Solute Transport Rate Research Articles

Intraperitoneal MASP-1 Levels are Associated with Peritoneal Solute Transport Rate in Peritoneal Dialysis Patients: A Retrospective Cohort Study.

A major limitation of long-term peritoneal dialysis (PD) is peritoneal membrane dysfunction characterized by faster peritoneal solute-transport rate (PSTR). This study aimed to identify efficient complement factors in peritoneal effluents of continuous ambulatory peritoneal dialysis (CAPD) patients that can predict the PSTR. A multiplex suspension protein array was used to screened related complement pathways in overnight peritoneal effluents among 58 CAPD patients. Then the related complement factors in lectin and classical pathways in effluents were analyzed using ELISA kits among another cohort of 129 CAPD patients. Logistic regression modeling was fitted to predict the PSTR of PD patients. The multiplex suspension protein array showed complement factors including C2, C4b, C5, C5a, Factor D, Factor I, and MBL were detected in effluents of CAPD patients, and the effluent C2 Appearance rate (Ar) and C4b Ar levels were significantly correlated with D/P Cr and D/D0 glucose. The levels of effluents MASP-1 Ar, M-Ficolin Ar, C2 Ar and C4b Ar, which belong to the lectin pathway were also positively correlated with D/P Cr according the ELISA results and these parameters were expressed higher in the high and high-average (H/HA) groups according to the PET results. Moreover, effluent Masp-1 was independently associated with increased PSTR and adverseevents relatedperitonealtransportfunction failure. This study suggested that the lectin pathway may be involvedin local complement activation and peritoneal injury of PD patients, intraperitoneal level of Masp-1 was an independent predictor of increased PSTR in PD patients.

Short-term peritoneal rest reduces peritoneal solute transport rate and increases ultrafiltration in high/high average transport peritoneal dialysis patients: a crossover randomized controlled trial

ABSTRACT Background The peritoneal solute transport rate (PSTR) tends to increase over time in some patients undergoing peritoneal dialysis (PD), potentially leading to ultrafiltration (UF) failure. Previous case reports have shown a significant decrease in PSTR and subsequent recovery of UF after discontinuing PD for a while. Therefore, we conducted a randomized controlled crossover study to evaluate the impact of short-term peritoneal rest on PSTR. Methods The study involved 14 continuous ambulatory peritoneal dialysis (CAPD) patients with high/high-average transport rate. Two groups were randomly assigned different treatment sequences: one group underwent daily intermittent peritoneal dialysis (IPD) for 4 weeks followed by CAPD, while the other group initially received CAPD treatment for 4 weeks and then switched to IPD. Peritoneal equilibration tests were performed before and after each treatment to evaluate PSTR and paired t-tests were used to compare the changes. Volume load, serum potassium and other clinical indicators were monitored at the same time. Results Short-term peritoneal rest (daily IPD) significantly reduced PSTR, with a decrease in the dialysate:plasma creatinine ratio from 0.71 ± 0.05 to 0.65 ± 0.07 (P < .001). Additionally, ultrafiltration significantly increased from 210 ± 165 ml to 407 ± 209 ml (P = .001). But there were no significant changes in interleukin-6 and vascular endothelial growth factor of PD effluent. No serious adverse events such as hypotension or hyperkalaemia occurred. Conclusions In PD patients with high and high-average transport, a 4-week period of short-term peritoneal rest by switching from CAPD to IPD (without long dwell) can lead to reductions in PSTR and increases in UF volumes, while maintaining clinical safety.

An Electrochemical Phase Field Model Applied to Molten Salt Dealloying Corrosion of Ni-Alloys

Metal alloys in contact with molten salts are known to corrode via a dealloying process, wherein the less-noble alloy elements (e.g. Cr) are selectively oxidized and dissolved, leaving behind a corroded structure that is enriched in the more-noble elements (e.g. Ni). In some cases, this can lead to molten salt infiltration into the alloy through discrete channels along specific microstructural features (e.g. grain boundaries). However, in other cases the dealloying process promotes a more full-scale attack of the alloy, generating a fine-scale ligament structure. This process can severely degrade the alloy’s structural integrity, which limits the practicality of these material systems in otherwise promising applications (e.g. molten salt-cooled power reactors).The thermokinetic conditions for dealloying corrosion depend on the salt chemistry and the metal microstructure, which together inform the reaction process occurring at their interface. The salt chemistry and oxidant content set the electrochemical potential for selective oxidation of the less-noble elements. The associated oxidation rate is expected to depend on the presence of an interfacial structure (e.g. double layer) and also on the transport rates of reactants towards the interface (e.g. species diffusion in the metal and oxidizer transport in the salt) and reaction products away from the interface (cation transport in the salt). The corrosion rate and morphology will also depend strongly on the rate of transport laterally along the metal-salt interface, since the reorganization of the more-noble species (Ni) towards ligament formation facilitates the attack of the alloy by the corrosive agent. It has been hypothesized that molten salts enhance this rate of solute diffusion along the metal interface.In this work, we propose an electrochemical phase field model to predict the microstructural evolution of model Ni-alloys undergoing dealloying corrosion in molten fluoride salts. The model incorporates metal oxidation and dissolution via experimentally determined redox potentials and activity coefficients for metal species in the molten salt. We show that the corrosion rate and development of pores is strongly dependent on solute transport rates within the metal and also along their solid-liquid interface. In particular, we reveal a mechanism in which grain boundaries couple with the solid-liquid corrosion front to promote rapid dealloying and molten salt attack. Oxidant content in the salt and double-layer formation at the interface are discussed for their roles in setting the electrochemical potential and reaction rate at the metal-salt interface. Finally, we discuss how the model leverages insights from atomistic modeling and highlight key knowledge gaps in the mesoscale modeling of electrochemical molten salt corrosion.

