27 research outputs found
Real-time myoelectric control of a multi-fingered hand prosthesis using principal components analysis
No full textAbstract Background In spite of the advances made in the design of dexterous anthropomorphic hand prostheses, these sophisticated devices still lack adequate control interfaces which could allow amputees to operate them in an intuitive and close-to-natural way. In this study, an anthropomorphic five-fingered robotic hand, actuated by six motors, was used as a prosthetic hand emulator to assess the feasibility of a control approach based on Principal Components Analysis (PCA), specifically conceived to address this problem. Since it was demonstrated elsewhere that the first two principal components (PCs) can describe the whole hand configuration space sufficiently well, the controller here employed reverted the PCA algorithm and allowed to drive a multi-DoF hand by combining a two-differential channels EMG input with these two PCs. Hence, the novelty of this approach stood in the PCA application for solving the challenging problem of best mapping the EMG inputs into the degrees of freedom (DoFs) of the prosthesis. Methods A clinically viable two DoFs myoelectric controller, exploiting two differential channels, was developed and twelve able-bodied participants, divided in two groups, volunteered to control the hand in simple grasp trials, using forearm myoelectric signals. Task completion rates and times were measured. The first objective (assessed through one group of subjects) was to understand the effectiveness of the approach; i.e., whether it is possible to drive the hand in real-time, with reasonable performance, in different grasps, also taking advantage of the direct visual feedback of the moving hand. The second objective (assessed through a different group) was to investigate the intuitiveness, and therefore to assess statistical differences in the performance throughout three consecutive days. Results Subjects performed several grasp, transport and release trials with differently shaped objects, by operating the hand with the myoelectric PCA-based controller. Experimental trials showed that the simultaneous use of the two differential channels paradigm was successful. Conclusions This work demonstrates that the proposed two-DoFs myoelectric controller based on PCA allows to drive in real-time a prosthetic hand emulator into different prehensile patterns with excellent performance. These results open up promising possibilities for the development of intuitive, effective myoelectric hand controllers.</p
PCA-based myoelectric control of prehension for multi-articulated hand prostheses
No full textA successful substitution of the natural hand could be achieved only by developing an anthropomorphic device with high dexterity and an intuitive and easy-to-use control system. In this work a new approach to multi-Degrees-of-Freedom (DoFs) control based on Principal Components Analysis is proposed and assessed, which allows driving a 16-DoF multi-fingered hand prosthesis by means of only 2 differential EMG channels. Trials with able-bodied subjects demonstrated that they soon learned how to correctly operate the hand to firmly grasp objects, and confirmed that the developed control strategy is successful
Principal components analysis based control of a multi-dof underactuated prosthetic hand
No full textAbstract Background Functionality, controllability and cosmetics are the key issues to be addressed in order to accomplish a successful functional substitution of the human hand by means of a prosthesis. Not only the prosthesis should duplicate the human hand in shape, functionality, sensorization, perception and sense of body-belonging, but it should also be controlled as the natural one, in the most intuitive and undemanding way. At present, prosthetic hands are controlled by means of non-invasive interfaces based on electromyography (EMG). Driving a multi degrees of freedom (DoF) hand for achieving hand dexterity implies to selectively modulate many different EMG signals in order to make each joint move independently, and this could require significant cognitive effort to the user. Methods A Principal Components Analysis (PCA) based algorithm is used to drive a 16 DoFs underactuated prosthetic hand prototype (called CyberHand) with a two dimensional control input, in order to perform the three prehensile forms mostly used in Activities of Daily Living (ADLs). Such Principal Components set has been derived directly from the artificial hand by collecting its sensory data while performing 50 different grasps, and subsequently used for control. Results Trials have shown that two independent input signals can be successfully used to control the posture of a real robotic hand and that correct grasps (in terms of involved fingers, stability and posture) may be achieved. Conclusions This work demonstrates the effectiveness of a bio-inspired system successfully conjugating the advantages of an underactuated, anthropomorphic hand with a PCA-based control strategy, and opens up promising possibilities for the development of an intuitively controllable hand prosthesis.</p
