Efficacy of combined disinfection with a nitric oxide donor in controlling biofilm formation on the reverse osmosis water pathway for hemodialysis.

The water treatment system for hemodialysis (HD) is used to treat multiple patients requiring HD simultaneously. This system requires a large amount of purified reverse osmosis (RO) water. However, a major drawback of this method is the formation of biofilms in dialysate pathways. The purpose of this study was to investigate the efficacy of NOC 18, a nitric oxide (NO) donor that can be used at neutral pH, in disinfecting the RO water pathway. Silicone tubes were obtained from the terminal sites of two different HD units. The biofilm coverage and mean biofilm thickness on the tube lumen were evaluated by scanning electron microscopy. The results demonstrated that treatment with NOC 18 alone and in conjunction with sodium hypochlorite reduced biofilm coverage and mean biofilm thickness. Thus, NO donor is a potential disinfectant that enhances bacterial dispersion from biofilms formed on the silicone tube lumen and reduces biofilm coverage and thickness on the RO water pathway at neutral pH. Furthermore, combined disinfection with the NO donor and sodium hypochlorite might enhance biofilmremoval efficacy in clinical practice.

Renal replacement therapy removes a large number of nitric oxide donors responsible for the nitrate-nitrite-nitric oxide pathway.

BACKGROUNDS: Nitric oxide has a broad-spectrum antibacterial property promising as a new therapeutic agent for severe acute respiratory syndrome coronavirus-2 because nitric oxide donor (such as S-nitroso-N-acetylpenicillamine) reduces the replication of coronavirus-2. Patients with coronavirus disease 2019 undergoing dialysis generally have a higher mortality rate than the general population. Although the higher mortality rate in these patients may be related to their advanced age, it has been suggested that plasma nitrite and nitrate levels (products of nitric oxide metabolism) are significantly decreased after hemodialysis which may compromise the nitrate-nitrite-nitric oxide pathway and impair nitric oxide homeostasis. It results in increased cardiovascular mortality in patients undergoing dialysis. However, the profile of nitric oxide-producing substances is poorly understood during renal replacement therapy. METHODS: We simulated continuous hemodialysis and hemodiafiltration to measure the amount of nitric oxide (nitric oxide-producing substance) clearance in vitro. RESULTS: The results demonstrated increased nitric oxide clearance and higher clearance than creatinine (molecular weight: 113) and vitamin B12 (molecular weight: 1355) using highly efficient renal replacement therapy modes. CONCLUSION: The high nitric oxide clearance may have partly contributed to the high cardiovascular and coronavirus-2 mortality risk in patients on dialysis.

Effectiveness of combination of heat water disinfection, continuous water circulation, and minimalized dead space for dialysis piping in maintaining ultrapure dialysis fluid and preventing biofilm formation in a central dialysis fluid delivery system.

Various benefits have been attached to purifying the dialysis fluid used for hemodialysis therapy. The central dialysis fluid delivery system can treat approximately 50 dialysis patients simultaneously and is convenient to operate. In contrast, the dialysis fluid supply piping is complicated, and bacterial growth can cause biofilms. This study aimed to develop sustainable cleaning strategies to solve the complicated dialysis fluid piping, which is a weakness of the central dialysis fluid delivery system, and provide ultrapure dialysis fluid for a long term. Combination of heat water disinfection, continuous water circulation, and minimalized dead space in the dialysis piping were designed for a central dialysis fluid delivery system and used in a clinic for 6 years. As an index of water purification, endotoxin concentrations and microbial colony counts in reverse osmosis water and dialysis fluid were measured. In addition, we performed scanning electron microscopy of the silicon tube surface that had been used for 5 years to confirm the presence or absence of biofilm formation. For 6 years, endotoxin concentrations and microbial colonies were not detected in reverse osmosis water and dialysis fluid using the multiple-patient dialysis fluid supply equipment. The purity of the dialysis fluid was maintained. No biofilm formation was observed by scanning electron microscopy. Combination of heat water disinfection, continuous water circulation, and minimalized dead space designs for dialysis piping can supply ultrapure dialysis fluid with minimal biofilm formation in the piping in the long term.

