90 research outputs found
« Et havendo parlato co Flaminio Romano, dichiarato e sententiato eretico ». Denunce e delazioni nella Siena del xvi secolo
No full textThe trials of Niccolo Amerighi and Flaminio Fabrizi are among the most interesting within the swath of documents emerging from the recently open Archive of the Congregation for the Doctrine of the Faith. While not covering the trials and their underlying ideas, this article intends to provide the reader with a glimpse of the network that Amerighi and Fabrizi established in Siena and the impact that their trials had in the city
Resonant Inelastic X-ray Scattering at the ESRF: Hard and Soft X-rays
No full textThe technique of Resonant Inelastic X-ray Scattering (RIXS) has been exploited at the ESRF since the very early days of the facility in the 1990s. Of particular importance has been the pioneering hard X-ray work on ID16 and that by the Milano group of L. Braicovich and G. Ghiringhelli in collaboration with the ESRF at the soft X-ray beamline (originally on ID12B and then at ID08). The success of these activities has in many cases led to the development of the technique at other facilities. Both the hard and soft X-ray RIXS facilities at the ESRF will be upgraded in the next two years so it is timely to briefly outline what scientific problems can be addressed by the method, what the current status is at the ESRF, and how the experimental capabilities will be enhanced in the near future
PARENTERAL NUTRITION AND BRANCHED CHAIN AMINO ACIDS: AN IN VIVO AND IN VITRO EVALUATION.
No full textParenteral nutrition (PN) offers the possibility to increase or to ensure nutrient intake, providing
nutrients in sufficient doses to meet the veterinary and human patient’s daily requirements. PN is a
complex admixture based on amino acids, dextrose, lipids. Safety issues related to parenteral nutrition
formulations have led to the development of guidelines for safe practices. The development of new
formulation and the evaluation of the already used solution is the main research in PN practice.
International guidelines are quite vague regarding the optimal doses of amino acid to administer to
malnourished patients affected by liver desease. A decreased ratio of branched-chain amino acids
(BCAA) to aromatic amino acids (AAA) is considered an important pathogenetic factor in hepatic
disease. The PN solution are composed by different compound, where the BCAAs are always
presents. Long-term oral supplementation with branched chain amino acids (BCAAs) as adjuvant
during liver injuries, both in humans and animals, is still not totally clear. Aim of the present study
was to determine how amino acids in PN and BCAAs on an in vitro study can preserve liver damage
and function. First purpose of this study was to evaluate the use of partial parenteral nutrition (PPN)
in dogs, using two different solutions: 11 dogs treated with a normal amino acidic concentration
(Medium/Low Protein Level group, Freamine concentration ≤ 25%;1,9-2,2 gr/kg/die amino
acids/proteins) as control group and 9 dogs with high-amino acid percentage (High Protein Level
group, Freamine > 25%; 3,6-6 gr/kg/die amino acids/proteins) as cases. The evaluation of the two
differents solutions is based on the liver damage during the therapy. Results reveal a not statistically
significatives differencies for liver damage between High Protein Level group and Medium/Low
Protein Level group. It means that an a hight amount of amino acids in PN could not affect and
overload the hepatic metabolism, despite carrying out their more advantage effects on body lean mass.
