Intradialytic ultrafiltration volume and vascular access outcomes: a Japan Dialysis Outcomes and Practice Patterns Study subanalysis.

INTRODUCTION: The relationship between intradialytic ultrafiltration volume and vascular access (VA) patency remains unclear. Using data from the Japan Dialysis Outcomes and Practice Patterns Study, we analyzed whether large-volume ultrafiltration was associated with VA failure in hemodialysis patients. METHODS: We included 2736 patients for whom it was possible to evaluate VA patency and bodyweight change during dialysis. Patients were divided into three groups according to the tertile of intradialytic ultrafiltration by bodyweight: low, -9.5%-3.8%; middle, 3.8%-5.1%; and high, 5.1%-13.7%. Primary VA patency was defined as the time to first VA intervention, and secondary patency as the time to creation of a new VA. Hazard ratios for VA failure were compared across groups by using Cox regression models adjusted for age, sex, body mass index, diabetes, hemoglobin and phosphorus levels, Kt/V, and erythropoiesis-stimulating agent and antiplatelet use. RESULTS: For the low, middle, and high groups, the incidences of primary and secondary VA patency were 4.7, 5.6, and 6.7 events/100 person-years and 1.3, 1.6, and 1.7 events/100 person-years, respectively. Adjusted hazard ratios for primary VA patency in the middle and high groups versus the low group were 1.16 (95% confidence interval [CI], 0.88-1.52) and 1.41 (95% CI, 1.07-1.87), respectively; those for secondary VA patency were 1.29 (95% CI, 0.78-2.13) and 1.45 (95% CI, 0.86-2.45), respectively. DISCUSSION: Large-volume ultrafiltration during dialysis tended to increase VA failure in hemodialysis patients. We thus recommend smaller ultrafiltration volumes during hemodialysis to secure VA safely.

Vascular access care and treatment practices associated with outcomes of arteriovenous fistula: international comparisons from the Dialysis Outcomes and Practice Patterns Study.

BACKGROUND: Vascular access (VA) guidelines recommend the native arteriovenous fistula (AVF) as VA of first choice for chronic hemodialysis patients. AVF management is important in hemodialysis patient care. AVF survival is associated with various physical factors, but the effects of dialysis treatment factors upon AVF survival are still not clear. METHODS: Study patients were treated at 498 dialysis facilities participating in the Dialysis Outcomes and Practice Patterns Study (DOPPS) 2 or 3 (2002-2007). Analyses included 1,183 incident hemodialysis patients (on dialysis ≤7 days and using an AVF at study entry) and 949 prevalent patients (on dialysis >7 days at DOPPS entry and using a new AVF created during study observation). AVF survival was modeled from the study entry date for incident patients and date of first AVF use for prevalent patients. Predictors of primary and final AVF survival were compared across Japan, North America and Europe/Australia/New Zealand (EUR/ANZ) with adjustments for patient characteristics. RESULTS: No meaningful relationship was seen between AVF survival and various physician and staff practices. However, patients with prior catheter use displayed higher rates of primary and final AVF failure. Final AVF failure rates were higher in facilities with higher median blood flow rates (BFR). They were also greater in North America and EUR/ANZ than in Japan, but this difference was substantially attenuated after accounting for regional differences in facility median BFR. CONCLUSION: AVF longevity differed according to the DOPPS region, and was related to prior patient catheter use and facility BFR practice. Further longitudinal studies may help demonstrate meaningful associations between VA-handling skill and patency.

Gene cloning and characterization of dihydrolipoamide dehydrogenase from Microbacterium luteolum: A useful enzymatic regeneration system of NAD+ from NADH.

