Liver transplant patients General population Severe COVID-19 Highlights The incidence of coronavirus disease 2019 (COVID-19) is higher in liver transplant patients. Mortality rates are lower than those observed in the matched general population. Immunosuppression withdrawal may not be justified. Mycophenolate may increase the risk of severe COVID-19 in a dosedependent manner.
Aspergillosis is a potential, severe, and usually early complication of liver transplantation. New promising strategies, such as detecting AspergiUzrs antigenemia, have been used for the diagnosis of aspergillosis in immunosuppressed patients, but the impact in solid organ transplantation is not well known. A case-control study in 260 adults who underwent liver transplantation from January 1994 to June 2000 was performed. A case was defined as any liver transplant recipient with a proven or probable diagnosis of invasive aspergillosis. Controls were defined as a liver transplant recipient without aspergillosis infection with a survival longer than two months after transplantation. Clinical and analytical variables, including Aspergi22u.s antigenemia, were compared. A special analysis was performed in patients in whom late aspergillosis developed (after day 100 posttransplantation). Among 260 patients, invasive aspergillosis developed in 15 (5.6%). Median time from transplantation to aspergillosis in 13 patients with sufficient data for analysis was 126 days (range, 22 to 1117). Seven (54%) developed the infection after day 100 posttransplantation. Thirty-eight patients were used as controls. Antigenemia was available in nine of 13 cases and in 33 of 38 controls. By multivariate analysis, retransplantation (OR, 29.9 [95% CI, 2.1 to 425.1]), dialysis requirements after transplantation (OR, 24.5 [95% CI, 1.25 to 354]), and the presence ofAspqz.2-2u.s antigenemia in serum at any time point after transplantation (OR, 50.0 [95% CI, 3.56 to 6501) were independently associated to aspergillosis. In the subgroup of patients that developed late aspergillosis, cytomegalovirus infection (OR, 6.7 [95% CI, 1.0 to 42.51) was the only independent factor associated. Hepatic and renal dysfunction predispose to Aspergilltcs infection in liver transplant recipients. Cytomegalovirus infection and increased immunosuppression favor invasive aspergillosis during the late posttransplantation period. Aspergillus antigenemia seems to be a good predictor of invasive aspergillosis.
Postmortem normothermic regional perfusion (NRP) is a rising preservation strategy in controlled donation after circulatory determination of death (cDCD). Herein, we present results for cDCD liver transplants performed in Spain 2012–2019, with outcomes evaluated through December 31, 2020. Results were analyzed retrospectively and according to recovery technique (abdominal NRP [A‐NRP] or standard rapid recovery [SRR]). During the study period, 545 cDCD liver transplants were performed with A‐NRP and 258 with SRR. Median donor age was 59 years (interquartile range 49–67 years). Adjusted risk estimates were improved with A‐NRP for overall biliary complications (OR 0.300, 95% CI 0.197–0.459, p < .001), ischemic type biliary lesions (OR 0.112, 95% CI 0.042–0.299, p < .001), graft loss (HR 0.371, 95% CI 0.267–0.516, p < .001), and patient death (HR 0.540, 95% CI 0.373–0.781, p = .001). Cold ischemia time (HR 1.004, 95% CI 1.001–1.007, p = .021) and re‐transplantation indication (HR 9.552, 95% CI 3.519–25.930, p < .001) were significant independent predictors for graft loss among cDCD livers with A‐NRP. While use of A‐NRP helps overcome traditional limitations in cDCD liver transplantation, opportunity for improvement remains for cases with prolonged cold ischemia and/or technically complex recipients, indicating a potential role for complimentary ex situ perfusion preservation techniques.
In this work, polarization attraction is meant to be the conservative nonlinear effect that transforms any arbitrary input state of polarization (SOP) of an intense optical signal beam fed to a nonlinear medium into approximately one and the same SOP at the output, provided that the medium is driven by a relatively stronger counterpropagating pump beam. Essentially, the combination of the nonlinear medium and the pump beam serves as a lossless polarizer for the signal beam. The degree of polarization of the outcoming signal beam can be close to 100% (90% in our present simulations). With an eye toward the development of such lossless polarizers for fiber optics applications, we theoretically study the polarization attraction effect in the optical fibers that are used in telecommunication links; i.e., randomly birefringent fibers. A generic model for the fiber-based lossless polarizers is derived, and a statistical scheme for the quantification of their performance is proposed.
Abstract-Raman assistance in distributed sensors based on Brillouin optical time-domain analysis can significantly extend the measurement distance. In this paper, we have developed a 2 m resolution long-range Brillouin distributed sensor that reaches 100 km using first-order Raman assistance. The estimated uncertainty in temperature discrimination is 1.2 C, even for the position of worst contrast. The parameters used in the experiment are supported by a simple analytical model of the required values, considering the main limitations of the setup.Index Terms-Brillouin scattering, distributed optic fiber sensor, distributed Raman amplification, Raman scattering, temperature sensor.
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