The second purpose and study, which is the most importan for us, was to evaluate two differents in
vitro models selected: A) hepatic rabbit cells plated in 2D monolayer and B) rabbit hepatic cells
cultured onto 3D scaffolds, obtained from decellularized rabbit liver. Both A and B cells were treated
with BCAAs. All cells adhered and proliferated, once plated. Moreover, the presence of hepatic
progenitors (HPCs), were detected by immuno staining assay and mRNA expression. However, A
cells were shown to produce albumin and FVII but quickly entered G0 and arrested growth by day
15. In contrast, cells in B, actively replicated and recellularized ECM rabbit liver, mimicking the
original organ cyto-architecture, until day 21. Interestingly, under defined conditions, BCAA
supplementation promoted vigorous growth of cell organoid and increased hepatocyte albumin and
FVII production and expression. A selective amplification of self-renewing bi-potent HPCs was also
observed. These results highlight the role of BCAAs in long term supplementation and support the
use of 3D cultures as reliable in vitro models. In conclusion, these finding suggest that an high amino
acidic diet with a high BCAAs/AAA ratio coud be a valid therapeutic option in cachectic patients or
patient with severe livere diseases
RixsToolBox: Software for the analysis of soft X-ray RIXS data acquired with 2D detectors
No full textA software with a graphical user interface has been developed with the aim of facilitating the data analysis for users of a new resonant inelastic X-ray scattering (RIXS) spectrometer installed at the ESRF beamline ID32. The software is organized in modules covering all relevant steps in the data reduction from a stack of several hundred two-dimensional CCD images to a single RIXS spectrum. It utilizes both full charge integration and single-photon centroiding to cope with high-flux and high-resolution requirements. Additional modules for further data analysis and the extraction of instrumental parameters are available. The software has been in routine use for about a year now and in that time many additional features have been incorporated. It now meets the users' need for an easy-to-use data analysis tool that allows looking at and understanding data as it is acquired and thus steering users' experiments more efficiently
Tracheal In Vitro Reconstruction Using a Decellularized Bio-Scaffold in Combination with a Rotating Bioreactor
No full textLong-segment airway stenosis as well as their neoplastic transformation is life-threatening and still currently represent unsolved clinical problems. Indeed, despite several attempts, definitive surgical procedures are not presently available, and a suitable tracheal reconstruction or replacement remains an urgent clinical need. A possible innovative strategic solution to restore upper airway function may be represented by the creation of a bioprosthetic trachea, obtained through the combination of tissue engineering and regenerative medicine.Here we describe a two-step protocol for the ex vivo generation of tracheal segments. The first step involves the application of a decellularization technique that allows for the production of a naturally derived extracellular matrix (ECM)-based bio-scaffold, that maintains the macro- and micro-architecture as well as 9 the matrix-related signals distinctive of the original tissue. In the second step chondrocytes are seeded onto decellularized trachea, using a rotating bioreactor to ensure a correct scaffold repopulation.This multi-step approach represents a powerful tool for in vitro reconstruction of a bioengineered trachea that may constitute a promising solution to restore upper airway function. In addition, the procedures here described allow for the creation of a suitable 3D platform that may find useful applications, both for toxicological studies as well as organ transplantation strategies
A Mathematical Model for the Vessel Recruitment in Coronary Microcirculation In the Absence of Active Autoregulation
No full textThis paper proposes a mathematical model for vessel recruitment in the microvascular coronary network. The model is based on microvascular network units (MVNUs), where we define aMVNU as a portion of the microvascular network comprising seven generations of identical, parallel-arranged vessels (upstream arteries, large and small arterioles, capillaries, small and large venules, and downstream veins). The model implements a new mechanism to describe the variation in the number of MVNU in response to sudden variations of the local input pressure. In particular, it describes a recruitment mechanismdependent on distal pressure which operates in the coronary microcirculatory network even in maximally dilated conditions. Weapply the model to interpret data from 29 patients who underwent revascularization by percutaneous coronary intervention (PCI). Treated vessels were the left anterior descending coronary artery, the left circumflex and the right coronary artery in 26, 2 and 1 patients, respectively. Following intracoronary adenosine administration, distal coronary pressure and blood flow were 48 ± 18 mm Hg and 45 ± 30 ml/min before PCI, respectively, and significantly increased afterwards to 80±17mmHg and 68±32 ml/min (p b 0.001). The model predicts an increase inMVNU number in patients with preserved wall motion in the myocardial region which underwent PCI. On the contrary, a decrease in MVNU number is predicted by the model in patients with regional dysfunction and implies a relatively lower response of maximal flow to revascularization
Whole-ovary decellularization generates an effective 3D bioscaffold for ovarian bioengineering
No full textPurpose: To develop a new protocol for whole-ovary decellularization for the production of a 3D bioscaffold suitable for in vitro/ex vivo studies and for the reconstruction of a bioengineered ovary.
Methods: Porcine ovaries were subjected to the decellularization process (DECELL; n = 20) that involved a freeze-thaw cycle, followed by sequential incubations in 0.5% SDS for 3 h, 1% Triton X-100 for 9 h, and 2% deoxycholate for 12 h. Untreated ovaries were used as a control (CTR; n = 6). Both groups were analyzed to evaluate cell and DNA removal as well as ECM preservation. DECELL bioscaffolds were assessed for cytotoxicity and cell homing ability.
Results: DECELL ovaries maintained shape and homogeneity without any deformation, while their color turned from red to white. Histological staining and DNA quantification confirmed a decrease of 98.11% in DNA content, compared with the native tissue (CTR). Histochemical assessments demonstrated the preservation of intact ECM microarchitecture after the decellularization process. This was also confirmed by quantitative analysis of collagen, elastin, and GAG contents. DECELL bioscaffold showed no cytotoxic effects in co-culture and, when re-seeded with homologous fibroblasts, encouraged a rapid cell adhesion and migration, with repopulating cells increasing in number and aggregating in cluster-like structures, consistent with its ability to sustain cell adherence, proliferation, and differentiation.
