High-flux and low-flux membranes: efficacy in hemodialysis

Urinary Biomarkers for Cell Cycle Arrest TIMP-2 and IGFBP7 for Prediction of Graft Function Recovery after Kidney Transplantation

TIMP-2 and IGFBP7 have been identified and validated for the early detection of renal injury in critically ill patients, but data on recovery of allograft function after kidney transplantation (KTx) are scarce. In a prospective observational multicenter cohort study of renal transplant recipients, urinary [TIMP-2] × [IGFBP7] was evaluated daily from day 1 to 7 after KTx. Different stages of early graft function were defined: immediate graft function (IGF) (decrease ≥ 10% in serum creatinine (s-crea) within 24 h post KTx); slow graft function (SGF) (decrease in s-crea < 10% within 24 h post KTx); and delayed graft function (DGF) (any dialysis needed within the first week after KTx). A total of 186 patients were analyzed. [TIMP-2] × [IGFBP7] was significantly elevated as early as day 1 in patients with DGF compared to SGF and IGF. ROC analysis of [TIMP-2] × [IGFBP7] at day 1 post-transplant for event "Non-DGF" revealed a cut-off value of 0.9 (ng/mL)2/1000 with a sensitivity of 87% and a specificity of 71%. The positive predictive value for non-DGF was 93%. [TIMP-2] × [IGFBP7] measured at day 1 after KTx can predict early recovery of transplant function and is therefore a valuable biomarker for clinical decision making.

High-Efficiency Water Filtration by Electrospun Expanded Polystyrene Waste Nanofibers

Nanofiber membranes were successfully synthesized from expanded polystyrene (EPS) waste with the addition of poly(vinylpyrrolidone) (PVP) for water microfiltration using the electrospinning method. The EPS-based nanofiber membranes exhibited a smooth morphology and were uniform in size. The concentration of the EPS/PVP solution changed some of the physical parameters of the nanofiber membrane, such as viscosity, conductivity, and surface tension. Greater viscosity and surface tension increase the nanofiber membrane diameter, whereas the addition of PVP results in hydrophilicity. Additionally, increasing the pressure increased the flux value of each variation of the nanofiber membranes. Furthermore, the rejection value was 99.99% for all variations. Finally, the use of EPS waste for nanofiber membranes is also beneficial for decreasing the amount of EPS waste in the environment and is an alternative to the current membranes available in the market for water filtration applications.

Validating a novel three-times-weekly post-hemodialysis ceftriaxone regimen in infected Indigenous Australian patients-a population pharmacokinetic study

OBJECTIVES

To describe the total and unbound population pharmacokinetics of a 2 g three-times-weekly post-dialysis ceftriaxone regimen in Indigenous Australian patients requiring hemodialysis.

METHODS

A pharmacokinetic study was carried out in the dialysis unit of a remote Australian hospital. Adult Indigenous patients on intermittent hemodialysis (using a high-flux dialyzer) and treated with a 2 g three-times-weekly ceftriaxone regimen were recruited. Plasma samples were serially collected over two dosing intervals and assayed using validated methodology. Population pharmacokinetic analysis and Monte Carlo simulations were performed using Pmetrics in R. The probability of pharmacokinetic/pharmacodynamic target attainment (unbound trough concentrations ≥1 mg/L) and toxicity [trough concentrations (total)  ≥100 mg/L] were simulated for various dosing strategies.

RESULTS

Total and unbound concentrations were measured in 122 plasma samples collected from 16 patients (13 female) with median age 57 years. A two-compartment model including protein-binding adequately described the data, with serum bilirubin concentrations associated (inversely) with ceftriaxone clearance. The 2 g three-times-weekly regimen achieved 98% probability to maintain unbound ceftriaxone concentrations ≥1 mg/L for a serum bilirubin of 5 µmol/L. Incremental accumulation of ceftriaxone was observed in those with bilirubin concentrations >5 µmol/L. Three-times-weekly regimens were less probable to achieve toxic exposures compared with once-daily regimens. Ceftriaxone clearance was increased by >10-fold during dialysis.

CONCLUSIONS

A novel 2 g three-times-weekly post-dialysis ceftriaxone regimen can be recommended for a bacterial infection with an MIC ≤1 mg/L. A 1 g three-times-weekly post-dialysis regimen is recommended for those with serum bilirubin ≥10 µmol/L. Administration of ceftriaxone during dialysis is not recommended.

