67 research outputs found
Vasculitides E. miscellaneous vasculitis (Behçet's Disease, Primary Angiitis of the Central Nervous System, Cogan's Syndrome, and Erythema Elevatum Diutinum)
No full textThe prevalence of Behçet's disease is highest in countries of the eastern Mediterranean, the Middle East, and East Asia. Aphthous oral ulcers are usually the first and most persistent clinical feature of Behçet's disease. Aphthous ulcers also occur frequently on the genitals (e.g., the scrotum or vulva). Uveitis-either anterior or posterior-is common in Behçet's disease and a source of major morbidity. Many forms of central nervous system disease may occur in Behçet's disease. These include aseptic meningitis and white matter lesions in the brainstem. Human leukocyte antigen (HLA)-B51 is a strong risk factor for Behçet's disease. The diagnosis of primary angiitis of the central nervous system is predicated upon either biopsy evidence of vasculitis or angiographic findings suggestive of vasculitis in the setting of other compelling features, for example, strokes demonstrated by magnetic resonance imaging or the findings of a cerebrospinal fluid pleocytosis. The diagnosis of primary angiitis of the central nervous system should never be made on the basis of an angiogram alone. Patients with benign angiopathy of the central nervous system are predominantly female, tend to present acutely with headache (with or without focal symptoms), and have normal or near normal cerebrospinal fluid. Cogan's syndrome refers to the association of inflammation in both the eyes and ears: specifically, the occurrence of nonsyphilitic interstitial keratitis and immune-mediated inner ear disease, resulting in audiovestibular dysfunction. Any type of ocular inflammation may occur in Cogan's syndrome (e.g., scleritis, uveitis, orbital pseudotumor). The inner ear disease associated with this condition often leads to deafness. In erythema elevatum diutinum, skin lesions consist of purple, red, or brown plaques and often have an annular or nodular appearance. The skin lesions have a predilection for the extensor surfaces of the distal extremities and often overlie joints, but may be generalized. © 2008 Springer Science+Business Media, LLC. © 2008 Springer-Verlag New York
First international conference on polymyalgia rheumatica and giant cell arteritis, Prato, Italy. May 25-26, 1999
No full textFirst international conference on polymyalgia rheumatica and giant cell arteritis, Prato, Italy. May 25-26, 1999
Do we need 18F-FDG-positron emission tomography as a functional imaging technique for diagnosing large vessel arteritis?
No full textTo discuss the role of 18F-FDG-positron emission tomography as a functional imaging technique for diagnosing large vessel arteriti
18F-fluorodeoxyglucose-positron emission tomography: a new explorative perspective
No full text18F-Fluorodeoxyglucose-positron emission tomography (18F-FDG-PET) is a new functional imaging technique available for clinical and experimental use. 18F-FDG-PET studies can be used for screening, localization and follow-up of hypermetabolic processes including malignancies, infections and autoimmune processes. For several years it has been applied in oncological, cardiological and neurological patients, but nowadays an increasing number of studies favours its use in patients with autoimmune diseases including large vessel arteritis. From the experimental view, this technique has even become more important since the introduction of a small PET scanner for the use in animal models. This review focuses on technical aspects, clinical experiences and experimental and future perspectives of 18F-FDG-PET, with a special emphasis on large vessel vasculitis and other autoimmune diseases
Primary CNS vasculitis with spinal cord involvement
No full textPrimary CNS vasculitis (PCNSV) is an uncommon disease in which lesions are limited to the brain and spinal cord. Our objective was to evaluate the frequency, clinical features, and outcome of spinal cord involvement in PCNSV
Primary central nervous system vasculitis: comparison of patients with and without cerebral amyloid angiopathy
No full textTo describe the clinical features and outcomes of patients with primary central nervous system vasculitis (PCNSV) and cerebral amyloid angiopathy (CAA) from a large cohort of consecutive patients with PCNSV treated at a single institution
Rapidly progressive primary central nervous system vasculitis
No full textTo describe a subset of cases in a large cohort of patients with primary CNS vasculitis (PCNSV) who appear to have a rapidly progressive clinical course
An investigation on the secondary stability of the Blasius boundary-layer
No full textLAUREA MAGISTRALEIl meccanismo fisico che provoca il passaggio dal regime laminare a quello
turbolento è molto complesso e non ancora compreso appieno. In ambito aeronautico, la transizione dello strato limite ha un’influenza considerevole sulle
prestazioni aerodinamiche dei profili alari e delle superfici portanti in generale.
