275 research outputs found
Inferior Mesenteric Artery Stenting as a Novel Treatment for Chronic Mesenteric Ischemia in Patients with an Occluded Superior Mesenteric Artery and Celiac Trunk
IntroductionChronic mesenteric ischemia (CMI) is a challenging problem, with revascularization the mainstay of treatment. Management of CMI is especially challenging in the patient with superior mesenteric artery (SMA) and celiac artery (CA) occlusions.ReportWe report a case series of four patients with chronic mesenteric ischemia who were not candidates for CA or SMA revascularization who were successfully treated with inferior mesenteric artery (IMA) angioplasty and stent placement to improve collateral circulation and palliate symptoms.DiscussionTo our knowledge, this is the largest case series to date reporting the use of an IMA stent to improve collateral circulation in patients with CMI
Predictors of mortality following emergency open colectomy for ischemic colitis: A single-center experience
Background: Ischemic colitis (IC) is a severe emergency in gastrointestinal surgery. The aim of the present study was to identify the predictors of postoperative mortality after emergent open colectomy for IC treatment. Additionally, we compared postoperative outcomes of patients undergoing emergent colectomy due to aortic surgery-related IC (AS-IC group) vs. other IC etiologies (Other-IC group). Methods: We analyzed records of consecutive patients who underwent emergency open colectomy for IC between 2008 and 2019. Logistic regression analysis was performed to identify clinical and operative parameters associated with postoperative mortality. The AS-IC and Other-IC groups were compared for mortality, morbidity, ICU stay, hospital stay, and survival. Results: During the study period, 94 patients (mean age, 67.4 ± 13.7 years) underwent emergent open colectomy for IC. In the majority of cases, IC involved the entire colon (53.2%) and vasopressor agents were required preoperatively (63.8%) and/or intraoperatively (78.8%). Thirty-four patients underwent surgery due to AS-IC, whereas 60 due to Other-IC causes. In the AS-IC group, 9 patients had undergone endovascular aortic repair and 25 open aortic surgery; 61.8% of patients needed aortic surgery for ruptured abdominal aortic aneurism (AAA). Overall, 66 patients (70.2%) died within 90 days from surgery. The AS-IC and Other-IC groups showed similar operative outcomes and postoperative complication rates. However, the duration of the ICU stay (19 days vs. 11 days; p = 0.003) and of the total hospital stay (22 days vs. 16 days; p = 0.016) was significantly longer for the AS-IC group than for the Other-IC group. The rate of intestinal continuity restoration at 1 year after surgery was higher for the Other-IC group than for the AS-IC group (58.8% vs. 22.2%; p = 0.05). In the multivariate model, preoperative increased lactate levels, a delay between signs/symptoms' onset and surgery > 12 h, and the occurrence of postoperative acute kidney injury were statistically associated with postoperative mortality. Neither IC etiology (aortic surgery vs. other etiology) nor ruptured AAA was associated with postoperative mortality. Conclusion: Emergency open colectomy for IC is associated with high postoperative mortality, which appears to be unrelated to the IC etiology. Preoperative lactate levels, > 12-h delay to surgery, and postoperative acute kidney injury are independent predictors of postoperative mortality
Transport in Quantum Dots from the Integrability of the Anderson Model
In this work we exploit the integrability of the two-lead Anderson model to
compute transport properties of a quantum dot, in and out of equilibrium. Our
method combines the properties of integrable scattering together with a
Landauer-Buttiker formalism. Although we use integrability, the nature of the
problem is such that our results are not generically exact, but must only be
considered as excellent approximations which nonetheless are valid all the way
through crossover regimes.
The key to our approach is to identify the excitations that correspond to
scattering states and then to compute their associated scattering amplitudes.
We are able to do so both in and out of equilibrium. In equilibrium and at zero
temperature, we reproduce the Friedel sum rule for an arbitrary magnetic field.
At finite temperature, we study the linear response conductance at the
symmetric point of the Anderson model, and reproduce Costi et al.'s numerical
renormalization group computation of this quantity. We then explore the
out-of-equilibrium conductance for a near-symmetric Anderson model, and arrive
at quantitative expressions for the differential conductance, both in and out
of a magnetic field. We find the expected splitting of the differential
conductance peak into two in a finite magnetic field, . We determine the
width, height, and position of these peaks. In particular we find for H >> T_k,
the Kondo temperature, the differential conductance has maxima of e^2/h
occuring for a bias V close to but smaller than H. The nature of our
construction of scattering states suggests that our results for the
differential magneto-conductance are not merely approximate but become exact in
the large field limit.Comment: 88 pages, 16 figures, uses harvmac.te
Thermodynamics of the dissipative two-state system: a Bethe Ansatz study
The thermodynamics of the dissipative two-state system is calculated exactly
for all temperatures and level asymmetries for the case of Ohmic dissipation.
