Interannual variability in marine debris accumulation on Hawaiian shores: The role of North Pacific Ocean basin-scale dynamics.

Community-based marine debris removal efforts on the Hawaiian Islands of Kaua'i and Hawai'i, spanning 2013-2022, provided large datasets and documented remarkable variations in annual amounts of debris, mainly from abandoned, lost and derelict fishing gear. To test the hypothesis that the influx of marine debris on Hawaiian shores is determined by the proximity of the North Pacific garbage patch, whose pattern changes under the control of large-scale ocean dynamics, we compared these observational data with the output of an oceanographic drift model. The high correlations between the total mass of debris collected and the model, ranging between r = 0.81 and r = 0.84, validate the attribution of the strong interannual signal to significant migrations of the garbage patch reproduced in the model experiments. Synchronous variations in marine debris fluxes on the two islands, separated by >500 km, confirm the large scale of the interannual changes in the North Pacific marine debris system.

Color-gradient-based phase-field equation for multiphase flow.

In this paper, the underlying problem with the color-gradient (CG) method in handling density-contrast fluids is explored. It is shown that the CG method is not fluid invariant. Based on nondimensionalizing the CG method, a phase-field interface-capturing model is proposed which tackles the difficulty of handling density-contrast fluids. The proposed formulation is developed for incompressible, immiscible two-fluid flows without phase-change phenomena, and a solver based on the lattice Boltzmann method is proposed. Coupled with an available robust hydrodynamic solver, a binary fluid flow package that handles fluid flows with high density and viscosity contrasts is presented. The macroscopic and lattice Boltzmann equivalents of the formulation, which make the physical interpretation of it easier, are presented. In contrast to existing color-gradient models where the interface-capturing equations are coupled with the hydrodynamic ones and include the surface tension forces, the proposed formulation is in the same spirit as the other phase-field models such as the Cahn-Hilliard and the Allen-Cahn equations and is solely employed to capture the interface advected due to a flow velocity. As such, similarly to other phase-field models, a so-called mobility parameter comes into play. In contrast, the mobility is not related to the density field but a constant coefficient. This leads to a formulation that avoids individual speed of sound for the different fluids. On the lattice Boltzmann solver side, two separate distribution functions are adopted to solve the formulation, and another one is employed to solve the Navier-Stokes equations, yielding a total of three equations. Two series of numerical tests are conducted to validate the accuracy and stability of the model, where we compare simulated results with available analytical and numerical solutions, and good agreement is observed. In the first set the interfacial evolution equations are assessed, while in the second set the hydrodynamic effects are taken into account.

Real-world Experiences in the Transplantation of Hepatitis C-NAAT-positive Organs.

Background: Hepatitis C virus (HCV) nucleic acid amplification test (NAAT)-positive donors have increased the organ pool. Direct-acting antivirals (DAAs) have led to high rates of treatment success and sustained virologic response (SVR) in recipients with donor-derived HCV infection without significant adverse effects, although variability remains in the timing and duration of antivirals. Methods: This retrospective study analyzed all adult HCV-NAAT-negative transplant recipients who received an organ from HCV-NAAT-positive donors from November 24, 2018, to March 31, 2022, at Duke University Medical Center with protocolized delay of DAA initiation until after hospital discharge, with at least 180-d follow-up on all patients. Transplant and HCV-related outcomes were analyzed. Results: Two hundred eleven transplants (111 kidneys, 41 livers, 34 hearts, and 25 lungs) were performed from HCV-NAAT-positive donors to HCV-NAAT-negative recipients. Ninety percent of recipients became viremic within 7 d posttransplant. Ninety-nine percent of recipients were initiated on pangenotypic DAAs in the outpatient setting a median of 52 d posttransplant, most commonly with 12-wk courses of sofosbuvir-velpatasvir (lungs) and glecaprevir-pibrentasvir (heart, kidney, and liver). Ninety-seven percent of recipients had SVR after a first-line DAA; all ultimately achieved SVR at 12 wk after subsequent treatment courses. The median peak HCV RNA for all organ systems was 2 436 512 IU/mL; the median time from antiviral to undetectable RNA was 48 d, although differences were noted between organ groups. No patient deaths or graft losses were directly attributable to HCV infection. Conclusions: One hundred percent of transplant recipients of HCV-NAAT-positive organs ultimately developed SVR without significant adverse effects when HCV antivirals were initiated in the outpatient setting after transplant hospitalization, suggesting that this real-world treatment pathway is a viable option.

