1,721,138 research outputs found
VALUTAZIONE DEL RUOLO DEI GENI ARX E CDKL5 NELLE ENCEFALOPATIE EPILETTICHE AD EZIOLOGIA SCONOSCIUTA CON INSORGENZA NEL PRIMO ANNO DI VITA
Full text linkSUMMARY
Introduction:
Epileptic encephalopathies starting within the first year of life are a group of etiologically and clinically heterogeneous disorders in which cognitive, sensory, and/or motor functions deteriorate mainly as a consequence of epileptic activity. Many etiological factors including hereditary and non-hereditary conditions have been reported. However, in up to a third of all cases determining the underlying cause is not possible. Recently the CDKL5 and ARX genes have been found to be involved in the pathogenesis of refractory early onset epilepsy, in neurologically delayed patients.
Objective:
To investigate the pathogenic role of CDKL5 and ARX in epileptic encephalopathy of unknown aetiology starting within the first year of life and to characterize the electroclinical picture associated with mutations of these genes.
Patients and Methods:
Eighty patients (40 females and 40 males, including two related boys, born to asymptomatic monozygotic twin sisters) with epileptic encephalopathy of unknown aetiology, with onset in the first year of life, were recruited and screened for mutations in the CDKL5 and ARX genes by DHPLC and direct sequence analysis. Retrospective clinical, neurological and epileptological data, and EEG recordings were collected and comprehensively evaluated.
Results:
Six novel de novo CDKL5 pathogenic mutations (3 missense; 2 nonsense; 1 frameshift mutations) were found in five females and in one 47,XXY male, for an overall mutation rate of 8% which, in female patients alone, account for a prevalence of 12,5%. Three male subjects, including a sporadic case and the two related boys, were found to carry two different, previously unreported, missense mutations of the ARX gene, accounting for a mutation rate of 7,5 % among the male patients of our cohort and demonstrating that mutations of the ARX gene, other than expansions of the polyalanine tracts, are involved in the pathogenesis of the epileptic encephalopathies.
Assessment of the electroclinical profile in our patients with CDKL5 mutations (mean age: 5,8 years, ranging from 15 months to 11 years) showed the following features:
a) early onset epilepsy (1-16 weeks of life) (6/6) in neurologically delayed girls with axial hypotonia and poor eye contact (6/6); frequent ab initio mixture of two or more types of seizures sometimes associated in the same event, such as spasms (4/6), myoclonias (4/6), focal seizures (3/6), and apparently generalized tonic or tonic-clonic seizures (2/6);
b) normal background activity on EEG at the onset of epilepsy (6/6), with presence of focal or multifocal interictal epileptiform and slow abnormalities (4/6);
c) unremarkable brain imaging (6/6);
d) subsequent progressively deterioration of the EEG background activity (6/6) and appearance - usually within the first two years of life - of an unusual electrical pattern characterized by high/very high amplitude more or less diffuse theta (4/6) or delta (1/6) activity with superimposed, often subcontinuous, multifocal high amplitude abnormalities (5/6) with tendency to become synchronous (4/6);
e) at the same time, increased frequency and persistence of multiple types of seizures, mainly tonic (3/6) and spasms (5/6), that, along with the increased EEG paroxysmal activity, contributed to the neurodevelopmental stagnation or regression (6/6), configuring an epileptic encephalopathy.
All these aspects collectively represent the earliest key clinical features that we have identified as a clear indication for CDKL5 molecular analysis.
The possible appearance of Rett-like clinical features, such as stereotypies (5/6) or autonomic dysfunctions (1/6), and the possible evolution to a myoclonic epileptic encephalopathy with pseudoperiodic bursts of abnormalities (3/6), represent further, but fairly late aspects that orient the diagnosis.
The three patients with ARX mutations (mean age: 7 years, ranging from 2 to 16 years) displayed at onset early infantile epileptic encephalopathy with suppression burst (EIEE), known as Ohtahara Syndrome. In the neonatal period (3/3), they presented a typical EEG pattern characterized by bursts of paroxysmal activity separated by episodes of flat or low amplitude tracing (3/3). Spasms or tonic spasms (2/3) were the main types of seizures at onset, in association with focal hemiclonic seizures (1/3), tonic seizures (1/3) and massive (1/3) or erratic myoclonias (1/3). A transition from EIEE into atypical West Syndrome (3/3), was followed, in the oldest patient of our series, by evolution into a Lennox-Gastaut-like syndrome. A severely compromised neurodevelopment (3/3) with profound mental retardation (3/3), absence of social skill (3/3) and tetra paresis (3/3) were evident at follow up, whereas longitudinal imaging showed brain atrophy (3/3).