#1980 Past peritonitis episodes are linked to decreased peritoneal Immune Cell Function and Associated with Chronic Increased Peritoneal Inflammation

Abstract Background and Aims Chronic peritoneal inflammation and infectious complications occur in a significant proportion of PD patients. A relationship between peritoneal IL-6 levels and local immunocompetence is suspected. To analyse local immunocompetence, an ex-vivo stimulation assay of PD effluent was developed. The aim of this study was to analyse peritoneal inflammation and immunocompetence in a PD cohort in relation to clinical outcomes. Method Prospectively, 245 routinely performed 4-hour PETs (143 patients, 2679 patient-months) of patients exclusively receiving 2. generation PD fluids (two-chamber, pH neutral, low amount of glucose degradation products) were analysed. An ex-vivo cell stimulation protocol of the fresh effluents was performed of all PETs. Peritoneal immune cell function was analysed using ex-vivo Toll-like receptor (LPS/Pam3Cys) stimulated IL-6 release as an index of immunocompetence. The molecular effects of effluent components and the addition of alanyl-glutamine to PD fluid were analysed in heterologous cell stimulation experiments and using an effluent proteomics and metabolomics approach. Results IL-6 in the effluent showed no association with various patient characteristics (incl. RRF, underlying disease, peritonitis episodes, time on PD). A significant association of peritoneal IL-6 with solute transport rates and systemic markers of uremic inflammation was found. IL-6 in effluent (HR 2.54) and stimulated 1 h effluent (HR 0.34) was predictive of subsequent peritonitis episodes. An inverse association was observed with ex-vivo stimulated IL-6 release from peritoneal cells (P = .02), most pronounced in patients with a history of peritonitis (P = .008). Patients with above median elevated IL-6 levels showed reduced peritoneal immune cell function. The results were validated in an independent multi-centre PD cohort (n = 48). A proteomics (n = 17) and targeted metabolomics (patients n = 134, 1004 metabolites) analysis of PD effluents show an overrepresentation of apoptosis and neutrophil degranulation pathways in patients with elevated effluent IL-6 levels and reduced response mechanisms to pathogens when compared to effluents from patients with low effluent IL-6 levels. Heterologous donor-PBMC stimulation (4 Healthy donors) with 4h PET PD-effluents of 20 patients showed reduced immunocompetence with elevated IL-6 (P = .038) and improved immunocompetence when 8 mM alanyl-glutamine were added to the PD fluid during the dwell. These results could also be validated in a post-hoc analysis of a RCT testing alanyl-glutamine addition to PD fluid for 8 weeks in PD patients. Conclusion This is the first longitudinal study to show the relationship between peritoneal inflammation and impaired immune function of peritoneal cells, possibly predisposing to infectious complications. The possible underlying mechanistic link may represent the biological correlate (“immune-paralysis”) for PD patients at increased risk for recurrent episodes of peritonitis.

Macropore flow in relation to the geometry and topology of soil macropore networks: Re-visiting the kinematic wave equation

The rapid flow of water through soil macropores significantly affects the partitioning of precipitation between surface runoff and infiltration and also the rate of solute transport in soil, both of which have an impact on the risk of contamination of surface water and groundwater. The kinematic wave equation is often employed as a model of gravity-driven water flow through soil macropores. The exponent in this simple model influences the pore water velocity attained in the macropores at any given input rate and is usually estimated by inverse modelling against measured flow rates or water contents. In theory, the exponent in the kinematic wave equation should depend on the geometry and topology of the conducting macropore networks, although these relationships have not so far been investigated. In this study, we related metrics of soil structure derived from X-ray images to values of the kinematic exponent estimated from drainage experiments on twenty-two columns sampled at three different field sites under two contrasting land uses and at three different depths.We found that smaller values of the exponent in the kinematic wave equation, which would equate to more rapid flow of water through soil macropores, were found in plough pan and subsoil columns of smaller macroporosity, for which biopores comprised a significant fraction. The macroporosity in these columns was more vertically oriented and poorly inter-connected, though still continuous across the sample. In contrast, topsoil columns from both arable land and grassland had better connected, denser and more isotropically-distributed macropore networks and larger values of the kinematic exponent. Our results suggest that for predictive modelling at large scales, it may be feasible to estimate the kinematic exponent using class pedotransfer functions based on pedological information such as land use and horizon type.