Phase shift micro-beamforming of CMUT arrays using the spring-softening effect
No full textIn phased array systems, a partial beamforming
can be carried out inside the probe to reduce the number of
signals to be processed by the main system. Such technique,
known as micro-beamforming, involves the application of a
delay-and-sum beamforming to small groups of adjacent array
elements using dedicated electronics. In this paper we show that,
due to the electrostatic spring-softening effect, the phase response
of Capacitive Micromachined Ultrasonic Transducers (CMUTs)
can be controlled by varying the bias voltage. Based on this
phenomenon, we propose a phase shift micro-beamforming
method of CMUT arrays. We analyze the performance
obtainable by applying this method to a typical phased array
configuration for medical imaging. We show that, with relatively
high quality factor CMUTs that still allow broadband immersion
operation, it is possible to obtain up to 90° phase shifts by varying
the bias voltage. Further, by inverting the sign of the bias voltage,
we show that it is possible to obtain an additional 180° phase
shift. Simulation results show that, with a 40% -3 dB one-way
fractional bandwidth CMUT, the grating lobe level of the
transmission radiation patterns, obtained with the proposed
micro-beamforming technique, may be kept below -23 dB using
broadband excitation signals for maximum steering angles of
±45°
Bio-Inspired Controller for a Dexterous Prosthetic Hand Based on Principal Components Analysis
No full textControlling a dexterous myoelectric prosthetic hand with many degrees of freedom (DoFs) could be a very demanding task, which requires the amputee for high concentration and ability in modulating many different muscular contraction signals. In this work a new approach to multi-DoF control is proposed, which makes use of Principal Component Analysis (PCA) to reduce the DoFs space dimensionality and allow to drive a 15 DoFs hand by means of a 2 DoFs signal. This approach has been tested and properly adapted to work onto the underactuated robotic hand named CyberHand, using mouse cursor coordinates as input signals and a principal components (PCs) matrix taken from the literature. First trials show the feasibility of performing grasps using this method. Further tests with real EMG signals are foreseen
Prognosi e fattori predittivi nel carcinoma midollare sporadico della tiroide: esperienza di 50 anni in un centro di riferimento
No full textIntroduzione - Il carcinoma midollare della tiroide (medullary thyroid cancer – MTC) è una rara neoplasia endocrina che origina dalle cellule C – o parafollicolari – della tiroide, che si occupano di produrre calcitonina. Le cellule C rappresentano dal 2 al 4% della popolazione cellulare tiroidea, e questo giustifica la relativa minore frequenza del carcinoma midollare rispetto agli altri sottotipi di carcinoma tiroideo (papillare, follicolare, insulare, scarsamente differenziato e anaplastico) che originano, invece, da cellule di natura epiteliale.
Il carcinoma midollare della tiroide può presentarsi in forma sporadica (75% dei casi) e in forma ereditaria (25% dei casi). In ambedue le forme la patogenesi è prevalentemente dovuta all’attivazione (perlopiù associata a mutazioni puntiformi o piccole inserzioni/delezioni) del protooncogene RET, che risulta mutato a livello germinale nella quasi totalità delle forme familiari e, a livello somatico nella metà, circa, delle forme sporadiche.
Dal punto di vista clinico, si presenta classicamente come un nodulo singolo o nel contesto di un gozzo multinodulare, associato o meno a linfoadenopatie o a metastasi a distanza. Nei casi più avanzati, i sintomi d’esordio possono essere diarrea o flushing (a causa degli elevati livelli di calcitonina nel sangue) o, in rari casi, sintomi da secrezione ectopica di ACTH. Diversa è la presentazione delle neoplasie endocrine multiple (MEN).
La diagnosi prevede un dosaggio della calcitonina sierica, un’ecografia del collo (loggia tiroidea e stazioni linfonodali) ed eventualmente un esame citologico (agoaspirazione) o istologico (agobiopsia) della lesione in esame.
A seguito o in concomitanza alla diagnosi di MTC, è indicata la ricerca della mutazione RET su sangue che, se positiva, dev’essere estesa anche ai familiari di primo grado del paziente, come screening. Il trattamento di scelta è rappresentato dalla tiroidectomia totale con linfadenectomia del comparto centrale e, eventualmente, delle stazioni linfonodali laterocervicali.
Dopo il trattamento iniziale, il paziente può essere sottoposto ad ulteriori interventi chirurgici, a radioterapia esterna, ad ablazione a radiofrequenze o laser (nel caso di recidiva locale o linfonodale), oppure (nel caso di recidiva a distanza) a trattamenti specifici delle lesioni a distanza o, ancora, a terapie sistemiche, quali target therapies (inibitori delle tirosin-chinasi o TKI), terapie a base di radionuclidi – sebbene supportate da scarse evidenze – oppure altre terapie sistemiche, come analoghi della somatostatina o bifosfonati/RANK-L inibitori (solo nel caso di metastasi ossee).
