2,682 research outputs found
The impact of the Geometric Correction Scheme on MEG functional topology at rest
Spontaneous activity is correlated across brain regions in large scale networks (RSN) closely resembling those recruited during several behavioral tasks and characterized by functional specialization and dynamic integration. Specifically, MEG studies revealed a set of central regions (dynamic core) possibly facilitating communication among differently specialized brain systems. However, source projected MEG signals, due to the fundamentally ill-posed inverse problem, are affected by spatial leakage, leading to the estimation of spurious, blurred connections that may affect the topological properties of brain networks and their integration. To reduce leakage effects, several correction schemes have been proposed including the Geometric Correction Scheme (GCS) whose theory, simulations and empirical results on topography of a few RSNs were already presented. However, its impact on the estimation of fundamental graph measures used to describe the architecture of interactions among brain regions has not been investigated yet. Here, we estimated dense, MEG band-limited power connectomes in theta, alpha, beta, and gamma bands from 13 healthy subjects (all young adults). We compared the connectivity and topology of MEG uncorrected and GCS-corrected connectomes. The use of GCS considerably reorganized the topology of connectivity, reducing the local, within-hemisphere interactions mainly in the beta and gamma bands and increasing across-hemisphere interactions mainly in the alpha and beta bands. Moreover, the number of hubs decreased in the alpha and beta bands, but the centrality of some fundamental regions such as the Posterior Cingulate Cortex (PCC), Supplementary Motor Area (SMA) and Middle Prefrontal Cortex (MPFC) remained strong in all bands, associated to an increase of the Global Efficiency and a decrease of Modularity. As a comparison, we applied orthogonalization on connectomes and ran the same topological analyses. The correlation values were considerably reduced, and orthogonalization mainly decreased local within-hemisphere interactions in all bands, similarly to GCS. Notably, the centrality of the PCC, SMA and MPFC was preserved in all bands, as for GCS, together with other hubs in the posterior parietal regions. Overall, leakage correction removes spurious local connections, but confirms the role of dynamic hub regions, specifically the anterior and posterior cingulate, in integrating information in the brain at rest
Natural history of patients with non cirrhotic portal hypertension: Comparison with patients with compensated cirrhosis
Background. The knowledge of natural history of patients with portal hypertension (PH) not due to
cirrhosis is less well known than that of cirrhotic patients.
Aim. To describe the clinical presentation and the outcomes of 89 patients with non-cirrhotic PH
(25 with non-cirrhotic portal hypertension, INCPH, and 64 with chronic portal vein thrombosis,
PVT) in comparison with 77 patients with Child A cirrhosis.
Methods. The patients were submitted to a standardized clinical, laboratory, ultrasonographic and
endoscopic follow-up. Variceal progression, incidence of variceal bleeding, portal vein thrombosis,
ascites and survival were recorded.
Results. At presentation, the prevalence of varices, variceal bleeding and ascites was similar in the
3 groups. During follow-up, the rate of progression to varices at risk of bleeding (p<0.0001) and the
incidence of first variceal bleeding (p=0.02) were significantly higher in non-cirrhotic then in
cirrhotic patients. A PVT developed in 32% of INCPH patients and in 18% of cirrhotics (p=0.02).
Conclusions. In the patients with non–cirrhotic PH variceal progression is more rapid and bleeding
more frequent than in cirrhotics. Patients with INCPH are particularly prompt to develop PVT. This
observational study suggests that the management of patients with non-cirrhotic PH should take
into consideration the natural history of portal hypertension in these patients and cannot be simply
derived by the observation of cirrhotic patients
EStereoregular 1,1 and 1,3 Constitutional Units from 1,3-Butadiene in Copolymerizations Catalyzed by a Highly HinderedC2Symmetric Metallocene
Marked efficacy of Rituximab in multifocal motor neuropathy associated with chronic lymphocytic leukemia
The authors describe a patient who presented a multifocal motor neuropathy (MMN) associated with a high anti-ganglioside antibody (anti-GM1 and anti-GD1) titer at the clinical onset of a B-cell chronic lymphocytic leukemia (B-CLL). Immunomodulation (IVIg plus cyclosporine) resulted in a neurological improvement and reduced anti-ganglioside antibody titers, both of which remained stable for at least six years. After this period, the patient had a severe relapse of the neuropathy, which was independent of the clinical course of the B-CLL. Both IVIg and cyclophosphamide were ineffective, and the patient became tetraplegic within six months; in the meantime, the patient displayed an increased antiganglioside antibody titer. Treatment with rituximab (RTX), which is designed to selectively inhibit B cell function, resulted in a dramatic, prompt and long-lasting neurological improvement as well as a reduced anti-ganglioside antibody titer. Although there are no previous reports of MMN in patients with B-CLL, the efficacy of RTX in the treatment of MMN in this patient may be considered remarkable. The expansion of B-cell clones may be a prerequisite for RTX effectiveness in MMN, and in dysimmune neuropathies in general
Marked efficacy of rituximab in multifocal motor neuropathy associated with chronic lymphocytic leukemia
The authors describe a patient who presented a multifocal motor neuropathy (MMN) associated with a
high anti-ganglioside antibody (anti-GM1 and anti-GD1) titer at the clinical onset of a B-cell chronic
lymphocytic leukemia (B-CLL). Immunomodulation (IVIg plus cyclosporine) resulted in a neurological
improvement and reduced anti-ganglioside antibody titers, both of which remained stable for at least six
years. After this period, the patient had a severe relapse of the neuropathy, which was independent of the
clinical course of the B-CLL. Both IVIg and cyclophosphamide were ineffective, and the patient became
tetraplegic within six months; in the meantime, the patient displayed an increased antiganglioside
antibody titer. Treatment with rituximab (RTX), which is designed to selectively inhibit B cell function,
resulted in a dramatic, prompt and long-lasting neurological improvement as well as a reduced antiganglioside
antibody titer. Although there are no previous reports of MMN in patients with B-CLL, the
eficacy of RTX in the treatment of MMN in this patient may be considered remarkable. The expansion of
B-cell clones may be a prerequisite for RTX effectiveness in MMN, and in dysimmune neuropathies in
general
No effect of albumin infusion on the prevention of hepatic encephalopathy after transjugular intrahepatic portosystemic shunt
Hepatic encephalopathy (HE) is a major problem in patients submitted to TIPS. Previous studies identified low albumin as a factor associated to post-TIPS HE. In cirrhotics with diuretic-induced HE and hypovolemia, albumin infusion reduced plasma ammonia and improved HE. Our aim was to evaluate if the incidence of overt HE (grade II or more according to WH) and the modifications of venous blood ammonia and psychometric tests during the first month after TIPS can be prevented by albumin infusion. Twenty-three patients consecutively submitted to TIPS were enrolled and treated with 1Â g/Kg BW of albumin for the first 2Â days after TIPS followed by 0,5Â g/Kg BW at day 4th and 7th and then once a week for 3Â weeks. Forty-five patients included in a previous RCT (Riggio et al. 2010) followed with the same protocol and submitted to no pharmacological treatment for the prevention of HE, were used as historical controls. No differences in the incidence of overt HE were observed between the group of patients treated with albumin and historical controls during the first month (34 vs 31Â %) or during the follow-up (39 vs 48Â %). Two patients in the albumin group and three in historical controls needed the reduction of the stent diameter for persistent HE. Venous blood ammonia levels and psychometric tests were also similarly modified in the two groups. Survival was also similar. Albumin infusion has not a role in the prevention of post-TIPS HE
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