Investigation of the inhibition of bacteria and endotoxin influx by back filtration through dialyzer membranes.

We investigated the usefulness of assays using human neutrophils for radical production as well as endotoxin (ET) measurement and bacterial culture for endotoxin and bacterial influx by back filtration using dialyzers with different membrane pore diameters. Three types of dialyzers made of cellulose triacetate membrane material with different pore size FB-110EG eco, FB-110U eco, and FB-150UHß eco were used. A circuit to generate back filtration was created. Back filtrate generated by hydraulic head pressure operation was collected. ET and bacteria were examined. Human neutrophils were exposed to back filtrate (experiments using three different membranes) and contaminated solution, and free radical production was measured using LBP-953 (Berthold) to see if there were differences in production. No bacteria were detected and the concentration of endotoxin was below the detection limit in the back filtrate from the three types of membranes and purified water. Free radical production from neutrophils in the contaminated water was highest at 4,405,750 ± 61,244 cpm (counts per minute) (mean ± SD) (P < 0.01 vs FB-150UHß eco, FB-110U-eco, and FB-110EG eco) followed by that in back filtrate via FB-150UHß eco, FB-110U-eco, FB-110EG eco. Radical production from neutrophils was thereby higher in the back filtrate of dialyzers with larger pore-size membranes. No bacteria were observed and the concentration of ET was below the detection limit in back filtrate from any of the membranes. However, when the reverse filtrate was exposed to neutrophils, radical production increased along with pore size, suggesting the influx of small pyrogens and other pyrogenic substances.

Examination of the Effect of Switching Dialysis Membranes on the Immune Response to Influenza Virus Vaccination in Hemodialysis Patients.

INTRODUCTION: In this study, we examined the effect of switching dialysis membranes on the response to influenza virus vaccination in HD patients. METHODS: This study consisted of two phases. In phase 1, antibody titers were measured and compared between HD patients and healthy volunteers (HVs) before and after vaccination against influenza virus. Using antibody titers 4 weeks after vaccination, HD patients and HVs were classified according to seroconversion (i.e., antibody titers against all four strains were >20-fold) or non-seroconversion (i.e., antibody titer against at least one strain was <20-fold). In the phase 2, we examined whether the change in the dialysis membrane from a polysulfone (PS) to a polymethyl methacrylate (PMMA) membrane affected the response to vaccination in HD patients without seroconversion in response to the vaccine the previous year. Patients with seroconversion and non-seroconversion were classified as responders and nonresponders, respectively. Additionally, we compared clinical data. RESULTS: In the phase 1, 110 HD patients and 80 HVs were enrolled, and their seroconversion rates were 58.6% and 72.5%, respectively. In the phase 2, 20 HD patients without seroconversion in response to the vaccine the previous year were enrolled, and the dialyzer membrane was changed to PMMA 5 months before annual vaccination. After annual vaccination, 5 and 15 HD patients were categorized as responders and nonresponders, respectively. In the responders, ß2-microglobulin, white blood cell counts, platelet counts, and serum albumin levels (Alb) were all higher than in the nonresponders. CONCLUSION: The responsiveness to vaccination against influenza virus was lower in HD patients compared with HVs. Changing the dialysis membrane from PS to PMMA appeared to affect the response to vaccination in HD patients.

Changes in practice patterns in Japan from before to after JSDT 2013 guidelines on hemodialysis prescriptions: results from the JDOPPS.

BACKGROUND: The Japanese Society for Dialysis Therapy (JSDT) published in 2013 inaugural hemodialysis (HD) guidelines. Specific targets include 1.4 for single-pool Kt/V (spKt/V) with a minimum dose of 1.2, minimum dialysis session length of 4 hours, minimum blood flow rate (BFR) of 200 mL/min, fluid removal rate no more than 15 mL/kg/hr, and hemodiafiltration (HDF) therapy for certain identified symptoms. We evaluated the effect of these guidelines on actual practice in the years spanning 2005 - 2018. METHODS: Analyses were carried out to describe trends in the above HD prescription practices from December 2005 to April 2013 (before guideline publication) to August 2018 based on prevalent patient cross-sections from approximately 60 randomly selected HD facilities participating in the Japan Dialysis Outcomes and Practice Patterns Study. RESULTS: From April 2006 to August 2017 continual rises occurred in mean spKt/V (from 1.35 to 1.49), and percent of patients having spKt/V>1.2 (71% to 85%). Mean BFR increased with time from 198.3 mL/min (April 2006) to 218.4 mL/min (August 2017) , along with percent of patients with BFR >200 ml/min (65% to 85%). HDF use increased slightly from 6% (April 2006 and August 2009) to 8% by April 2013, but increased greatly thereafter to 23% by August 2017. In contrast, mean HD treatment time showed little change from 2006-2017, whereas mean UFR declined from 11.3 in 2006 to 8.4 mL/Kg/hour in 2017. CONCLUSIONS: From 2006 - 2018 Japanese HD patients experienced marked improvement in reaching the spKt/V target specified by the 2013 JSDT guidelines. This may have been due to moderate increase in mean BFR even though mean HD session length did not change much. In addition, HDF use increased dramatically in this time period. Other HD delivery changes during this time, such as increased use of super high flux dialyzers, also merit study. While we cannot definitively conclude a causal relationship between the publication of the guidelines and the subsequent practice changes in Japan, those changes moved practice closer to the recommendations of the guidelines.