Model for particle capture by the solid-liquid interface during solidification of metal matrix nanocomposites

A sharp-interface model for solidification of nanocomposites with nanoparticle-interface interaction is presented. The main novelty of the work is that the engulfment or non-engulfment of nanoparticles is modelled as a function of the local interface velocity and a particle size-based critical velocity. This is incorporated through a variable partitioning coefficient while solving the nanoparticle conservation equation which is modelled similar to an alloying constituent. The movement of nanoparticles is governed by nanoparticle-interface interaction and by diffusion due to Brownian motion. The model couples a sharp-interface solidification model, species transport model and nanoparticle transport model. Thus, the engulfment and the resultant distribution of nanoparticles in the solidified region can be predicted for different combinations of initial undercooling and nanoparticle size. The effect of accumulated nanoparticles on the solute transport and solidification rate is also included in the model. Results show that the engulfment of smaller nanoparticles is very low resulting in high accumulation near the interface. This results in a high restriction to solute diffusion and solidification. Combined variation of initial undercooling and particle size shows that the average engulfment values for initial undercooling of 0.3, 0.5, and 0.7 are 2.75 %, 7.75 % and 21.50 % for r* = 0.1, 15.5 %, 53.5 %, and 82.5 % for r* = 0.5, and 38.0 %, 77.75 %, and 93.25 % for r* = 0.9. Thus, the engulfment of nanoparticles into the solid improves with increase in nanoparticle size and with the increase in solidification rate.

A benchmark for variably saturated variable-density variable-viscosity flow and solute transport in porous media

In natural environments, fluid density and viscosity can be affected by spatial and temporal variations of solute concentration, for example, due to saltwater intrusion in coastal aquifers, leachate infiltration from waste disposal sites, and upconing of saline water from deep aquifers. Potentially unstable situations may arise in which a dense fluid overlies a less dense fluid. This situation can produce instabilities manifested by dense plume fingers moving vertically downwards counterbalanced by vertical upward flow of the less dense fluid. The resulting free convection increases solute transport rates over large distances and times relative to constant-density flow. Unstable brine flow is further complicated if the porous medium is variably saturated. The results from a laboratory experiment of variably saturated variable-density flow and solute transport from Simmons et al. (2002) are used as the physical basis to define a new mathematical benchmark. This benchmark aims at realistically reproducing the experimental fingering patterns. Random hydraulic conductivity fields were used in the simulations as a numerical perturbation method to realistically mimic the observed dense plume fingering. The HydroGeoSphere code coupled with PEST are used to calibrate the parameter set that defines the benchmark. A grid convergence analysis is performed to obtain the adequate spatial and temporal discretizations. The new mathematical benchmark is useful for model comparison and testing of variably saturated variable-density flow in porous media. Simmons CT, Pierini ML, Hutson JL (2002) Laboratory investigation of variable-density flow and solute transport in unsaturated–saturated porous media. Transp Porous Media. 47(2): 215–244, 10.1023/A:1015568724369.

Sizes and shapes of perivascular spaces surrounding murine pial arteries

BackgroundFlow of cerebrospinal fluid (CSF) through brain perivascular spaces (PVSs) is essential for the clearance of interstitial metabolic waste products whose accumulation and aggregation is a key mechanism of pathogenesis in many diseases. The PVS geometry has important implications for CSF flow as it affects CSF and solute transport rates. Thus, the size and shape of the perivascular spaces are essential parameters for models of CSF transport in the brain and require accurate quantification.MethodsWe segmented two-photon images of pial (surface) PVSs and the adjacent arteries and characterized their sizes and shapes of cross sections from 14 PVS segments in 9 mice. Based on the analysis, we propose an idealized model that approximates the cross-sectional size and shape of pial PVSs, closely matching their area ratios and hydraulic resistances.ResultsThe ratio of PVS-to-vessel area varies widely across the cross sections analyzed. The hydraulic resistance per unit length of the PVS scales with the PVS cross-sectional area, and we found a power-law fit that predicts resistance as a function of the area. Three idealized geometric models were compared to PVSs imaged in vivo, and their accuracy in reproducing hydraulic resistances and PVS-to-vessel area ratios were evaluated. The area ratio was obtained across different cross sections, and we found that the distribution peaks for the original PVS and its closest idealized fit (polynomial fit) were 1.12 and 1.21, respectively. The peak of the hydraulic resistance distribution is 1.73times 10^{15} Pa s/m^{5} and 1.44times 10^{15} Pa s/m^{5} for the segmentation and its closest idealized fit, respectively.ConclusionsPVS hydraulic resistance can be reasonably predicted as a function of the PVS area. The proposed polynomial-based fit most closely captures the shape of the PVS with respect to area ratio and hydraulic resistance. Idealized PVS shapes are convenient for modeling, which can be used to better understand how anatomical variations affect clearance and drug transport.

