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Membranes made from synthetic polymers, in general, are considered as being biocompatible membranes and tend to be treated as a homogeneous group. However, all of these membranes have multiple and different characteristics that may contribute to interactions with blood components. As a consequence, the biocompatibility profile of synthetic membranes may vary. In the present cross-over study, we examined by flow cytometry the effects (expressed as % change from predialysis values) of three different synthetic polymers (polysulfone, PSF; polyacrylonitrile-co-sodium methallyl sulfonate, AN69; ethylenevinylalcohol, EVAL) on the expression of leukocyte adhesion molecules (CD11b/CD18, CD15s) and the interactions between leukocytes and platelets under conditions of routine clinical use. For neutrophils, a statistically significant difference was found in CD15s expression for EVAL as compared to AN69 (p Our data demonstrate that in terms of leukocyte adhesion receptors and platelet-leukocyte interactions, the biocompatibility profile of the synthetic membranes polysulphone, AN69 and EVAL shows many similarities but also several significant differences. Our results support the concept that biocompatibility evaluation of each membrane should be based exclusively on data generated by that membrane in order to avoid errors based on assumptions about group characteristics.

High molecular weight (MW) solutes are not removed during conventional hemodialysis (HD), and their accumulation is thought to play a role in some long-term HD complications (anemia, bone and joint pain, neuropathy, itching). The present trial was conducted to evaluate the removal capacity during in vivo HD of a new polymethylmethacrylate (PMMA) membrane (Filtryzer BK-F, 1.3 m2) compared to conventional PMMA (BK-P, 1.6 m2) and to cellulose acetate (CA, 1.3 m2). BK-F dialyzers, with a pore size of 100 A° and 62% porosity, are designed to remove high MW substances. Ten stable anuric RDT patients (53 ± 13 years) were treated for one week with each membrane in a randomized sequence. Plasma concentrations of creatinine, BUN and beta2-microglobulin (beta2-M) were measured before (b) and after (a) HD to determine the reduction rate for these substances (%). Beta2-M concentration after HD was corrected for changes in distribution volume. Samples of spent dialysate were collected after 3 minutes, 120 minutes and at the end of HD sessions, and appropriately treated and concentrated for HPLC analysis. The reduction rate for BUN and creatinine was similar for the 3 membranes. BK-F showed a higher beta2-M reduction rate than BK-P (p 10 kDa were infrequently detected. Peak profile during HD with BK-F was quite different, showing a predominant peak > 50 kDa which also included albumin. However, albumin loss significantly decreased after 120 minutes and at the end of dialysis compared with the 3-minute values, and was lower than that reported in CAPD patients. With BK-F a peak of MW > 500 kDa was also detected which previous studies indicated as a range characterized by the presence of erythropoiesis inhibitors. Use of the BK-F membrane in HD could afford satisfactory removal of high MW substances, thereby preventing or controlling some long-term HD complications such as anemia or beta2-M amyloid formation.

The use of recombinant human erythropoietin (rHuEPO) has revolutionized the treatment of renelanemia, but the dose regimens, the optimal frequency, and the effects on other target organs like the central nervous systems (CNS) are still under discussion. We designed a prospective, ongoing study with 10 stable continuous ambulatory peritoneal dialysis (CAPO) patients (6 males, 4 females; mean age 64.4±7.8 years), with a pretreatment hemoglobin (Hb) The target hematocrit was 33% and Hb 10.0 g%. The CNS activity was recorded as visual (YEP), brainstem (BAER), and somatosensory (SEP)-evoked potentials. The mean Hb concentration Increased from 6.9± 1.2g% to 10.3± 1.6 g% (p Parallel to the Improvement of red cell Indices, patients experienced a dramatic Improvement In well-being. The subcutaneous administration of a single vial of rHuEPO Is safe, convenient, and Inexpensive In CAPO. The role of rHuEPO treatment In Improving the electro-physiological brain function In uremic and anemic patients remains to be studied and may not necessarily be based on Improved cerebral oxygenation.