Conclusions:
Our data confirm the pivotal role of CDKL5 and ARX mutations in the pathogenesis of epileptic encephalopathies in infancy and identify early key clinical and EEG phenotypical features. With the aid of these tools, in the clinical setting, molecular analysis of these two genes, CDKL5 for females and ARX for males, should be considered in neurologically compromised neonates and infants, with early onset severe, otherwise unexplained, epilepsy.SOMMARIO
Introduzione:
Le encefalopatie epilettiche ad esordio nel primo anno di vita sono un gruppo clinicamente ed eziologicamente eterogeneo di disordini in cui le funzioni cognitive, sensoriali, e/o motorie si deteriorano principalmente a causa dell’attività epilettica. Numerosi sono i fattori eziologici che sono stati riportati, incluse condizioni ereditarie e non ereditarie. Comunque, in quasi un terzo dei casi non è possibile identificare una causa sottostante. Recentemente è stato segnalato il coinvolgimento dei geni CDKL5 ed ARX nella patogenesi dell’epilessia refrattaria ad esordio precoce, in bambini neurologicamente compromessi.
Obiettivi:
Investigare il ruolo patogenetico di CDKL5 ed ARX nelle encefalopatie epilettiche ad eziologia sconosciuta con esordio nel primo anno di vita e caratterizzare i quadri elettroclinici associati con mutazioni di tali geni.
Pazienti e metodi
Sono stati reclutati ed analizzati per mutazioni di CDKL5 ed ARX, mediante DHPLC e sequenziamento diretto, ottanta pazienti (40 femmine e 40 maschi, inclusi 2 cugini, nati da madri asintomatiche gemelle monozigoti) con encefalopatia epilettica ad eziologia sconosciuta con esordio durante il primo anno di vita. I dati clinici, neurologici, epilettologici e le registrazioni EEG sono stati retrospettivamente raccolti e globalmente valutati.
Risultati:
Sono state identificate 6 nuove mutazioni patogenetiche de novo di CDKL5 (3 missense; 2 nonsense; 1 frameshift) in 5 femmine e in un maschio 47,XXY, per un tasso complessivo di mutazione pari all’8%, ovvero una prevalenza del 12,5 % se si considerano solamente le femmine. In tre soggetti maschi, tra cui un caso sporadico ed i due cugini, sono state identificate due nuove diverse mutazioni missense del gene ARX (per un tasso di mutazione pari a 7,5% considerando esclusivamente i soggetti maschi della nostra coorte), dimostrando che mutazioni di ARX, diverse dalle espansioni dei tratti polialaninici, possono essere coinvolte nella patogenesi delle encefalopatie epilettiche.
La valutazione del profilo elettroclinico dei nostri pazienti con mutazioni del gene CDKL5 (età media: 5,8 anni, range 15 mesi - 11 anni) ha evidenziato le seguenti caratteristiche:
a) esordio precoce di epilessia (1-16 settimane di vita) (6/6) in bambini neurologicamente compromessi con ipotonia assiale e scarso contatto visivo (6/6); frequente commistione ab initio di più tipi di crisi, talora associate nel medesimo evento, quali spasmi (4/6), mioclonie (4/6), crisi focali (3/6), e crisi tonico o tonico cloniche apparentemente generalizzate (2/6);
b) normale attività di fondo all’EEG all’esordio (6/6) con presenza di anomalie intercritiche epilettiformi o lente, focali o multifocali (4/6);
c) neuroimaging non significativo (6/6);
d) successivo progressivo deterioramento dell’attività EEG di fondo (6/6) e comparsa - generalmente entro il secondo anno di vita - di un pattern elettrico inusuale caratterizzato da un’attività theta (4/6) o delta (1/6) di ampio/amplissimo voltaggio, più o meno diffusa, con sovrascritte, spesso subcontinue, anomalie multifocali ampie (5/6) con tendenza a divenire sincrone (4/6);
e) contemporaneo incremento in frequenza e persistenza di più tipi di crisi, principalmente crisi toniche (3/6) e spasmi (5/6), che, assieme all’aumento dell’attività EEG parossistica, contribuivano alla stagnazione o regressione dello sviluppo neurologico (6/6), configurando un’encefalopatia epilettica.
Tutti assieme questi aspetti costituiscono le più precoci caratteristiche cliniche che abbiamo identificato come una chiara indicazione all’analisi molecolare di CDKL5.
La possibile comparsa di caratteristiche cliniche Rett-like, quali stereotipie (5/6) o disfunzioni autonomiche (1/6), e la possibile evoluzione verso un’encefalopatia mioclonica con burst pseudoperiodici di anomalie (3/6), rappresentano ulteriori, ma un po’ tardivi, aspetti che orientano la diagnosi.