#4452 ICODEXTRIN EFFICIENCY IN FLUID AND SODIUM REMOVAL REMAINS STABLE DURING LONG PERITONEAL DWELLS

Abstract Background and Aims Inadequate fluid and sodium removal has been shown to increase risk of overhydration and hypertension. In peritoneal dialysis, icodextrin-based solution provides sustained ultrafiltration, and therefore can be used for the long exchanges, especially in patients with fast solute transport rates in whom the effective ultrafiltration period is shortened. We investigated to which extent the efficiency of icodextrin in fluid and sodium removal is changing during 16-hour peritoneal dwells. Method Data on intraperitoneal volume, and concentrations of icodextrin and sodium in dialysate during 16 hours of peritoneal dwells with icodextrin-based solution were analysed in 11 clinically stable patients. Labeled serum albumin (RISA) was used as a volume marker and dialysate samples of 12 mL were collected at 8, 12, and 16 hours of peritoneal dwell. Residual volume was evaluated from marker dilution after 16 hours by rinsing peritoneal cavity with 2 L of fresh 1.36% glucose dialysis fluid. Ultrafiltration (UF) was calculated for each patient and each sampling time as the difference between drained and initially infused volume corrected for the sample volume. The total absorption of icodextrin-derived carbohydrates (AbsCHO) was calculated for each patient as the difference between initially infused and drained carbohydrates mass. The icodextrin ultrafiltration efficiency (UFE) was calculated for each sampling time as the ultrafiltration divided by the amount of icodextrin mass absorbed (AbsCHO). The efficiency of icodextrin in sodium removal (NaRE) was calculated for each sampling time as the sodium mass removed (difference between drained and initially infused sodium mass) divided by the corresponding icodextrin mass absorbed (AbsCHO). Correction for the residual volume and samples collections were applied for AbsCHO, UFE and NaRE calculations. Results After 16-hour dwell with icodextrin-based solution the ultrafiltration was positive in all except one patient, being on average (mean±SD) 669±369 mL. During the dwell, icodextrin was slowly absorbed from the peritoneal cavity, see Figure 1, left panel. At 16 hours, the mean cumulative CHO absorption (AbsCHO) reached 68.0±20.7 g (44±13% of initial CHO mass) while 56% of initial icodextrin mass infused still remained in dialysate, Figure 1, left panel. Icodextrin UF efficiency (UFE) calculated at 8, 12, and 16 hours remained stable (p = 0.6, ANOVA repeated measures) and was on average 9.9±5.8 mL/g, Figure 1, right panel. Moreover, icodextrin sodium removal efficiency (NaRE) also remained stable after 8 hours (p = 0.6, ANOVA repeated measures) and was on average 1.2±0.7 mmoL/g, Figure 1, right panel. Conclusion During 16 hours of peritoneal dialysis dwells with icodextrin-based solution, icodextrin was slowly absorbed with 56% of the osmotic agent remaining in the dialysate after 16 hours. The efficiency of icodextrin in terms of fluid (UFE) and sodium (NaRE) removal remained stable and did not subside from 8 to 16 hours of the dwell.

Solute transport characteristics in the streambed due to rigid non-submerged plants: Experiment and simulations

The presence of aquatic plants in natural and artificial rivers can cause substantial changes in the flow pattern. In this study, laboratory experiments and numerical simulations are conducted to explore the influences of rigid non-submerged plant densities on the transport of solutes in the hyporheic zone. The laboratory experiments and numerical modelling results show that solute enters into the streambed around plant, and solute in the overlying water experienced a sharp decrease at the beginning, followed by a gradual decline phase. The concentration in the shallow pore water increases rapidly, and increases at a decreasing rate with the increase of depth. The presence of a plant causes pressure gradients at the sediment–water interface before and after the plant. Specifically, the presence of plants induces the convection exchange of surface water and pore water, enables the solute to transport in the streambed through three circulation flows. Solute tends to transport to the root of the plant, or bypass the plant and return to the overlying water over time. The rate and quantity of solute transport in the streambed are related to the streamwise and spanwise distances of the plant. When the plant densities reach the distance that affect the flow structures near each other, smaller streamwise distances lead to the transport of fewer solutes into the streambed and prevent them from penetrating to the deeper part of the streambed, while larger spanwise distances have the same effect on solute transport in the streambed. The solute effective exchange depth for streamwise distance of 20 cm is 4.3 times that of 3 cm, while which for spanwise distance of 3 cm is 5.05 times that of 15 cm at time of 28 h. This study shows that the presence of aquatic plants leads to the circulation of solutes in the hyporheic zone, which promotes the transport of pollutants from overlying water to streambed through hyporheic exchange after the occurrence of a water pollution event. Further, plants densely in the streamwise direction and sparsely in the spanwise direction will reduce the range of pollutants transport in the streambed. This study is of great significance for water ecological restoration through rational arrangement density of aquatic plants.