Il presente lavoro si occupa della stabilità secondaria del flusso di strato limite
di Blasius, introducendo, rispetto alla formulazione originaria della stabilità
secondaria introdotta da Herbert, gli effetti di non parallelismo e quelli non
lineari. Matematicamente, il problema consiste nello studio della stabilità
del flusso di Blasius forzato da un’onda di Tollmien–Schlichting periodica nel
tempo che può essere eseguito tramite la teoria di Floquet. Le equazioni di
Navier-Stokes sono integrate tramite uno schema di correzione della pressione
basato sulla tecnica del direction-splitting mentre per il calcolo dei modi
secondari tridimensionali e dei corrispondenti moltiplicatori di Floquet, viene
utilizzato il metodo IRAM implementato nel software ARPACK. Lo spettro
degli autovalori è valutato per tre valori di frequenza ridotta dell’onda T-S, con
particolare riguardo all’influenza che ha l’ampiezza dell’onda primaria sulle
caratteristiche dell’instabilità. Si trova che i modi sincroni sono associati ai
maggiori tassi di crescita considerando tutto l’intervallo di numeri d’onda nella
direzione trasversale. Il modo subarmonico è il più instabile per valori bassi o
medi dell’ampiezza dell’onda T-S. Invece, quando si considera un’ampiezza
elevata, è il modo fondamentale, con lo stesso periodo temporale dell’onda,
ad essere il più instabile. Per alti valori di ampiezza, l’instabilità coinvolge un
vasto intervallo di numeri d’onda trasversali e l’intervallo di frequenze che va
da quella subarmonica a quella fondamentale. I risultati mostrano un ottimo
accordo qualitativo con quelli ottenuti tramite la teoria originale di Herbert
anche se l’aggiunta degli effetti di non parallelismo e di non linearità nel flusso
base, porta la soglia di ampiezza al quale l’instabilità si sviluppa molto vicino
ai dati sperimentali. Viene eseguita una serie di simulazioni DNS per valutare
se le perturbazioni tridimensionali calcolate portano il flusso di Blasius al
regime turbolento. Le simulazioni numeriche mostrano che, dopo una iniziale
fase lineare in cui l’evoluzione dei disturbi è prossima a quanto previsto dai
calcoli di stabilità, la non linearità porta alla formazione di vortici Λ che
provocano il passaggio al regime turbolento del flusso di strato limite. La
disposizione di queste strutture Λ è allineata in file o sfalsata, a seconda di
quale modo secondario viene introdotto nel flusso dello strato limite di Blasius.
Le due disposizioni di queste strutture corrispondono ai ben noti regimi di
tipo H e di tipo K dominati rispettivamente dal modo subarmonico o dal
modo fondamentale. Pertanto, le autofunzioni del problema agli autovalori
della stabilità secondaria forniscono le perturbazioni
di vorticità vicino alla parete responsabili degli scenari di transizione naturale
comunemente osservati nelle applicazioni pratiche.The physical mechanism which drives a laminar flow to the turbulent regime
is extremely complex and not yet completely understood. Considering the
aeronautical field, the transition of the boundary-layer has a remarkable
influence on the aerodynamic performance of airfoils and lifting surfaces in
general. The present work deals with the secondary stability analysis of
the Blasius boundary-layer flow, introducing, with respect to the original
secondary stability theory proposed by Herbert, the non-parallel and non-linear effects. Mathematically, the problem consists in studying the stability
of the Blasius flow forced by a time-periodic Tollmien–Schlichting wave by
means of the Floquet theory. An incremental pressure-correction scheme based
on the direction-splitting technique is used to integrate the Navier-Stokes
equations whereas, for the computation of the three-dimensional secondary
modes and the correspondent Floquet multipliers, the implicitly restarted
Arnoldi method (IRAM), implemented in the software package ARPACK, is
employed. The eigenvalue spectrum is evaluated for three reduced frequencies
of the T-S wave, giving particular attention to the influence that the maximum
amplitude reached by the primary wave has on the instability behaviour. It
is found that the synchronous modes are associated to the largest growth
rates among the whole range of spanwise wavenumbers. The subharmonic
mode is the most unstable for low and medium amplitudes of the T-S wave
while, as the amplitude increases, the fundamental mode, with the same
period of the primary wave, becomes the most unstable. For high amplitudes