Selectively mixed matrix hemodialysis membrane for adequate clearance of p-cresol by the incorporation of imprinted zeolite

The adequacy in uremic toxin removal upon hemodialysis treatment is essential in patients with kidney failure diseases as poor removal leads to heart failure, hypertension, and stroke. The combination of adsorption and diffusion processes has become very advantageous for hemodialysis membranes. By this mechanism, water-soluble uremic toxins (WSUTs) and protein-bounded uremic toxins (PBUTs) could be removed at one time. Therefore, this study aimed to develop a novel imprinted zeolite by p-cresol (IZC) and then incorporated it into polyethersulfone (PES) and poly(vinyl pyrrolidone) (PVP) to produce hollow fiber mixed matrix membrane (HF-MMM). The IZC proved to be sensitive in attracting the adsorbate, classifying it as having a strong adsorption behavior. Accordingly, IZC is very promising to be applied as an adsorbent in the hemodialysis treatment. In this study, IZC as p-cresol's adsorbent was incorporated into a PES-based polymeric membrane with a small addition of PVP to produce HF-MMM using a dry/wet spinning process. The effect of air gap distance between the spinneret and coagulant bath and percentage loading for PES, PVP, and IZC were studied and optimized to obtain the best performance of HF-MMM. The 40 cm of air gap distance, 16 wt% of PES, 2 wt% of PVP, and 1 wt% of IZC loading were able to produce a superior hemodialysis membrane. These optimized parameters showed sufficient uremic toxin removal, i.e., 60.74% of urea, 52.35% of p-cresol in the phosphate buffer saline solution, and 66.29% of p-cresol in bovine serum albumin solution for 4 h permeation using the dialysis system. These HF-MMMs also achieved pure water flux of 67.57 L m^-2 h^-1 bar^-1 and bovine serum albumin rejection of 95.05%. Therefore, this membrane has proven to be able to clean up WSUT and PBUT through a one-step process. Moreover, as compared to the neat PES membrane, MMM was able to remove p-cresol at 186.22 times higher capability.

Waste acrylonitrile butadiene styrene (ABS) incorporated with polyvinylpyrrolidone (PVP) for potential water filtration membrane

Acrylonitrile butadiene styrene (ABS) is one of the most common fused-filament feedstocks for 3D printing. The rapid growth of the 3D printing industry has resulted in huge demand for ABS filaments; however, it generates a large amount of waste. This study developed a novel method using waste ABS to fabricate electrospun nanofiber membranes (ENMs) for water filtration. Polyvinylpyrrolidone (PVP) was employed to modify the properties of waste ABS, and the effect of PVP addition in the range of 0-5 wt% was investigated. The results showed that adding PVP increased the viscosity and surface tension but decreased the conductivity of the precursor solution. After electrospinning, PVP could reduce the number of beads, increase the porosity and fiber diameter, and improve the wettability of the fabricated fibers. Moreover, the bilayer of ABS ENMs achieved a high flux value between 2951 and 48 041 L m^-2 h^-1 and a high rejection rate of 99%. Our study demonstrates a sustainable strategy to convert waste plastics to inexpensive materials for wastewater treatment membranes.

Dialysis Membranes for Acute Kidney Injury

Mortality and morbidity rates among critically ill septic patients having acute kidney injury (AKI) are very high, considering the total number of deaths after their admission. Inappropriate selection of the type of continuous renal replacement therapy and inadequate therapy become the immediate causes of these issues. Dialysis is a commonly used treatment intended to prolong the life of AKI patients. Dialysis membranes, which are the core of dialysis treatment, must be properly selected to ensure fair treatment to the patients. The accumulation of certain types of molecules must be dealt with using the right membrane. Whether it is low-flux, high-flux, or adsorptive type, the dialysis membrane should be chosen depending on the condition of the patients. The selection of dialysis membranes should also be based on their effect on the treatment outcomes and well-being. All these options are needed to serve the patients of different clinical settings. The use of dialysis membranes is not restricted to conventional haemodialysis, but rather they can be employed in haemoperfusion, haemofiltration, haemodiafiltration, or a combination of any two of them. This review focuses in-depth on different types of dialysis membranes, their characteristics, and approaches in addressing the issues encountered in patients having AKI with sepsis and/or multiorgan failure in intensive care units.

A Review of Commercial Developments and Recent Laboratory Research of Dialyzers and Membranes for Hemodialysis Application

Dialyzers have been commercially used for hemodialysis application since the 1950s, but progress in improving their efficiencies has never stopped over the decades. This article aims to provide an up-to-date review on the commercial developments and recent laboratory research of dialyzers for hemodialysis application and to discuss the technical aspects of dialyzer development, including hollow fiber membrane materials, dialyzer design, sterilization processes and flow simulation. The technical challenges of dialyzers are also highlighted in this review, which discusses the research areas that need to be prioritized to further improve the properties of dialyzers, such as flux, biocompatibility, flow distribution and urea clearance rate. We hope this review article can provide insights to researchers in developing/designing an ideal dialyzer that can bring the best hemodialysis treatment outcomes to kidney disease patients.

