Dialysis Filter Research Articles

Summaries for patients. Timing of evaluation by specialists for patients with chronic kidney disease.

Summaries for Patients17 September 2002Timing of Evaluation by Specialists for Patients with Chronic Kidney DiseaseSearch for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-137-6-200209170-00001 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail What is the problem and what is known about it so far?The kidneys filter out wastes and water from the blood. Chronic kidney disease causes kidney function to slowly worsen over time until the patient needs dialysis to survive. Dialysis filters the blood through artificial means. The care of patients with chronic kidney disease involves managing diet, blood pressure, and medications to delay the need for dialysis as long as possible, and then making an organized transition to dialysis. Some evidence suggests that the earlier patients with kidney disease receive care from a nephrologist (a doctor who specializes in ... Author, Article, and Disclosure InformationAffiliations: The summary below is from the full report titled “The Timing of Specialist Evaluation in Chronic Kidney Disease and Mortality.” It is in the 17 September 2002 issue of Annals of Internal Medicine (volume 137, pages 479-486). The authors are KS Kinchen, J Sadler, N Fink, R Brookmeyer, MJ Klag, AS Levey, and NR Powe.Summaries for Patients are a service provided by Annals to help patients better understand the complicated and often mystifying language of modern medicine.Summaries for Patients are presented for informational purposes only. These summaries are not a substitute for advice from your own medical provider. If you have questions about this material, or need medical advice about your own health or situation, please contact your physician. The summaries may be reproduced for not-for-profit educational purposes only. Any other uses must be approved by the American College of Physicians-American Society of Internal Medicine. PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetailsSee AlsoThe Timing of Specialist Evaluation in Chronic Kidney Disease and Mortality Kraig S. Kinchen , John Sadler , Nancy Fink , Ronald Brookmeyer , Michael J. Klag , Andrew S. Levey , and Neil R. Powe Metrics 17 September 2002Volume 137, Issue 6Page: I-24KeywordsBloodChronic kidney diseaseHealth insuranceKidneysLaboratory testsMedical conditionsMedical dialysisMortalityPatientsRenal diseases ePublished: 17 September 2002 Issue Published: 17 September 2002 Copyright & PermissionsCopyright © 2002 by American College of Physicians. All Rights Reserved.PDF downloadLoading ...

Plasma total antioxidant capacity in hemodialyzed patients and its relationships to other biomarkers of oxidative stress and lipid peroxidation.

Patients undergoing long-term hemodialysis (HD) exhibit increased levels of oxidative stress, likely contributing to the increased rate of cardiovascular disease. The present study represents a critical evaluation of some of the most widely used oxidative indicators, as applied to the monitoring of hemodialysis-associated oxidative stress. Total plasma antioxidant capacity was determined by two independent procedures, the total antioxidant status (TAS) and the ferric reducing ability of plasma (FRAP) methods. Plasma lipid peroxidation was assessed by determining the peroxidation products malonaldehyde and 4-hydroxynonenal (MDA-4HNE) as well as lipid hydroperoxides ("Fox-2" and "d-ROMs" methods). Total plasma thiols and plasma alpha-tocopherol were also determined. MDA-4HNE levels were higher in HD patients and decreased following HD, possibly due to passive diffusion across dialysis filters. d-ROMs were also higher in HD patients but exhibited a further increase following the dialysis procedure. Serum alpha-tocopherol did not show any significant differences. Plasma thiols were lower in HD patients and were restored following HD. Plasma total antioxidant capacity determined with either method was unexpectedly higher in HD patients compared to controls, and decreased following HD. These data indicate that, of the biomarkers studied, d-ROMs level is the one more accurately reflecting the oxidative alterations taking place in HD patients, while determination of MDA-4HNE fails to detect oxidation occurring during the HD sessions. In addition, our findings point out that the determination of total antioxidant capacity in HD patients is severely affected by the concomitant fluctuations in plasma urate levels and therefore needs careful interpretation.