Percolation and conductivity in evolving disordered media.

Percolation theory and the associated conductance networks have provided deep insights into the flow and transport properties of a vast number of heterogeneous materials and media. In practically all cases, however, the conductance of the networks' bonds remains constant throughout the entire process. There are, however, many important problems in which the conductance of the bonds evolves over time and does not remain constant. Examples include clogging, dissolution and precipitation, and catalytic processes in porous materials, as well as the deformation of a porous medium by applying an external pressure or stress to it that reduces the size of its pores. We introduce two percolation models to study the evolution of the conductivity of such networks. The two models are related to natural and industrial processes involving clogging, precipitation, and dissolution processes in porous media and materials. The effective conductivity of the models is shown to follow known power laws near the percolation threshold, despite radically different behavior both away from and even close to the percolation threshold. The behavior of the networks close to the percolation threshold is described by critical exponents, yielding bounds for traditional percolation exponents. We show that one of the two models belongs to the traditional universality class of percolation conductivity, while the second model yields nonuniversal scaling exponents.

Human wastewater tracking in tropical Hawaiian island streams using qualitative and quantitative assessments of combined fecal indicating bacteria and sucralose, an organic micropollutant of emerging concern.

Prevalence of cesspools on tropical islands suggests that high concentrations of enteric bacteria in streams and coastal waters are an indicator of groundwater contamination by human wastewater. But enterococci bacteria may also be from homeothermic animals common to these watersheds or bacteria living in sediments. Sucralose, a manufactured chemical not destroyed in passage through the human gut, cesspools, septic systems, or wastewater treatment facilities, was used to test for the presence of human wastewater in streams on the island of Kauai, Hawaii. Effluent from six municipal wastewater treatment plants showed an average concentration of 39,167 ng/L of sucralose, roughly back-calculated to 9 ng/L per person, enough to present itself in cesspool effluent contaminated waters. Of 24 streams tested, 79% were positive for sucralose at least once in four sets of sampling. All streams tested positive for enterococci bacteria above established standards. Serial testing of the pair of indicators in the same location over time and applying the Multiplication Rule to the independent samples provide a probabilistic certainty level that the water is chronically polluted by human waste. When repeatedly paired with tests for enterococci, sucralose testing is a cost-effective means for assessing human health risk and for developing proper waste management programs that has been underutilized in under-developed tropical and island settings.

Transplanting hepatitis B surface antigen-positive livers in the United States: Outcomes and opportunities.

Livers from donors with positive hepatitis B surface antigens (HBsAg+) have been used to expand the donor pool; however, outcome data are limited. We aim to evaluate survival following liver transplant (LT) from HBsAg+ donors. Using the United Network for Organ Sharing registry, we identified HBsAg+ donors used for LT from 2009 to 2020. We used Kaplan-Meier survival and Cox proportional hazards regression to compare post-LT survival in hepatitis B virus-negative recipients who utilized HBsAg+ donors to propensity-matched cohorts who utilized other types of donors. From 2009-2020, 70 patients received HBsAg+ livers, and 58 of them did not carry a diagnosis of chronic hepatitis B virus. The 1- and 3-year post-LT survival for hepatitis B virus-negative patients who received livers from HBsAg+ donors were 96.6% and 91.4%, respectively, with no statistical differences compared with patients who received livers from hepatitis C virus viremic donors (96.5%/93.0%, P = .961/.427), donation after cardiac death donors (93.0%/86.0%, P = .651/.598), average-risk donors (89.5%/86.0%, P = 0.264/0.617), and a combination of extended-criteria donors, including donation after cardiac death, donor age over 70, and graft with greater than 30% steatosis (93.0%/91.2%, P = .621/.785). Recipients of HBsAg+ livers have similar post-LT survival compared with those receiving other types of grafts. Increasing the utilization of HBsAg+ livers could safely expand the donor pool.

