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Banchelli M, Cascella R, D'Andrea C, Cabaj L, Osticioli I, Ciofini D, Li MS, Skupień K, de Angelis M, Siano S, Cecchi C, Pini R, La Penna G, Chiti F, Matteini P. Nanoscopic insights into the surface conformation of neurotoxic amyloid β oligomers. RSC Adv 2020; 10:21907-21913. [PMID: 35516647 PMCID: PMC9054531 DOI: 10.1039/d0ra03799k] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 06/01/2020] [Indexed: 11/21/2022] Open
Abstract
Raman spectroscopy assisted by localized plasmon resonances generating effective hot spots at the gaps between intertwined silver nanowires is herein adopted to unravel characteristic molecular motifs on the surface of Aβ42 misfolded oligomers that are critical in driving intermolecular interactions in neurodegeneration. Unraveling characteristic structural determinants at the basis of Aβ42 oligomers' neurotoxicity by a sub-molecular SERS investigation of their surface.![]()
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Cacciari I, Ciofini D, Baija H, Siano S. Terahertz Time-Domain Reconstruction of Coating Microstratigraphy on Gilded Surfaces. Materials (Basel) 2019; 12:E3822. [PMID: 31766348 PMCID: PMC6926600 DOI: 10.3390/ma12233822] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 11/16/2022]
Abstract
Here, a systematic study in order to assess the potential of THz time domain reflectometry for measuring the thicknesses of overpaint layers applied on original gilded surfaces was carried out. The work is part of a thorough characterization campaign, which is going on at the Rijksmuseum for addressing the conservation problems of a set of 19th century gilded picture frames on which heavy coatings were applied in previous undocumented restoration interventions. To perform such non-invasive thickness measurements, an analytical protocol based on Gaussian fits of the THz pulse-echo temporal profiles was optimized through the preparation of suitable technical samples and the comparison with direct thickness measurements. Finally, the methodology was validated by characterizing the microstratigraphy of an original sculptural element from a gilded picture frame in the Rijksmuseum collection. The results achieved show the effectiveness of the present approach in revealing multi-layered dielectric microstructures with a spatial resolution of about 30 µm when using a spectral range up to 1.5 THz.
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Affiliation(s)
- Ilaria Cacciari
- Istituto di Fisica Applicata “Nello Carrara”, Consiglio Nazionale delle Ricerche, v. M. del Piano 10, 50019 Sesto Fiorentino (FI), Italy; (D.C.); (S.S.)
| | - Daniele Ciofini
- Istituto di Fisica Applicata “Nello Carrara”, Consiglio Nazionale delle Ricerche, v. M. del Piano 10, 50019 Sesto Fiorentino (FI), Italy; (D.C.); (S.S.)
| | - Hubert Baija
- Rijksmuseum Amsterdam, Museumstraat 1, Postbus 74888, 1070 DN Amsterdam, The Netherlands;
| | - Salvatore Siano
- Istituto di Fisica Applicata “Nello Carrara”, Consiglio Nazionale delle Ricerche, v. M. del Piano 10, 50019 Sesto Fiorentino (FI), Italy; (D.C.); (S.S.)
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Cavigli L, Centi S, Borri C, Tortoli P, Panettieri I, Streit I, Ciofini D, Magni G, Rossi F, Siano S, Ratto F, Pini R. 1064-nm-resonant gold nanorods for photoacoustic theranostics within permissible exposure limits. J Biophotonics 2019; 12:e201900082. [PMID: 31155855 DOI: 10.1002/jbio.201900082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/03/2019] [Accepted: 05/30/2019] [Indexed: 05/07/2023]
Abstract
Therapeutic and diagnostic methods based on photomechanical effects are attracting much current attention in contexts as oncology, cardiology and vascular surgery, for such applications as photoacoustic imaging or microsurgery. Their underlying mechanism is the generation of ultrasound or cavitation from the interaction of short optical pulses with endogenous dyes or targeted contrast agents. Among the latter, gold nanorods are outstanding candidates, but their use has mainly been reported for photoacoustic imaging and photothermal treatments. Conversely, much less is still known about their value as a precision tool for photomechanical manipulations, such as to impart local damage with high spatial resolution through the expansion and collapse of microbubbles. Here, we address the feasibility of gold nanorods exhibiting a distribution of surface plasmon resonances between about 900 to above 1100 nm as a contrast agent for photoacoustic theranostics. After testing their cytotoxicity and cellular uptake, we discuss their photostability and use to mediate cavitation and the photomechanical destruction of targeted cells. We find that the choice of a plasmonic band peaking around 1064 nm is key to enhance the translational potential of this approach. With respect to the standard alternative of 800 nm, at 1064 nm, relevant regulations on optical exposure are less restrictive and the photonic technology is more mature.