A retrospective study of baseline peritoneal transport character and left ventricular hypertrophy in incident peritoneal dialysis patients: interrelationship and prognostic impacts

Background Left ventricular hypertrophy is associated with adverse outcomes among peritoneal dialysis patients. The aim of this study was to evaluate the prognostic impact of baseline left ventricular hypertrophy and its relationship with baseline peritoneal transfer characteristics in peritoneal dialysis patients. Methods We enrolled 151 incident peritoneal dialysis patients to perform a multicentric retrospective cohort study since January 1, 2017 to January 31, 2021. Patients were grouped based on baseline dialysate-to-plasma creatinine ratio at 4 h as follows: low (<0.50), low average (0.5–0.64), high average (0.65–0.80) and high (≥0.81). Echocardiography and clinic data were recorded yearly. The Cox proportional hazards models and competing risk model were used to evaluate patients’ survival. Generalized linear mixed models were performed to explore risk factors associated with left ventricular hypertrophy. Results During a median follow-up period of 33 months (range, 16–48 months), 21 (13.9%) patients died, including 16 (10.60%) cardiovascular deaths. Controlling the competing risks of switching to hemodialysis, kidney transplantation and loss to follow-up, baseline left ventricular hypertrophy was an independent risk factor for all-cause mortality (subdistribution hazard ratio, 2.645; 95% confidence interval, 1.156–6.056; p = 0.021). Baseline high and high average transport status were positively related to left ventricular mass index and left atrium diameter 2 years after PD initiation. Conclusion Baseline fast peritoneal solute transport rate may be an effect factor for aggravating left ventricular hypertrophy which predicted poor outcomes for peritoneal dialysis patients. The findings offered important ideas for further prospective intervention study.

Relationship between peritoneal solute transport and dialysate inflammatory markers in peritoneal dialysis patients: A cross-sectional study

BackgroundThe associated factors of peritoneal small solute transport was not fully understood. This research aimed to investigate the connection between dialysate inflammatory markers (e.g. macrophage migration inhibitory factor, MIF) in peritoneal dialysis (PD) effluent and peritoneal solute transport rate (PSTR) properties. Subjects and designA total of 80 stable PD patients in the First ShaoYang Hospital were enrolled in present study. Overnight PD effluent and serum inflammatory markers including MIF, MCP-1, VEGF, IL-6, TNFα and TGFβ were detected. Pearson correlation analysis and Logistic regression was performed to determine the risk factors for the increased PSTR. ResultsA trend toward increased values of MIF, MCP-1 and IL-6 in PD effluent was observed in subjects with high PSTR when compared with those with low PSTR. The Pearson correlation test showed that D/P Cr exhibited positive correlations with dialysis effluent MIF (r=0.32, p=0.01), MCP-1 (r=0.47, p=0.01), IL-6 (r=0.48, p=0.01). Conversely, no significant correlation was found between D/P Cr and TGF-β (r=0.04, p=0.70), TNF-ɑ (r=0.22, p=0.05), VEGF (r=0.02, p=0.86) and serum inflammatory markers. In the unadjusted regression analysis, dialysis effluent MIF (OR 2.41), MCP-1 (OR 1.72), IL-6 (OR 1.55) were associated with high PSTR condition. Multivariate logistic regression analysis showed that the adjusted odds ratios (OR) of dialysis effluent MIF for high PSTR were 2.47 in all subjects (p=0.03). ConclusionElevated MIF, MCP-1 and IL-6 levels in PD effluent were associated with increased PSTR. Elevated dialysis effluent MIF levels was an independent risk factor for high PSTR in subjects with PD treatment.