Electrophysiological insights into the relationship between calcium dynamics and cardiomyocyte beating function in chronic hemodialysis treatment.

For patients in which the Ca2+ concentration of dialysis fluid is lower than that in plasma, chronic hemodialysis treatment often leads to cardiac beating dysfunction. By applying these conditions to an electrophysiological mathematical model, we evaluated the impact of body fluid Ca2+ dynamics during treatment on cardiomyocyte beating and, moreover, explored measures that may prevent cardiomyocyte beating dysfunction. First, Ca2+ concentrations in both plasma and interstitial fluid were decreased with treatment time, which induced both a slight decline in beating rhythm on a sinoatrial nodal cell and a wane in contraction force on a ventricular cell. These simulated results were in agreement with clinical observations. Next, a relationship between the intracellular Ca2+ concentration and ion current dynamics of ion transporters were examined to elucidate the mechanism underlying cardiomyocyte beating dysfunction. The inward current of the Na/Ca exchanger (NCX) increased with a decrease in Ca2+ concentration in interstitial fluid and induced a reduction in intracellular Ca2+ concentration during treatment. Furthermore, the decline in intracellular Ca2+ concentration reduced the contraction force. These findings implied that ion transport through the NCX is a dominant factor that induces cardiomyocyte beating dysfunction during hemodialysis. Finally, the replenishment of Ca2+ or application of an NCX inhibitor during treatment suppressed the decrease in intracellular Ca2+ concentration and contributed to the stabilization of cardiomyocyte beating function. In summary, the clinical implementation of hepatically cleared NCX inhibitor may be a suitable approach to improving the quality of life for patients on chronic hemodialysis.

A Clinical Significance of Intermittent Infusion Hemodiafiltration Using Backfiltration of Ultrapure Dialysis Fluid Compared to Hemodialysis: A Multicenter Randomized Controlled Crossover Trial.

BACKGROUND: Intermittent infusion hemodiafiltration -(I-HDF) using repeated infusion of ultrapure dialysis fluid through a dialysis membrane or sterile nonpyrogenic substitution fluid was developed to prevent a rapid decrease in blood pressure by increasing the patient's circulating blood volume, to enhance the plasma refilling rate by improving peripheral circulation, and to enhance solute transfer from the extravascular space to the intravascular space by enhancing the plasma refilling rate. Furthermore, the effect of fouling caused by attachment of proteins to the membrane as a result of ultrafiltration can be reduced by backflushing of the membrane with the purified dialysate in I-HDF. Although there have been several clinical trials of I-HDF, there have been no comparisons of the clinical significance of and indications for -I-HDF with those of conventional hemodialysis (HD). OBJECTIVE: The aim of this multicenter randomized controlled crossover trial was to compare the clinical significance of -I-HDF with that of HD in Japan. METHOD: Patients were randomized to receive HD, I-HDF, and HD (group A) or I-HDF, HD, and I-HDF (group B) in that order for 14 weeks each. The sample size of 70 was determined based on the operability and patient availability. Treatment outcomes were evaluated 5 and 14 weeks after the start of each treatment period. The patients received 4-h treatment sessions with no changes in session duration or anticoagulant therapy during the study. I-HDF was performed using a GC-110N dialysis machine. Two hundred milliliters of ultrapure dialysis fluid were infused at a rate of 150 mL/min by backfiltration every 30 min during treatment. The first and last infusions were performed 30 min after the start and 30 min before the end of treatment, respectively. The total estimated infusion volume per session was 1.4 L (i.e., 200 mL × 7 infusions). I-HDF is a type of online HDF with a small fluid replacement volume. An ABH-P polysulfone membrane hemodiafilter was used for -I-HDF and a class 1 or 2 hemodialyzer with a polysulfone membrane not coated with vitamin E and approved by the Japanese reimbursement system was used for HD. The primary outcomes were the Short Form-36 version 2 summary scores for quality of life and the visual analog scale scores for clinical symptoms. Secondary outcomes were vital signs, number of interventions, and pre-treatment blood test results. These variables were evaluated 1 week before at the start of the study, and at 5 and 14 weeks after the start of each treatment period. The removal characteristics of the various solutes were evaluated when possible on the first day of each treatment period. All patients provided written informed consent to participate. RESULTS: Thirty-two patients in group A and 32 patients in group B completed the trial. There were no differences in the primary or secondary outcomes between I-HDF and HD. Serum α1-microglobulin (MG) levels at 14 weeks were significantly lower for I-HDF than for HD. During treatment, the removal rates for urea and creatinine, which are low molecular weight substances, were significantly lower during I-HDF than during HD. In contrast, the ß2-MG and α1-MG removal rates were significantly higher during I-HDF than during HD. Furthermore, there was significantly less albumin leak during I-HDF than during HD. The solute removal results reflect the difference in pore size between the hemodiafilter used for I-HDF and the hemodialyzer used for HD and the difference in convective transport attributable to filtration between the 2 methods. CONCLUSIONS: These findings show that the removal rates of low molecular weight substances are significantly lower and those of medium to high molecular weight substances are significantly higher with I-HDF than with HD. They also indicate that there is significantly less albumin leak during I-HDF than during HD, meaning that I-HDF may be a particularly suitable dialysis modality for patients with malnutrition and the elderly in Japan.