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Affiliation(s)
- Lucia Cavigli
- Istituto di Fisica Applicata 'Nello Carrara', Consiglio Nazionale delle Ricerche IFAC-CNR, Sesto Fiorentino, Italy
| | - Sonia Centi
- Istituto di Fisica Applicata 'Nello Carrara', Consiglio Nazionale delle Ricerche IFAC-CNR, Sesto Fiorentino, Italy
| | - Claudia Borri
- Istituto di Fisica Applicata 'Nello Carrara', Consiglio Nazionale delle Ricerche IFAC-CNR, Sesto Fiorentino, Italy
| | - Paolo Tortoli
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Sesto Fiorentino, Italy
| | - Ilaria Panettieri
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Politecnico di Torino, Torino, Italy
| | | | - Daniele Ciofini
- Istituto di Fisica Applicata 'Nello Carrara', Consiglio Nazionale delle Ricerche IFAC-CNR, Sesto Fiorentino, Italy
| | - Giada Magni
- Istituto di Fisica Applicata 'Nello Carrara', Consiglio Nazionale delle Ricerche IFAC-CNR, Sesto Fiorentino, Italy
| | - Francesca Rossi
- Istituto di Fisica Applicata 'Nello Carrara', Consiglio Nazionale delle Ricerche IFAC-CNR, Sesto Fiorentino, Italy
| | - Salvatore Siano
- Istituto di Fisica Applicata 'Nello Carrara', Consiglio Nazionale delle Ricerche IFAC-CNR, Sesto Fiorentino, Italy
| | - Fulvio Ratto
- Istituto di Fisica Applicata 'Nello Carrara', Consiglio Nazionale delle Ricerche IFAC-CNR, Sesto Fiorentino, Italy
| | - Roberto Pini
- Istituto di Fisica Applicata 'Nello Carrara', Consiglio Nazionale delle Ricerche IFAC-CNR, Sesto Fiorentino, Italy
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Agresti J, Mencaglia AA, Siano S. High Energy Double Peak Pulse Laser Induced Plasma Spectroscopy for Metal Characterization Using a Passively Q-Switched Laser Source and CCD Detector. Sensors (Basel) 2019; 19:s19173634. [PMID: 31438514 PMCID: PMC6749410 DOI: 10.3390/s19173634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 08/10/2019] [Accepted: 08/19/2019] [Indexed: 06/10/2023]
Abstract
Here, the development and testing of a portable double peak pulse laser induced plasma spectroscopy (DPP-LIPS) based on passively Q-switched Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser excitation is reported. The latter delivered structured laser pulses at a repetition rate of up to 20 Hz, including two energy peaks of about 100 mJ each with a relative temporal spacing of about 80 µs. Plasma spectra were collected using a low-cost Czerny-Turner spectrometer equipped with a non-intensified CCD (Charge-Coupled Device) array. Such a DPP-LIPS setup is technologically simpler and cheaper than the usual ones. Despite the relatively large temporal separation between the mentioned laser peaks, significant spectral intensity enhancements with respect to the usual single peak pulse configuration were observed. The amplification factor measured ranged between 2 and 10, depending on the specific emission peaks and the Q-switched configuration, and a consequent significant improvement of the detection limit of trace elements was observed. The instrument was calibrated for the quantitative analysis of copper alloy through systematic measurements carried out on reference samples and was then tested in an example archaeometric characterization of a statuette from the Egyptian Museum of Florence.