Leakage of Endotoxins through the Endotoxin Retentive Filter: An in vitro Study.

INTRODUCTION: Ultrapurification of dialysis fluid has enabled highly efficient dialysis treatments. Online hemodiafiltration is one such treatment that uses a purified dialysis fluid as a supplemental fluid. In this method, an endotoxin retentive filter (ETRF) is used in the final step of dialysis fluid purification, with the aim of preventing leakage of endotoxins. Sodium hypochlorite and peracetic acid are used as disinfecting agents for the dialysis fluid pipes containing the ETRF; however, the effects of these agents on ETRF membrane pores have not been fully clarified. METHODS: Water permeability (flux) and endotoxin permeability were assessed in 3 types of ETRFs made with different membrane materials: polyester polymer alloy (PEPA), polyether sulfone (PES), and polysulfone (PS). High-concentration sodium hypochlorite and 2 types of peracetic acid were used as disinfecting agents, and the changes in flux and the endotoxin sieving coefficient (SC) were measured. RESULTS: After repeated use of high concentrations of sodium hypochlorite and peracetic acid, the PEPA and PES ETRFs did not permit passage of endotoxins, regardless of their flux. However, in the PS ETRF, the flux and endotoxin SC increased with the number of cleaning cycles. No differences were observed according to the concentration of peracetic acid disinfecting agents. CONCLUSION: PEPA and PES ETRFs completely prevent endotoxin leakage and can be disinfected at concentrations higher than the conventionally recommended concentration without affecting pore expansion. Even new PS ETRFs have low levels of endotoxin leakage, which increase after disinfection cycles using sodium hypochlorite and peracetic acid.

Nitric oxide delivery using nitric oxide-containing fluid in continuous hemofiltration: an in vitro study.

Administering nitrite has therapeutic effects on ischemic conditions wherein the enzymatic production of nitric oxide depends on oxygen. We developed a supplemental fluid containing nitric oxide (NO) and determined the clearance and supply between the pre- and post-dilution modes of continuous hemofiltration in vitro. Nitric oxide gas, 1000 mL or 2000 mL, at a concentration of 1000 ppm, was injected into 2020 mL of conventional supplemental fluid (experimental solution). The same volume of nitrogen gas was injected into the supplemental fluid (control solution). NO concentrations were measured using commercially available NO assay kit. Pre- or post-dilution continuous hemofiltration was performed using a control solution as supplemental fluid to determine the NO clearance. We determined the NO concentration of the outlet blood circuit to confirm the NO supply using the experimental solution as supplemental fluid. Also, using the bovine blood, white blood cell and platelet change rates and the dialysis membrane water flux during continuous hemodiafiltration were evaluated ex vivo as index of the biocompatibilities of a nitric oxide-containing solution. NO was not detected in the control solutions. The experimental solutions significantly increased in nitric oxide concentrations. NO clearance increased as the increase in supplemental and ultrafiltration flow rates using the control solution as supplemental fluid. However, using the experimental solution as supplemental fluid, nitric oxide supply showed a similar trend of NO clearance. Without any changes in biocompatibility using the supplemental fluid containing NO, it could maintain intravascular nitric oxide during continuous renal replacement therapy.

Data on producing an infusion fluid that contains nitric oxide.