Patient-reported advantages and disadvantages of peritoneal dialysis: results from the PDOPPS.

BACKGROUND: Patient-reported measures are increasingly recognized as important predictors of clinical outcomes in peritoneal dialysis (PD). We sought to understand associations between patient-reported perceptions of the advantages and disadvantages of PD and clinical outcomes. METHODS: In this cohort study, 2760 PD patients in the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS) completed a questionnaire on their PD experience, between 2014 and 2017. In this questionnaire, PDOPPS patients rated 17 aspects of their PD experience on a 5-category ordinal scale, with responses scored from - 2 (major disadvantage) to + 2 (major advantage). An advantage/disadvantage score (ADS) was computed for each patient by averaging their response scores. The ADS, along with each of these 17 aspects, were used as exposures. Outcomes included mortality, transition to hemodialysis (HD), patient-reported quality of life (QOL), and depression. Cox regression was used to estimate associations between ADS and mortality, transition to HD, and a composite of the two. Logistic regression with generalized estimating equations was used to estimate cross-sectional associations of ADS with QOL and depression. RESULTS: While 7% of PD patients had an ADS < 0 (negative perception of PD), 59% had an ADS between 0 and < 1 (positive perception), and 34% had an ADS ≥1 (very positive perception). Minimal association was observed between mortality and the ADS. Compared with a very positive perception, patients with a negative perception had a higher transition rate to HD (hazard ratio [HR] = 1.67; 95% confidence interval [CI]: 1.21, 2.30). Among individual items, "space taken up by PD supplies" was commonly rated as a disadvantage and had the strongest association with transition to HD (HR = 1.28; 95% CI 1.07, 1.53). Lower ADS was strongly associated with worse QOL rating and greater depressive symptoms. CONCLUSIONS: Although patients reported a generally favorable perception of PD, patient-reported disadvantages were associated with transition to HD, lower QOL, and depression. Strategies addressing these disadvantages, in particular reducing solution storage space, may improve patient outcomes and the experience of PD.

Interdialytic Weight Gain: Trends, Predictors, and Associated Outcomes in the International Dialysis Outcomes and Practice Patterns Study (DOPPS).