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Affiliation(s)
- Juri Agresti
- Istituto di Fisica Applicata "Nello Carrara"-CNR, 50019 Sesto Fiorentino, Italy.
| | | | - Salvatore Siano
- Istituto di Fisica Applicata "Nello Carrara"-CNR, 50019 Sesto Fiorentino, Italy
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Mencaglia AA, Osticioli I, Ciofini D, Gallo L, Siano S. Raman spectrometer for the automated scan of large painted surfaces. Rev Sci Instrum 2019; 90:053101. [PMID: 31153252 DOI: 10.1063/1.5088039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 04/14/2019] [Indexed: 06/09/2023]
Abstract
In this work, a novel Raman scanner capable of performing point-to-point mapping of relatively large surface of paintings is presented. This device employs an excitation wavelength of 1064 nm, and it is equipped with a high efficiency probe in order to collect the back-scattered light from each point of analysis. The use of long depth-of-field optics as well as an autofocus system allowed maintaining the best conditions for the Raman signal acquisition during the scanning, regardless of the surface irregularities. The small dimension of the optical components and the reasonable size of mechanical parts made this instrumentation particularly suitable for on-site measurements. Finally, the Raman scanner was also equipped with an online temperature control using a thermal sensor, which allows modulating automatically the output power of the laser source in order to prevent overheating and alteration effects during the scanning process. The capabilities of the Raman scanner were evaluated scanning two valuable paintings one attributed to Ambrogio Lorenzetti and the other to Duccio da Buoninsegna of the fourteenth century.
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Affiliation(s)
| | - Iacopo Osticioli
- Institute of Applied Physics "Nello Carrara" (IFAC-CNR), Florence, Italy
| | - Daniele Ciofini
- Institute of Applied Physics "Nello Carrara" (IFAC-CNR), Florence, Italy
| | | | - Salvatore Siano
- Institute of Applied Physics "Nello Carrara" (IFAC-CNR), Florence, Italy
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Ciofini D, Oujja M, Cañamares MV, Siano S, Castillejo M. Detecting molecular changes in UV laser-ablated oil/diterpenoid resin coatings using micro-Raman spectroscopy and Laser Induced Fluorescence. Microchem J 2018. [DOI: 10.1016/j.microc.2018.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
Pressure transients occurring inside the eyeball as a consequence of excimer laser ablation of the cornea were measured at various distances along the optical axis, on enucleated porcine eyes. Positive (compressive) pressure spikes up to 90 bars were observed, lasting 100 ns, and developing, as they propagated in the eyeball, satellite rarefaction pulses with negative pressure as high as -40 bar. Such rarefaction wavefronts can trigger the formation of cavitation bubbles, in both the anterior and posterior chamber, depending on the ablation geometry. The potential risks associated with these photoacoustic phenomena, particularly for retina and corneal endothelium, are outlined.
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Affiliation(s)
- P G Gobbi
- Laser Medicine Research, Scientific Institute H S. Raffaele, Milano, Italy
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Osticioli I, Ciofini D, Mencaglia AA, Siano S. Automated characterization of varnishes photo-degradation using portable T-controlled Raman spectroscopy. Spectrochim Acta A Mol Biomol Spectrosc 2017; 172:182-188. [PMID: 27017061 DOI: 10.1016/j.saa.2016.03.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 01/08/2016] [Accepted: 03/16/2016] [Indexed: 06/05/2023]
Abstract
In this work, a portable-Raman device (excitation wavelength 1064nm) was employed for the first time for continuously monitoring the complex molecular dynamics of terpenoid resins (dammar, mastic, colophony, sandarac and shellac), which occur during their ageing under artificial light exposure. The instrumentation was equipped with a pyroelectric sensor allowing for temperature control of the sample's irradiated surface while the acquisition of spectra occurs by setting fixed maximum temperature and total radiant exposure. Resins were dropped into special pits over a dedicated rotating wheel moved by a USB motor. The rotation allowed samples sliding between the positions designated for the acquisition of the Raman spectra and that for artificial ageing. Samples were exposed to artificial light for 45-days and almost 400 spectra for each resin sample were collected. The exposure to artificial light led to significant changes allowing the characterization of the alteration process. The automated acquisition of a large number of spectra overtime during light-exposure has given the possibility to distinguish fast dynamics, mainly associated to solvent evaporation, from those slower due to resins photo-degradation processes.
