Glomerular sieving of anionic and neutral bovine albumins in proteinuric rats

Glomerular sieving of anionic and neutral bovine albumins in proteinuric rats. To characterize the defect in glomerular permeability leading to albuminuria in rats made nephrotic acutely by infusion of hexadimethrine (HDM) or chronically by administration of Adriamycin® (doxorubicin) (Adria), we developed and validated a tissue accumulation method for simultaneous determination of the glomerular sieving coefficients (GSC) of anionic 131I-labeled bovine albumin (BSA-pI 4.9) and 125I-labeled charge-modified neutral BSA (nBSA-pI 7.5 to 8.0). Total filtered marker was calculated by adding marker excreted in the urine to that filtered but reabsorbed by the tubules. The latter was determined by subtracting interstitial marker present in the left kidney, rendered non-filtering by ureteral ligation during mannitol diuresis, from the total marker accumulating within the right, filtering kidney. Experiments showed that markers circulated and were excreted intact and were neither degraded nor deiodinated during the period of the clearance studies.In control animals the GSC of nBSA (0.026 ± 0.004) greatly exceeded that of BSA (0.0006 ± 0.0002), demonstrating the normal charge dependence of permeability. Both proteinuric groups had marked increases in the GSC of BSA (HDM: 0.021 ± 0.005; Adria: 0.025 ± 0.004), which correlated with appearance of rat albumin in their urine. HDM rats also had a twofold increase in the GSC of nBSA (0.049 ± 0.005), indicating alteration of the size dependence of permeability. The absolute increase of GSC of BSA and nBSA was similar, suggesting that albuminuria resulted from appearance of new “pores” in the glomerular filter that were not charge selective for proteins of the size of albumin. Thus, infusion of HDM, which binds to and neutralizes GBM anions, appears to produce albuminuria by inducing a structural change in the glomerular filter. Conversely, Adria rats had no significant increase in the GSC of nBSA (0.031 ± 0.005), indicating no significant change in the size dependence of permeability for proteins of the size of albumin. In these animals, the GSC of the anionic BSA approached that of the neutral nBSA, indicating that Adriamycin induces albuminuria by markedly reducing the normal charge dependence of permeability

The Mouse Cer1 (Cerberus related or homologue) Gene Is Not Required for Anterior Pattern Formation

AbstractCer1 is the mouse homologue of the Xenopus Cerberus gene whose product is able to induce development of head structures during embryonic development. The Cer1 protein is a member of the cysteine knot superfamily and is expressed in anterior regions of the mouse gastrula. A segmental pattern of expression with nascent and newly formed somites is also seen. This suggests an additional role in development of the axial skeleton, musculature, or peripheral nervous system. Xenopus animal cap assays and mouse germ-layer explant recombination experiments indicate that the mouse protein can act as a patterning molecule for anterior development in Xenopus, including induction of Otx2 expression, and suggest it may have a similar role in mouse development. However, we present here genetic data that demonstrate that Cer1 is not necessary for anterior patterning, Otx2 expression, somite formation, or even normal mouse morphogenesis

Improving the Segmentation of Scanning Probe Microscope Images using Convolutional Neural Networks

A wide range of techniques can be considered for segmentation of images of nanostructured surfaces. Manually segmenting these images is time-consuming and results in a user-dependent segmentation bias, while there is currently no consensus on the best automated segmentation methods for particular techniques, image classes, and samples. Any image segmentation approach must minimise the noise in the images to ensure accurate and meaningful statistical analysis can be carried out. Here we develop protocols for the segmentation of images of 2D assemblies of gold nanoparticles formed on silicon surfaces via deposition from an organic solvent. The evaporation of the solvent drives far-from-equilibrium self-organisation of the particles, producing a wide variety of nano- and micro-structured patterns. We show that a segmentation strategy using the U-Net convolutional neural network outperforms traditional automated approaches and has particular potential in the processing of images of nanostructured systems.Comment: 21 pages, 10 figure

Analytical characteristics and comparative evaluation of Aptima HCV quant Dx assay with the Abbott RealTime HCV assay and Roche COBAS AmpliPrep/COBAS TaqMan HCV quantitative test v2.0