Conclusion: The protocol described allows for the generation of a 3D bioscaffold that may constitute a suitable model for ex vivo culture of ovarian cells and follicles, as well as a promising tool for the reconstruction of a bioengineered ovary.
Purpose: To develop a new protocol for whole-ovary decellularization for the production of a 3D bioscaffold suitable for in vitro/ex vivo studies and for the reconstruction of a bioengineered ovary.
Methods: Porcine ovaries were subjected to the decellularization process (DECELL; n = 20) that involved a freeze-thaw cycle, followed by sequential incubations in 0.5% SDS for 3 h, 1% Triton X-100 for 9 h, and 2% deoxycholate for 12 h. Untreated ovaries were used as a control (CTR; n = 6). Both groups were analyzed to evaluate cell and DNA removal as well as ECM preservation. DECELL bioscaffolds were assessed for cytotoxicity and cell homing ability.
Results: DECELL ovaries maintained shape and homogeneity without any deformation, while their color turned from red to white. Histological staining and DNA quantification confirmed a decrease of 98.11% in DNA content, compared with the native tissue (CTR). Histochemical assessments demonstrated the preservation of intact ECM microarchitecture after the decellularization process. This was also confirmed by quantitative analysis of collagen, elastin, and GAG contents. DECELL bioscaffold showed no cytotoxic effects in co-culture and, when re-seeded with homologous fibroblasts, encouraged a rapid cell adhesion and migration, with repopulating cells increasing in number and aggregating in cluster-like structures, consistent with its ability to sustain cell adherence, proliferation, and differentiation.
Conclusion: The protocol described allows for the generation of a 3D bioscaffold that may constitute a suitable model for ex vivo culture of ovarian cells and follicles, as well as a promising tool for the reconstruction of a bioengineered ovary
Magnetic, orbital and charge fluctuations in layered cuprates studied by resonant soft X-ray scattering
No full textQuesta tesi è basata sui miei 3 anni di attività nel gruppo dei Prof. L. Braicovich e G. Ghiringhelli durante i quali ho partecipato attivamente a numerosi esperimenti di Resonant Inelastic X-ray Scattering (RIXS) e X-ray Absorption Spectroscopy (XAS), presso la beamline ID08 dell’European Synchrotron Radiation Facility (ESRF) di Grenoble (FR), dove mi sono anche trasferito stabilmente per un anno, e la beamline ADRESS dello Swiss Light Source (SLS) di Villigen (CH), per un totale di oltre 30 settimane di esperimenti. Dopo una breve introduzione sulla tecnica spettroscopica e la strumentazione utilizzata, la tesi presenta i principali risultati ottenuti con il RIXS, lavorando prevalentemente allo spigolo L3 del Rame. Abbiamo studiato una vasta gamma di sistemi cuprati con diversi drogaggi, sia in forma di film sottili che di cristalli, in particolare Nd1.2Ba1.8Cu3O6+x (NBCO) e YBa2Cu3O6+x (YBCO). In questi sistemi abbiamo dimostrato la permanenza nei piani CuO2 di un’eccitazione disperdente, figlia del magnone visibile nei parent compounds isolanti, anche nel caso di campioni superconduttori fortemente drogati. Tale eccitazione “paramagnonica” costituisce una fortissima prova a sostegno dell’interpretazione della superconduttività ad alta temperatura che assegna all’ordine magnetico un ruolo dominante e propone i magnoni come collanti delle coppie di Cooper nei cuprati. Seguendo lo stesso percorso logico abbiamo misurato le fluttuazioni magnetiche in alcuni superreticoli (SR) artificiali a base di SrTiO3 e CaCuO2, un cuprato dalla struttura cristallina molto semplice che lo rende un sistema modello per lo studio dei piani CuO2. Questi SR, benché composti di materiali isolanti, si sono recentemente dimostrati superconduttori se cresciuti in alta pressione di ossigeno. Anche in questo caso abbiamo riscontrato la presenza di eccitazioni magnetiche di energia tale da poter sostenere la superconduttività mentre le informazioni sul campo cristallino fornite dalle eccitazioni dd ci hanno permesso di comprendere come varia la struttura elettronica del rame alle interfacce di questi SR e di fare alcune interessanti ipotesi sulla struttura di quest’ultime e sul loro ruolo nel meccanismo di drogaggio. Infine abbiamo studiato le fluttuazioni di carica nei piani CuO2 di cuprati drogati, raccogliendo una ricca casistica relativa alla presenza di una risonanza quasi-elastica al