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Your search keyword '"Fradiani, PIERA ASSUNTA"' showing total 9 results
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9 results on '"Fradiani, PIERA ASSUNTA"'

2. H-NS regulation of virulence gene expression in enteroinvasive Escherichia coli harboring the virulence plasmid integrated into the host chromosome

Author

Colonna, Bianca, Casalino, Mariassunta, Fradiani, Piera Assunta, Zagaglia, Carlo, Naitza, Silvia, Leoni, Livia, Prosseda, Gianni, Coppo, Anna, Gheraldini, Patrizia, and Nicoletti, Mauro

Subjects
Pathogenic microorganisms -- Research, Plasmids -- Genetic aspects, Escherichia coli -- Research, Biological sciences
Abstract

Virulence gene expression in enteroinvasive Escherichia coli requires all three virulence regulatory genes: virB, virF and hns. The integration of the virulence plasmid pINV produces a noninvasive strain by repressing virB transcription, despite virF and hns remaining unaffected. H-NS in the pINV-strain binds more stably to virB, preventing virF activation but an increase in virF gene dosage, for autonomously replicating pINV, overcomes H-NS' negative regulatory effect on virB transcription.

Published
1995

3. Lentiviral shRNA delivery reduces apical sodium channel activity in differentiated human airway epithelial cells

Author

Aarbiou, J., Copreni, E., Buijs Offerman, R. M., van der Wegen, P., Castellani, S., Carbone, A., Tilesi, Francesca, Fradiani, PIERA ASSUNTA, Hiemstra, P. S., Yueksekdag, G., Diana, A., Rosenecker, J., Ascenzioni, Fiorentina, Conese, M., and Sholte, B. J.

Subjects
Cystic Fibrosis, cell - biology, virology - lentiviruses, respiratory medicine, RNA - interference
Published
2012

4. Design and validation of siRNAs and shRNAs

Author

Tilesi, Francesca, Fradiani, PIERA ASSUNTA, Socci, V., Willems, D., and Ascenzioni, Fiorentina

Subjects
microrna, Reproducibility of Results, rnai, off-target, short hairpin rna, sirna, sirna design, MicroRNAs, Drug Design, Drug Discovery, Animals, Humans, RNA Interference, RNA, Small Interfering, Algorithms
Abstract

RNAi is a highly conserved intracellular mechanism, whereby dsRNA strands conduct post-transcriptional modulation of gene expression through a degradation or inhibition of the translation of target mRNA. Since its discovery in 1998, RNAi has been identified in many different organisms, including mammals, and this mechanism has provided new approaches for studies in cellular and molecular biology, functional genomics and drug discovery. siRNAs can be predicted by sequence and thermodynamic features, and the wide and proficient application of RNAi relies on the ability to select the most active siRNAs from among numerous predicted molecules. Recently, the first-generation prediction algorithms based on the characteristics of siRNAs, short hairpin (sh)RNAs and micro-(mi)RNAs have been improved by the use of computational models that account for the experimentally determined activities of large numbers of siRNAs/shRNAs and miRNAs. These second-generation algorithms differ from the first-generation algorithms in the computational tools that are used for the prediction of siRNA efficacy; although these new algorithms improve the design of effective siRNAs, they do not eliminate the requirement for an experimental evaluation of the activities of siRNAs. This review reports on the most significant second-generation algorithms of siRNA and shRNA characteristics, as well as on recently designed systems for the experimental evaluation of siRNA activities.

Published
2009

8. Expression of the Virulence Plasmid-Carried Apyrase Gene (apy) of Enteroinvasive Escherichia coliandShigella flexneriIs under the Control of H-NS and the VirF and VirB Regulatory Cascade

Author

Berlutti, Francesca, Casalino, Mariassunta, Zagaglia, Carlo, Fradiani, Piera Assunta, Visca, Paolo, and Nicoletti, Mauro