Il follow-up prevede l’esecuzione di ecografia del collo, il dosaggio della calcitonina sierica e, se necessario, un agoaspirato (su lesioni sospette) oppure un’indagine strumentale, come la TC, nel sospetto di una recidiva a distanza.
Il comportamento biologico del MTC è molto più aggressivo rispetto agli altri carcinomi differenziati della tiroide, anche se meno aggressivo rispetto al carcinoma anaplastico. La prognosi dipende da molti fattori, ma lo stadio alla diagnosi rimane il fattore prognostico più rilevante nella maggior parte dei pazienti.
Scopo dello studio - Scopo del presente studio è stato quello di valutare la presentazione clinica e l’andamento della malattia nel corso del tempo in un’ampia casistica di pazienti affetti da carcinoma midollare sporadico della tiroide seguiti negli ultimi 50 anni in un Centro di Riferimento, valutando eventuali cambiamenti nella presentazione e nell’andamento di malattia dividendo i pazienti per anno di diagnosi.
Pazienti e metodi
Abbiamo valutato retrospettivamente i dati epidemiologici, clinici e patologici di 1001 pazienti afferiti presso l’U.O. Endocrinologia dell’Azienda Ospedaliero-Universitaria Pisana tra il 1961 e il 2024, con diagnosi istologica di carcinoma midollare sporadico della tiroide.
Criteri di esclusione sono stati:
- Pazienti con diagnosi istologica diversa da quella del carcinoma tiroidea (iperplasia delle cellule C, altro tipo di tumore tiroideo)
- Pazienti con carcinoma midollare familiare isolato (FMTC) o nel contesto di sindromi da neoplasie endocrine multiple (MEN 2A, MEN 2B).
Risultati - Abbiamo analizzato retrospettivamente una coorte di 1001 pazienti, prima nella sua totalità e in seguito suddividendoli in tre gruppi in base all’anno della diagnosi istologica: gruppo 1 con diagnosi ≤ all’anno 2000, gruppo 2 tra 2001 e 2012, e gruppo 3 tra 2013 e 2024. Il follow-up mediano è stato di 72 mesi mentre i dati sulla sopravvivenza sono riportati in una mediana di tempo di 92 mesi.
La prevalenza nei due sessi è cambiata nel tempo essendo più frequente nel sesso femminile nel gruppo 1 fino ad arrivare alla medesima prevalenza nei 2 sessi nel gruppo 3. L’età alla diagnosi è invece significativamente aumentata nel tempo, essendo inferiore nel gruppo 1 e superiore nel gruppo 3 (mediana 48 vs 56 aa). Abbiamo notato anche una modifica sostanziale nella tecnica chirurgica essendo nel tempo aumentati gli interventi di svuotamento linfonodale del comparto centrale con una contestuale riduzione di quello laterocervicale.
Nel tempo le dimensioni tumorali sono state inferiori, si è ridotto il numero di pazienti con metastasi del comparto centrale, laterocervicale e a distanza. Inoltre, i pazienti sono stati sottoposti sempre meno a ulteriori interventi, di qualunque tipologia, dopo la chirurgia iniziale.
L’analisi della sopravvivenza ha mostrato come nella coorte totale la DSS sia stata 86% a 5 aa e 80% a 10 aa, ricalcando quella che era anche l’OS. L’analisi per sottogruppi alla diagnosi ha evidenziato come, indipendentemente dall’anno della diagnosi, i pazienti con malattia intratiroidea alla diagnosi o con metastasi linfonodali del comparto centrale (N1a) avevano una sopravvivenza significativamente maggiore di quelli con metastasi linfonodali laterocervicali (N1b) o a distanza (M1). La differenza principale nel corso degli anni sembra essere una diagnosi più precoce e quindi un miglior outcome dei pazienti con malattia intratiroidea o con N1a, ma anche in parte N1b, rispetto invece ai pazienti M1 dove negli anni non sembra essere particolarmente cambiato l’outcome.
Conclusioni - Da questo studio è emerso come, nonostante vi siano diversi fattori a condizionare la prognosi, lo stadio alla diagnosi ne rappresenti il principale fattore predittivo. Il dosaggio di screening della calcitonina sierica e l’ecografia, consentendo una diagnosi precoce, hanno permesso di diagnosticare neoplasie sempre più piccole, meno estese e diffuse, e di ridurre il numero di pazienti affetti da metastasi linfonodali e/o a distanza alla diagnosi, nonché di coloro che eseguivano altre terapie dopo la chirurgia.