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Affiliation(s)
- I Osticioli
- Institute of Applied Physics "Nello Carrara" (IFAC-CNR), Florence, Italy.
| | - D Ciofini
- Institute of Applied Physics "Nello Carrara" (IFAC-CNR), Florence, Italy
| | - A A Mencaglia
- Institute of Applied Physics "Nello Carrara" (IFAC-CNR), Florence, Italy
| | - S Siano
- Institute of Applied Physics "Nello Carrara" (IFAC-CNR), Florence, Italy
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Agresti J, Osticioli I, Guidotti MC, Kardjilov N, Siano S. Non-invasive archaeometallurgical approach to the investigations of bronze figurines using neutron, laser, and X-ray techniques. Microchem J 2016. [DOI: 10.1016/j.microc.2015.10.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Ciofini D, Oujja M, Cañamares MV, Siano S, Castillejo M. Spectroscopic assessment of the UV laser removal of varnishes from painted surfaces. Microchem J 2016. [DOI: 10.1016/j.microc.2015.10.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Siano S, Salimbeni R. Advances in laser cleaning of artwork and objects of historical interest: the optimized pulse duration approach. Acc Chem Res 2010; 43:739-50. [PMID: 20108953 DOI: 10.1021/ar900190f] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Laser ablation has found numerous applications in biomedical and industrial settings but has not spread as quickly as a means of cleaning artwork. In this Account, we report recent advances in the study and application of laser cleaning to the conservation of cultural heritage. We focus on the solution of representative cleaning problems of encrusted stones, metals, and wall paintings that were achieved through the optimization of laser pulse duration. We begin by introducing the basic mechanisms involved in the laser ablation of stratified materials and the criteria for preventing undesired side effects to the substrate and then briefly present case studies for each of these materials. Laser interaction effects are reviewed in a schematic way, with a concise overview of the physical models needed to support intuitive interpretations of the phenomenology observed, both in laboratory tests and in practical applications on important artifacts. This approach aims to provide keys of generalization that will favor the rigorous application of laser cleaning, repeatability of the successful results reported in this work, and further dissemination and acceptance of the technique. The topics treated examine the ablation mechanisms along with the efficiency, gradualness, selectivity, and effectiveness of the technique as a function of the pulse duration of neodymium laser systems and the operating conditions. Physical modeling and experimental evidence support the selection of pulse durations of between several tens of nanoseconds and several tens of microseconds, making it possible to minimize the risk of photothermal and photomechanical effects and maximize the selectivity of the ablation process. The sections dedicated to stones and metals also deal with the important problem of discoloration, which has significantly slowed the spread of the laser cleaning technique. The well-known problem of a yellowish appearance after laser cleaning is shown to be closely related to the ablation process; it can therefore be prevented by a suitable selection of irradiation parameters. The metal surfaces investigated are amalgam gilding, gold leaf gilding, and, for the first time, silver artifacts. We also describe the criteria used for applying laser ablation techniques to restoring unique masterpieces, such as Lorenzo Ghiberti's Porta del Paradiso and Donatello's David. Furthermore, a novel and unusual cleaning approach for archaeological silver is reported. Based on underwater laser irradiation, it provides a way to prevent oxidative effects and amplify the photomechanical coupling to the hard, thick concretions that usually accompany archaeological pieces. Finally, the experimental extension of the laser cleaning approach to wall painting and its practical use in important restoration works is presented. The practical examples reveal a significant advance in perspective for the application, which was unthinkable until recently. In sum, this Account describes novel technological and methodological contributions of laser cleaning that are having a significant impact in the field of cultural heritage conservation.
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Affiliation(s)
- Salvatore Siano
- Istituto di Fisica Applicata “Nello Carrara”, Consiglio Nazionale delle Ricerche, Sesto Fiorentino (Florence), Italy
| | - Renzo Salimbeni
- Istituto di Fisica Applicata “Nello Carrara”, Consiglio Nazionale delle Ricerche, Sesto Fiorentino (Florence), Italy
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Cupello A, Balestrino M, Gatta E, Pellistri F, Siano S, Robello M. Activation of cerebellar granule cells GABA(A) receptors by guanidinoacetate. Neuroscience 2008; 152:65-9. [PMID: 18222046 DOI: 10.1016/j.neuroscience.2007.12.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 12/04/2007] [Accepted: 12/12/2007] [Indexed: 10/22/2022]
Abstract
The extracellular concentration of guanidinoacetate (GAA) in the brain increases in guanidino acetate methyl transferase (GAMT) deficiency, an inherited disorder. We tested whether the levels which this substance can reach in the brain in GAMT deficiency are able to activate GABA(A) receptors in key cerebellar neurons such as the cerebellar granules. GAA in fact activates these receptors in rat cerebellar granules in culture although at quite high concentrations, in the millimolar range. However, these millimolar GAA levels are not reached extracellularly in the brain in GAMT deficiency. In addition, GAA does not act as a partial agonist on granules' GABA(A) receptors. This appears to deny an effect by this molecule on cerebellar function in the disease via interference with granule cells' GABA(A) receptors. Study of partial blockage by furosemide of chloride currents activated by GABA and GAA in granule cells allowed us to distinguish two populations of GABA(A) receptors presumably involved in granule cells' tonic inhibition. One is devoid of alpha6 subunit and another one contains it. The latter when activated by GABA has a decay kinetics much slower than the former. GAA does not distinguish between these two populations. In any case, the very high extracellular GAA concentrations able to activate them are not likely to be reached in GAMT deficiency.