Abstract

ABSTRACTThe transcription of the virulence plasmid (pINV)-carried invasion genes of Shigella flexneriand enteroinvasiveEscherichia coli(EIEC) is induced at 37°C and repressed at 30°C. In this work, we report that the O135: K−:H− EIEC strain HN280 and S. flexneriSFZM53, M90T, and 454, of serotypes 4, 5, and 2a, respectively, produce apyrase (ATP-diphosphohydrolase), the product of the apygene. In addition, the S. flexneristrains, but not the EIEC strain, produce a nonspecific phosphatase encoded by the phoN-Sfgene. Both apyand phoN-Sfare pINV-carried loci whose contribution to the pathogenicity of enteroinvasive microorganisms has been hypothesized but not yet established. We found that, like that of virulence genes, the expression of both theapyand the phoN-Sfgenes was temperature regulated. Strain HN280/32 (a pINV-integrated avirulent derivative of HN280 which has a severe reduction of virBtranscription) expressed the apygene in a temperature-regulated fashion but to a much lower extent than wild-type HN280, while the introduction of the Δhnsdeletion in HN280 and in HN280/32 induced the wild-type temperature-independent expression of apyrase. These results indicated that a reduction of virBtranscription, which is known to occur in the pINV-integrated strain HN280/32, accounts for reduced apyrase expression and that the histone-like protein H-NS is involved in this regulatory network. Independent spontaneously generated mutants of HN280 and of SFZM53 which had lost the capacity to bind Congo red dye (Crb−) were isolated, and the molecular alterations of pINV were evaluated by PCR analysis. Alterations of pINV characterized by the absence of virFor virBand by the presence of the intact apylocus or intactapyand phoN-Sfloci were detected among Crb−mutants of HN280 and SFZM53, respectively. While all Crb−apy+mutants of HN280 failed to produce apyrase, Crb−apy+phoN-Sf+mutants of SFZM53 lacked apyrase activity but produced a nonspecific phosphatase, like parental SFZM53. Moreover, the introduction of recombinant plasmids carrying clonedvirF(pMYSH6504) or virB(pBN1) into Crb−mutants of HN280 and SFZM53 lacking virFor virB, respectively, fully restored temperature-dependent apyrase expression to levels resembling those of the parental strains. Taken together, our results demonstrate that, as has already been shown for invasion genes, apyis another locus whose expression is controlled by temperature, H-NS, and the VirF and VirB regulatory cascade. In contrast, the temperature-regulated expression of the nonspecific phosphatase does not appear to be under the control of the same regulatory network. These findings led us to speculate that apyrase may play a role in the pathogenicity of enteroinvasive bacteria.

Published
1998
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9. Biofilm-mediated antibiotic tolerance in Staphylococcus aureus from spinal cord stimulation device-related infections.

Author

Sivori F, Cavallo I, Truglio M, Pelagalli L, Mariani V, Fabrizio G, Abril E, Santino I, Fradiani PA, Solmone M, Pimpinelli F, Toma L, Arcioni R, De Blasi RA, and Di Domenico EG

Abstract

Staphylococcus aureus is a predominant cause of infections in individuals with spinal cord stimulation (SCS) devices. Biofilm formation complicates these infections, commonly requiring both surgical and antibiotic treatments. This study explored the biofilm matrix composition and antimicrobial susceptibility of planktonic and biofilm-growing S. aureus isolates from individuals with SCS-related infections. Whole-genome sequencing (WGS) examined genotypes, virulome, resistome, and the pan-genome structure. The study also analyzed biofilm matrix composition, early surface adhesion, hemolytic activity, and antibiotic-susceptibility testing. WGS revealed genetic diversity among isolates. One isolate, though oxacillin susceptible, contained the mec A gene. The median number of virulence factor genes per isolate was 58. All isolates harbored the biofilm-related ica A/D genes. When assessing phenotypic characteristics, all strains demonstrated the ability to form biofilms in vitro . The antimicrobial susceptibility profile indicated that oxacillin, rifampin, and teicoplanin showed the highest efficacy against S. aureus biofilm. Conversely, high biofilm tolerance was observed for vancomycin, trimethoprim/sulfamethoxazole, and levofloxacin. These findings suggest that S. aureus isolates are highly virulent and produce robust biofilms. In cases of suspected biofilm infections caused by S. aureus , vancomycin should not be the primary choice due to its low activity against biofilm. Instead, oxacillin, rifampin, and teicoplanin appear to be more effective options to manage SCS infections.IMPORTANCESCS devices are increasingly used to manage chronic pain, but infections associated with these devices, particularly those caused by Staphylococcus aureus , present significant clinical challenges. These infections are often complicated by biofilm formation, which protects bacteria from immune responses and antibiotic treatments, making them difficult to eradicate. Understanding the genetic diversity, virulence, and biofilm characteristics of S. aureus isolates from SCS infections is critical to improving treatment strategies. Our study highlights the need to reconsider commonly used antibiotics like vancomycin, which shows reduced activity against biofilm-growing cells. Identifying more effective alternatives, such as oxacillin, rifampin, and teicoplanin, provides valuable insight for clinicians when managing biofilm-related S. aureus infections in patients with SCS implants. This research contributes to the growing evidence that biofilm formation is crucial in treating device-related infections, emphasizing the importance of tailoring antimicrobial strategies to the biofilm phenotype.

Published
2024
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