1,721,208 research outputs found
Cerebellar damage impairs detection of somatosensory input changes. A somatosensory mismatch-negativity study
Full text linkseveral recent studies support the view that the cerebellum's contribution to sensory processing is not limited to movement regulation. In a previous paper (restuccia d, valeriani m, barba c, le pera d, capecci m, filippini v, molinari m. functional changes of the primary somatosensory cortex in patients with unilateral cerebellar lesions. brain 2001; 124: 757-68) we showed that the cerebellum influences somatosensory input processing at very early stages. the present study was aimed at verifying whether an analogous influence is also exerted at higher levels. for some time it has been known that in the auditory modality a specific event-related potential (ERP), that is, mismatch negativity (MMN), reflects preattentive detection of changes in the incoming stimulus by comparing the new stimulus with sensory memory traces. to test the cerebellar influence on the processing of incoming somatosensory stimuli we first verified whether the electrical stimulation of fingers, according to an 'oddball' paradigm within a stimulus-ignored condition, was able to elicit event-related components specifically linked to the preattentive detection of change. we analysed scalp responses obtained from eight healthy volunteers during frequent and rare electrical stimulation of the first and fifth finger of the left hand, respectively. to ensure that responses to deviant stimuli were due to changes in detection mechanisms, rather than to activation of new afferents, we also analysed responses to rare stimulation alone ('standard-omitted' condition). the 'oddball' stimulation was able to elicit a parieto-occipital extra negativity that was different in scalp distribution and latency from the N140 response to the 'standard-omitted' stimulation. we considered that this response was related to changes in detection mechanisms and labelled it somatosensory mismatch negativity (S-MMN). When the same procedure was applied to six patients with unilateral cerebellar lesions we found that the S-MMN was clearly abnormal after stimulation of the affected hand (ipsilateral to the affected cerebellar hemisphere). Earlier ERPs, as well as ERPs elicited during the 'standard-omitted' condition, were fully normal. present data indicate that cerebellar processing is involved in preattentive detection of somatosensory input changes. In conclusion, this study demonstrates the reliability of S-MMN recordings and indicates that subjects with cerebellar damage may be impaired in the cortical processing of incoming somatosensory inputs
High frequency oscillations after median nerve stimulations in healthy children and adolescents
No full textThe aim of the present research was to address somatosensory high frequency oscillations (400–800 Hz) in healthy children and adolescents in comparison with healthy adults. We recorded somatosensory evoked potentials following median nerve stimulation in nineteen resting healthy children/adolescents and in nineteen resting healthy adults with eyes closed. We administered six consecutive stimulation blocks (500 sweeps each). The presynaptic component of high frequency oscillations amplitudes was smaller in healthy children/adolescents than in healthy adults (no difference between groups was found as far as the postsynaptic component was concerned). Healthy children/adolescents had smaller presynaptic component than the postsynaptic one (the postsynaptic component amplitude was 145% of the presynaptic one), while healthy adults showed the opposite (reduction of the postsynaptic component to 80% of the presynaptic one). No habituation phenomena concerning high frequency oscillation amplitudes were registered in neither healthy children/adolescents nor healthy adults. These findings suggest that healthy children/adolescents present with significantly different pattern of somatosensory high frequency oscillations compared with healthy adults’ ones. This different pattern is reasonably expression of higher cortical excitability of the developing brain cortex
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No full textSi tratta di una raccolta di sentenze recenti di varie tematiche sul diritto privato oggetto del corso di Istituzioni di diritto privato insegnato nella facoltà di Giurisprudenza per la laurea triennale in Scienze dei servizi giuridici, in cui gli studenti anelano ad imparare a trattare anche dei casi pratici.
Nel volume gli Autori con uno schema unitario, trattano il caso pratico dopo un’introduzione istituzionale sull’istituto di riferimento per il caso giurisprudenziale, in modo da conoscere, prima della lettura della sentenza le regole ed i principi fondamentali dell’argomento in questione, in successione il testo della sentenza con evidenziati i passaggi cruciali della pronuncia ed il commento rapido alla sentenza per comprenderne al meglio i principi e le conclusioni.
Esso si propone di essere un rapido ed utile strumento per le matricole per introdurle alla conoscenza, alla miglior comprensione di un testo giuridico, per insegnare loro come si affronta lo studio di una sentenza
Giant subcortical high-frequency SEPs in idiopathic generalized epilepsy: A protective mechanism against seizures?