BACKGROUND: High interdialytic weight gain (IDWG) is associated with adverse outcomes in hemodialysis (HD) patients. We identified temporal and regional trends in IDWG, predictors of IDWG, and associations of IDWG with clinical outcomes. STUDY DESIGN: Analysis 1: sequential cross-sections to identify facility- and patient-level predictors of IDWG and their temporal trends. Analysis 2: prospective cohort study to assess associations between IDWG and mortality and hospitalization risk. SETTING & PARTICIPANTS: 21,919 participants on HD therapy for 1 year or longer in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases 2 to 5 (2002-2014). PREDICTORS: Analysis 1: study phase, patient demographics and comorbid conditions, HD facility practices. Analysis 2: relative IDWG, expressed as percentage of post-HD weight (<0%, 0%-0.99%, 1%-2.49%, 2.5%-3.99% [reference], 4%-5.69%, and ≥5.7%). OUTCOMES: Analysis 1: relative IDWG as a continuous variable using linear mixed models; analysis 2: mortality; all-cause and cause-specific hospitalization using Cox regression, adjusting for potential confounders. RESULTS: From phase 2 to 5, IDWG declined in the United States (-0.29kg; -0.5% of post-HD weight), Canada (-0.25kg; -0.8%), and Europe (-0.22kg; -0.5%), with more modest declines in Japan and Australia/New Zealand. Among modifiable factors associated with IDWG, the most notable was facility mean dialysate sodium concentration: every 1-mEq/L greater dialysate sodium concentration was associated with 0.13 (95% CI, 0.11-0.16) greater relative IDWG. Compared to relative IDWG of 2.5% to 3.99%, there was elevated risk for mortality with relative IDWG≥5.7% (adjusted HR, 1.23; 95% CI, 1.08-1.40) and elevated risk for fluid-overload hospitalization with relative IDWG≥4% (HRs of 1.28 [95% CI, 1.09-1.49] and 1.64 [95% CI, 1.27-2.13] for relative IDWGs of 4%-5.69% and ≥5.7%, respectively). LIMITATIONS: Possible residual confounding. No dietary salt intake data. CONCLUSIONS: Reductions in IDWG during the past decade were partially explained by reductions in dialysate sodium concentration. Focusing quality improvement strategies on reducing occurrences of high IDWG may improve outcomes in HD patients.

Significance of tonsillectomy combined with steroid pulse therapy for IgA nephropathy with mild proteinuria.

BACKGROUND: Medical intervention for patients with IgA nephropathy and mild proteinuria (<1.0 g/day) is controversial, and the effectiveness of tonsillectomy plus steroid pulse therapy (TSP) for such patients remains obscure. METHODS: Among 323 patients in our multicenter cohort study, 79 who had mild proteinuria (0.4-1.0 g/day) at diagnosis were eligible to participate in this study. We compared the clinicopathological findings at diagnosis, a decline in renal function defined as a 50 or 100% increase in serum creatinine (sCr) and clinical remission (CR) defined as the disappearance of hematuria and proteinuria (<0.3 g/day) among groups given TSP (n = 46), steroid therapy (ST) (n = 9), and non-ST (n = 24). Factors contributing to CR were also evaluated using multivariate analysis. RESULTS: Background factors at diagnosis including age, ratio (%) of patients with hypertension, sCr, proteinuria, and histological severity did not significantly differ among the groups. Only two patients each in the TSP (4.3%) and non-ST (8.3%) groups achieved a 50% increase in sCr during a mean follow-up period of 4.7 years. At the final observation, 71.7, 44.4, and 41.7% of patients in the TSP, ST, and non-ST groups, respectively, achieved CR (p = 0.032). Cox proportional hazards models revealed that TSP led to CR more effectively than non-TSP by a factor of about threefold (hazard ratio, 2.74; p = 0.008). CONCLUSION: TSP therapy has potential for inducing CR in patients with IgAN and mild proteinuria (<1.0 g/day).

Impact of tonsillectomy combined with steroid pulse therapy on immunoglobulin A nephropathy depending on histological classification: a multicenter study.

BACKGROUND: In addition to corticosteroids and inhibition of the renin-angiotensin-aldosterone system, tonsillectomy with steroid pulse therapy (TSP) may have a beneficial impact on the clinical course of IgA nephropathy (IgAN). However, there is still much uncertainty regarding the indications for therapy, treatment protocol, and therapeutic options for IgAN. METHODS: In this multicenter retrospective cohort study, we enrolled 284 patients with biopsy-proven IgAN who received TSP or corticosteroid therapy or conservative therapy. The effects of TSP on clinical remission (CR) were evaluated after a median follow-up period of 4.1 years in relation to histological classifications. RESULTS: Among the 284 participants, 161 patients received TSP. During the observation time, 141 patients (49.6%) achieved CR, with a median time to remission of 397 days. In multivariate Cox regression analyses, TSP had an impact on achieving CR in only the group with histological grade 3 defined as glomerulosclerosis, crescent formation or adhesion to Bowman's capsule in 10-30% of all biopsied glomeruli, or mild cellular infiltration in the interstitium (hazard ratio (HR) 4.29, 95% confidence interval (95%CI) 1.88-11.19, P < 0.001). TSP independently contributed to a higher incidence of CR, particularly in the patient group showing evident mesangial hypercellularity (HR 2.54, 95%CI 1.38-5.08, P = 0.002). CONCLUSIONS: TSP may have a beneficial effect on the clinical course in IgAN patients with mild to moderate glomerular and interstitial lesions, particularly with distinct mesangial cell proliferation.

