performance? The case of national competition authorities in the European Union
No full textDespite having always been assumed to be true, a relationship between the independence of regulatory agencies and their performance has never been formally tested. This paper aims at verifying whether formal regulatory independence affects the performance of national competition authorities in the EU member states. The author presents and discusses a statistical analysis which shows that greater formal independence leads competition authorities to investigate more cases and to issue more decisions
Caterina Colombini (1304 ca.-1387) o della cugina sedotta. Una ‘ricostruzione’ della figura di Caterina attraverso i testi letterari, in Le vestigia dei gesuati. L’eredità culturale del Colombini e dei suoi seguaci, a cura di I. Gagliardi, Firenze, Firenze University Press, 2020, pp. 57-71 ISBN 978-88-5518-227-0
No full textIn this essay the author demonstrates that it is possible to reconstruct the figure of Caterina Colombini (1340?-1387) – Giovanni Colombini's cousin – through a group of texts: the hagiography of Caterina, the letters sent to her by Giovanni Colombini and, finally, Giovanni's biography written by Feo Belcari. The author divides his text into four parts: the first part analyzes the content of Caterina's hagiography; the second examines the linguistic form of the hagiographic text; in the third, the author analyzes the latent meaning of the window, a symbolic place where Giovanni and Caterina converse on divine topics; in the last part, to conclude, the teachings that Giovanni gives to Catherine and her spiritual daughters – the Gesuate – are analyzed
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