Oxidative stress is reduced by the long-term use of vitamin E-coated dialysis filters

Oxidative stress during hemodialysis is thought to promote the progression of vascular complications in hemodialysis patients. The protective role of vitamin E as a lipophilic antioxidant against oxidative stress has been widely investigated. Here we investigated the effects of a vitamin E-coated regenerated cellulose hollow fiber dialyzer (CL-EE) on oxidative stress compared with a polysulfone hollow fiber (CL-PS). For at least three months before beginning the protocol, 10 nondiabetic (NDM) patients (70.0 +/- 7.5 years; 6 males and 4 females) and 8 diabetic (DM) patients (65.0 +/- 7.4 years; 4 males, 4 females) were dialyzed with CL-PS. After that, we treated all of the patients with CL-EE for six months. Malondialdehyde (MDA), advanced glycation end products (AGEs), and 8-hydroxydeoxyguanosine (8-OHdG) were monitored as biomarkers for oxidative stress at the start and then at one, three, and six months into treatment with CL-EE. Serum MDA, AGE, and 8-OHdG levels increased after the hemodialysis with CL-PS. The increase of the biomarkers was completely prevented by a single use of CL-EE. Long-term hemodialysis with CL-EE for six months significantly reduced the basal levels of the oxidant markers at one month for AGE and at six months for 8-OHdG in both DM and NDM patients. Serum MDA was reduced in only DM patients at three months. The improvement of the oxidative stress with CL-EE was more prominent in the DM patients. Long-term treatment with CL-EE efficiently improves the oxidative stress associated with hemodialysis and potentially reduces dialysis complications due to oxidative stress.

Electrical Current Leakage during Hemodialysis May Increase Blood-Membrane Interaction

During hemodialysis blood - membrane interaction causes complement activation. During dialysis there may be an electrical current leakage to the dialyzer, especially if there is a broken ground or a defect in another electrical device coupled to the patient. This study investigated whether an electric current of 1.5 mA DC could alter blood membrane interaction as measured by changes in C3d in the blood. Such a high current leakage could occur because there is no protection in the dialysis machine (Class 1B) against auxiliary current leakage. Such a current could come from a defective external device in contact with the patient during hemodialysis. A dialysis machine (Fresenius 2008C) with a filled blood-line system containing about 350 ml whole blood from each of 8 different donors was used in vitro. Each of the eight test-runs also contained 1000 U added heparin. The dialysis procedure was performed using hemophan membranes (GFS + 12, Gambro) with bicarbonate and potassium 3.0 (D210, Gambro) as dialysate. Two electric poles were placed in the blood line, before and after the dialyzer (connected in parallel) and the ground was placed at entry and exit of the dialysate fluid coming from the machine to the dialysis filter. C3d was measured before the start of "dialysis" and at 15, 30, 45 and 60 min, during dialysis. Thereafter the 1.5 mA current was switched on and additional samples were drawn at 75 and 90 min. The mean C3d values were calculated. Paired non-parametric statistical analyses were performed. There was a significant and continuous increase in C3d as compared to the "predialysis" level. The increase during 0 to 30 minutes was greater than that from 30 to 60 minutes (p=0.018); the increase in C3d during 60 to 90 min, was greater than that from 30 to 60 min (p=0.018) and there was no difference between the 0 to 30 and the 60 to 90 min increases. A current, used in this study, was able to induce a blood membrane interaction during in vitro dialysis. Even a weaker current leakage might have such adverse effects and similar interactions seem possible during regular dialysis depending on the extent of the leakage.

Fatal microcystin intoxication in haemodialysis unit in Caruaru, Brazil

After a drought in February, 1996, all 126 patients in a haemodialysis unit in Caruaru, north-east Brazil, developed signs and symptoms of acute neurotoxicity and subacute hepatotoxicity following the use of water from a lake with massive growth of cyanobacteria (blue-green algae). 60 patients died. Besides recording clinical details and outcome at follow-up, we arranged laboratory, radiological, and histological investigations on the patients and toxicological studies of serum and haemodialysis water filters. The acute presentation was with malaise, myalgia and weakness, nausea and vomiting, and tender hepatomegaly, with a range of neurological symptoms from tinnitus, vertigo, headaches, and deafness to blindness and convulsions. Liver injury ranged from abnormal liver-function test results to rapidly progressive and fatal hepatic failure. Biochemical investigations revealed gross hyperbilirubinaemia, abnormal liver enzyme activities, and hypertriglyceridaemia, but there was no evidence of haemolysis or microangiopathy. Histology revealed a novel acute toxic hepatitis with diffuse panlobular hepatocyte necrosis, neutrophil infiltration, canalicular cholestasis, and regenerative multinucleate hepatocytes. Samples of serum, dialysis filters, and water-treatment columns contained microcystins, the highly toxic low-molecular-weight hepatotoxins produced by cyanobacteria. Cyanobacteria present water-borne hazards to health via drinking water and recreational water. Haemodialysis presents an additional high-risk exposure route: when they enter directly into the circulation, microcystins can lead to fatal clinical syndromes ranging from acute neurotoxic illness to subacute liver failure.