Nitric oxide (NO) is a vasodilator and platelet aggregation inhibitor. In patients with pulmonary hypertension, inhalation of NO is used as a therapeutic option. It has been proposed that nitrite (NO2 -) is a constitute intravascular storage and delivery source of NO, a potent cardioprotective-signaling molecule. The administration of NO2 - could have therapeutic effects in conditions where the oxygen-dependent enzymatic production of NO is compromised (i.e., ischemia). Thus, if NO could be supplied by an intravenous infusion fluid, it would be an easier method than by inhalation or delivery to the blood vessels by the blood stream. We produced 2 types of solutions, i.e., a nitrogen gas injected solution (control solution) and NO gas injected solution (experimental solution). NO was measured by the Microplate Photometer (MultiSkan FC, Thermo Fisher Scientific K.K., Tokyo, Japan) with a 540-nm wavelength and NO assay kit (Quantichrom™ Nitric Oxide Assay Kit, BioAssay Systems, Hayward, CA, USA). Gas profiles were measured by the EG6+ (Abbott Japan Co., Ltd., Osaka, Japan) with an i-STAT system (300F, Abbott Japan Co., Ltd.). Comparisons of gas profiles and measured NO concentrations in vitro and ex vivo are shown between the control and experimental solutions. Since NO is oxidized to NO2 - and nitrate (NO3 -), it is common practice to quantitate total NO2 -/NO3 - as a measure of the NO level. We used the assay that was designed to accurately measure NO production following reduction of NO3 - to NO2 - using the Griess method. The data in this document describe production of an infusion fluid that contains NO without any special devices.

Oxygen delivery to the blood stream by the dialysis fluid during continuous renal replacement therapy ex vivo.

Continuous renal replacement therapy (CRRT) maintains a balance in body water and electrolytes. CRRT supplies a higher quantity of fluid than intravenous fluid therapy along with simultaneous fluid withdrawal. We hypothesized that use of a high-oxygen-containing solution for high-volume fluid exchange would improve oxygenation in the blood during CRRT. To start with, we prepared a solution containing high oxygen. The objective of this study was to determine if this solution would increase the partial pressure of oxygen (pO2) in the blood more than that using a conventional solution during CRRT. We compared the gas profile of the experimental fluid ex vivo in a simulated CRRT for 24 h, using 2-L batches of bovine blood. A significant increase in the pO2, pH, and total oxygen delivery, and a significant decrease in the partial pressure of carbon dioxide (pCO2) were estimated in the bovine blood using the experimental solution during the simulated CRRT. This method is simpler to apply for oxygenation than the conventional method, and will be beneficial to hypoxic patients in terms of improving their blood oxygenation during CRRT.

Data on a simple method for producing a solution that contains a high partial pressure of oxygen and a low partial pressure of carbon dioxide.

The data presented here shows a simple method for producing a solution that contains a high partial pressure of oxygen (pO2) and a low partial pressure of carbon dioxide (pCO2). This novel solution was created by simply injecting oxygen gas into conventional supplemental bicarbonate fluid for renal replacement therapy. We compared the gas profiles of the novel solution and the conventional fluid in vitro. There was a significant increase in pO2 and pH, and a significant decrease in pCO2 in the experimental solution, in each of which an additional volume of oxygen was injected. The method shown here is capable of facilitating an increase of pO2 and decrease of pCO2 by using a closed fluid bag without any special devices.

Simple method to make a supersaturated oxygen fluid.

Intravenous oxygenation has demonstrated significant increase in partial pressure of oxygen (PO2) in animal models. A highly dissolved oxygen solution might be able to provide a sufficient level of oxygen delivery to the tissues and organs in patients with hypoxia. However, conventional fluid oxygenation methods have required the use of original devices. If simpler oxygenation of a solution is possible, it will be a useful strategy for application in clinical practice. We simply developed its administration by injection of either air or oxygen gas into conventional saline. We determined the PO2 values in the solutions in comparison with conventional saline in vitro. To examine the effects of the administration of the new solutions on the blood gas profile, we diluted bovine blood with either conventional or the new solutions and analyzed PO2, oxygen saturation (SO2) and total oxygen content. PO2 levels in the blood and new solution mixture significantly increased with each additional injected gas volume. Significant increases in the PO2 and SO2 of the bovine blood were found in those blood samples with the new solution, as compared with those with the control solution. These results suggest that this solution promotes oxygen delivery to the hypoxic tissue and recovery from hypoxia. This method is simpler and easier than previous methods.