Questo lavoro ha anche dimostrato un miglioramento della sopravvivenza malattia-specifica, con particolare riguardo ai casi intratiroidei e con metastasi linfonodali. Resta ancora da migliorare la sopravvivenza dei casi, peraltro numericamente ridotti, che si presentano con metastasi a distanza al momento della diagnosi
Receptor tyrosine kinase-dependent PI3K activation is an escape mechanism to vertical suppression of the EGFR/RAS/MAPK pathway in KRAS-mutated human colorectal cancer cell lines
No full textColorectal cancer; Epidermal growth factor receptor (EGFR); MAPK pathwayCàncer colorectal; Receptor epidèrmic de factor del creixement (EGFR); Via MAPKCáncer colorrectal; Receptor epidérmico de factor del crecimiento (EGFR); Vía MAPKBACKGROUND:
Previous studies showed that the combination of an anti-Epidermal growth factor (EGFR) and a MEK-inhibitor is able to prevent the onset of resistance to anti-EGFR monoclonal antibodies in KRAS-wild type colorectal cancer (CRC), while the same combination reverts anti-EGFR primary resistance in KRAS mutated CRC cell lines. However, rapid onset of resistance is a limit to combination therapies in KRAS mutated CRC.
METHODS:
We generated four different KRAS mutated CRC cell lines resistant to a combination of cetuximab (an anti-EGFR antibody) and refametinib (a selective MEK-inhibitor) after continuous exposure to increasing concentration of the drugs. We characterized these resistant cell lines by evaluating the expression and activation status of a panel of receptor tyrosine kinases (RTKs) and intracellular transducers by immunoblot and qRT-PCR. Oncomine comprehensive assay and microarray analysis were carried out to investigate new acquired mutations or transcriptomic adaptation, respectively, in the resistant cell lines. Immunofluorescence assay was used to show the localization of RTKs in resistant and parental clones.
RESULTS:
We found that PI3K-AKT pathway activation acts as an escape mechanism in cell lines with acquired resistance to combined inhibition of EGFR and MEK. AKT pathway activation is coupled to the activation of multiple RTKs such as HER2, HER3 and IGF1R, though its pharmacological inhibition is not sufficient to revert the resistant phenotype. PI3K pathway activation is mediated by autocrine loops and by heterodimerization of multiple receptors.
CONCLUSIONS:
PI3K activation plays a central role in the acquired resistance to the combination of anti-EGFR and MEK-inhibitor in KRAS mutated colorectal cancer cell lines. PI3K activation is cooperatively achieved through the activation of multiple RTKs such as HER2, HER3 and IGF1R
Receptor tyrosine kinase-dependent PI3K activation is an escape mechanism to vertical suppression of the EGFR/RAS/MAPK pathway in KRAS-mutated human colorectal cancer cell lines
No full textColorectal cancer; Epidermal growth factor receptor (EGFR); MAPK pathwayCàncer colorectal; Receptor epidèrmic de factor del creixement (EGFR); Via MAPKCáncer colorrectal; Receptor epidérmico de factor del crecimiento (EGFR); Vía MAPKBACKGROUND:
Previous studies showed that the combination of an anti-Epidermal growth factor (EGFR) and a MEK-inhibitor is able to prevent the onset of resistance to anti-EGFR monoclonal antibodies in KRAS-wild type colorectal cancer (CRC), while the same combination reverts anti-EGFR primary resistance in KRAS mutated CRC cell lines. However, rapid onset of resistance is a limit to combination therapies in KRAS mutated CRC.
METHODS:
We generated four different KRAS mutated CRC cell lines resistant to a combination of cetuximab (an anti-EGFR antibody) and refametinib (a selective MEK-inhibitor) after continuous exposure to increasing concentration of the drugs. We characterized these resistant cell lines by evaluating the expression and activation status of a panel of receptor tyrosine kinases (RTKs) and intracellular transducers by immunoblot and qRT-PCR. Oncomine comprehensive assay and microarray analysis were carried out to investigate new acquired mutations or transcriptomic adaptation, respectively, in the resistant cell lines. Immunofluorescence assay was used to show the localization of RTKs in resistant and parental clones.
RESULTS:
We found that PI3K-AKT pathway activation acts as an escape mechanism in cell lines with acquired resistance to combined inhibition of EGFR and MEK. AKT pathway activation is coupled to the activation of multiple RTKs such as HER2, HER3 and IGF1R, though its pharmacological inhibition is not sufficient to revert the resistant phenotype. PI3K pathway activation is mediated by autocrine loops and by heterodimerization of multiple receptors.