LR-3 and LR-4 Lesions Are More Likely to Be Hepatocellular Carcinoma in Transplant Patients with LR-5 or LR-TR Lesions.

BACKGROUND: Liver Imaging Reporting and Data System (LI-RADS) classifies liver nodules from LR-1 to LR-5 based on risk for hepatocellular carcinoma (HCC). It is challenging to know the nature of the LR-3 and LR-4 lesions. AIMS: To test our hypothesis that in patients with a definite HCC (LR-5) or treated HCC (LR-TR), a coexisting LR-3 or LR-4 lesion is more likely to represent HCC compared to patients without LR-5 or LR-TR lesions. METHODS: We conducted a retrospective study including all adult patients who received liver transplantation in our institution from 1/1/2014 to 3/3/2020 who had any LR-3 or LR-4 lesion on pre-transplant MRI. RESULTS: Seventy-eight patients were included in the final cohort (115 LR-3 and LR-4 lesions total). When accompanied by LR-5 or LR-TR lesions, 41% (28/69) of LR-3 lesions were HCC compared to 12% (3/25) when not accompanied by LR-5 LR-TR lesions. When accompanied by LR-5 or LR-TR lesions, 83% (10/12) of LR-4 lesions were HCC, versus 33% (3/9) when not accompanied by LR-5 or LR-TR lesions. In a multivariable analysis of all lesions, the presence of a LR-5 or LR-TR lesion was significantly associated with LR-3 or LR-4 lesions representing HCC (OR 6.4, p = 0.01). CONCLUSION: LR-3 and LR-4 lesions are more likely to be HCC in patients with LR-5 or LR-TR lesions. The presence of coexisting definite HCC may be a useful diagnostic feature to improve risk stratification of lesions without typical imaging features of HCC. This may also affect decision-making prior to liver transplant when HCC burden must be accurately determined.

Shuffle & untangle: novel untangle methods for solving the tanglegram layout problem.

Motivation: A tanglegram is a plot of two-tree-like diagrams, one facing the other, and having their labels connected by inter-tree edges. These two trees, which could be both phylogenetic trees and dendrograms stemming from hierarchical clusterings, have thus identically labelled leaves but different topologies. As a result, the inter-tree edges of a tanglegram can be intricately tangled and difficult to be analysed and explained by human readers. To better visualize the tanglegram (and thus compare the two dendrograms) one may try to untangle it, i.e. search for that series of flippings of the various branches of the two trees that minimizes the number of crossings among the inter-tree edges. The untanglement problem has received significant interest in the past decade, and several techniques have been proposed to address it. These techniques are computationally efficient but tend to fail at finding the global optimum configuration generating the least tangly tanglegram. Results: We leverage the existing results to propose untanglement methods that are characterized by an overall slower convergence method than the ones in the literature, but that produce tanglegrams with lower entanglements. Availability and implementation: One of the algorithms is implemented in Python, and available from https://github.com/schlegelp/tanglegram.

Immune Thrombocytopenia Associated with Hepatitis B Virus and Autoimmune Hepatitis and Recovery of Platelet Count following Liver Transplantation.