The Impact of Potassium Dynamics on Cardiomyocyte Beating in Hemodialysis Treatment.

Background: Observational studies of intermittent hemodialysis therapy have reported that the excess decrease in K+ concentration in plasma (KP) during treatment is associated with the destabilization of cardiac function. Elucidating the mechanism by which the decrease in KP impairs myocardial excitation is indispensable for a deeper understanding of prescription design. Methods: In this study, by using an electrophysiological mathematical model, we investigated the relationship between KP dynamics and cardiomyocyte excitability for the first time. Results: The excess decrease in KP during treatment destabilized cardiomyocyte excitability through the following events: (1) a decrease in KP led to the prolongation of the depolarization phase of ventricular cells due to the reduced potassium efflux rate of the Kr channel, temporarily enhancing contraction force; (2) an excess decrease in KP activated the transport of K+ and Na+ through the funny channel in sinoatrial nodal cells, disrupting automaticity; (3) the excess decrease in KP also resulted in a significant decrease in the resting membrane potential of ventricular cells, causing contractile dysfunction. Avoiding an excess decrease in KP during treatment contributed to the maintenance of cardiomyocyte excitability. Conclusions: The results of these mathematical analyses showed that it is necessary to implement personal prescription or optimal control of K+ concentration in dialysis fluid based on predialysis KP from the perspective of regulatory science in dialysis treatment.

Association of dialysate bicarbonate concentration with mortality in the Dialysis Outcomes and Practice Patterns Study (DOPPS).

BACKGROUND: Most hemodialysis patients worldwide are treated with bicarbonate dialysis using sodium bicarbonate as the base. Few studies have assessed outcomes of patients treated with different dialysate bicarbonate levels, and the optimal concentration remains uncertain. STUDY DESIGN: The Dialysis Outcomes and Practice Patterns Study (DOPPS) is an international prospective cohort study. SETTING & PARTICIPANTS: This study included 17,031 patients receiving thrice-weekly in-center hemodialysis from 11 DOPPS countries (2002-2011). PREDICTOR: Dialysate bicarbonate concentration. OUTCOMES: All-cause and cause-specific mortality and first hospitalization, using Cox regression to estimate the effects of dialysate bicarbonate concentration, adjusting for potential confounders. MEASUREMENTS: Demographics, comorbid conditions, laboratory values, and prescriptions were abstracted from medical records. RESULTS: Mean dialysate bicarbonate concentration was 35.5 ± 2.7 (SD) mEq/L, ranging from 32.2 ± 2.3 mEq/L in Germany to 37.0 ± 2.6 mEq/L in the United States. Prescription of high dialysate bicarbonate concentration (≥38 mEq/L) was most common in the United States (45% of patients). Approximately 50% of DOPPS facilities used a single dialysate bicarbonate concentration. 3,913 patients (23%) died during follow-up. Dialysate bicarbonate concentration was associated positively with mortality (adjusted HR, 1.08 per 4 mEq/L higher [95% CI, 1.01-1.15]; HR for dialysate bicarbonate ≥38 vs 33-37 mEq/L, 1.07 [95% CI, 0.97-1.19]). Results were consistent across levels of pre-dialysis session serum bicarbonate and between facilities that used a single dialysate bicarbonate concentration and those that prescribed different concentrations to individual patients. The association of dialysis bicarbonate concentration with mortality was stronger in patients with longer dialysis vintage. LIMITATIONS: Due to the observational nature of the present study, we cannot rule out that the reported associations may be biased by unmeasured confounders. CONCLUSIONS: High dialysate bicarbonate concentrations, especially prolonged exposure, may contribute to adverse outcomes, likely through the development of postdialysis metabolic alkalosis. Additional studies are warranted to identify the optimal dialysate bicarbonate concentration.

Optimal composition of dialysis fluid for on-line hemodiafiltration in central dialysis fluid delivery system.

In this paper, we propose 'the preferred composition of dialysis fluid for on-line hemodiafiltration (HDF) in central dialysis fluid delivery system, (CDDS)': sodium concentration 138-140 mEq/l; potassium concentration 2.0 mEq/l; calcium concentration 2.5-3.5 mEq/l; glucose concentration 1.0-1.5 g/l; buffer: bicarbonate (acetate free is preferred). Concentrations of electrolytes in dialysis fluid (= substitution fluid) are applied to the compositions of launched dialysis fluid in Japan. From the viewpoint of biocompatibility and correction of metabolic acidosis, acetate-free bicarbonate buffer is thought to be important. This proposal of the preferred composition of dialysis fluid for on-line HDF in CDDS is based on a few reports. Further investigations and research to reveal the optimal composition of dialysis fluid for on-line HDF are expected in the future.