I tre pazienti identificati con mutazioni del gene ARX (età media: 7 anni, range 2 - 16 anni) presentavano all’esordio una early infantile epileptic encephalopathy with suppression burst (EIEE), nota come Sindrome di Ohtahara. Nel periodo neonatale (3/3), era presente un pattern caratterizzato da burst di attività parossistica separata da episodi di appiattimento o attenuazione in voltaggio del tracciato (3/3). Spasmi o crisi toniche (2/3) costituivano il principale tipo di crisi all’esordio, in associazione con crisi emicloniche (1/3), toniche (1/3) e mioclonie massive (1/3) o erratiche (1/3). Una transizione da EIEE a Sindrome di West atipica (3/3), era seguita, nel paziente più vecchio della nostra serie, da un’evoluzione verso una sindrome di Lennox-Gastaut-like. Uno sviluppo neurologico severamente compromesso (3/3) con ritardo mentale profondo (3/3), assenza di abilità sociali (3/3) e tetraparesi (3/3) erano evidenti al follow up, mentre i controlli neuroradiologici mostravano atrofia cerebrale (3/3).
Conclusioni:
I nostri dati confermano il ruolo cruciale di mutazioni dei geni CDKL5 e ARX nella patogenesi delle encefalopatie epilettiche dell’infanzia ed identificano delle caratteristiche fenotipiche chiave, sia cliniche che EEG. Con l’aiuto di questi strumenti, l’analisi molecolare di questi due geni (CDKL5 per le femmine ed ARX per i maschi) dovrebbe essere presa in considerazione, nella pratica clinica, in neonati e lattanti neurologicamente compromessi, con epilessia severa ad esordio precoce, altrimenti non spiegata
ENHANCEMENT OF Ti6Al4V MACHINABILITY THROUGH THE USE OF INNOVATIVE COOLING/LUBRICATING TECHNOLOGIES
Full text linkThe machining operations of Difficult-to-cut materials such as Titanium and its alloys, has an important role in the development of new techniques with the aim to improve both the process productivity and the final product quality.
The performances of the cutting fluids have recently been under investigation to drive machining operations towards cleaner and more sustainable targets. Several efforts are being made to test new formulations of coolants and to implement cooling/lubricating strategies alternative to standard flooding. As reported in literature the low-temperature cooling seems to be an efficient solution to enhance the process sustainability, among its several advantages, no contaminants are left on the chips and workpiece, hence reducing the chip disposal costs and limiting skin and breath diseases for the machine tool operators. Furthermore, in case of surgical prosthesis, it can help reducing the cleaning steps before the final sterilization. However its industrial application is still limited due to the cryogenic coolant extremely low temperatures that could determine a loss of geometrical accuracy of the machined components as a consequence of the thermal contraction induced mechanical components of the CNC machine tool.
Another interesting solution that minimizes the consumption of cutting fluid consumption without determine the above mentioned problems typical of the pure cooling techniques, consists in the use of Minimum Quantitative Lubrication (MQL) technologies. Nevertheless the low lubricating capacity of the cutting fluid does not allow to efficiently inhibit the tool activated wear mechanisms responsible to cutting edge degradation.
In this PhD thesis, several cooling, lubricating and hybrid technologies have been developed and implemented to improve the machinability of Ti6Al4V alloys, as promising alternatives to standard cooling methods applied in semi-finishing turning operations.
To reduce the main critical issues of the cryogenic cooling strategies different solutions have been proposed:
(i) For the first time an innovative cooling approach based on the use of gaseous Nitrogen (N2) cooled by LN2 in a range of temperature between 0° and -150°C.
(ii) Tool holder re-designed in order to make competitive the use of cryogenic coolant (LN2) reducing the thermal distortions.
As concerning the strategies to improve the minimal lubricating technologies both the Solid Lubricant assisted technologies and the hybrid ones (Minimum Quantitative Cooling Lubrication) were investigated. Two SL-assisted strategies were considered, namely an MQL vegetable oil enriched with PTFE particles and an aqueous solution added with graphite at different percentages, while for the MQCL technology the MQL system was implemented together with Liquid Nitrogen (LN2) and Carbon Dioxide (CO2) distribution systems designing the position of the nozzles to optimize the lubrication and cooling effects.
The Ti6Al4V machinability has been firstly investigated through an experimental approach, evaluating both the tool wear mechanisms and the surface integrity, using thedry cutting and the wet strategies as a reference.
Lastly the effects onto the machinability of Ti6Al4V alloy of different microstructurevariants produced though both conventional and Additive Manufacturing technologiesand different insert coatings were evaluated
SVILUPPO DI UN METODO DIGITALE PER L’ANALISI DELLE SOLLECITAZIONI IN COMPONENTI MECCANICI FORTEMENTE INTAGLIATI
No full textThe thesis proposed a experimental method for the assessment of the Notch Stress Intensity Factors (NSIF) of V-notches under mixed mode loadings without the use of particular techniques of experimental type in the preparation of the specimen and the use of sophisticated optical equipment laboratory.