Dihydrolipoamide dehydrogenase (LPD), a useful biocatalyst for regenerating NAD(+), was purified from Microbacterium luteolum JCM 9174, and the gene encoding LPD was cloned from the genomic DNA. The gene contained an opening reading frame consisting of 1395 nucleotides encoding 465 amino acid residues with a predicted molecular weight of 49912.1 Da, which displayed 36-78% homology to known LPDs. Moreover, the FAD- and NAD(+)-binding sites and the two catalytic residues in the LPDs were conserved. The enzyme was expressed in recombinant Escherichia coli cells and purified to homogeneity by column chromatography. LPD of M. luteolum (MluLPD) accepted not only lipoamide but also some artificial electron acceptors such as dichlorophenolindophenol (DCIP) and nitrotetrazolium blue (NTB), that is, it functions as a diaphorase. NAD(+) demonstrated a strong activating effect on MluLPD, and the activity was 5.2 times higher than that without NAD(+). The enzyme was suitable for regenerating NAD(+) in biocatalytic reactions because of its high affinity for NADH (6.1 microM). An NAD(+)-regenerating system with MluLPD and laccase using 2,5-dimethoxy-1,4-benzoquinone as a hydrogen acceptor was demonstrated.

Renal proximal tubular metabolism of protein-linked pentosidine, an advanced glycation end product.

BACKGROUND: Pentosidine, an advanced glycation end product, accumulates in plasma proteins of uremic patients. Its fate is, however, yet to be fully understood. METHODS: Three cell lines, JTC-12 (proximal tubular cells), MDCK (distal tubular cells), and BALB3T3 (nonrenal cells), were cultured in a double chamber system and were exposed to uremic serum, and the contents of protein-linked pentosidine derived from uremic sera were determined in each medium by HPLC assay. The presence of pentosidine in the cytoplasm of these cells was assessed by immunoperoxidase staining. RESULTS: When the apical cell membrane was exposed to uremic serum (fortified in the upper chamber), the contents of protein-linked pentosidine in the upper medium decreased by up to 30% after 24- and 48-hour incubations of JTC-12 cells but not of other cells. On the other hand, the contents of protein-linked pentosidine in the lower medium did not change. By contrast, exposure of the basolateral cell membrane of the three cell lines to uremic serum (fortified in the lower chamber) did not change the contents of protein-linked pentosidine both in the upper and lower medium after a 24-hour incubation. Pentosidine was detected immunohistochemically in the cytoplasm of JTC-12 cells, but not of BALB3T3 and MDCK cells, the apical membranes of which were exposed to uremic sera for 8 h. The immunoreaction disappeared 48 h after exposure. Pentosidine was not detected in the cytoplasm of JTC-12 cells, the basolateral membranes of which were exposed to uremic sera. The relevance of the in vitro results to humans was demonstrated by immunohistochemical studies in normal human kidney tissues showing that pentosidine was identified in the proximal renal tubules. CONCLUSION: These results suggest that the proximal tubular cells play a role in the disposal of plasma pentosidine.

Evaluation of Na+ active transport and morphological changes for bioartificial renal tubule cell device using Madin-Darby canine kidney cells.

The function of current hemodialysis as an artificial kidney is insufficient because of the lack of reabsorptive function. In this study, we intend to develop a bioartificial renal tubule cell device (RTD) using tubular epithelial cells and artificial membranes and to evaluate the reabsorptive function of the confluent layers. Madin-Darby canine kidney (MDCK) cells were cultured on a nucleopore polycarbonate membrane for up to 4 weeks after confluence to examine the influence of the culture period on their ability to transport Na+ actively using Na+/K+ATPase (NKA). The results were (1) active Na+ transport of the cells averaged 24.8 mM/m(2) x 24 h during the initial 2 weeks after confluence and then decreased to about 4.2 mM/m(2) x 24 h during the next 2 weeks; (2) NKA localized on the basal-lateral sides of the cells during the initial 2 weeks, whereas it also localized on the apical side of the cells during the next 2 weeks; (3) long-term culture resulted in an increased number of upheaving cell mass, increased fatty droplets in the cells, and necrosis; and (4) scanning electron microscopy showed fewer microvilli 3-four weeks after confluence. It is concluded that the culture period is critical for developing RTD using cultured renal tubular epithelial cells.