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Affiliation(s)
- A Cupello
- Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16133 Genova, Italy.
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Siano S. The use of time of flight neutron diffraction in bronze archaeometallurgy. Acta Crystallogr A 2006. [DOI: 10.1107/s0108767306098904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Cantore M, Siano S, Coronnello M, Mazzetti L, Franchi-Micheli S, Boldrini E, Ciuffi M, Failli P. Pirenoxine prevents oxidative effects of argon fluoride excimer laser irradiation in rabbit corneas: biochemical, histological and cytofluorimetric evaluations. Journal of Photochemistry and Photobiology B: Biology 2005; 78:35-42. [PMID: 15629247 DOI: 10.1016/j.jphotobiol.2004.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Revised: 07/23/2004] [Accepted: 09/13/2004] [Indexed: 11/20/2022]
Abstract
The production of reactive oxygen species (ROS) associated with excimer laser irradiation is recognized as a possible cause of corneal haze following photorefractive keratectomy (PRK). Our work was aimed at investigating in vitro the oxidative effects induced by subablative laser fluences and at demonstrating the protective effectiveness of pirenoxine. Comparative trials of subablative fluence on rabbit eyes with or without 10(-5) M pirenoxine were carried out. Superoxide anion (O(2)(-)), conjugated diene (CD), and thiobarbituric acid reagent substance (TBARS) formation were analyzed. Cellular death was evaluated by flow cytometry. Histological examinations were also performed. No appraisable differences in O(2)(-),CD,andTBARS formation were detected soon after irradiation, whereas they all increased following incubation. Pirenoxine inhibited such increases. Cytofluorimetric and histological observations gave coherent results. The experimental data indicate that oxidative and toxic effects are ascribable to ROS avalanches triggered by laser irradiation-induced photodissociation and are inhibited by pirenoxine.
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Affiliation(s)
- Miriam Cantore
- Department of Preclinical and Clinical Pharmacology, University of Florence, V.le Pierraccini, 6, Florence, Italy
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Fusi F, Mercatelli L, Basile V, Pucci M, Siano S, Antonio Bernabei P, Monici M. A new method based on contact surface profilometry for quantitative measurement of resorbed bone volume. Phys Med 2005; 21:41-6. [DOI: 10.1016/s1120-1797(05)80018-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2004] [Revised: 12/28/2004] [Accepted: 12/30/2004] [Indexed: 11/29/2022] Open
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Siano S, Pini R, Gobbi PG, Salimbeni R, Vannini M, Carones F, Trabucchi G, Brancato R. Intraocular measurements of pressure transients induced by excimer laser ablation of the cornea. Lasers Surg Med 2000; 20:416-25. [PMID: 9142681 DOI: 10.1002/(sici)1096-9101(1997)20:4<416::aid-lsm7>3.0.co;2-t] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND AND OBJECTIVE The evolution of pressure waves induced by argon-fluoride laser ablation of the cornea in the typical operative conditions of clinical laser keratectomy has been studied experimentally and analyzed. MATERIALS AND METHODS Freshly enucleated porcine eyes were irradiated at a laser fluence of 180 mJ/cm2 with various spot diameters in the range 1-6.5 mm. Pressure transients were detected by a fast rise time needle hydrophone inserted into the eyeball from the posterior pole and moved along the eye optical axis toward the cornea. RESULTS Pressure peaks as high as 90 bar and 50 ns pulse duration (FWHM) were measured in the anterior chamber. Observation of the pulse shape evolution during propagation put in evidence the onset of a marked rarefaction phase following the compressional spike, with intense negative peaks (up to -40 bar) located at increasing distances from the corneal surface for increasing spot diameters. CONCLUSIONS This behavior was explained by means of simplified models describing pressure pulse generation and diffraction effects occurring during its propagation. Implications to clinical procedures, as possible damages due to tissue stretching and cavitation formation, are also discussed.