variare del momento trasferito negli spettri RIXS. Tale risonanza è connessa con un ordinamento dei piani CuO2 in cui strisce di carica si alternano a strisce in cui è preservato l’ordine antiferromagnetico. Abbiamo documentato questo effetto nei sistemi (Y,N)BCO ottenendo un quadro completo della fenomenologia: in particolare al diminuire della temperatura la risonanza cresce, è massima alla temperatura critica e quindi decresce, confermando la presenza di un ordine di carica di tipo charge density wave che compete con la superconduttività e mai osservato prima in questi materiali.This thesis presents the results achieved on cuprates with resonant soft x-ray scattering (RXS) during my activity in the group of Prof. G. Ghiringhelli and Prof. L. Braicovich of the Physics Department of Politecnico di Milano (Italy). The group has a well-established experience in synchrotron-based spectroscopies for the study of magnetic and electronic properties of transition-elements and rare earth compounds. In the last years they focused their activity especially on resonant inelastic x-ray scattering (RIXS), contributing substantially to the development of the technique, both from the point of view of science and instrumentation. They designed and built two high resolution spectrometers dedicated to RIXS: AXES (Advanced X-ray Emission Spectrometer) and SAXES (Super-AXES). AXES is working since 1995 at the beamline ID08 of the European Synchrotron Radiation Facility in Grenoble, France. SAXES, which is the evolution of AXES, has been installed in 2006 at the ADRESS beamline at the Swiss Light Source in Villigen, Switzerland. It is working since July 2007 and by now it holds the world record of resolving power with a combined resolution of 130 meV at Cu L3 edge (930 eV).
In this thesis I present some of the results obtained with these spectrometers on insulating and superconducting layered cuprates using Cu L3 edge RIXS. This technique is shown to be the optimal probe to study magnetic, orbital and charge fluctuations in the CuO2 planes of these compounds, allowing energy and momentum-resolved measurements and adding crucial pieces to the puzzle of high temperature superconducitivity.
CuO2 planes are the common feature of all layered cuprates and the set where high-Tc superconductivity emerges: these planes consist of Cu2+ ions alternated to O2− ions and they are separated each other by “blocking layers”. Although it has one hole per Cu site, each CuO2 plane is originally insulating, due to the large electron correlation typical of transition-element oxides. The Cu2+ ions (3d9 configuration) have one unpaired spin-1/2 per site and they are coupled via superexchange interaction J, i.e. the exchange mediated by oxygen, so to produce a bidimensional antiferromagnetic (AF) lattice. The hybridization with the oxygen ions is so strong that the superexchange is exceptionally high in cuprates (J > 100 meV), allowing the study of the associated magnetic excitations without the need of a few meV resolution. When the insulating parent compounds are doped, the additional degrees of freedom from dopant charges further complicate the electronic situation. A critical doping is required to destroy the various long range orders and superconductivity emerges when charges coming from the blocking layers dope the CuO2 sheets in a number that alters the situation and triggers the transition.
Despite more than 25 years of studies, the origin of the superconducting state in cuprates is still unclear and remains the subject of intense scrutiny. In particular one of the central unanswered questions concerns the nature of the normal-state spin fluctuations that may be responsible for the pairing. Because of technical limitations, the experimental investigation of doped cuprates has been until now largely focused on low-energy excitations in a small range of momentum space.
In this thesis we used high resolution RIXS to show that a large family of high-Tc superconductors (HTS), i.e. (Y,Nd)Ba2Cu3O6+x (RBCO), exhibits high-energy damped spin excitations (paramagnons) over a wide range of doping, with dispersions and spectral weights closely similar to those of magnons in undoped cuprates.
The comprehensive experimental description that comes out from our systematic data acquisition enables quantitative tests of magnetic Cooper pairing models and supports the paramagnons as strong candidates to cover the role of glue for the Cooper’s pairs.
