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Laser welding of dura mater by means of indocyanine green-infused chitosan patches
Get PDFLa ricostruzione della dura madre rappresenta una delle ultime ma fondamentali fasi di un intervento neurochirurgico. Infatti, un’inadeguata chiusura della dura espone i pazienti a temibili complicanze che aumentano in modo significativo i tassi di morbidità e mortalità post-operatoria. Diversi sostituti/sigillanti durali sono utilizzati con risultati non sempre ottimali. Per risolvere tale problematica, il nostro gruppo ha precedentemente proposto, e verificato la fattibilità in un modello porcino, una saldatura laser della dura madre mediante patch di chitosan imbevuti con verde di indocianina. In questo lavoro, presentiamo l’ottimizzazione della suddetta tecnica di sutura durale, sia ex vivo (su dura madre di maiale ed umana) sia in vivo (in ratti adulti ed anziani).
Un laser ad emissione continua (lunghezza d’onda 810 nm) è stato utilizzato per saldare patch di chitosan imbevuti con verde di indocianina alla dura madre. Test ex vivo hanno permesso di ottimizzare i parametri del laser, eseguendo una valutazione istologica e della pressione di tenuta per studiare la saldatura stessa. I test in vivo sono stati eseguiti su 32 ratti Wistar adulti e 16 anziani: la saldatura laser è stata effettuata in 16 ratti adulti e 8 anziani (gruppi di trattamento sperimentale), mentre una matrice collagene non suturabile è stata utilizzata per la duroplastica nei restanti animali (gruppi di controllo). Successivamente, ai follow-up pianificati (rispettivamente, i ratti adulti a 20, 60, 90, o 120 giorni dall’intervento chirurgico, e gli anziani il ventesimo o novantesimo giorno post-operatorio), 4 ratti nel gruppo di trattamento e 4 nel gruppo di controllo sono stati anestetizzati per eseguire test di tenuta della duroplastica, e per prelevare campioni per analisi istologica ed immunoistochimica.
I risultati dello studio hanno indicato che la procedura di saldatura laser da noi proposta determina, sia ex vivo sia in vivo, un’immediata chiusura durale senza la necessità di aggiuntive suture convenzionali, potenzialmente riducendo quindi i tempi chirurgici. Nei differenti modelli, i valori della pressione di tenuta sono stati sempre più elevati della normale pressione intracranica. Inoltre, nel modello murino, la saldatura laser ha permesso di ottenere pressioni di tenuta statisticamente più elevate di quelle registrate con la matrice collagene. Nessuna complicanza, né deficit post-operatorio, è occorsa nei ratti. L’analisi istologica ha documentato una buona adesione tra i patch di chitosan e la dura madre, senza un significativo effetto termico. I patch di chitosan hanno efficacemente funzionato da scaffold biopolimerici per la rigenerazione della dura madre, come evidenziato dall’analisi istologica e dalla microscopia confocale. La saldatura laser della dura madre è stata eseguita in sicurezza e in modo efficace anche nei ratti anziani. I nostri dati sono in favore del presumibile ritardo età-dipendente nel processo di guarigione. Tuttavia, nessuna significativa differenza funzionale è stata rilevata in termini di pressione di tenuta. Inoltre, la massima temperatura registrata dopo l’irradiazione (<55°C) è, di gran lunga, inferiore alle temperature riportate nei precedenti studi di saldatura laser della dura madre.
Quindi, la tecnica di saldatura laser da noi proposta può rappresentare un’alternativa sicura e valida alle tecniche tradizionali di chiusura durale, in particolare quando le tecniche di sutura convenzionali potrebbero essere rischiose e/o estremamente difficili, ad esempio quando si lavora in corridori chirurgici stretti e profondi (approcci key-hole o endoscopici endonasali), in caso di re-intervento, o in seguito a radioterapia.Dura mater reconstruction represents a crucial step of a neurosurgical procedure. Indeed, an inadequate dural closure may determine dreadful consequences that significantly increase morbidity and mortality rates. Different dural substitutes/sealants have been used with suboptimal results. To overcome this issue, we previously proposed a laser-based approach to the bonding of porcine dura mater by means of Indocyanine Green (ICG)-infused chitosan patches, evidencing the feasibility of the laser assisted procedure. In this work, we present the optimization of the laser bonding approach for dura mater reconstruction, both ex vivo (in porcine and human tissues) and in vivo (in adult and old rats).
An 810 nm continuous-wave diode laser was used to weld the ICG stained chitosan patch to the dura. The ex vivo tests enabled to optimize the laser parameters, using histology and leak pressure evaluation to study the bonding effect. The in vivo tests were performed on 32 adult and 16 old Wistar rats: laser bonding was carried out in 16 adult and 8 old rats (treatment groups), while a non suturable collagen matrix was used for duroplasty in the remaining animals (control groups). Then, at the planned follow-ups (respectively, the adult rats at 20, 60, 90, or 120 days after surgery, and the old rats on postoperative day 20 or 90), four rats in the treatment and four rats in the control groups were anesthetized for fluid leakage pressure test of the duroplasty, as well as for obtaining specimens for standard histology and immunohistochemistry.