No full textobjective: recently, we found that high-frequency somatosensory evoked potentials (HF-SEPs), which are modulated by arousal-related structures, were abnormally enhanced during N-REM sleep in two seizure-free IGE patients [restuccia d, rubino m, valeriani m, della marca g. increase of brainstem high-frequency SEP subcomponents during light sleep in seizure-free epileptic patients. clin neurophysiol 2005; 116: 1774-1778]. Here, we aimed at verifying whether similar HF-SEP abnormalities were significantly correlated to the clinical outcome in a larger population of untreated IGE patients. methods: patients were classified as juvenile myoclonic epilepsy (JME; six patients) and childhood or juvenile absence epilepsy (CAE and JAE, six patients). they were untreated because newly diagnosed, or because seizure-free. HF-SEPs from patients were compared with those obtained from 21 healthy volunteers. results: HF-SEPs were abnormally enhanced in all seizure-free CAE-JAE patients, whereas they were normal in all JME patients and in CAE-JAE patients with frequent seizures. not only scalp distribution, but also dipolar source analysis suggested a subcortical origin for these enhanced subcomponents, possibly in the brainstem. conclusions: the enhancement of HF-SEPs might reflect the hyperactivity of arousal-related brainstem structures; such an enhancement was found in all seizure-free CAE-JAE patients, while it was never observed in JME patients. significance: we speculate that the hyperactivity of arousal-related brainstem structures might account for the different clinical outcome among IGE subsyndromes. (c) 2006 international federation of clinical neurophysiology
Campionamento e valutazione analitica del grado di inquinamento da idrocarburi policiclici aromatici di un sito industriale dismesso deposito di coke di petrolio
No full textSimple and rapide determination of polycyclic aromatic hydrocarbons in different wastewaters, sewage sludges and stream waters samples by liquid chromatography with fluorimetric and UV detection
No full textSelective abnormality of the N13 spinal SEP to dermatomal stimulation in patients with cervical monoradiculopathy
No full textScalp somatosensory evoked potentials (SEP) to dermatomal stimulation have so far proved to be only partially useful in the diagnosis of monoradiculopathy, mostly in cases without motor impairment. The aim of our study was to test the sensitivity of the spinal N13 potential in uncovering lesions of single cervical roots. We studied five patients suffering from cervical monoradiculopathy, using a recording technique allowing specific recording of the genuine N13 potential which is probably generated by dorsal horn cells. No patient showed signs of muscle impairment and needle EMG was always normal. In four patients, the N13 SEP was, absent following stimulation of the dermatome corresponding to the damaged root, while both the lemniscal P14 and the cortical N20 components were normal. SEP recorded after stimulation of upper limb troncular nerves showed no abnormality in all patients. Our findings suggest that the N13 potential, the loss of which after dermatomal stimulation could be due to deafferentation of dorsal horn neurones, is particularly sensitive to initial root compression. Therefore, our montage allowing analysis of the genuine N13 SEP can improve the sensitivity of dermatomal SEP recording in patients with cervical monoradiculopathies
Central scalp projection of the N30 SEP source activity after median nerve stimulation
Full text linkConflicting results have been reported about abnormalities of the N30 somatosensory evoked potential (SEP) in movement disorders. In these studies, the N30 amplitude was measured in the frontal scalp region. Our aim was to identify the scalp electrodes recording the genuine activity of the N30 generator. In 18 subjects, we recorded the scalp SEPs from 19 electrodes and found a negative potential around 30 ms reaching its maximal amplitude in the frontal region. However, neither simple visual inspection of the frontal traces nor topographic analysis could distinguish the N24 from the N30 component of the frontal negativity. Brain electrical source analysis of SEPs showed that a four dipolar source model could well explain the scalp SEP distribution. We calculated the scalp field distributions of the source activities as modeled from the scalp recordings and observed that the maximal field distribution reflecting the activity of the N30 source was in the central region, whereas that reflecting the N24 source activity was frontal. We conclude that the negative response recorded around 30 ms in the central traces represents "genuine" N30 source activity, whereas the frontal negativity, which is higher in amplitude, is a mixture of the activities of both the N30 and N24 sources. (C) 2000 John Wiley & Sons, Inc. Muscle Nerve 23: 353-360, 2000
Natural Compounds and Biopolymers-Based Hydrogels Join Forces to Promote Wound Healing
No full textRapid and complete wound healing is a clinical emergency, mainly in pathological conditions such as Type 2 Diabetes mellitus. Many therapeutic tools are not resolutive, and the research for a more efficient remedial remains a challenge. Wound dressings play an essential role in diabetic wound healing. In particular, biocompatible hydrogels represent the most attractive wound dressings due to their ability to retain moisture as well as ability to act as a barrier against bacteria. In the last years, different functionalized hydrogels have been proposed as wound dressing materials, showing encouraging outcomes with great benefits in the healing of the diabetic wounds. Specifically, because of their excellent biocompatibility and biodegradability, natural bioactive compounds, as well as biomacromolecules such as polysaccharides and protein, are usually employed in the biomedical field. In this review, readers can find the main discoveries regarding the employment of naturally occurring compounds and biopolymers as wound healing promoters with antibacterial activity. The emerging approaches and engineered devices for effective wound care in diabetic patients are reported and deeply investigated
Valutazione economica della possibilità di coesistenza delle forme di agricoltura convenzionale e biologica con la coltivazione di organismi transgenici
No full textGli Organismi Geneticamente Modificati (OGM) in agricoltura rappresentano la "nuova frontiera": nel nostro paese il loro utilizzo non è permesso a livello di commercializzazione
ma solo a livello di sperimentazione.
A livello comunitario, negli alimenti è obbligatorio darne evidenza nell ' etichetta qualora uno qualsiasi degli ingredienti contenga almeno l' l o/o di OGM così come previsto dal Reg. CE 49/2000. Lo studio delle possibili implicazioni derivanti dalla deliberata immissione di OGM nell'ambiente risulta di difficile valutazione; come pure l'analisi dell'impatto economico della coesistenza di coltivazioni convenzionali, biologiche e geneticamente
modificate. Ciò in parte deriva dalla complessità delle diverse pratiche agricole che comportano costi elevati e procedure complesse. Pertanto, l' analisi dei dati, condotta
attraverso l'applicazione di modelli matematici, può fornire solo una stima del fenomeno in esame e non una sua reale valutazione economica
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