Rapid measurement of Gd-DTPA extraction fraction in a dialysis system using echo-planar imaging.

Gd-DTPA (Magnevist, Berlex, Wayne, NJ) extraction fractions (EF) have been measured for three dialysis filter types using an echo-planar imaging (EPI) Look-Locker T1 measurement technique under conditions of fast and slow flow. The mean EF measured in Fresenius (Bad Homburg, Germany) F3, F6, and F8 dialysis filters were 0.015 +/- 0.005, 0.053 +/- 0.004, and 0.084 +/- 0.003, respectively, under conditions of fast flow which provided complete refreshment of spins in the intervals between read-out pulse samples of the T1 relaxation recovery. Data acquisition and post-processing techniques were developed to extend the accuracy of the LL technique to systems with slow flow which did not provide complete refreshment of spins between samples of the T1 recovery. A multi-shot EPI LL interleaved acquisition of relaxation recovery space (IRRS) provided T1 measurement accuracy comparable to the refreshed system, +/- 10, but at the expense of increased scan times (factor of 2 or 3). Discarding the first few non-equilibrium relaxation recovery samples from the T1 fit allowed accurate T1 estimation (+/- 10) with a single-shot EPI LL method under conditions of slow flow. These EPI LL EF measurement methods may provide useful techniques for evaluating renal function in vivo.

Studies on platelet membrane glycoproteins and platelet function during hemodialysis.

Hemodialysis only partially corrects the defects in platelet function associated with uremia. Platelet contact with the artificial surfaces of the dialysis filter during hemodialysis can itself cause platelet activation, degranulation, and loss of platelet membrane glycoproteins. Although the transient platelet dysfunction that occurs after platelet contact with foreign surfaces during cardiopulmonary bypass has been well characterized, there has been no such investigation of hemodialysis. In this study of hemodialysis patients, bleeding times (BT) and the response of their platelets to thrombin, ristocetin, and collagen were measured before, immediately after, and in some patients, the day after hemodialysis. In addition, membrane glycoproteins in platelets obtained at these time intervals were studied using fluorescein isothiocyanate (FITC) conjugated monoclonal antibodies (mAb) CD42b (anti-GPIb), CD41a (anti-GPIIb/IIIa), and CD62 (anti-P-selectin), with flow cytometry. BT was significantly prolonged, and response to thrombin and ristocetin was significantly decreased immediately after hemodialysis (P < 0.01). Binding of CD42b mAb to the platelet membrane was decreased in platelets obtained immediately after hemodialysis. Most patients had shortened BT and demonstrated increased response of their platelets to thrombin and increased CD42b binding to their platelets the day after hemodialysis. These findings suggest that in uremic patients, hemodialysis is associated with transient platelet dysfunction and decreased membrane expression of GPIb.

Heparin-free hypothermal hemodialysis at 20 degrees C improves biocompatibility.

We investigated the effect of cooling blood to 20 degrees C on the reactions and dialysis efficiency in a model using pigs. Eighteen uremic pigs were hemodialyzed. Nine pigs were hemodialyzed cooling the blood in the dialysis filter and rewarmed using microwaves to body temperature before being returned to the pigs; no heparin was added. Nine pigs (control group) were dialyzed using heparin without blood cooling. A significant decrease in the number of leukocytes was observed after 15 min in the control group, whereas no change was observed in the hypotherm-dialyzed group. We conclude that heparin-free hemodialysis performed at 20 degrees C with microwave rewarming is possible, improving biocompatibility significantly.