Oxone®-Mediated TEMPO-Oxidized Cellulose Nanomaterial Ultrafiltration and Dialysis Mixed-Matrix Hollow Fiber Membranes

Recent exploration of cellulose nanomaterials has resulted in the creation of Oxone^®-Mediated TEMPO-Oxidized Cellulose Nanomaterials (OTO-CNMs). These materials, when incorporated into a polymer matrix, have properties showing increased flux, decreased membrane resistance, and improved clearance, making them an ideal material for dialysis. This study is the first to focus on the implementation of OTO-CNMs into hollow fiber membranes and a comparison of these membranes for ultrafiltration and dialysis. Ultrafiltration and dialysis were performed using bovine serum albumin (BSA), lysozyme, and urea to analyze various properties of each hollow fiber membrane type. The results presented in this study provide the first quantitative evaluation of the clearance and sieving characteristics of Oxone^®-Mediated TEMPO-Oxidized Cellulose-Nanomaterial-doped cellulose triacetate mixed-matrix hemodialyzers. While the cellulose nanomaterials increased flux (10–30%) in ultrafiltration mode, this was offset by increased removal of albumin. However, in dialysis mode, these materials drastically increased the mass transfer of components (50–100%), which could lead to significantly lower dialysis times for patients. This change in the performance between the two different modes is most likely due to the increased porosity of the cellulose nanomaterials.

Recent Progress of Microfluidic Devices for Hemodialysis

Microfluidic hemodialysis techniques have recently attracted great attention in the treatment of kidney disease due to their advantages of portability and wearability as well as their great potential for replacing clinical hospital-centered blood purification with continuous in-home hemodialysis. This Review summarizes the recent progress in microfluidic devices for hemodialysis. First, the history of kidney-inspired hemodialysis is introduced. Then, recent achievements in the preparation of microfluidic devices and hemodialysis nanoporous membrane materials are presented and categorized. Subsequently, attention is drawn to the recent progress of nanoporous membrane-based microfluidic devices for hemodialysis. Finally, the challenges and opportunities of hemodialysis microfluidic devices in the future are also discussed. This Review is expected to provide a comprehensive guide for the design of hemodialysis microfluidic devices that are closely related to clinical applications.

Efficacy of different hemodialysis methods on dendritic cell marker CD40 and CD80 and platelet activation marker CD62P and P10 in patients with chronic renal failure

BACKGROUND

Chronic renal failure (CRF) has become a major public health concern, which increases the risk of stroke and systemic thromboembolism. Therefore, therapeutic strategies are in urgent requirement. This study was conducted for investigating efficacy of hemodialysis (HD), hemodiafiltration (HDF), and hemoperfusion (HP) in patients with CRF and the correlation with the presence of complications following HD therapy.

METHODS

The therapeutic effect, living quality, biochemical indicators, and dry weight were detected before and after the treatment regimens. Flow cytometry was conducted to detect expressions of dendritic cell markers (CD40 and CD80) and platelet activation markers (CD62P and P10), and the relationship between their expression and therapeutic effect as well as the association of these expressions with complications was analyzed.

RESULTS

After HD therapy, patients presented with decreased serum creatinine, serum phosphorus, triglyceride, parathyroid hormone, and β₂ -MG expression; increased hemoglobin, plasma albumin expressions, and dry weight; and enhanced therapeutic effect and living quality. CD62P and P10 expressions decreased, while CD40 and CD80 expressions increased following HD therapy. The therapeutic effect improved in patients with low expressions of CD40 and CD80 and high expressions of CD62P and P10 following HP treatment and complications were lower after treatment of HDF and HP.

CONCLUSION

The aforementioned results indicated that CRF patients treated with HP exhibited higher expression of CD40 and CD80 and lower expression of CD62P and P10, suggesting that HP is conferred to have better efficacy than HDF and HD. Therefore, HP may be a promising clinical regimen for treatment of CRF patients.

Severe Destructive Tendinopathy in the Wrist Due to Dialysis-Related Amyloidosis

Dialysis-related amyloidosis (DRA) is a specific subtype of amyloidosis with several clinical presentations. Herein we report a case of severe destructive tendinopathy around the wrist associated with long-standing hemodialysis (HD). A 63-year-old female patient who had been on regular HD for 23 years suffered from symptoms of pain and a palpable mass around the wrist. Magnetic resonance imaging showed an ill-defined soft tissue mass around the extensor tendons that partially invaded the wrist joint. We performed surgical excision and tenolysis for the mass. The operative finding revealed an ill-defined yellowish soft tissue mass extensively invading the extensor tendons and wrist joint. The tendon fibers were severely fibrillated and showed impending rupture due to the infiltrated mass. Histological examination showed DRA. Amyloidosis-induced tendinopathy should be considered when a patient on long-term HD complains of an unusual mass-like lesion in the extremity and/or nonspecific joint stiffness. Early surgical intervention improves patient's disability and decreases the risk of spontaneous tendon rupture.