1,582 research outputs found

    Is porto sinusoidal vascular disease to be actively searched in patients with portal vein thrombosis?

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    Porto sinusoidal vascular liver disease (PSVD) and portal vein thrombosis (PVT) are distinct vascular liver diseases characterized, respectively, by an intrahepatic and a prehepatic obstacle to the flow in the liver portal system. PVT may also occur as a complication of the natural history of PSVD, especially if a prothrombotic condition coexists. In other cases, it is associated to local and systemic pro-thrombotic conditions, even if its cause remains unknown in up to 25% despite an active search. In our opinion, the presence of PSVD should be suspected in patients with PVT especially in those with PVT "sine causa" and the active search of this condition should be included in their diagnostic work-out. However, sometimes the diagnosis of pre-existing PSVD is very hard. Biopsy cannot be fully discriminant as similar histological data have been described in both conditions. Liver stiffness may help as it has been shown to be higher in PSVD than in "pure" PVT, due to the presence of sclerosis in the portal venous radicles observable in PSVD patients. Nevertheless, comparing liver stiffness between PVT and PSVD has until now been restricted to very limited series of patients. In conclusion, even if it is still totally hypothetical, our point of view may have clinical consequences, especially when deciding to perform a liver biopsy in patients with a higher liver stiffness and suspending the anticoagulation in patients with PVT and no detectable prothrombotic factors

    Characterization of autonomic states by complex sympathetic and parasympathetic dynamics*

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    Assessment of heartbeat dynamics provides a promising framework for non-invasive monitoring of cardiovascular and autonomic states. Nevertheless, the non-specificity of such measurements among clinical populations and healthy conditions associated with different autonomic states severely limits their applicability and exploitation in naturalistic conditions. This limitation arises especially when pathological or postural change-related sympathetic hyperactivity is compared to autonomic changes across age and experimental conditions. In this frame, we investigate the intrinsic irregularity and complexity of cardiac sympathetic and vagal activity series in different populations, which are associated with different cardiac autonomic dynamics. Sample entropy, fuzzy entropy, and distribution entropy are calculated on the recently proposed sympathetic and parasympathetic activity indices (SAI and PAI) series, which are derived from publicly available heartbeat series of congestive heart failure patients, elderly and young subjects watching a movie in the supine position, and healthy subjects undergoing slow postural changes. Results show statistically significant differences between pathological/old subjects and young subjects in the resting state and during slow tilt, with interesting trends in SAI- and PAI-related entropy values. Moreover, while CHF patients and healthy subjects in upright position show the higher cardiac sympathetic activity, elderly and young subjects in resting state showed higher vagal activity. We conclude that quantification of intrinsic cardiac complexity from sympathetic and vagal dynamics may provide new physiology insights and improve on the non-specificity of heartbeat-derived biomarkers

    Radiological Intervention for Shunt Related Encephalopathy

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    Hepatic Encephalopathy (HE) is a neuropsychiatric syndrome that occurs in up to 30% of patients with cirrhosis. HE may be a consequence of pure liver failure, as in patients with fulminant hepatitis, or of the combination of liver failure and portal-systemic shunting, as in patients with liver cirrhosis. Several clinical and pathophysiologic observations suggest the importance of portal-systemic shunts in the development of HE. Episodes of HE are usually related to precipitating events, such as infections or gastrointestinal bleeding; a minority of cirrhotic patients experienced a chronic HE, refractory to standard medical treatment. This latter type of HE should be related to spontaneous or radiological (such as Transjugular Intrahepatic Portosystemic Shunt (TIPS)) portal systemic shunts, that could be restricted or occluded in patients with chronic HE. Both TIPS reduction and shunt occlusion are radiological procedures, safe and effective to ameliorate neurological symptoms in patients with refractory HE

    Effective Edge-Fault-Tolerant Single-Source Spanners via Best (or Good) Swap Edges

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    Computing \emph{all best swap edges} (ABSE) of a spanning tree TT of a given nn-vertex and mm-edge undirected and weighted graph GG means to select, for each edge ee of TT, a corresponding non-tree edge ff, in such a way that the tree obtained by replacing ee with ff enjoys some optimality criterion (which is naturally defined according to some objective function originally addressed by TT). Solving efficiently an ABSE problem is by now a classic algorithmic issue, since it conveys a very successful way of coping with a (transient) \emph{edge failure} in tree-based communication networks: just replace the failing edge with its respective swap edge, so as that the connectivity is promptly reestablished by minimizing the rerouting and set-up costs. In this paper, we solve the ABSE problem for the case in which TT is a \emph{single-source shortest-path tree} of GG, and our two selected swap criteria aim to minimize either the \emph{maximum} or the \emph{average stretch} in the swap tree of all the paths emanating from the source. Having these criteria in mind, the obtained structures can then be reviewed as \emph{edge-fault-tolerant single-source spanners}. For them, we propose two efficient algorithms running in O(mn+n2log⁥n)O(m n +n^2 \log n) and O(mnlog⁥ι(m,n))O(m n \log \alpha(m,n)) time, respectively, and we show that the guaranteed (either maximum or average, respectively) stretch factor is equal to 3, and this is tight. Moreover, for the maximum stretch, we also propose an almost linear O(mlog⁥ι(m,n))O(m \log \alpha(m,n)) time algorithm computing a set of \emph{good} swap edges, each of which will guarantee a relative approximation factor on the maximum stretch of 3/23/2 (tight) as opposed to that provided by the corresponding BSE. Surprisingly, no previous results were known for these two very natural swap problems.Comment: 15 pages, 4 figures, SIROCCO 201

    Path-Fault-Tolerant Approximate Shortest-Path Trees

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    Let G=(V,E)G=(V,E) be an nn-nodes non-negatively real-weighted undirected graph. In this paper we show how to enrich a {\em single-source shortest-path tree} (SPT) of GG with a \emph{sparse} set of \emph{auxiliary} edges selected from EE, in order to create a structure which tolerates effectively a \emph{path failure} in the SPT. This consists of a simultaneous fault of a set FF of at most ff adjacent edges along a shortest path emanating from the source, and it is recognized as one of the most frequent disruption in an SPT. We show that, for any integer parameter k≥1k \geq 1, it is possible to provide a very sparse (i.e., of size O(kn⋅f1+1/k)O(kn\cdot f^{1+1/k})) auxiliary structure that carefully approximates (i.e., within a stretch factor of (2k−1)(2∣F∣+1)(2k-1)(2|F|+1)) the true shortest paths from the source during the lifetime of the failure. Moreover, we show that our construction can be further refined to get a stretch factor of 33 and a size of O(nlog⁡n)O(n \log n) for the special case f=2f=2, and that it can be converted into a very efficient \emph{approximate-distance sensitivity oracle}, that allows to quickly (even in optimal time, if k=1k=1) reconstruct the shortest paths (w.r.t. our structure) from the source after a path failure, thus permitting to perform promptly the needed rerouting operations. Our structure compares favorably with previous known solutions, as we discuss in the paper, and moreover it is also very effective in practice, as we assess through a large set of experiments.Comment: 21 pages, 3 figures, SIROCCO 201
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