1,720,968 research outputs found
STARD3 and the identification of new cholesterol transport inhibitor
Full text linkAlthough many advances in the cancer treatment have been made, the research is
continuously searching new perspectives in order to provide the best possible outcome for all
patients. An emerging challenge is the identification of new genes involved in cancer
development and progression in order to develop novel therapeutic molecules to use alone or
in combination with current therapies. In the last years, some research groups have focused
their attention on a protein initially discovered to be overexpressed in breast cancer samples:
the StAR-related lipid transfer domain-3 (STARD3). STARD3 is a member of a subfamily of
lipid trafficking proteins characterized by a C-terminal steroidogenic acute regulatory domain
(STARD), which shares a 35% of homology with the domain of StAR protein, STARD1, a
transporter of cholesterol in mitochondria. They both belong to the START (steroidogenic
acute regulatory protein–related lipid transfer) proteins family, involved in the non-vesicular
transport of lipids in membranes. The crystal structure of the START domain of STARD3
revealed a hydrophobic cavity formed by the α/β helix grip structure of the 210 amino acids
with which it binds one molecule of cholesterol at an equimolar ratio 1:1, transporting sterol
from the endoplasmic reticulum (ER) to the endosomes. In human, it was demonstrated that
STARD3 is overexpressed in different cancer cell lines and, in particular, in Her2
overexpressing breast cancer. In fact, STARD3 and HER2 are co-amplified and cooverexpressed
in about 25% of breast cancers. The molecular mechanism by which STARD3
cooperates with others oncogene such as HER2 is still unclear. Nevertheless, STARD3 is implicated in therapy resistance of breast cancer, moreover,
patients with a high level of STARD3 expression display metastasis, local recurrence and
shorter overall survival. Recently, new evidences suggested a possible STARD3
overexpression also in colorectal, prostate and gastric cancers. Due to its involvement in
cancer, STARD3 represents an attractive candidate as a target to cancer therapy and the identification of selective inhibitors is an undiscovered but interesting field of study. In
collaboration with the University of Pisa that has developed the first pharmacophore-based
virtual screening (VS) platform focuses on the identification of new inhibitors of the STARD3
mediated cholesterol transport, we carried out a study to identify a lead compound (VS1)
endowed with an interesting activity, thus representing the first reported STARD3 inhibitor.
The activity of the inhibitor was evaluated in breast and colorectal cancer cell lines by
analyzing cell vitality and the level of focal adhesion kinase (FAK). Inhibition of STARD3 by
VS1 results in a consistent reduction of cell vitality; additionally the activation of a specific
STARD3 target (FAK) produced by the ligand, suggests a potent and specific activity of VS1 at cellular level
Next Generation Sequencing in rare childhood epilepsy of suspected genetic etiology
Full text linkMutations in several genes are associated with epilepsy (e.g. SCN1A, MECP2, ARX). Identifying genetic causes in epileptic syndromes is crucial to avoid a complex diagnostic work up, to provide genetic counseling, to start a tailored treatment in some cases and to avoid drugs potentially worsening seizures in others.Next Generation Sequencing (NGS) technologies allow analyzing a large number of genes in a single experiment, shortening the time to reach a definite diagnosis, and saving costs.Aim of this research was to identify gene variants underlying epilepsies with a challenging etiological classification. DNA from 81 pediatric epileptic patients was analyzed with a gene panel set up by child epileptologists, neurophysiologists and geneticists. This included 55 genes, later extended to 91, associated or not to intellectual disability, additional neurological signs, and complex malformations.In 14 patients pathogenic mutations were individuated, with an overall mutational frequency of 17,2% (14/81).
90,5% of patients had previously undergone unrevealing cytogenetic or single-gene analyses, thus our population was highly selected at the time NGS was performed.It is essential to underline that NGS must not be considered a screening examination, and that it requires a multidisciplinary approach in patients’ selection, and results interpretation
Interaction between nanostructured materials and synthetic and plasmatic membranes
No full textUnderstanding the interplay between nanostructured materials and cell membranes is the basis of their possible usage for therapeutics and for engineering new bio-applications. With the aim to unravel the mechanisms of interaction at the molecular scale, I have studied during my PhD the interaction between CdSe/CdS semiconductor nanorods (NRs) and polymeric micelles with model and plasmatic lipid membranes. NRs were in-house synthetized and functionalized with different amount of bis-amino polyetilenglycol (PEG) and a tertiary amine to tune their surface potential (ζ) between -50 mV and +10 mV. Their interaction with lipid mixtures of different composition in form of supported lipid bilayers (SLBs), lipid monolayers (LMs) and different in vitro cell lines was tested. In particular, NRs adsorption to SLBs was monitored by quartz crystal microbalance with dissipation monitoring (QCM-D) varying lipid mixtures charge and investigating the influence of gel phase domains; interactions with LMs same in composition as SLBs were measured by surface pressure-area isotherms. Results showed that tuning the mutual properties of the system regulates the interaction with NRs on the membranes and that the increase of membrane complexity inhibits it: in particular a strong interaction was registered with fluid state membranes and NRs opposite in charge when Δζ > 70 mV, whereas the interaction was hindered in presence of gel phase domains. LMs models gave more detailed information, showing removal of lipid molecules from air-water interface or insertion of NRs between lipids according to the overall system charge. QCM-D and surface pressure-area isotherms results were in agreement.
Since the polymer coating of the NRs was shown to regulate the interaction, in order to elucidate its effect I have employed also fluorescent polymeric micelles of different dimension (60 and 300 nm in diameter). I have tested the interaction of both NRs and micelles with different cell lines, namely post-natal mouse neuronal network (known to have a dynamically changing membrane potential), mouse neuroblastoma Neuro2a (that can differentiate in neuronal-like cells) and Chinese hamster ovary cells (epithelial, with a static membrane potential), using confocal microscopy both on fixed samples and in real time. Preliminary results showed adhesion of negatively charged NRs and micelles on both dynamic potential membrane cell lines. Again a threshold value was found for NRs interacting with neurons (ζNR < -18 mV), similarly to what was observed with models. A neurotoxin was then introduced in the experiments, to reduce the spikes of the active cells. A satellite project is finally presented as a full paper at the end of the thesis. The project concerns the fabrication and characterization of thin anodic porous alumina (tAPA) substrates, which surface was made surface-enhanced Raman spectroscopy (SERS) -active by coating with a thin gold (Au) layer. My part in this project was related to the monitoring of the chemisorption of thiols and the formation of SLB models from lipid vesicles by using the QCM-D technique on Au substrates
Surface charge regulated adsorption of semiconductor polymer coated nanorods on lipid membranes
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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