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Affiliation(s)
- S Siano
- Quantum Electronic Institute, National Research Council, Florence, Italy
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Brancato R, Schiavone N, Siano S, Lapucci A, Papucci L, Donnini M, Formigli L, Orlandini SZ, Carella G, Carones F, Capaccioli S. Prevention of corneal keratocyte apoptosis after argon fluoride excimer laser irradiation with the free radical scavenger ubiquinone Q10. Eur J Ophthalmol 2000; 10:32-8. [PMID: 10744203 DOI: 10.1177/112067210001000106] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE To assess in vitro the potential of the free radical scavenger ubiquinone Q10 in preventing keratocyte apoptosis after argon fluoride (ArF) excimer laser irradiation. METHODS Cultured rabbit keratocytes were irradiated at very low single-pulse laser fluences. The cumulative effects generated by three total fluence doses between 12 and 45 mJ/cm2, representative of single-pulse subablative doses during photorefractive keratectomy (PRK) in humans, were evaluated. We employed the following parameters to compare pretreated (10 microM ubiquinone Q10) and untreated samples: 1) number and morphology of living cells by Trypan blue test and ultramicroscopy, respectively; 2) level of free-radical formation assessed by malonaldehyde quantitation; 3) cellular energy level evaluated by ATP assay. RESULTS Excimer laser irradiation kills cultured keratocytes by inducing apoptosis. The effect increases with the cumulative fluence dose. In the samples pretreated with ubiquinone Q10 there were significantly fewer cumulative apoptotic events than in the untreated ones. Quantitative analysis of malonaldehyde cellular levels suggested this protective action of ubiquinone Q10 was connected with its ability to scavenge laser-generated free radicals. ATP assay also confirmed that it raised cellular energy levels. CONCLUSIONS The treatment of corneal keratocytes with relatively low concentrations of ubiquinone Q10 can prevent apoptosis after ArF excimer laser irradiation. If these findings are confirmed on human keratocytes this treatment could be usefully exploited in the PRK surgical procedure. That might lead to a reduction in the occurrence of haze and curvature regression triggered by programmed cell death.
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Affiliation(s)
- R Brancato
- Department of Ophthalmology and Visual Sciences, San Raffaele Hospital, University of Milano, Italy.
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Siano S, Margheri F, Pini R, Mazzinghi P, Salimbeni R. Cleaning processes of encrusted marbles by Nd:YAG lasers operating in free-running and Q-switching regimes. Appl Opt 1997; 36:7073-7079. [PMID: 18259583 DOI: 10.1364/ao.36.007073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The removal process of degraded superficial layers from marble samples by Nd:YAG lasers was studied while simulating operative conditions of stone artwork restoration. The effects of laser irradiation at 1064 nm with three different pulse durations of 6 ns, 20 micros, and 200 micros were investigated by time-resolved shadowgraphy and emission spectroscopy of the ejection plume to characterize the specific interaction regimes, with particular concern given to the occurrence of side effects, such as thermal and mechanical damages to the substrate, that could affect the laser cleaning procedure.
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Affiliation(s)
- S Siano
- Istituto di Elettronica Quantistica, Consiglio Nazionale delle Ricerche, Via Panciatichi 56/30, I-50127 Firenze, Italy
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Schilling V, Siano S, Etling D. Dispersion of aircraft emissions due to wake vortices in stratified shear flows: A two-dimensional numerical study. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jd02013] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Siano S, Caserio G. [Bacteriological research on vacuum-packed salt meat products]. Arch Vet Ital 1967; 18:93-101. [PMID: 5605846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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23
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Siano S, Cantoni C. [On the isolation of salmonellae from chocolate]. Nuovi Ann Ig Microbiol 1965; 16:529-32. [PMID: 5888006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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