The NSIFs are calculated on the basis of a comparison of two digital photos of a calculation grid placed in the area of maximum stress concentration taken whit a digital camera.
The photos are calculated to different load conditions and taken with a commercial digital camera.
The method is particularly flexible in order to effect the introduction of an innovative compensation system errors and misalignments.
The function performed by the compensation system can also seen as a calibration performed on the image and not a priori.
The position of each dot in the refinement mesh is read automatically by the software. By using the parameter JV (J-integral applied to the V-grooves) provides directly NSIF of the notch under mixed mode (I and II).
A mesh of dark spots is created on the surface near the notch tip and yhr spots have a diameter of abaut 20 pixel which is equivalent to a few tenths of a millimetre in standard applications.
The technique is also applicable to plane models that reproduce the resistant section of a weld, in particular will be considered classical form of cruciform joints.
Staric measurements were performed with normale tensile loads on speciments PVC or Aluminium.
Is finally proposed an alternative employment of the technique for direct application on the surface instead of the notch in section for measuring the KI.
This application is interesting because it potentially also be applied directly to the components in use.
The accuracy of the experimental method with respect to the FE analysis is around then per cent
Calcolo degli stress intensity factors di saldature con tecniche digitali
No full textNel presente articolo, sfruttando una nuova metodologia di misura messa a punto in un precedente lavoro, si calcolano i Notch Stress Intensity Factors (NSIF) di modelli di saldature con angolo d’apertura variabile da 30 a 135 gradi. Confrontando due foto digitali di una griglia di calcolo posta nella zona di massima concentrazione delle tensioni, è possibile ricavare, dopo una elaborazione numerica delle immagini, la misura dei NSIF. La griglia, che costituisce il campo di misura, è incollata alla superficie del pezzo da analizzare ed è composta da puntini scuri non sovrapposti aventi un diametro di qualche decimo di millimetro. Le misure statiche sono state eseguite con carichi nominali di trazione su provini in PVC o in alluminio. I valori sperimentali dei NSIF ottenuti dall’elaborazione software dell’immagine sono confrontati con i rispettivi valori calcolati con l’ausilio degli elementi finiti
Valutazione sperimentale degli stress intensity factors di intagli a v acuti sollecitati in modo misto
No full textNel presente articolo viene proposta una nuova metodologia di tipo sperimentale per il calcolo dei Notch Stress Intensity Factors (NSIF) di intagli acuti a V sollecitati in modo misto. Il metodo si basa sul confronto di due foto digitali di un intaglio piano relative a differenti condizioni di carico e scattate con una macchina fotografica di tipo commerciale. La preparazione del provino consiste nel predisporre sulla superficie, in prossimità dell’intaglio, una griglia di puntini scuri non sovrapposti aventi un diametro di qualche decimo di millimetro. La lettura della posizione dei puntini ed il loro relativo spostamento è fatta automaticamente dal software che, utilizzando il parametro JV (J-integral applicato agli intagli a V) fornisce direttamente i NSIF dell’intaglio in esame sollecitato in modo misto (I e II) con errori rispetto agli elementi finiti nell’ordine del dieci per cento
Trattamento dello stato di male epilettico in età pediatrica: revisione della letteratura r proposta di linee guida
No full textN-methyl-D-aspartate receptor encephalitis: laboratory diagnostics and comparative clinical features in adults and children.
No full textN-methyl-D-aspartate receptor (NMDAR) encephalitis is the most common autoimmune encephalitis due to autoantibodies against neuronal surface antigens, can affect both children and adults, leading to neurological and neuropsychological sequelae. However, it is potentially treatable and the prompt start of immunotherapy associates with better prognosis. Conversely, misdiagnosis can be harmful. The detection of NMDAR antibodies in serum and cerebrospinal fluid plays a pivotal role in the diagnostic work-up. Reliable methods for NMDAR antibody detection are thus fundamental to assure accurate diagnosis and allow early treatments. Areas covered: This review recapitulates the pathogenic mechanisms of NMDAR encephalitis as a model of antibody mediated synaptopathy, and gives insights into the related state-of-the-art laboratory testing. The differences in clinical presentations, tumor associations and responses to treatments between adults and children are also described. Expert commentary: The relevance of NMDAR encephalitis has placed neuroimmunology laboratories in a crucial position, but methods for NMDAR antibody detection are awaiting thorough and consensus-based standardizations. In the next few years, this process, along with novel insights into the pathogenic mechanisms, could improve the disease management and clarify the still pending role of NMDAR antibodies in healthy people and in other more common neuropsychiatric disorders
Experimental investigation on the feasibility of dry and cryogenic machining as sustainable strategies when turning Ti6Al4V produced by Additive Manufacturing
No full text
- …