Mortality, hospitalization and transfer to haemodialysis and hybrid therapy, in Japanese peritoneal dialysis patients.

BACKGROUND AND OBJECTIVES: Survival of peritoneal dialysis (PD) patients in Japan is high, but few reports exist on cause-specific mortality, transfer to haemodialysis (HD) or hybrid dialysis and hospitalisation risks. We aimed to identify reasons for transfer to HD, hybrid dialysis and hospitalisation in the Japan Peritoneal Dialysis and Outcomes Practice Patterns Study. METHODS: This observational study included 808 adult PD patients across 31 facilities in Japan in 2014-2017. Information on all-cause and cause-specific mortality and hospitalisation and permanent transfer to HD and PD/HD hybrid therapy were prospectively collected and rates calculated. RESULTS: Median follow-up time was 1.66 years where 162 patients transferred to HD, 79 transferred to hybrid dialysis and 74 patients died. All-cause and cardiovascular disease (CVD)-related mortality rates were 5.1 and 1.7 deaths/100 patient-years, respectively. Rates of transfer to HD and hybrid therapy were 11.2 and 5.5 transfers/100 patient-years, respectively. Among HD transfers, 40% were due to infection (including peritonitis), while 20% were due to inadequate solute/water clearance. Eighty-one percent of hybrid dialysis transfers were due to inadequate solute/water clearance. All--cause, peritonitis-related and CVD-related hospitalisation rates were 120.4, 21.1 and 15.6/100 patient-years, respectively. Median hospital length of stay was 19 days. CONCLUSIONS: Mortality, hospitalisation and transfer to HD/hybrid dialysis rates are relatively low in Japan compared to many other countries with hybrid transfers, accounting for one-third of dialysis transfers from PD. Further study is needed to explain the high inter-facility variation in hospitalisation rates and how to further reduce hospitalisation rates for Japanese PD patients.

Mechanism of action of non-camptothecin inhibitor Genz-644282 in topoisomerase I inhibition.

Topoisomerase I (TOP1) controls the topological state of DNA during DNA replication, and its dysfunction due to treatment with an inhibitor, such as camptothecin (CPT), causes replication arrest and cell death. Although CPT has excellent cytotoxicity, it has the disadvantage of instability under physiological conditions. Therefore, new types of TOP1 inhibitor have attracted particular attention. Here, we characterised the effect of a non-camptothecin inhibitor, Genz-644282 (Genz). First, we found that treatment with Genz showed cytotoxicity by introducing double-strand breaks (DSBs), which was suppressed by co-treatment with aphidicolin. Genz-induced DSB formation required the functions of TOP1. Next, we explored the advantages of Genz over CPT and found it was effective against CPT-resistant TOP1 carrying either N722S or N722A mutation. The effect of Genz was also confirmed at the cellular level using a CPT-resistant cell line carrying N722S mutation in the TOP1 gene. Moreover, we found arginine residue 364 plays a crucial role for the binding of Genz. Because tyrosine residue 723 is the active centre for DNA cleavage and re-ligation by TOP1, asparagine residue 722 plays crucial roles in the accessibility of the drug. Here, we discuss the mechanism of action of Genz on TOP1 inhibition.

Acetate-free blood purification can impact improved nutritional status in hemodialysis patients.

Effects of online hemodiafiltration (HDF) using acetate-free bicarbonate dialysis (AFD) fluid on microinflammation, resulting in improved nutritional status in hemodialysis patients, were examined and compared with conventional acetate-containing bicarbonate dialysis (ACD) fluid. A total of 24 hemodialysis patients were registered for a cross-over design study for a 6-month period. These patients were subjected to ACD for the first 3 months followed by AFD fluid for the latter 3 months. Blood variables of C-reactive protein (CRP), interleukin-6 (IL-6), leptin, neuropeptide Y (NPY), protein catabolic rate (PCR) and %creatinine (Cr) index were determined after the first and last 3-month period. The filters and the conditions of HDF and drug regimens including erythropoiesis-stimulating agents were unchanged throughout the cross-over study. Predialysis blood pH and bicarbonate were significantly higher in the AFD phase than in the ACD phase. Blood CRP and IL-6 levels were significantly decreased in the AFD group compared to the ACD group. Concerning nutritional evaluation, leptin and NPY were significantly lower and higher, respectively, in the AFD phase than in the ACD phase. PCR tended to be higher in the AFD phase than in the ACD phase. A significantly higher %Cr index level was observed in the AFD phase than in the ACD phase. These results suggest that online HDF using AFD fluid contributes to alleviating bioincompatible events associated with microinflammation, leading to improvement in the nutritional status in hemodialysis patients.