Numerical investigation of solute transport into deformable marine sediments driven by ocean waves

Most existing studies do not consider the effect that the deformability of submarine sediments may have on solute transport under the action of ocean waves. In this study a two-dimensional numerical model based on Biot’s poro-elastic consolidation theory and an advection–dispersion equation is established to investigate the transport of non-reactive solute into a deformable porous seabed under the influence of ocean waves. The numerical model is then validated against experimental and analytical results in order to demonstrate its accuracy and robustness. The simulation results indicate that ignoring the deformability of seabed soil and associated seepage force due to ocean waves may lead to a significant underestimation of the rate of solute transport in shallow layers of marine sediment, particularly fine sand or silt. The effects of parameters such as the shear modulus, non-dimensional mechanical dispersion coefficient (related to particle size and permeability), dimensionless sediment thickness, wave steepness and the relative water depth have on solute transport into deformable sediments were investigated. The results indicate that the ratio of the longitudinal coefficient of mechanical dispersion between deformable and non-deformable sediments that can represent the enhancement of solute migration due to soil deformation may reach up to 85. This becomes more pronounced as the shear modulus and permeability of sediments decrease and the depth of water increases when the sediment thickness is less than 0.8 times the wavelength. The rate of solute transport in deformable sediments reaches its maximum when the sediment thickness is about 0.2 times the wavelength. In fact, as the relative water depth increases from 0.1 to 0.3, the enhancement of solute migration due to wave-induced soil deformation increases by about 60%-80%. In comparison to linear waves, shallow water waves, e.g., the first-order cnoidal waves, can increase the transport of solute more due to its strong non-linear behaviour, particularly in deformable seabed.

The benefits of peritoneal dialysis (PD) solution with low-glucose degradation product in residual renal function and dialysis adequacy in PD patients: A meta-analysis.

The peritoneal effects of low-glucose degradation product (GDP)-containing peritoneal dialysis (PD) solutions have been extensively described. To systematically evaluate the efficacy and safety of low GDP solution for PD patients, specifically the effect on residual renal function (RRF) and dialysis adequacy, we conducted a meta-analysis of the published randomized controlled trials (RCTs). Different databases were searched for RCTs that compared low GDP-PD solutions with conventional PD solutions in the treatment of PD patients with continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD). The outcomes of RCTs should include RRF and may include small solute clear-ance, peritoneal transport status, nutritional status, and all-cause mortality. Seven studies (632 patients) were included. Compared with the conventional solution, low-GDP solution preserved RRF in PD patients over time (MD 0.66 mL/min, 95% CI 0.34 to 0.99; p&lt;0.0001), particularly in one year of treatment (p&lt;0.01), and improved weekly Kt/V (MD 0.11, 95% CI 0.05 to 0.17; p=0.0007) without an increased 4-hour D/Pcr (MD 0.00, 95% CI -0.02 to 0.02; p=1.00). Notably, the MD of RRF and urine volume between the two groups tended to decrease as time on PD progressed up to 24 months. Patients using low GDP PD solutions did not have an increased risk of all-cause mortality (MD 0.97, 95% CI 0.50 to 1.88; p=0.93). Our meta-analysis confirms that the low GDP PD solution preserves RRF, improves the dialysis adequacy without increasing the peritoneal solute transport rate and all-cause mortality. Further trials are needed to deter-mine whether this beneficial effect can affect long-term clinical outcomes.

MO715: The Role of Duration and Modality Choice on Sodium and Water Removal for Peritoneal Dialysis Patients

Abstract BACKGROUND AND AIMS Hypervolemia is common in peritoneal dialysis (PD) and contributes to hypertension and left ventricular hypertrophy, thus increasing the cardiovascular risk of these patients. The achievement of adequate water and sodium balance is considered a major determinant of dialysis adequacy and seems to have a greater effect on PD outcome than Kt/V and small solute clearances. However, the contribution of different PD modalities to dialytic sodium removal remains not well defined. The aim of this study was to explore the effect of different PD modalities on sodium and water removal. METHOD This is a single-center cohort study of 21 patients (m = 12, f = 9). They were examined according to their modality of PD: CAPD (continuous ambulatory PD n = 9) and APD (continuous cycler PD n = 12). CAPD patients’ median age was 74 years (66–79), median time on PD was 37 months (24–59), median Kt/V 2.4 (1.9–3.1) and median eGFR 9.9 mL/min (3.5–12.4). APD patients’ median age was 47 years (32–75), median time on PD 65 months (52–87), median Kt/V 2.439 (2.12–2.8) and median eGFR 2.3 mL/min (0–5). We used the modified peritoneal equilibration test (PET with DW 4.25%) and double mini-PET to calculate the small solute transport rate (D/P of creatinine), water removal (FWT—free water transport, ΔNa—sodium dip, OCG—osmotic conductance of glucose) and mesothelial cell integrity (CA125 appearance rate in dialysis effluent). We also calculate the total amount of sodium excretion from the 24 h PD effluent collection and urine collection. Using bioimpedance spectroscopy we calculate the patients’ total body water, the overhydration and the intracellular and extracellular volume (ECV). RESULTS We did not find between the two groups any statistically significant difference for water movement through the membrane (ΔNa P = 0.427; FWT P = 0.384; OCG P = 0.27), for the marker of mesothelial cell mass (CA125AR P &amp;gt; 0.05) or for hydration status (OH, ECV). There was a statistically significant difference between the two groups for the small solute transport rate (Cr d/p, P = 0.025), for the total daily amount of sodium excretion through the membrane (P &amp;lt; 0.001), i.e. patients on APD having faster solute movement and excrete more sodium during the day compared to CAPD patients. Additionally, from the regression analysis there was statistically significant correlation between the daily dialysis sodium excretion and solute movement (P = 0.007, r = 0.58) and total time on PD (P = 0.004, r = 0.612). CONCLUSION These results indicate that there is no inferiority of APD compared to CAPD for sodium excretion due to the smaller time duration of the cycles (sodium sieving). Additionally, we notice that even though the patients on APD remained longer on PD and received larger daily volumes of PD effluent there was not any difference in mesothelial cell marker or water transport indicators. Inevitable time probably through neo angiogenesis results in faster solute transport.

