Ultrafiltration and endotoxin removal from dialysis fluids.

Biocompatibility in hemodialysis is now regarded as a multifactorial problem and dialysate represents a main risk. Pyrogenic fractions mostly coming from gram-negative bacteria easily pass through dialysis membrane, either by backdiffusion or by backfiltration, and induce blood cell activation. To demonstrate the long-term efficiency of a 2 m2 polyamide ultrafilter in producing a pyrogen free solution, we used an experimental circuit ultrafiltering for 240 hours (500 ml/min) a bicarbonate dialysate contaminated (5 to 48 EU/ml) by a Pseudomonas aeruginosa filtrate. The efficiency was monitored by LAL-test and IL-1 PBMC so to detect not only lipid A containing endotoxins but also other cytokines inducing bacterial fractions. At the post-ultrafilter sampling port the LAL-test was < 0.005 to 0.034 EU/ml; IL-1 PBMC was below the detection limit (20 pg/ml) being 27 to 63 pg/ml at the pre-ultrafilter level. Polyamide ultrafiltration represents an efficient system to obtain an endotoxin-free dialysate and a single filter works up to 240 hours.

Removal of limulus reactivity and cytokine-inducing capacity from bicarbonate dialysis fluids by ultrafiltration.

Bicarbonate-based dialysate solutions support the rapid growth of bacteria. The long-term (360-h) efficacy of ultrafiltration by two polysulphone ultrafilters in removing not only endotoxin but also the cytokine(IL-1, TNF)-inducing capacity was evaluated using an experimental circuit contaminated with Pseudomonas aeruginosa filtrates. One of the polysulphone ultrafilters was submitted to a standard sanitization procedure every 12 h (hypochlorite 1.2% solution for 5 min and rinsing for 20 min). Endotoxin was detected by the kinetic quantitative chromogenic limulus amoebocyte lysate (LAL) assay. Immunoreactive IL-1 and TNF were evaluated in the lysates of peripheral blood mononuclear cells containing 5 x 10(5) human monocytes. The results of the present studies show that although LAL-reactive bacterial products were significantly removed in post-ultrafilter samples, they remained detectable, albeit below the upper limit accepted by the present European pharmacopeias (< 0.125 EU/ml). The removal of cytokine-inducing capacity was time-dependent and correlated with time of use in the case of the sanitized ultrafilter. Beyond the time of use, two other factors emerged as possibly capable of reducing the efficacy of the ultrafilter in removing LAL-reactive bacterial components, namely the pressure and the cytokine-inducing activity in pre-ultrafilter samples. Preincubation with polymyxin B, an agent that irreversibly binds lipid A and blocks lipid A-induced biological activities, did not abrogate the cytokine-inducing capacity in all post-ultrafilter samples; this suggests that either low-molecular-weight endotoxin subunits or lipid A-unrelated components may be responsible for the residual biological activity in post-ultrafilter samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Liquid nitrogen snap frozen saphenous vein for vascular access in dialysis.

In the authors' centers, fresh saphenous veins (FSV) procured from routine saphenectomies have been preferred to synthetic prostheses in cases of difficult vascular accesses (VA) for dialysis. The need for veins of different lengths and diameters prompted them to preserve SV by instantaneous freezing in liquid nitrogen since November 1987. Until now, 59 patients have received 35 FSV and 32 cryopreserved SV (CSV). Actuarial patency rates after 1 year are 82% and 72%, respectively. The 6-keto prostaglandin F1 alpha measured on punches of both veins showed residual production of prostacyclin even in CSV, but this was unresponsive to stimulation by arachidonic acid and bradykinin, or to inhibition by aspirin. In the authors' opinion, despite marked endothelial damage, satisfactory clinical results can be obtained by this very simple and cheap method of storing biologic prostheses for dialysis VA.

[Prolonged preservation of venous allografts for vascular access in hemodialysis]. / Conservation prolongée d'allogreffes veineuses pour les abords vasculaires en hémodialyse.