Prospective multicenter observational study of encapsulating peritoneal sclerosis with neutral dialysis solution--the NEXT-PD study.

Many observational studies have been conducted on the occurrence of encapsulating peritoneal sclerosis (EPS). However, poorly biocompatible acidic glucose-based dialysis solutions were used in all previous studies. Today, dialysis solutions that are more biocompatible have become widely available. We therefore initiated a new prospective observational study on the occurrence of EPS. The study design is based on that of a previous study conducted in Japan that used solutions high in glucose degradation products (GDPs). Patients undergoing dialysis with a low-GDP dialysis solution, which is considered to show excellent biocompatibility, will be followed for 4 years, and the study will evaluate withdrawal from peritoneal dialysis, incidence of EPS, and factors related to EPS occurrence with the new dialysis solution. This study is expected to clarify the effects of biocompatible dialysis solutions.

Glutathione depletion as a mechanism of 3,4-dideoxyglucosone-3-ene-induced cytotoxicity in human peritoneal mesothelial cells: role in biocompatibility of peritoneal dialysis fluids.

BACKGROUND: The potential detrimental effects of glucose degradation products (GDPs) contained in peritoneal dialysis fluids (PDFs) on peritoneal mesothelial cells (PMCs) may impair intraperitoneal homeostasis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). A recent study showed that 3,4-dideoxyglucosone-3-ene (3,4-DGE) was the most strongly cytotoxic among all identified GDPs in PDFs. The present study examined the effects of clinically relevant concentrations of 3,4-DGE on the proliferative capacity of PMCs and oxidative injury to them. METHOD: The concentrations of eight GDPs in commercially available PDFs were determined by HPLC. The effect of cell growth media spiked with GDPs on the proliferation capacity of PMCs was evaluated. As a marker of the cellular redox status, total cellular glutathione (tGSH) was determined in PMCs incubated with GDPs. The reaction of 3,4-DGE with GSH under nonenzymatic conditions was analysed by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). RESULT: The concentrations of 3,4-DGE in a heat-sterilized single-compartment standard-type PDF (S-PDF) and in a heat-sterilized dual-chamber-type PDF (N-PDF) were 16 microM and 1.7 microM, respectively. The most cytotoxic GDP was 3,4-DGE, and the concentration at which it causes 50% inhibition of cell growth was 35 microM. A significant decrease in the cellular tGSH levels was observed in the cells treated with 10 microM 3,4-DGE. 3,4-DGE disappeared on incubation with GSH under nonenzymatic conditions for 1 h, and the 3,4-DGE-GSH conjugate was confirmed by accurate mass measurement using LC-ESI-MS. These data demonstrated that the change in the cellular redox status by GSH depletion might be a contributory factor in 3,4-DGE-induced cytotoxicity. CONCLUSION: 3,4-DGE is a highly reactive GDP and is responsible for the depletion of the total intracellular glutathione. 3,4-DGE has an intense impact on PMC growth at concentrations found in standard PDFs. It is desired that the amount of 3,4-DGE in PDFs should be minimized.

Tonsillectomy and steroid pulse (TSP) therapy for patients with IgA nephropathy: a nationwide survey of TSP therapy in Japan and an analysis of the predictive factors for resistance to TSP therapy.