Soret &amp; Dufour and Triple Stratification Effect on MHD Flow with Velocity Slip towards a Stretching Cylinder

The phenomenon of convective flow with heat and mass transfer has been studied extensively due to its applications in various fields. The effects of nonlinear thermal radiation (NLTR), slip, thermal-diffusion (Soret) and diffusion-thermo (Dufour) on magenoto-hydrodynamic (MHD) flow towards a stretching cylinder in the presence of triple stratification (TSF) are investigated in this paper. The governing equations are transformed into an ODE by suitable transformations. The homotopy analysis method (HAM) is used to solve the ODE. The revamping of fluid flow, and heat transfer due to the presence of the Soret and Dufour effect, concentration slip and concentration stratification are analyzed. The temperature and local Sherwood number increases as the Dufour number rises, whereas the local Nusselt number decreases. While elevating the Soret number, the Sherwood number diminishes, whereas the concentration profile rises. The thermal boundary layer thickness enhances when thermal radiation increases. The rate of solute transport reduces while the concentration slip increases.

Peritoneal dialysis effluent-derived exosomal miR-432-5p: an assessment tool for peritoneal dialysis efficacy.

BackgroundUltrafiltration (UF) volume and peritoneal solute transport rate (PSTR) are common parameters used to evaluate the efficacy of peritoneal dialysis (PD) on individual patients. It is unclear whether the level of exosomal microRNA (miRNA) in peritoneal dialysis effluent (PDE) can predict UF or PSTR. This study was designed to investigate if there is a correlation between PDE exosomal miRNA (miR-432-5p) levels and various UF volumes and PSTRs in PD patients. It also aimed to explore the underlying mechanism of water and dialytic sodium removal (DSR).MethodsThe PSTR was quantified using the 4-hour (4 h) 3.86% dialysate to plasma creatinine ratio. The PDE exosomes (PDE-exo) were isolated by ultracentrifugation. An miRNA assay was used to identify the different miRNA in the PDE-exo of patients in a high (H; PSTR >0.65, n=5) and low (L; PSTR <0.65, n=5) group. We focused on miR-432-5p as bioinformatic analysis had shown that it could be involved in sodium transport. We used mimic/inhibitor transfection and dual luciferase reporter assay to verify the target genes of miR-432-5p. We used PKH-67 stained PDE-exo to observe their interaction with human MeT-5A mesothelial cells.ResultsOur results showed that the PDE-exo-miR-432-5p level was higher in group H than in group L. The levels of PDE-exo-miR-432-5p were positively correlated with PSTR (r=0.391; P<0.05; n=40) and negatively correlated with the 4 h UF volume (r=−0.376; P<0.05; n=40) and 4 h DSR (r=−0.535; P<0.01; n=24). Epithelial sodium channel α subunit (α-ENaC) was revealed as a direct target gene of miR-432-5p and expressed on both human peritoneum and MeT-5A cells. Furthermore, we found the PKH67 labeled-PDE-exo could be internalized into MeT-5A cells.ConclusionsA high PDE-exo-miR-432-5p level was associated with poor UF volume and DSR. It may be that PDE-exo-miR-432-5p affects DSR through downregulating α-ENaC expression.

Glycoprotein 96 in Peritoneal Dialysis Effluent-Derived Extracellular Vesicles: A Tool for Evaluating Peritoneal Transport Properties and Inflammatory Status.