Asymmetric triacetate membrane keeps high water flux during ultrafiltration: in vitro study.

Membrane fouling is a primary challenge encountered during the administration of hemodialysis (HD) and hemodiafiltration (HDF). A high-flux membrane is suitable for dialyzer reuse, since it is used repeatedly. Water flux is a benchmark used to assess the effectiveness of the dialysis membrane during treatment and it is usually evaluated to determine whether membrane fouling has occurred. Polysulfone (PS) membrane has good biocompatibility and solute permeability; however, polyethersulfone (PES) is often used as a hemodiafilter membrane because of better hydrophilicity compared to PS. We evaluated water flux across hemodiafilters using newly developed asymmetric triacetate (ATA) and PES as conventional membranes in vitro. Water flux of across ATA and PES membranes significantly decreased 30 min after the start of the experiments and thereafter showed stabilization. Water flux across the ATA membrane consistently showed significantly higher values of greater than 100 mL/m2/h/mmHg, compared to lower values observed across the PES membrane. These results suggest that the ATA membrane has a potential use not only for HDF, but also for long-time therapies of HD and HDF.

Hyperbaric Oxygen Therapy Suppresses Apoptosis and Promotes Renal Tubular Regeneration After Renal Ischemia/Reperfusion Injury in Rats.

BACKGROUND: Renal ischemia/reperfusion (I/R) injury remains a major cause of acute kidney injury (AKI), in addition to I/R injury-induced tissue inflammation, necrosis and apoptosis. Hyperbaric oxygen therapy (HBO) is defined as a treatment in which a patient is intermittently exposed to 100% oxygen pressurized to a pressure above sea level (> 2.0 atmospheres absolute (ATA), 1.0 ATA = 760 mmHg). It has been used in a number of medical conditions with a proven efficacy in a limited number of disorders. However, the effects of HBO therapy on apoptosis and proliferative activity after I/R injury have not been fully understood. OBJECTIVES: We studied the possible beneficial effects of HBO therapy on apoptosis and tubular cell regeneration after renal I/R injury in rats. MATERIALS AND METHODS: Sprague-Dawley (SD) rats were randomized into three groups: Sham (Sham-operated rats); I/R (animals submitted to I/R); and I/R + HBO (I/R rats exposed to HBO). Tubular cell apoptosis was confirmed by DNA laddering and the terminal deoxynucleotidyl transferase-mediated uridine triphosphate nick end labeling (TUNEL) assay. Cellular proliferation activity was determined using the anti-Ki-67 antibody. RESULTS: A significant decrease in apoptotic cells and increase in proliferative reaction were observed in the I/R + HBO group compared to the I/R group. CONCLUSIONS: We demonstrated that HBO suppressed apoptosis, which caused inflammation after renal I/R, and promoted tubular cell regeneration. HBO has protective effects against AKI caused by renal I/R through the inhibition of apoptosis.

Dialysate with high dissolved hydrogen facilitates dissociation of indoxyl sulfate from albumin.

BACKGROUND: Protein-bound toxins such as indoxyl sulfate (IS) are not efficiently removed by conventional hemodialysis (HD). OBJECTIVES: To improve the removal of IS, we performed an in vitro study to evaluate the effects of high dissolved hydrogen on the dissociation of IS from albumin using simulated HD. MATERIALS AND METHODS: Wasted dialysate from peritoneal dialysis was concentrated a hundred times using extracorporeal ultrafiltration method. Dialysate with high dissolved hydrogen was made by mixing concentrated dialysis solution and electrolyzed-reduced water. The amounts of free fractions of IS were determined by high performance liquid chromatography. RESULTS: IS was significantly dissociated from albumin using dialysate with high dissolved hydrogen compared with conventional dialysate (P < 0.05). CONCLUSIONS: Effective removal of IS is expected using a dialysate with high dissolved hydrogen.