The results of this study pointed out that the laser bonding procedure provides, both ex vivo and in vivo, an immediate dural closure without the need of any standard suturing, thus potentially reducing surgery times. In all the different models, the fluid leakage pressure values were always higher than the normal intracranial pressure. In addition, in the murine model, the laser bonding allowed to achieve fluid leakage pressure values statistically higher than those recorded with the collagen matrix as dural graft. No postoperative complication/neurological injury occurred in rats. The histological analysis evidenced a good adhesion between the chitosan patches and the dura mater, without a significant thermal effect. Chitosan patches effectively worked as biopolymeric scaffolds for dura mater regeneration, as evidenced by the histological analysis and the confocal microscopy. The laser bonding of dura mater was safely and effectively employed in old rats. Our data were in favor of the suggested age-related delay in the healing process. However, no significant functional differences were revealed in terms of fluid leakage pressure. Moreover, the maximum measured temperature after irradiation (<55°C) was, by far, well below the value reported in the previous studies on dural closure with laser tissue welding.
Hence, the technique can be proposed as a safe and valid alternative to traditional procedures for dural closure, in particular when the conventional suture technique is risky and/or extremely difficult, i.e. when working through narrow and deep surgical corridors (e.g. key-hole or endoscopic approaches), in case of reoperation, or following radiotherapy
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Skin flap complications after decompressive craniectomy and cranioplasty: Proposal of classification and treatment options
No full textVariations on the Author
Get PDF“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
Delayed diagnosed intermuscular lipoma causing a posterior interosseous nerve palsy in a patient with cervical spondylosis: the "priceless" value of the clinical examination in the technological era
No full textPosterior interosseous nerve (PIN) palsy may present with various symptoms, and may resemble cervical spondylosis
Painting authentication by means of a biometric-like approach
No full textArtwork counterfeiting is a wide problem in the art market, both for private subjects and museums. For this reason, it is important to introduce innovative authentication solutions, based on state-of-the-art technologies. In particular, in this paper, the proposed solution is based on a mobile architecture, starting from the consideration that nowadays mobile phones include quality photo and video cameras, access to wireless networks and the internet, GPS assistance and other innovative systems. The proposed solution uses smartphones as simple, robust and efficient sensor for artworks authentication. When we buy an artwork object, the seller issues a certificate of authenticity, which contains specific details about the artwork itself. Unscrupulous sellers can duplicate the classic certificates of authenticity, and then use them to "authenticate" non-genuine works of art. In this way, the buyer will have a copy of an original certificate to attest that the "not original artwork" is an original one. A solution for this problem would be to insert a system that links together the certificate and the related specific artwork. To do this it is necessary, for a single artwork, to find unique, unrepeatable, and unchangeable characteristics. In this article we propose an innovative and non-invasive method for the authentication of artworks based on random intrinsic object characteristics. This approach is based on biometry paradigm (analogue fingerprinting). The paper presents a stand-alone solution, and an internet-based one, necessary for granting security verification also in case of problems with the used RFID tag. The proposed method uses an RFID Tag and a 2D barcode, in conjunction with an Internetbased Authentication Archive
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Autologous Vascularized Dural Wrapping for Temporalis Muscle Preservation and Reconstruction After Decompressive Craniectomy: report of twenty-five cases
Get PDFTemporalis muscle reconstruction is a necessary step during frontotemporal cranioplasty ensuing decompressive craniectomy (DC). During this procedure, scarring between the temporalis muscle and the dural layer may lead to complicated muscle dissection, which carries an increased risk of dura and muscle damage. At time of DC, temporalis muscle wrapping by an autologous vascularized dural flap can later on facilitate dissection and rebuilding during the subsequent cranioplasty. In a span of 2 years, we performed 57 DCs for different etiologies. In 30 cases, the temporalis muscle was isolated by wrapping its inner surface using the autologous dura. At cranioplasty, the muscle could easily be dissected from the duraplasty. The inner surface was easily freed from the autologous dural envelope, and reconstruction achieved in an almost physiological position. Follow-up examinations were held at regular intervals to disclose signs of temporalis muscle depletion. Twenty-five patients survived to undergo cranioplasty. Muscle dissection could always be performed with no injury to the dural layer. No complications related to temporalis muscle wrapping were recorded. Face asymmetry developed in four cases but it was always with bone resorption. None of the patients with a good neurological recovery reported functional or aesthetic complaints. In our experience, temporalis muscle wrapping by vascularized autologous dura proved to be effective in preserving its bulk and reducing its adhesion to duraplasty, thereby improving muscle dissection and reconstruction during cranioplasty. Functional and aesthetic results were satisfying, except in cases of bone resorption
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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