BackgroundExtracellular vesicles (EVs) from peritoneal dialysis effluent (PDE), containing molecules such as proteins and microRNAs (miRNAs), may be potential biological markers to monitor peritoneal function or injury. Peritoneal inflammation is an important determinant of peritoneal solute transport rate (PSTR). Thus, the aim of this study is to determine whether the specific proteins capable of evaluating the PSTR could be found in PDE-EVs, and explore the underlying mechanism for the association between PSTR and peritoneal inflammation.MethodsSixty patients undergoing peritoneal dialysis (PD) were divided into two groups: high/high average transport (H/A) group (PET >0.65) and low/low average transport (L/A) group (PET <0.65). EVs derived from PDE (PDE-EVs) were isolated by ultracentrifugation. Proteomic analysis was performed to explore the differentially expressed proteins and identify the potential biomarkers in PDE-EVs from the two groups, and we focused on glycoprotein 96 (GP96) as it could be involved in the inflammatory process. The expression of GP96 in PDE-EVs and inflammatory cytokines was quantified by real-time PCR and enzyme-linked immunosorbent assay. The infiltration of macrophages and neutrophils into the peritoneum was detected using immunohistochemistry in a PD rat model.ResultsThe expression of PDE-EVs-GP96 was significantly higher in the H/A group, and was positively correlated with the PSTR and the level of the inflammatory factor interleukin (IL)-6. GP96-enriched EVs enhanced the secretion of proinflammatory cytokines IL-1β, IL-6, tumor necrosis factor (TNF)-α, and IL-8 in macrophages, which was reversed by a pharmacological GP96-specific inhibitor (PU-WS13). The GP96 inhibitor also reduced local peritoneal inflammation by decreasing the infiltration of inflammatory cells and levels of proinflammatory cytokines (IL-6 and TNF-α) and chemokines (CCL2, CXCL1, and CXCL2) in a PD rat model.ConclusionsPDE-EVs-GP96 is a new promising tool to evaluate the status of peritoneal inflammation and PSTR, and the mechanism may be related to affecting the inflammatory properties of macrophages.

Relationship between peritoneal solute transport and dialysate inflammatory markers in peritoneal dialysis patients: A cross-sectional study

BackgroundThe associated factors of peritoneal small solute transport was not fully understood. This research aimed to investigate the connection between dialysate inflammatory markers (e.g. macrophage migration inhibitory factor, MIF) in peritoneal dialysis (PD) effluent and peritoneal solute transport rate (PSTR) properties. Subjects and designA total of 80 stable PD patients in the First ShaoYang Hospital were enrolled in present study. Overnight PD effluent and serum inflammatory markers including MIF, MCP-1, VEGF, IL-6, TNFα and TGFβ were detected. Pearson correlation analysis and Logistic regression was performed to determine the risk factors for the increased PSTR. ResultsA trend toward increased values of MIF, MCP-1 and IL-6 in PD effluent was observed in subjects with high PSTR when compared with those with low PSTR. The Pearson correlation test showed that D/P Cr exhibited positive correlations with dialysis effluent MIF (r=0.32, p=0.01), MCP-1 (r=0.47, p=0.01), IL-6 (r=0.48, p=0.01). Conversely, no significant correlation was found between D/P Cr and TGF-β (r=0.04, p=0.70), TNF-ɑ (r=0.22, p=0.05), VEGF (r=0.02, p=0.86) and serum inflammatory markers. In the unadjusted regression analysis, dialysis effluent MIF (OR 2.41), MCP-1 (OR 1.72), IL-6 (OR 1.55) were associated with high PSTR condition. Multivariate logistic regression analysis showed that the adjusted odds ratios (OR) of dialysis effluent MIF for high PSTR were 2.47 in all subjects (p=0.03). ConclusionElevated MIF, MCP-1 and IL-6 levels in PD effluent were associated with increased PSTR. Elevated dialysis effluent MIF levels was an independent risk factor for high PSTR in subjects with PD treatment.

Mass Advection–Diffusion in Creeping Flow Through an Orifice Plate: A Model for Nanoporous Atomically Thin Membranes

Abstract Continuum transport equations are commonly applied to nanopores in atomically thin membranes for simple modeling. Although these equations do not apply for nanopores approaching the fluid or solute molecule size, they can be reasonably accurate for larger nanopores. Relatively large graphene nanopores have applications in small particle filtration and appear as unwanted defects in large-area membranes. Solute transport rates through these nanopores determine the rejection performance of the membrane. Atomically thin membranes commonly operate in a regime where advection and diffusion both contribute appreciably to transport. Solute mass transfer rates through larger nanopores have previously been modeled by adding continuum estimates for pure diffusion and pure advection through an infinitesimally thick orifice plate, as if the separate contributions were independent. We show here that estimating the transport rate in this way is accurate to within 30%. We further derive an expression for the net mass transfer rate in advection–diffusion through an infinitesimal thickness orifice plate at low Reynolds numbers that is accurate to within 1% for positive Péclet numbers (where diffusion is in the same direction as advection) and applies for negative Péclet numbers as well. Based on our expression, we devise an equation for the net mass transfer rate in creeping flow through orifice plates of arbitrary thickness that matches finite volume calculations to within 3% for positive Péclet numbers. These simple but accurate analytical equations for mass transfer rates in creeping flow through an orifice plate are useful tools in constructing approximate transport models.