The technique of deep-freezing in liquid nitrogen of stripped saphenous veins permitted their long-term preservation, and the subsequent creation of a "bank" of venous allografts, used for arteriovenous internal shunts for hemodialysis. Histological, histochemical and immunological tests, and first clinical results have been favorable.

Absence of rejection in cryopreserved saphenous vein allografts for hemodialysis.

Since November 1987, a total of 16 dialysis patients in the authors' Center, received a cryopreserved saphenous vein allograft (CSVA) as "third choice" vascular access. ABO and HLA-A-B compatibilities were determined but not considered. Saphenous veins were cryopreserved in liquid nitrogen for variable periods (1-6 mo), so that there was the opportunity to choose the most suitable in dimension. In February, 1989, a total of 13 patients retained a well-functioning access site, whereas three had died from causes unrelated to CSVA. Because rejection of venous allografts still is debated among angiologists, recipient T lymphocyte subsets (CD3-CD4-CD8 and CD4/8) were examined, as were lymphocytotoxic antibodies, before and on days 15 and 30 after implantation. No evidence of immunologic activation was found. Moreover, in 10 of 16 patients the surgeons subcutaneously implanted a fragment of CSVA, and an immunohistochemical study was carried out using an alkaline phosphatase-antialkaline phosphatase (APAAP) technique and a panel of monoclonal antibodies. Minimal infiltration of the outer layer of adventitia was found, mainly caused by monocyte macrophages (Leu M3+) with few T lymphocytes (CD3+). The authors conclude that rejection is not a major cause of failure in CSVA in dialysis patients.

[Effect of plasmapheresis in kidney transplantation--a controlled study]. / Wirkung der Plasmapherese bei Nierentransplantation--eine kontrollierte Studie.

Until recently it has been controversial whether plasmapheresis is benefitial in graft rejection therapy. Here we present a controlled trial in 44 kidney transplanted patients with biopsy proven acute vascular rejection and specific anti-HLA-antibodies. 23 randomized patients were treated additionally with plasmaexchange (group A), whereas the remaining 21 received drug therapy only (group B). 7 out of 23 (30%) lost their graft in group A and 17 out of 21 (81%) in group B. Mean serum creatinine and actuarial graft survival underline the significant effect of plasmaexchange therapy which appears especially benefitial when rejection occurs later than one month after surgery.

Short-term, high-dose muzolimine treatment in patients with chronic renal failure and acute fluid retention.

Muzolimine, the new sulphonamide-free loop-diuretic with both high ceiling and long-lasting activities, was tested in 21 adult patients with chronic renal failure (CRF) (creatinine clearance ranging from 30 to 5 ml/min) and acute fluid overload. Low-protein diet and individual drug therapy were unchanged throughout the study. All patients received a single oral dose of 240 mg of muzolimine for 4 or 6 consecutive days depending on individual response. Clinical status, diuresis, body weight, blood and urine chemistry were recorded daily. In 19 out of 21 patients muzolimine treatment induced reversal of edema and congestive heart failure and a satisfactory fluid balance was achieved. Only two patients did not respond to diuretic treatment and required dialysis to control fluid balance and azotemia. In responsive patients diuresis increased by 50-100% and no rebound antidiuresis was observed after drug withdrawal. Body weight decreased meanly by 9%. No significant change occurred in serum concentration of K throughout the study, even in the 11 patients on digoxin. Except for a slight decrease of serum Cl by the end of treatment, no significant change in serum electrolytes was recorded. No effect was observed on blood glucose, urea and creatinine clearance whereas a slight increase of serum uric acid was recorded. Urinary lysozyme and gamma-GT were similar before and after the trial. Apart from a single case of muscle cramps, no significant side-effects were recorded. In conclusion, the present results indicate that short-term, high-dose oral muzolimine treatment is effective and safe in most patients with advanced CRF and acute fluid retention.