BACKGROUND: Tonsillectomy and steroid pulse (TSP) therapy was proposed as a curative treatment for IgA nephropathy by Hotta et al. (Am J Kidney Dis 38:736-742, 2001) based on data that about 50% of patients achieved clinical remission (CR) of urinary abnormalities. MATERIALS AND METHODS: As a primary survey, we sent a questionnaire and letter to 848 hospitals in Japan, each of which employed a Fellow of the Japanese Society of Nephrology between October and December of 2006, in order to gather information about the prevalence and efficacy of TSP therapy for patients with IgA nephropathy. As a secondary survey, we collected data from both low- and high-CR-rate groups to determine which factors predicted resistance to TSP therapy. RESULTS: A total of 2,746 patients received TSP therapy between 2000 and 2006. The CR rates, calculated by measuring urinary criteria 6 and 12 months after TSP therapy, were 32.0% (347/1,085) and 45.6% (452/991), respectively. Analysis of the 30 hospitals in which TSP therapy had been performed on at least ten patients revealed that the CR rates varied from below 10% to 100%. A secondary survey of ten hospitals revealed that, after correction of the CR rate from each hospital, patients could be categorized into three groups: those with a low CR rate (122 patients in four hospitals), a middle CR rate (78 patients in four hospitals), and a high CR rate (103 patients in two hospitals). The CR rate of all patients (N = 303) was 54.1%. A comparison of patient data between the low- and high-CR-rate groups showed a significant difference in age at onset (years; P = 0.05), amount of proteinuria (g/day; P = 0.02), total protein (g/dl; P = 0.02), pathological grade (P = 0.009), and prognostic score as described by Wakai et al. [Nephrol Dial Transplant 21:2800-2808, 2006, (P = 0.04)]. Univariate analysis revealed that there was a significant difference between non-CR and CR subgroups in duration from diagnosis until TSP therapy (6.9 +/- 6.8 versus 5.3 +/- 5.2 years; P = 0.02), amount of proteinuria (1.5 +/- 1.6 versus 0.8 +/- 0.8 g/day; P < 0.0001), serum creatinine (0.99 +/- 0.40 versus 0.87 +/- 0.34 mg/dl; P = 0.006), pathological grade (P = 0.0006), and Wakai et al.'s prognostic score (37.4 +/- 17.8 versus 28.1 +/- 15.1; P < 0.0001). A multivariate logistic analysis demonstrated that resistance to TSP therapy depends on age at onset, amount of proteinuria, hematuria grade, and pathological grade, and a score predicting resistance to TSP therapy could be derived by the formula: [(-0.0330) x (age) + (0.4772) x log (amount of proteinuria) - (0.0273) x (hematuria grade: 0, 1, 2, and 3) + (0.7604) x (pathological grade: 1, 2, 3, and 4) - 0.1894]. A receiver operating characteristic (ROC) curve showed that patients with a resistance score of greater than -0.02 easily resist TSP therapy (sensitivity 69%, specificity 75%, positive likelihood ratio 2.76). CONCLUSION: TSP therapy shows promise as a treatment that can bring about CR of urinary abnormalities, but unfortunately the average CR rate is about 50% at 1 year after treatment. Predictive factors for resistance to TSP therapy are age at onset, amount of proteinuria, hematuria grade, and pathological grade. The present study suggests that patients with either early-stage or mild to moderate IgA nephropathy easily achieve CR following TSP therapy, whereas patients with late-stage or severe disease are prone to TSP therapy resistance.

Standardization of water purification in the central dialysis fluid delivery system: validation and parametric method.

The central dialysis fluid delivery system (CDDS) has been mainly used for hemodialysis therapy in Japan. Validation and a parametric method are necessary for the quality control of dialysis fluid in CDDS. Validation is a concept for the assurance of system compatibility and product quality, and is defined as follows: the manufacturing and quality control methods including the system design and equipment of the manufacturing facility, manufacturing procedure and processes. Confirmed results must be kept within acceptable limits and they must be documented in a record. Important parameters for validating CDDS include: (1) setting the sterilized area; (2) decision of sterilization level; (3) confirmation of the maximum bio-burden; (4) performance of endotoxin retentive filter and reverse osmosis (RO) module, and (5) checkpoints of purity of dialysis water in the system. Taking the concept of validation and a parametric method in the management of CDDS into consideration enables the supply the purified dialysis fluid or the online prepared substitution fluid that meet the 2008 standards of the Japanese Society for Dialysis Therapy.

The new standard of fluids for hemodialysis in Japan.

The standard of fluids for hemodialysis is being evaluated by the International Organization for Standardization (ISO), and will be decided within a few years. In 2008, the Japanese Society for Dialysis Therapy (JSDT) proposed the standard of fluids for hemodialysis by taking the draft ISO standard into consideration and the circumstances in Japan. It was characteristically a standard for Japan, where the central dialysis fluid delivery system (CDDS) is routinely used. In addition, the therapeutic application of each dialysis fluid is clarified. Since high-performance dialyzers are frequently employed in Japan, the standard recommends that ultrapure dialysis fluid be used for all dialysis modalities at all dialysis facilities. It also recommends that the dialysis equipment safety management committee at each facility validate the microbiological qualities of online-prepared substitution fluid, making the responsibility of the dialysis facility clear. This standard is more rigid than those of other countries, and is expected to contribute to improvements in the survival outcome of dialysis patients.