Subsequently we have exploited the capability of RIXS to work very well on thin films, in order to study both insulating and superconducting cuprate-based heterostructures. Recently the technical progress in epitaxial growth has lead to the discovery of a panoply of exceptional magnetic and transport properties in artificial heterostructures of 3d transition metal oxides in general. Electronic, lattice and orbital reconstruction occurring at the interfaces can in fact influence the charge transfer between the oxides, while the modified dimensionality can affect the magnetic properties of the oxides. Among these heterostructures cuprate-based superlattices (SLs) are particularly interesting since they can be considered as new, artificial HTS, offering the opportunity of freely choosing the two building blocks i.e., the superconducting CuO2 planes and the charge reservoir blocking layers. We have carried out Cu L3 RIXS measurements on both insulating and superconducting (CaCuO2)m/(SrTiO3)n SLs and compared the results with those on a 14 nm thick CaCuO2 film, in order to understand what happens to magnons when the CuO2 planes are at the interfaces of a SL and if a (para)magnon-mediated superconductivity could still be possible. In all insulating samples spin excitations are in the form of dispersing magnons and in the SLs magnons have similar spectral intensity but reduced dynamics with respect to pure CaCuO2. This is the demonstration that the AF order is preserved in the insulating SLs, down to very small cuprate layer thickness and despite the chemical and structural alterations at the interfaces. On the other hand the superconducting SLs exhibit dispersing paramagnons, similarly to the case of superconducting RBCO. Moreover the orbital excitations, visible in RIXS spectra together with magnons and due to the ligand field felt by Cu2+ ions, have revealed a pyramidal coordination of copper atoms at the CaCuO2/SrTiO3 interfaces. These findings open the way to the production of new, artificial HTS based on cuprate/noncuprate SLs where the charge reservoir layer is constituted by the interface itself.
Any successful theory for HTS should require a detailed understanding not only of the spin but also of the charge correlations in the normal state from which superconductivity emerges. Therefore we have studied charge fluctuations in the CuO2 planes by means of RXS. Despite intense efforts, to the present date only two clear ordering phenomena have been reported for correlations in the copper oxide sheets of cuprates: the above cited uniform AF in undoped cuprates and a uniaxially modulated AF, combined with charge order, in the so-called “214” family [with chemical composition La2−x−y(Sr,Ba)x(Nd,Eu)yCuO4]. The latter is known as “stripe order”, with a commensurate charge modulation with a period 4 lattice units, which greatly reduces the superconducting transition temperature of 214 materials at a doping level p ≈ 1/8 per planar Cu atom. Incommensurate spin and charge fluctuations in 214 materials with p ≠ 1/8 have been interpreted as evidence of fluctuating stripes. These findings have generated a long-standing debate around the questions of whether stripe order is a generic feature of the copper oxides and if stripe fluctuations are essential for superconductivity. We have used RXS to assess this issue and identify two-dimensional charge fluctuations with an incommensurate periodicity of 3.2 lattice units in the CuO2 planes of the superconductors RBCO, with hole concentrations p of 0.09 to 0.13 per planar Cu ion. The intensity and correlation length of the signal increase strongly upon cooling towards Tc, while further cooling below Tc abruptly reverses the divergence of the charge correlations. In combination with earlier observations, these data indicate an incipient charge density wave (CDW) instability that competes with superconductivity and, for the first time, we have the evidence that the anomalously low Tc found in underdoped cuprates is due to CDW, and not other phenomena.DIPARTIMENTO DI FISICA25GHIRINGHELLI, GIACOMO CLAUDIOTARONI, PAOL
Creation of a Bioengineered Ovary: Isolation of Female Germline Stem Cells for the Repopulation of a Decellularized Ovarian Bioscaffold
No full textOvarian failure is the most common cause of infertility and affects about 1% of young women. One innovative strategy to restore ovarian function may be represented by the development of a bioprosthetic ovary, obtained through the combination of tissue engineering and regenerative medicine.We here describe the two main steps required for bioengineering the ovary and for its ex vivo functional reassembling. The first step aims at producing a 3D bioscaffold, which mimics the natural ovarian milieu in vitro. This is obtained with a whole organ decellularization technique that allows the maintenance of microarchitecture and biological signals of the original tissue. The second step involves the use of magnetic activated cell sorting (MACS) to isolate purified female germline stem cells (FGSCs). These cells are able to differentiate in ovarian adult mature cells, when subjected to specific stimuli, and can be used them to repopulate ovarian decellularized bioscaffolds. The combination of the two techniques represents a powerful tool for in vitro recreation of a bioengineered ovary that may constitute a promising solution for hormone and fertility function restoring. In addition, the procedures here described allow for the creation of a suitable 3D platform with useful applications both in toxicological and transplantation studies
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