Abstract Background The Aptima HCV Quant Dx assay (Aptima assay) is a fully automated quantitative assay on the Panther® system. This assay is intended for confirmation of diagnosis and monitoring of HCV RNA in plasma and serum specimens. The purpose of the testing described in this paper was to evaluate the performance of the Aptima assay. Methods The analytical sensitivity, analytical specificity, precision, and linearity of the Aptima assay were assessed. The performance of the Aptima assay was compared to two commercially available HCV assays; the Abbott RealTime HCV assay (Abbott assay, Abbott Labs Illinois, USA) and the Roche COBAS Ampliprep/COBAS Taqman HCV Quantitative Test v2.0 (Roche Assay, Roche Molecular Systems, Pleasanton CA, USA). The 95% Lower Limit of Detection (LoD) of the assay was determined from dilutions of the 2nd HCV WHO International Standard (NIBSC 96/798 genotype 1) and HCV positive clinical specimens in HCV negative human plasma and serum. Probit analysis was performed to generate the 95% predicted detection limits. The Lower Limit of Quantitation (LLoQ) was established for each genotype by diluting clinical specimens and the 2nd HCV WHO International Standard (NIBSC 96/798 genotype 1) in HCV negative human plasma and serum. Specificity was determined using 200 fresh and 536 frozen HCV RNA negative clinical specimens including 370 plasma specimens and 366 serum specimens. Linearity for genotypes 1 to 6 was established by diluting armored RNA or HCV positive clinical specimens in HCV negative serum or plasma from 8.08 log IU/mL to below 1 log IU/mL. Precision was tested using a 10 member panel made by diluting HCV positive clinical specimens or spiking armored RNA into HCV negative plasma and serum. A method comparison was conducted against the Abbott assay using 1058 clinical specimens and against the Roche assay using 608 clinical specimens from HCV infected patients. In addition, agreement between the Roche assay and the Aptima assay using specimens with low HCV concentrations (</= 25 IU/mL by Roche) was tested using 107 clinical specimens. Results The 95% LoD was 5.1 IU/mL or lower for serum and 4.8 IU/mL or lower for plasma depending on the HCV genotype. The LLoQ for the assay was 10 IU/mL. Specificity was 100% with 95% confidence intervals of 99.6 to 100% for serum and plasma data combined. The assay demonstrated good linearity across the range for all genotypes. The Precision as estimated by the standard deviation (sd) was 0.17 log or lower across the range of the assay for both serum and plasma. HCV viral load results were compared using the Aptima assay and the Abbott assay giving a slope of 1.06, an intercept of 0.08 and an R2 of 0.98. HCV viral load results were compared for the Aptima and Roche assays giving a slope of 1.05, an intercept of −0.12 and an R2 of 0.96. Positive and negative agreement for the Aptima assay vs the Roche assay was 89% for low level specimens. Conclusion The Aptima assay is a highly sensitive and specific assay. The assay gave comparable HCV viral load results when compared to the Abbott and Roche assays. The performance of the Aptima assay makes it an excellent candidate for the detection and monitoring of HCV

Spatially Explicit Modeling Reveals Cephalopod Distributions Match Contrasting Trophic Pathways in the Western Mediterranean Sea

Populations of the same species can experience different responses to the environment throughout their distributional range as a result of spatial and temporal heterogeneity in habitat conditions. This highlights the importance of understanding the processes governing species distribution at local scales. However, research on species distribution often averages environmental covariates across large geographic areas, missing variability in population- environment interactions within geographically distinct regions. We used spatially explicit models to identify interactions between species and environmental, including chlorophyll a (Chla) and sea surface temperature (SST), and trophic (prey density) conditions, along with processes governing the distribution of two cephalopods with contrasting life-histories (octopus and squid) across the western Mediterranean Sea. This approach is relevant for cephalopods, since their population dynamics are especially sensitive to variations in habitat conditions and rarely stable in abundance and location. The regional distributions of the two cephalopod species matched two different trophic pathways present in the western Mediterranean Sea, associated with the Gulf of Lion upwelling and the Ebro river discharges respectively. The effects of the studied environmental and trophic conditions were spatially variant in both species, with usually stronger effects along their distributional boundaries. We identify areas where prey availability limited the abundance of cephalopod populations as well as contrasting effects of temperature in the warmest regions. Despite distributional patterns matching productive areas, a general negative effect of Chla on cephalopod densities suggests that competition pressure is common in the study area. Additionally, results highlight the importance of trophic interactions, beyond other common environmental factors, in shaping the distribution of cephalopod populations. Our study presents a valuable approach for understanding the spatially variant ecology of cephalopod populations, which is important for fisheries and ecosystem management.Versión del editor4,411

