Effect of gamma radiation versus ethylene oxide sterilization of dialyzers and blood lines on plasma levels of granulocyte elastase in hemodialyzed patients

The effect of gamma versus ethylene oxide sterilization of different dialyzers (polyacrylonitrile, cuprophan) and blood lines on plasma levels of granulocyte elastase and of lysozyme during hemodialysis was investigated in 17 chronically uremic patients. Plasma levels of granulocyte elastase increased during hemodialysis but significantly less in the presence of polyacrylonitrile compared with cuprophan membranes. In contrast, enhanced lysozyme plasma levels decreased during dialysis using the polyacrylonitrile dialyzer to values of healthy controls and remained unchanged using the cuprophan dialyzer. Both effects were not influenced by the way of sterilization. We conclude that granulocyte activation during hemodialysis occurs independently of the sterilization procedure of dialyzers and blood lines in patients showing no clinical signs of hypersensitivity.     

Influence of the type of membrane and heparin on serum lipid parameters during a dialysis session: a pilot study

BACKGROUND/AIM: The type of heparin and membrane used might influence the lipids in patients on hemodialysis (HD). However, there are limited and debatable data concerning the lipid changes during an HD session. The aim of our study was to examine the changes in serum lipid parameters during the HD session in relation to the heparin and dialysis membrane used. METHODS: Ten patients on HD 3 times/week participated in the study. The study was performed in three phases (A, B, C), each of 1 week's duration. The types of membranes used were Hemophan (phase A), ethylene vinyl alcohol (phase B) and polyacrylonitrile (phase C), respectively, in a random order. During the midweek session of each phase we used classic heparin, while during the session at the end of the week low molecular weight heparin was administered. Serum total cholesterol, triglycerides, HDL cholesterol, Lp(a), albumin and total proteins were measured before and 5 min after the HD and hourly during the HD session. RESULTS: In all phases, we found a progressive increase in all lipid parameters during the HD session, except Lp(a). This increase, however, was possibly due to hemoconcentration. CONCLUSIONS: This pilot study showed that (1) the type of heparin and membrane used does not seem to affect the serum lipid profile during a single HD procedure, and (2) the changes observed in serum lipid parameters are mainly due to hemoconcentration.     

The effects of intravenous iron treatment on oxidant stress and erythrocyte deformability in hemodialysis patients

BACKGROUND: It is well known that free iron causes oxidant stress to increase. However data concerning whether intravenously (I.V) administered iron in maintenance doses (10-20 mg) gives rise to increased oxidant stress and disturbed erythrocyte deformability (EDEF) in hemodialysis (HD) patients is lacking. In the present study, we aimed to evaluate and compare the effects of I.V iron on oxidant stress and EDEF. PATIENTS AND METHODS: Thirteen HD patients (10 males, 3 females, mean age: 49.9 +/- 13.4 years), given I.V iron were included in the study. All patients were undergone three consecutive HD session. The first HD session was performed without iron administration (Group 1), whereas in the following sessions the same patients were given 20 mg (Group 2) and 100 mg (Group 3) iron III hydroxide sucrose (Venofer--Abdi Ibrahim) I.V at the end of the dialysis session. In study periods, 7 blood samples were drawn from each patient: before dialysis, at the end of the dialysis (just after the session), 15, 30, 60, 90 and 120 minutes after each dialysis session. However 15 minute samples were not drawn in the third group, since I.V iron was given by infusion in 30 minutes. EDEF and plasma malondialdehyde (MDA) were studied in all samples. RESULTS: When the results of the session without iron were considered, bivariate correlation analysis did not reveal any correlation between MDA and EDEF. When the course of each parameter were considered separately, MDA levels 90 and 120 minutes after HD session were significantly higher than that of the before and just after the HD session (p < 0.05). Whereas EDEF in 60, 90 and 120 minutes after HD session was found to be worsened when compared to before and just after HD sessions' values (p < 0.05). When results of the session with 20 mg iron were considered, EDEF and MDA values were not found to be correlated and throughout the course. Although EDEF did not present any significant change, MDA levels 60, 90 and 120 minutes after HD session were found to be significantly higher than that of the 15 and 30 minutes after HD session (p < 0,05). When results of the session with 100 mg iron were considered, MDA levels 30, 60, 90 and 120 minutes after HD session were found to be significantly higher than that of the before and just after the HD sessions' (p < 0,05). EDEF in 90 and 120 minutes after HD session was improved and no correlation between MDA and EDEF was observed. When groups were compared with each other, plasma MDA levels in session with 100 mg iron at the beginning, at the end and 30 minutes after HD were significantly lower than that of the without iron group (p < 0.05). Similarly MDA levels in session with 100 mg iron at the beginning, at the end, 30 minutes and 120 minutes after HD were significantly lower than that of the 20 mg iron (p < 0.05). When EDEF values in sessions with 20 mg iron and without iron were considered, only values 60 and 90 minutes after dialysis were significantly improved in 20 mg iron group. The others were statistically similar. CONCLUSION: In the present study, it was observed that I.V administered iron in 20 and 100 mg doses did not cause additional deteriorating effect on oxidant stress and EDEF was even improved by I.V iron.     