We exploit the equivalence of the two-state system to the anisotropic Kondo
model and extract the thermodynamics of the former by solving the thermodynamic
Bethe Ansatz equations of the latter. The universal scaling functions for the
specific heat and static dielectric susceptibility
are extracted for all dissipation strengths for
both symmetric and asymmetric two-state systems. The logarithmic corrections to
these quantities at high temperatures are found in the Kondo limit , whereas for we find the expected power law temperature
dependences with the powers being functions of the dissipative coupling
. The low temperature behaviour is always that of a Fermi liquid.Comment: 24 pages, 32 PS figures. Typos corrected, final versio
FREE ORAL COMMUNICATIONS 2: ALCOHOL AND LIVER—CLINICAL RESEARCHO2.1RAPID DECLINE OF LIVER STIFFNESS WITH ALCOHOL WITHDRAWAL IN HEAVY DRINKERS
Background and aims. Measurement of liver stiffness using real-time elastography appears as a promising tool to evaluate the severity of chronic liver diseases. Previous studies in patients with alcoholic liver disease have suggested that fibrosis was the only histological parameter to influence liver stiffness. To challenge this hypothesis, we have prospectively tested the short-term impact of alcohol withdrawal on liver stiffness value. Methods. All patients hospitalized for alcohol withdrawal in our Liver Unit between September 2008 and December 2010 had a liver stiffness determination (using a FibroScan® device) at entry (D0) and 7 days after alcohol withdrawal (D7). Stiffness values were compared using non-parametric test for paired-values. We compared (i) the 10 measures performed at D0 and at D7 for each patient; (ii) the variation of the median result of all patients (using Wilcoxon test in both cases). Results. A total of 138 patients were included in the study [median alcohol consumption: 150g/day (range: 40-400); hepatitis C: n=22 (15.9%); cirrhosis: n=29 (21.0%)]. From D0 to D7, the liver stiffness decreased significantly in 61 patients (44.2%) and increased significantly in 18 (13.0%). Considering all patients, median liver stiffness value decreased from 7.25 to kPa (P<0.001). The stage of fibrosis indicated by liver stiffness changed in 47 patients between D0 and D7 (decrease in 33 and increase in 14). Conclusion. Liver stiffness decreases significantly in nearly half of alcoholic patients after only 7 days of abstinence. This result strongly suggests that non-fibrotic lesions (such as inflammatory ones) may influence liver stiffness. From a practical point of view, it also shows that variation in alcohol consumption must be taken into account for the interpretation of liver stiffness valu
RGTA® or ReGeneraTing Agents mimic heparan sulfate in regenerative medicine: from concept to curing patients
The importance of extracellular matrix (ECM) integrity in maintaining normal tissue function is highlighted by numerous pathologies and situations of acute and chronic injury associated with dysregulation or destruction of ECM components. Heparan sulfate (HS) is a key component of the ECM, where it fulfils important functions associated with tissue homeostasis. Its degradation following tissue injury disrupts this delicate equilibrium and may impair the wound healing process. ReGeneraTing Agents (RGTA®s) are polysaccharides specifically designed to replace degraded HS in injured tissues. The unique properties of RGTA® (resistance to degradation, binding and protection of ECM structural and signaling proteins, like HS) permit the reconstruction of the ECM, restoring both structural and biochemical functions to this essential substrate, and facilitating the processes of tissue repair and regeneration. Here, we review 25 years of research surrounding this HS mimic, supporting the mode of action, pre-clinical studies and therapeutic efficacy of RGTA® in the clinic, and discuss the potential of RGTA® in new branches of regenerative medicine
Thermodynamic analysis of the Quantum Critical behavior of Ce-lattice compounds
A systematic analysis of low temperature magnetic phase diagrams of Ce
compounds is performed in order to recognize the thermodynamic conditions to be
fulfilled by those systems to reach a quantum critical regime and,
alternatively, to identify other kinds of low temperature behaviors. Based on
specific heat () and entropy () results, three different types of
phase diagrams are recognized: i) with the entropy involved into the ordered
phase () decreasing proportionally to the ordering temperature
(), ii) those showing a transference of degrees of freedom from the
ordered phase to a non-magnetic component, with their jump
() vanishing at finite temperature, and iii) those ending in a
critical point at finite temperature because their do not decrease
with producing an entropy accumulation at low temperature.
Only those systems belonging to the first case, i.e. with as
, can be regarded as candidates for quantum critical behavior.
Their magnetic phase boundaries deviate from the classical negative curvature
below \,K, denouncing frequent misleading extrapolations down to
T=0. Different characteristic concentrations are recognized and analyzed for
Ce-ligand alloyed systems. Particularly, a pre-critical region is identified,
where the nature of the magnetic transition undergoes significant
modifications, with its discontinuity strongly
affected by magnetic field and showing an increasing remnant entropy at . Physical constraints arising from the third law at are discussed
and recognized from experimental results
Interaction of ITER-like ICRF antenna with Tore Supra plasmas: insight from modelling
The non-linear interaction of ion cyclotron resonance frequency (ICRF) waves with the plasma edge is one of the challenges faced by high power wave heating systems in next step devices. Such interaction is often associated with parallel RF electric fields excited by spurious parallel RF currents flowing on the antenna front face I -Experimental results 1 -ICRF antenna configurations. The prototype launcher ITER-lik
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