COVID-19 Patients Require Prolonged Extracorporeal Membrane Oxygenation Support for Survival Compared With Non-COVID-19 Patients

OBJECTIVES: To investigate the ICU survival of venovenous extracorporeal membrane oxygenation (ECMO) patients suffering from COVID-19–related acute respiratory distress syndrome (ARDS) versus ECMO patients without COVID-19 (non-COVID-19)–related ARDS. DESIGN: Preliminary analysis of data from two prospective ECMO trials and retrospective analysis of a cohort of ARDS ECMO patients. SETTING: Single-center ICU. PATIENTS: Adult ARDS ECMO patients, 16 COVID-19 versus 23 non-COVID-19 patients. Analysis of retrospective data from 346 adult ARDS ECMO patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: COVID-19 and non-COVID-19 ARDS patients did not differ with respect to preexisting disease or body mass index. ICU survival rate was 62% for COVID-19 ECMO patients and 70% for non-COVID-19 ECMO patients. COVID-19 ECMO survivors were supported with ECMO for a median of 43 days (interquartile range [IQR], 18–58 d) versus 16 days (IQR, 19–39 d; p = 0.03) for non-COVID-19 patients. The median duration of ECMO therapy for all ARDS patients between 2007 and 2018 was 15 days (IQR, 6–28 d). The subgroup of patients suffering from any viral pneumonia received ECMO support for a median of 16 days (IQR, 9–27 d), survivors of influenza pneumonia received ECMO support for 13 days (IQR, 7–25 d). CONCLUSIONS: COVID-19 patients required significant longer ECMO support compared with patients without COVID-19 to achieve successful ECMO weaning and ICU survival

The role of cell-free hemoglobin and haptoglobin in acute kidney injury in critically ill adults with ARDS and therapy with VV ECMO

Background: Increased plasma concentrations of circulating cell-free hemoglobin (CFH) are supposed to contribute to the multifactorial etiology of acute kidney injury (AKI) in critically ill patients while the CFH-scavenger haptoglobin might play a protective role. We evaluated the association of CFH and haptoglobin with AKI in patients with an acute respiratory distress syndrome (ARDS) requiring therapy with VV ECMO. Methods: Patients with CFH and haptoglobin measurements before initiation of ECMO therapy were identified from a cohort of 1044 ARDS patients and grouped into three CFH concentration groups using a risk stratification. The primary objective was to assess the association of CFH and haptoglobin with KDIGO stage 3 AKI. Further objectives included the identification of a target haptoglobin concentration to protect from CFH-associated AKI. Measurements and main results: Two hundred seventy-three patients fulfilled the inclusion criteria. Of those, 154 patients (56.4%) had AKI at ECMO initiation. The incidence of AKI increased stepwise with increasing concentrations of CFH reaching a plateau at 15 mg/dl. Compared to patients with low [= 15 mg/dl] CFH concentrations had a three- and five-fold increased risk for AKI (adjusted odds ratio [OR] moderate vs. low, 2.69 [95% CI, 1.25-5.95], P = 0.012; and OR high vs. low, 5.47 [2.00-15.9], P = 0.001). Among patients with increased CFH concentrations, haptoglobin plasma levels were lower in patients with AKI compared to patients without AKI. A haptoglobin concentration greater than 2.7 g/l in the moderate and 2.4 g/l in the high CFH group was identified as clinical cutoff value to protect from CFH-associated AKI (sensitivity 89.5% [95% CI, 83-96] and 90.2% [80-97], respectively). Conclusions: In critically ill patients with ARDS requiring therapy with VV ECMO, an increased plasma concentration of CFH was identified as independent risk factor for AKI. Among patients with increased CFH concentrations, higher plasma haptoglobin concentrations might protect from CFH-associated AKI and should be subject of future research

Characterizing driver–response relationships in marine pelagic ecosystems for improved ocean management