the instability affects a wide range of spanwise wavenumbers and the whole
frequency range from the subharmonic to the fundamental one. The results
show high qualitative agreement with those provided by Herbert’s formulation
and it is found that, due to the inclusion of the non-linear and non-parallel
effects in the base flow, the threshold amplitude for the instability is close to
that observed in the experiments. A series of DNS simulations is performed to
investigate if the computed three-dimensional perturbations lead the Blasius
flow to the turbulent regime. The transition simulations show that, after an
initial linear stage in which the disturbance evolution is close to what predicted
by the stability calculations, the nonlinearity leads to the formation of Λ
vortices that drive the boundary-layer flow to transition. The arrangement
of these Λ structures is either aligned in rows of staggered, depending on
which secondary mode is introduced in the boundary-layer flow. The two
observed arrangements of the flow structures correspond to the well known
H-type and K-type regimes dominated by the subharmonic or the fundamental
mode, respectively. Therefore, the eigenfunctions of the secondary stability
eigenvalue problem provide the near-wall vorticity perturbations responsible
for the commonly observed natural transition scenarios
Interplay of passive and active drug disposition in in vitro models of drug absorption and distribution
No full textThe course and outcome of unilateral intracranial arteriopathy in 79 children with ischaemic stroke
No full textArteriopathies are the commonest cause of arterial ischaemic stroke (AIS) in children. Repeated vascular imaging in children with AIS demonstrated the existence of a 'transient cerebral arteriopathy' (TCA), characterized by lenticulostriate infarction due to non-progressive unilateral arterial disease affecting the supraclinoid internal carotid artery and its proximal branches. To further characterize the course of childhood arteriopathies, and to differentiate TCA from progressive arterial disease, we studied the long-term evolution of unilateral anterior circulation arteriopathy, and explored predictors of stroke outcome and recurrence. From three consecutive cohorts in London, Paris and Utrecht, we reviewed radiological studies and clinical charts of 79 previously healthy children with anterior circulation AIS and unilateral intracranial arteriopathy of the internal carotid bifurcation, who underwent repeated vascular imaging. The long-term evolution of arteriopathy was classified as progressive or TCA. Clinical and imaging characteristics were compared between both groups. Logistic regression modelling was used to determine possible predictors of the course of arteriopathy, functional outcome and recurrence. After a median follow-up of 1.4 years, 5 of 79 children (6%) had progressive arteriopathy, with increasing unilateral disease or bilateral involvement. In the others (94%), the course of arteriopathy was classified as TCA. In 23% of TCA patients, follow-up vascular imaging showed complete normalization, the remaining 77% had residual arterial abnormalities, with improvement in 45% and stabilization in 32%. Stroke was preceded by chickenpox in 44% of TCA patients, and in none of the patients with progressive arteriopathies. Most infarcts were localized in the basal ganglia. In 14 (19%) of TCA patients, transient worsening of the arterial lesion was demonstrated before the arteriopathy stabilized or improved. Thirteen TCA patients (18%) had a recurrent stroke or TIA. Thirty TCA patients (41%) had a good neurological outcome, compared with none of the five patients with progressive arteriopathy. Arterial occlusion, moyamoya vessels and ACA involvement were more frequent in progressive arteriopathies. Cortical infarct localization was significantly associated with poor neurological outcome (OR 6.14, 95% CI 1.29-29.22, P = 0.02), while there was a trend for occlusive arterial disease to predict poor outcome (OR 3.00, 95% CI 0.98-9.23, P = 0.06). Progressive arteriopathy was associated with recurrence (OR 18.77, 95%CI 1.94-181.97, P = 0.01). The majority of childhood unilateral intracranial anterior circulation arteriopathies (94%) have a course that is consistent with TCA, in which transient worsening is common. Although the arterial inflammation probably causing TCA is 'transient', most children are left with permanent arterial abnormalities and residual neurological deficit
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