Immune thrombocytopenia is a consumptive coagulopathy that can be either idiopathic or associated with infectious or autoimmune etiologies. Here, we present a case of immune thrombocytopenia in the setting of acute liver failure due to coexisting diagnoses of hepatitis B virus and autoimmune hepatitis. Our patient underwent orthotopic liver transplantation and recovered hemostatic platelet counts after treatment with romiplostim, a thrombopoietin receptor agonist, 51 days after transplantation. To our knowledge, this is the first case report of immune thrombocytopenia secondary to both hepatitis B virus and autoimmune hepatitis in a patient with acute liver failure.

Left lateral segment liver volume is not correlated with anthropometric measures.

BACKGROUND: Liver transplantation is definitive therapy for end stage liver disease in pediatric patients. Living donor liver transplantation (LDLT) with the left lateral segment (LLS) is often a feasible option. However, the size of LLS is an important factor in donor suitability - particularly when the recipient weighs less than 10 kg. In the present study, we sought to define a formula for estimating left lateral segment volume (LLSV) in potential LLS donors. METHODS: We obtained demographic and anthropometric measurements on 50 patients with Computed Tomography (CT) scans to determine whole liver volume (WLV), right liver volume (RLV), and LLSV. We performed univariable and multivariable linear regression with backwards stepwise variable selection (p < 0.10) to determine final models. RESULTS: Our study found that previously reported anthropometric and demographics variables correlated with volume were significantly associated with WLV and RLV. On univariable analysis, no demographic or anthropometric measures were correlated with LLSV. On multivariable analysis, LLSV was poorly predicted by the final model (R2 = 0.10, Coefficient of Variation [CV] = 42.2) relative to WLV (R2 = 0.33, CV = 18.8) and RLV (R2 = 0.41, CV = 15.8). CONCLUSION: Potential LLS living donors should not be excluded based on anthropometric data: all potential donors should be evaluated regardless of their size.

The Impact of the 2017 Kidney Allocation Policy Change on Simultaneous Liver-Kidney Utilization and Outcomes.

Historically in the United States, kidneys for simultaneous liver-kidney transplantation (SLKT) candidates were allocated with livers, prioritizing SLKT recipients over much of the kidney waiting list. A 2017 change in policy delineated renal function criteria for SLKT and implemented a safety net for kidney-after-liver transplantation. We compared the use and outcomes of SLKT and kidney-after-liver transplant with the 2017 policy. United Network for Organ Sharing Standard Transplant Analysis and Research files were used to identify adults who received liver transplantations (LT) from August 10, 2007 to August 10, 2012; from August 11, 2012 to August 10, 2017; and from August 11, 2017 to June 12, 2019. LT recipients with end-stage renal disease (ESRD) were defined by dialysis requirement or estimated glomerular filtration rate <25. We evaluated outcomes and center-level, regional, and national practice before and after the policy change. Nonparametric cumulative incidence of kidney-after-liver listing and transplant were modeled by era. A total of 6332 patients received SLKTs during the study period; fewer patients with glomerular filtration rate (GFR) ≥50 mL/min underwent SLKT over time (5.8%, 4.8%, 3.0%; P = 0.01 ). There was also less variability in GFR at transplant after policy implementation on center and regional levels. We then evaluated LT-alone (LTA) recipients with ESRD (n = 5408 from 2012-2017; n = 2321 after the policy). Listing for a kidney within a year of LT increased from 2.9% before the policy change to 8.8% after the policy change, and the rate of kidney transplantation within 1 year increased from 0.7% to 4% (P < 0.001). After the policy change, there was no difference in patient survival rates between SLKT and LTA among patients with ESRD. Implementation of the 2017 SLKT policy change resulted in reduced variability in SLKT recipient kidney function and increased access to deceased donor kidney transplantation for LTA recipients with kidney disease without negatively affecting outcomes.

Regional and global perspectives of honey as a record of lead in the environment.