Scientists and resources managers often use methods and tools that assume ecosystem components respond linearly to environmental drivers and human stressor. However, a growing body of literature demonstrates that many relationships are non-linear, where small changes in a driver prompt a disproportionately large ecological response. Here we aim to provide a comprehensive assessment of the relationships between drivers and ecosystem components to identify where and when non-linearities are likely to occur. We focus our analyses on one of the best-studied marine systems, pelagic ecosystems, which allowed us to apply robust statistical techniques on a large pool of previously published studies. In this synthesis, we (1) conduct a wide literature review on single driver-response relationships in pelagic systems, (2) use statistical models to identify the degree of non-linearity in these relationships, and (3) assess whether general patterns exist in the strengths and shapes of non-linear relationships across drivers. Overall we found that non-linearities are common in pelagic ecosystems, comprising at least 52% of all driver-response relationships. This is likely an underestimate, as papers with higher quality data and analytical approaches reported non-linear relationships at a higher frequency - on average 11% more. Consequently, in the absence of evidence for a linear relationship, it is safer to assume a relationship is non-linear. Strong non-linearities can lead to greater ecological and socio-economic consequences if they are unknown (and/or unanticipated), but if known they may provide clear thresholds to inform management targets. In pelagic systems, strongly non-linear relationships are often driven by climate and trophodynamic variables, but are also associated with local stressors such as overfishing and pollution that can be more easily controlled by managers. Even when marine resource managers cannot influence ecosystem change, they can use information about threshold responses to guide how other stressors are managed and to adapt to new ocean conditions. As methods to detect and reduce uncertainty around threshold values improve, managers will be able to better understand and account for ubiquitous non-linear relationships

Regularity for eigenfunctions of Schr\"odinger operators

We prove a regularity result in weighted Sobolev spaces (or Babuska--Kondratiev spaces) for the eigenfunctions of a Schr\"odinger operator. More precisely, let K_{a}^{m}(\mathbb{R}^{3N}) be the weighted Sobolev space obtained by blowing up the set of singular points of the Coulomb type potential V(x) = \sum_{1 \le j \le N} \frac{b_j}{|x_j|} + \sum_{1 \le i < j \le N} \frac{c_{ij}}{|x_i-x_j|}, x in \mathbb{R}^{3N}, b_j, c_{ij} in \mathbb{R}. If u in L^2(\mathbb{R}^{3N}) satisfies (-\Delta + V) u = \lambda u in distribution sense, then u belongs to K_{a}^{m} for all m \in \mathbb{Z}_+ and all a \le 0. Our result extends to the case when b_j and c_{ij} are suitable bounded functions on the blown-up space. In the single-electron, multi-nuclei case, we obtain the same result for all a<3/2.Comment: to appear in Lett. Math. Phy

Urine Injury Biomarkers and Risk of Adverse Outcomes in Recipients of Prevalent Kidney Transplants: The Folic Acid for Vascular Outcome Reduction in Transplantation Trial

Recipients of kidney transplants (KTR) are at increased risk for cardiovascular events, graft failure, and death. It is unknown whether urine kidney injury biomarkers are associated with poor outcomes among KTRs. We conducted a post hoc analysis of the Folic Acid for Vascular Outcome Reduction in Transplantation (FAVORIT) Trial using a case-cohort study design, selecting participants with adjudicated cardiovascular events, graft failure, or death. Urine neutrophil gelatinase–associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), IL-18, and liver–type fatty acid binding protein (L-FABP) were measured in spot urine samples and standardized to urine creatinine concentration. We adjusted for demographics, cardiovascular risk factors, eGFR, and urine albumin-to-creatinine ratio. Patients had 291 cardiovascular events, 257 graft failure events, and 359 deaths. Each log increase in urine NGAL/creatinine independently associated with a 24% greater risk of cardiovascular events (adjusted hazard ratio [aHR], 1.24; 95% confidence interval [95% CI], 1.06 to 1.45), a 40% greater risk of graft failure (aHR, 1.40; 95% CI, 1.16 to 1.68), and a 44% greater risk of death (aHR, 1.44; 95% CI, 1.26 to 1.65). Urine KIM-1/creatinine and IL-18/creatinine independently associated with greater risk of death (aHR, 1.29; 95% CI, 1.03 to 1.61 and aHR, 1.25; 95% CI, 1.04 to 1.49 per log increase, respectively) but not with risk of cardiovascular events or graft failure. Urine L-FABP did not associate with any study outcomes. In conclusion, among prevalent KTRs, higher urine NGAL, KIM-1, and IL-18 levels independently and differentially associated with greater risk of adverse outcomes