CONCLUSIONS:
PI3K activation plays a central role in the acquired resistance to the combination of anti-EGFR and MEK-inhibitor in KRAS mutated colorectal cancer cell lines. PI3K activation is cooperatively achieved through the activation of multiple RTKs such as HER2, HER3 and IGF1R
Video reportaje de la representación simbólica de los lugares turísticos del cantón Rumiñahui
No full textMediante la investigación y realización del producto audiovisual, la presente investigación permite analizar y conocer las representaciones simbólicas e identidad cultural de los lugares turísticos del Cantón Rumiñahui: “Monumento a la Resistencia”, Cascada “Vilatuña” y Cascada “Cóndor Machay”, tres lugares emblemáticos del cantón Rumiñahui, que forman parte de la diversidad cultural y social de los ciudadanos. Gracias a esta investigación y mediante la publicación del producto video-reportaje se propuso obtener una herramienta investigativa y comunicativa de transmisión de saberes que permitirá conocer el significado de los lugares turísticos del cantón Rumiñahui. La misma tuvo como objetivo general elaborar un video reportaje sobre la representación simbólica de los lugares turísticos del Cantón Rumiñahui, y tres objetivos específicos: (1) Investigar la historicidad del Cantón Rumiñahui, (2) Analizar la representación simbólica de tres lugares turísticos del Cantón Rumiñahui, (3) Examinar el consumo cultural de los lugares turísticos por parte de los moradores del Cantón Rumiñahui. A través de la aplicación de una metodología mixta compuesta por 150 encuestas y entrevistas realizadas a turistas y moradores del cantón, a través de un análisis de datos e información se consiguieron como resultados: a) un bajo conocimiento sobre los lugares antes mencionados, b) un bajo consumo cultural que se dio durante el periodo de la pandemia del COVID-19 sin embargo, se registra c) un alto interés en tener tal consumo, d) un alto compromiso por parte de los moradores del Cantón en la promoción y desarrollo del mismo.
Además, se utilizó categorías como consumo cultural, representaciones simbólicas e identidad cultural, para sustentar las categorías mencionadas recurrimos en la investigación al autor Néstor García Canclini.
Los tres lugares turísticos; “Monumento a la Resistencia”, Cascada “Vilatuña” y Cascada “Cóndor Machay”, son representados por un símbolo que conlleva a un sentido y significado definido, tanto sugerido y subjetivo como objetivo en la forma en la que a todos se les presenta de la misma forma, se estudió también desde el interaccionismo simbólico, tomando en consideración que el objeto de estudio, siendo tanto real simbólico, se caracteriza por integrar al sujeto investigador y a su objeto.Through the investigation and realization of the audiovisual product, the present investigation allows analyzing and knowing the symbolic representations and cultural identity of the tourist places of the Rumiñahui Canton: "Monumento a la Resistencia", Cascada "Vilatuña" and Cascada "Cóndor Machay", three places emblematic of the Rumiñahui canton, which are part of the cultural and social diversity of the citizens. Thanks to this research and through the publication of the video-report product, an investigative and communicative tool for the transmission of knowledge will be obtained that will allow knowing the meaning of the tourist places of the Rumiñahui canton. The same had as general objective to elaborate a video report on the symbolic representation of the tourist places of the Rumiñahui Canton, and three specific objectives: (1) Investigate the historicity of the Rumiñahui Canton, (2) Analyze the symbolic representation of three tourist places of the Canton Rumiñahui, (3) Examine the cultural consumption of tourist places by the inhabitants of the Rumiñahui Canton. Through the application of a mixed methodology composed of 150 surveys and interviews with tourists and residents of the canton, through an analysis of data and information, the following results were obtained: a) a low knowledge about the places previously recorded, b) a low cultural consumption that occurred during the period of the COVID-19 pandemic, however, c) a high interest in having such consumption is recorded, d) a high commitment on the part of the residents of the Canton in the promotion and development of the same.
In addition, categories such as cultural consumption, symbolic representations and cultural identity were highlighted, to support the recurring categories mentioned in the research on the author Néstor García Canclini.
The three tourist places; “Monumento a la Resistencia”, Cascada “Vilatuña” and Cascada “Cóndor Machay”, are represented by a symbol that carries a defined sense and meaning, both suggested and subjective as well as objective in the way in which it is presented to everyone in the In the same way, it was also studied from symbolic interactionism, taking into consideration that the object of study, being both real and symbolic, is characterized by integrating the research subject and its object