Honey from Apis mellifera is a useful and inexpensive biomonitor for mapping metal distributions in urban centers. The sampling resolution of a biomonitoring survey (e.g., city versus global scale) determines which geochemical processes are reflected in the results. This study presents Pb isotopic compositions and metal concentrations in honey from around the world, sampled at varying resolutions: honey from Canada (n = 21), the United States (n = 111), Belgium (n = 25), and New Zealand (n = 10), with additional samples from Afghanistan, Brazil, Cuba, Germany, Liberia, Taiwan, and Turkey. Honey was sampled at high resolution in two uniquely different land-use settings (New York Metro Area and the Hawaiian island of Kaua'i), at regional-scale resolution in eastern North America (including the Great Lakes region), and Pb isotopic compositions of all samples were compared on a global scale. At high sampling resolution, metal concentrations in honey reveal spatially significant concentration gradients: in New York City, metals associated with human activity and city infrastructure (e.g., Pb, Sb, Ti, V) are more concentrated in honey collected within the city compared to honey from upstate New York, and metal concentrations in honey from Kaua'i suggest polluting effects of nearby agricultural operations. At lower resolution (regional and global scales), lead isotopic compositions of honey are more useful than metal concentrations in revealing large-scale Pb processes (e.g., the enduring legacy of global leaded gasoline use throughout the twentieth century) and the continental origin of the honey. Lead isotopic compositions of honey collected from N. America (especially from the eastern USA) are more radiogenic (206Pb/207Pb: 1.132-1.253, 208Pb/206Pb: 2.001-2.129) compared to European honey, and honey from New Zealand, which has the least radiogenic isotopic compositions measured in this study (206Pb/207Pb: 1.077-1.160, 208Pb/206Pb: 2.090-2.187). Thus, biomonitoring using honey at different resolutions reflects differing processes and, to some extent, a honey terroir defined by the Pb isotopic composition. The data presented here provide important (and current) global context for future studies that utilize Pb isotopes in honey. Moreover, this study exhibits community science in action, as most of the honey was collected by collaborators around the world, working directly with local apiarists and hobby beekeepers.

Need for Pretransplant Midodrine Does Not Negatively Impact Simultaneous Liver-kidney Transplant Outcomes.

BACKGROUND: Midodrine is often needed pretransplant to improve hemodynamics in simultaneous liver-kidney transplant candidates. Previous research has shown that patients requiring midodrine before kidney transplant alone have increased posttransplant risk for delayed allograft function, graft failure, and death. However, the impact of pretransplant midodrine use on outcomes after simultaneous liver-kidney transplant is unknown. METHODS: We performed a retrospective study of all adult (age ≥18 y) simultaneous liver-kidney transplant recipients from a single academic transplant center from February 1, 2002, to June 30, 2019. RESULTS: Sixty-four simultaneous liver-kidney transplants were performed in our institution during this time period, of which, 43 were not on midodrine before transplant, 17 were on midodrine alone, and 4 were on intravenous (IV) vasopressor therapy. Despite the midodrine group having a higher MELD-Na at listing, higher MELD-Na at transplant, and being older, there were no significant differences in key outcomes including delayed renal allograft function, estimated glomerular filtration rate at transplant discharge, and estimated glomerular filtration rate at 1 y after transplant compared with the nonmidodrine group. There was no significant difference in graft failure or survival at last follow-up. CONCLUSIONS: Our study suggests that need for pretransplant midodrine should not be a barrier to simultaneous liver-kidney transplant.

Effects of Sofosbuvir-Based Hepatitis C Treatment Regimens on Calcineurin Inhibitor Dosing in Liver and Kidney Transplant Recipients.