In vitro germination of the trinucleate pollen of Limonium perezii

Optimal conditions for in vitro germination and tube growth of Limonium perezii (Plumbaginaceae) pollen were established. Boric acid, calcium nitrate, casein hydrolysate and sucrose were all important medium components. A dialysis tubing & filter paper support combined with using polyethylene glycol as an osmoticum in the medium provided appropriate physical conditions for L. perezii pollen germination. An in vitro pollen germination rate of about 40% was achieved. The longest pollen tube observed was four times the pollen grain diameter. While prehydration did not improve L. perezii pollen germination percentage nor the final pollen tube length, temperature influenced both of these factors. The optimum temperature range for germination was between 15°C and 35°C but the optimum temperature for pollen tube length was in the range 20°C‐25°C.

Soluble intercellular adhesion molecule-1 provokes polymorphonuclear leukocyte elastase release by CD18

Elevated levels of soluble intercellular adhesion molecule-1 (sICAM-1) correlate with the development of postinjury multiple organ failure. Soluble ICAM-1 secretion is known to be induced in endothelial cells and monocytes by diverse inflammatory stimuli. We have found that incubation of quiescent polymorphonuclear leukocytes (PMNs) with sICAM-1 elicits elastase release and, more recently, that cross-linking CD18 receptors on PMNs also produces elastase release. Consequently, our study hypothesis was that sICAM-1 provokes PMN elastase release through its interaction with CD18. To obtain sICAM-1, Chinese hamster ovarian cells transfected with human ICAM-1 were lysed and centrifuged at 150,000 g for 1 hour; the supernatant was passed over an ICAM-1 affinity column, eluted with 0.1 mmol/L glycine HCl, and concentrated with dialysis filter. Human PMNs (2.5 x 10(5)) were saturated with specific monoclonal antibodies for the beta 2 subunits (CD11a, CD11b, CD18) or nonspecific monoclonal antibodies for 30 minutes on ice before a 1-hour incubation with sICAM-1 (75 ng/ml) at 37 degrees C. Elastase activity was measured by the cleavage of n-methoxysuccinyl-A-A-P-V-p-nitroanilide. Neutrophil incubation with sICAM-1 resulted in 19.2% +/- 2.8% of total PMN elastase, compared with 2.4% +/- 0.5% in the controls. Blockade of CD18 abrogated sICAM-1 provoked elastase release with monoclonal antibodies to CD18 (TS1/18, 31H8) resulting in 4.3% +/- 1.0% and 5.5% +/- 1.4% elastase release, respectively. Blockade of CD11a, CD11b, and nonspecific antibody controls had no effect on sICAM-1 induced elastase release. In vitro, sICAM-1 provokes PMN elastase release through CD18. This may represent a mechanism by which elevated levels of circulating sICAM-1, released from local injury sites, provoke distal organ dysfunction.

Isolation of haemorphin-related peptides from filter membranes collected in connection with haemofiltration of human subjects

This paper describes the extraction and isolation from dialysis filters of two peptides containing the opioid active sequence haemorphin-7. The filter devices were obtained from uraemic subjected to haemofiltration. Following acidic extraction of the filter membranes the peptides were purified by size-exclusion, ion-exchange chromatography and finally by reversed-phase chromatography using different columns and different chromatographic systems. The purification was guided by radioimmunoassay and the structure of the final products was elucidated by N-terminal sequencing and fast-atom bombardment mass spectrometry as well as micro-electrospray mass spectrometry. The isolated peptides were suggested to be identical to fragments 1–41 and 32–41 of the β-chain of human haemoglobin.

Adaptive control of ultrafiltration

An adaptive controller has been developed and implemented for the control of ultrafiltration in dialysis treatments of patients with renal problems. The reason for using adaptive control is the large difference in process dynamics when different dialysis filters are used. For several reasons, an adaptive pole-placement controller with least-squares identification was chosen. Due to the nature of the process, special attention was paid to the problem of having a smooth startup. This and other design considerations are discussed in a special section following the description of the process and the control design. A few registrations of signals from the real process are also shown.

Do septic patients with acute renal failure (ARF) benefit from continuous hemodialysis (CVVHD)?

The results are consistent with the hypothesis that septic mediators are bound to the surface of polysulfone membranes, which become saturated after 7–9 hrs. It might be necessary to change dialysis filters frequently during CVVHD to prevent membrane saturation and to achieve a persistent increase in MAP.

Albumin Treatment Reduces in Vitro Platelet Deposition to Pmma Dialysis Membrane

We investigated in an in vitro system the effect of albumin on the interaction between circulating platelets and artificial membranes used for hemodialysers. Using a recently described method we evaluated platelet adhesion to polymethylmethacrylate (PMMA) and cuprophan (CU) hollow-fibers. Deposition of washed radiolabelled platelets on these two membranes was measured in small dialysis filters with or without previous perfusion with an albumin solution. Also measured was the amount of albumin that adhered to the membranes after perfusion of the filters with radiolabelled albumin. Platelet deposition to PMMA was significantly reduced by albumin treatment (from 1070 +/- 498 to 296 +/- 174 plt/mm2, P < 0.01). Platelet deposition on the CU membrane was comparable with and without albumin pre-perfusion (141 +/- 70 vs. 152 +/- 100 plt/mm2). Deposition of radiolabelled albumin was higher on PMMA than on CU membrane. Thus, higher adsorption of this protein, observed in our in vitro system, might explain the lower platelet deposition found on the PMMA rather than on the CU membrane. These results suggest that platelet interactions with PMMA during dialysis could be improved by treating the dialyser with albumin before blood contact. However, before this treatment is used clinically further experimental studies are required to confirm that our in vitro observation also applies to in vivo conditions.

Kinetic and equilibrium characterization of the Tet repressor-tetracycline complex by fluorescence measurements: Evidence for divalent metal ion requirement and energy transfer

The interaction of Tet repressor protein with the inducer tetracycline was studied by fluorescence measurements, equilibrium dialysis and nitrocellulose filter binding. The repressor-tetracycline complex was formed from two molecules of tetracycline and one Tet repressor dimer. Formation of the complex requires divalent cations, and results in drastic effects upon the fluorescence spectra of both compounds. The fluorescence of Tet repressor was quenched about 70%, while that of tetracycline was increased between three- and eightfold, depending upon pH. In addition, the emission maximum of the protein was shifted from 330 to 340 nm, and the excitation maximum of tetracycline dropped from 380 to 370 nm. The latter shift is accompanied by a similar change in the absorption spectra. An analogous effect was observed upon changing the environment of the drug by the addition of sodium dodecyl sulphate. These results suggest that tetracycline binds to a hydrophobic region of the protein. A new excitation band in the fluorescence spectrum of the complex is observed. This presumably arises from energy transfer from a tryptophan to the drug. The association rate constant for formation of the complex is 3.3(±0.3) × 10 5 m −1 s −1, and the equilibrium association constant is 2.8(±0.5) × 10 9 m −1. These results are discussed with respect to the biological function of the Tet repressor.

Interaction of kanamycin and related antibiotics with the large subunit of ribosomes and the inhibition of translocation

The binding of [ 3H ]kanamycin to E. coli ribosomes and ribosomal subunits was studied by equilibrium dialysis and Millipore filter methods. The 70S ribosome bound ca. two molecules up to the antibiotic concentration of 10 uM, and more at higher concentrations. Each ribosomal subunit was observed to possess one major binding site, and the affinity of the small ribosomal subunit was greater than that of the large subunit. The binding of [ 3H ]kanamycin to ribosomes and ribosomal subunits was reversed by neomycin or gentamicin, but not by streptomycin and chloramphenicol. Kanamycin, neomycin and gentamicin interfered with the binding of [ 14C ] tuberactinomycin O. Translocation of N-Ac-Phe-tRNA was markedly inhibited by kanamycin, neomycin or gentamicin, but not by streptomycin.

Quantitative assay of the binding of small molecules to protein: Comparison of dialysis and membrane filter assays

A rapid assay involving filtration through a nitrocellulose filter is described for the quantitative detection of a protein which specifically and reversibly binds a small molecule. This assay is quantitatively characterized by direct comparison with equilibrium dialysis. The filtration assay is highly sensitive and reproducible when applied to the binding of histidine by the J protein, a component of histidine transport. The effects of several variables on this method are examined. Also, an equilibrium dialysis procedure designed for optimal sensitivity and range in the assay of proteins by binding activity is described.