OBJECTIVES: Available data have suggested that directacting antivirals for hepatitis C virus may decrease calcineurin inhibitor concentrations. In this study, our aim was to determine the effects of hepatitis C directacting antivirals on calcineurin inhibitor doses and trough levels. MATERIALS AND METHODS: This retrospective, singlecenter study included 52 abdominal transplant recipients treated with sofosbuvir-based regimens between 2014 and 2017. The primary outcome was percent change in calcineurin inhibitor troughs and total daily doses between the week before treatment with direct-acting antivirals, days 21 to 35 oftreatment, and days 21 to 35 aftertreatment. Secondary outcomes included sustained virologic response and biopsyproven acute rejection rates. RESULTS: The median percent difference in calcineurin inhibitor troughs from pretreatment to during treatment was -20.5% (interquartile range, -36.2% to 13.1%) and from pretreatment to posttreatment was -13.5% (interquartile range, -33.7% to 10.7%). Corresponding percent changes in calcineurin inhibitor doses were 0% (interquartile range, 0%-0%) and 0% (interquartile range, -10.5% to 33.3%), respectively. Patients on tacrolimus experienced statistically significant changes in troughs but not doses. During treatment, 65% of patients required no dose change, 23% underwent a dose increase, and 12% had a dose decrease. The sustained virologic response rate was 98%, and the biopsy-proven acute rejection rate was 0%. CONCLUSIONS: Hepatitis C direct-acting antiviraltherapy may decrease calcineurin inhibitor levels, but this was not associated with clinically different dosing requirements or rejection rates.

Geometrically derived efficiency of slow immiscible displacement in porous media.

The efficiency of a displacement is the fraction of applied work over the change in free energy. This displacement efficiency is essential for linking wettability to applied work during displacement processes. We quantify the efficiency of slow immiscible displacements in porous media from pore space geometry. For this end, we introduce pore-scale definitions for thermodynamically reversible (ison) and irreverisble (rheon) processes. We argue that the efficiency of slow primary displacement is described by the geometry of the pore space for porous media with a sufficient number of pore bodies. This article introduces how to calculate such geometry-based efficiency locally, and integrating this local efficiency over the pore space yields an aggregate efficiency for the primary displacement in the porous medium. Further, we show how the geometrical characterization of the displacement efficiency links the efficiency to the constriction factor from transport processes governed by the Laplace equation. This enables estimation of displacement efficiency from traditional and widely available measurements for porous media. We present a thermodynamically based wettability calculation based on the local efficiency and a method to approximate this thermodynamically based wettability from traditional experiments.

Textbook Outcomes in Liver Transplantation.

BACKGROUND: Textbook outcome (TO) is an emerging concept within multiple surgical domains, which represents a novel effort to define a standardized, composite quality benchmark based on multiple postoperative endpoints that represent the ideal "textbook" hospitalization. We sought to define TO for liver transplantation (LT) using a cohort from a high procedural volume center. METHODS: Patients who underwent LT at our institution between 2014 and 2017 were eligible for the study. The definition of TO was determined by clinician consensus at our institution to include freedom from: mortality within 90 days, primary allograft non-function, early allograft dysfunction (EAD), rejection within 30 days, readmission with 30 days, readmission to the ICU during index hospitalization, hospital length of stay > 75th percentile of all liver transplant patients, red blood cell (RBC) transfusion requirement greater than the 75th percentile for all liver transplant patients, Clavien-Dindo Grade III complication (re-intervention), and major intraoperative complication. RESULTS: Two hundred and thirty-one liver transplants with complete data were performed within the study period. Of those, 71 (31%) achieved a TO. Overall, the most likely event to lead to failure to achieve TO was readmission within 30 days (n = 57, 37%) or reoperation (n = 49, 32%). Overall and rejection-free survival did not differ significantly between the 2 groups. Interestingly, patients who achieved TO incurred approximately $60,000 less in total charges than those who did not. When we limit this to charges specifically attributable to the transplant episode, the difference was approximately $50,000 and remained significantly less for those that achieved TO. CONCLUSIONS: Here, we present the first definition of TO in LT. Though not associated with long-term outcomes, TO in LT is associated with a significantly lower charges and costs of the initial hospitalization. A multi-institutional study to validate this definition of TO is warranted.