Apoptotic markers on lymphocytes and monocytes are unchanged during single hemodialysis sessions using either regenerated cellulose or polysulfone membranes

BACKGROUND: There is an increased rate of apoptosis of peripheral blood mononuclear cells (PBMCs) in patients undergoing hemodialysis (HD), but little is known about how different dialysis membranes may contribute to the process. We, therefore, studied the influence of two different dialysis membranes on apoptotic markers during HD. METHODS: 8 healthy controls and 8 patients on regular HD 3 times per week were enrolled in this cross-controlled study. Patients received HD using polysulfone and then regenerated cellulose dialysis membranes for one week each, sequentially. Serum was collected for C-reactive protein (CRP) detection; flow cytometry with dual antibody staining was used to measure the apoptotic markers Fas (CD95), FasL (CD 178) and TNF-R2 (CD120b) in T cells (CD3+), B cells (CD19+), and monocytes (CD14+) at 0, 15, 120 and 240 min after starting HD. We also measured total leukocyte numbers and differential white cell counts. RESULTS: Hemodialysis patients revealed lymphocytopenia, monocytopenia, higher CRP levels and higher Fas and TNF-R2 expression on lymphocytes and monocytes at baseline when compared with normal controls. Leukocyte numbers, including neutrophils, lymphocytes and monocytes, dropped significantly after 15 min of dialysis. There were no significant differences in Fas levels during hemodialysis on T and B lymphocytes or on monocytes. T lymphocyte FasL (CD 178) levels remained unchanged throughout the process. There was a significantly lower overall level of CD120b at 15 min of HD, whereas this marker was higher on monocytes after dialysis. There were no significant differences in the levels of apoptotic markers between the two membranes. CONCLUSION: Our results suggest that uremia itself contributes to PBMC apoptosis. The two different dialysis membranes used in this study did not influence apoptotic markers on PBMCs significantly, but increased TNF-R2 expression on monocytes during a single dialysis session.     

Influence of predialysis oxidative stress on peroxidation processes after renal transplantation

Oxidative stress occurs as a result of reactive oxygen species (ROS) overproduction. The content of carbonyl groups (CG), malonyldialdehyde, 4-hydroxynonenal (MDA, 4-HNE) represent markers of protein and lipid peroxidation processes, respectively. The aim of the present study was to determine CG and MDA/4-HNE in the serum of 30 hemodialyzed patients (-HD; 13 men, 17 women of mean age 47.7 +/- 15.3 years) before and after a hemodialysis session, of 20 transplant patients (TX; 10 men, 10 women of mean age 40.7 +/- 11.3 years) before and after the procedure (RT), and of a control group (n = 47; including 30 women, 17 men of mean age 38.7 +/- 14.0 years). The CG content was evaluated using the 2,4-dinitrophenylhydrazine assay and MDA/4-HNE by the Oxis Bioxytech colorimetric method. Among the HD group the concentrations of MDA/4-HNE and CG were higher than control subjects (P <.05). In the HD group CG concentrations before and after dialysis session were similar while MDA/4-HNE concentrations were higher before the dialysis session (P <.01). One day after RT, MDA/4-HNE and CG concentrations had increased but at 7 days they had decreased and the CG level was increased. A high production of ROS can be assumed in dialysis patients. MDA/4-HNE concentrations, however, decreased after the dialysis treatment, because as low-weight molecules they diffused across the dialysis filter. On the first day after RT a high intensity of lipid and protein peroxidation was observed. During the first week after RT, accumulation of protein peroxidation products was observed but simultaneously lipid peroxidation product concentrations decreased due to quick metabolism. The intensity of lipooxidation during first day after RT seems to be dependent upon the ischemia time.     

Myeloperoxidase serves as a marker of oxidative stress during single haemodialysis session using two different biocompatible dialysis membranes.

BACKGROUND: There is increased oxidative stress in patients undergoing haemodialysis (HD); however, little is known of how different dialysis membranes contribute to the oxidative stress induced by the dialysis procedure per se. We therefore studied the influence of two different dialysis membranes on oxidative stress during HD. METHODS: Eight patients undergoing HD three times per week were enrolled in this cross-controlled study. Patients sequentially received HD using polysulphone (PS) and regenerated cellulose (RC) dialysis membranes for 1 week each. Blood samples were collected in the last section of each hollow fibre 0, 15, 120 and 240 min after starting HD. We determined superoxide anion production derived from neutrophils, superoxide dismutase (SOD) and glutathione peroxidase (GPx) derived from washed red cells, plasma myeloperoxidase (MPO), plasma thiobarbituric acid-reactive substances (TBARS), plasma advanced oxidation protein products (AOPP) and serum 8-hydroxy-2'-deoxyguanosine (8-OHdG). RESULTS: Leukocyte numbers, including neutrophils, lymphocytes and monocytes, decreased significantly after 15 min of dialysis, more so with RC than with PS membrane. For both membranes, superoxide anion production transiently increased during the first 15 min whereas the post-dialysis production was decreased. Plasma MPO levels persistently increased during dialysis with the two membranes. Moreover, the increase was more marked with RC than with PS membrane. AOPP and 8-OHdG levels increased progressively when using RC membranes. There were no significant differences in SOD, GPx, TBARS, AOPP and 8-OHdG levels between the two membranes. CONCLUSIONS: The biocompatibility of the dialyser affects oxidative stress production during a single dialysis session. The measurement of MPO may serve as a reliable marker of the degree of oxidative stress induced using dialysis membranes of different biocompatibilities.     

Effect of sterilization on bone morphogenetic protein

Demineralized bone matrix and bone morphogenetic protein have been used clinically to accelerate bone regeneration. However, the best method of sterilization has been the subject of controversy. Some investigators have used ethylene oxide, but others have reported that doses adequate for sterilization destroyed the osteoinductivity of demineralized bone matrix and that gamma irradiation was less harmful in this respect. We used partially purified bone morphogenetic protein and type-I collagen to investigate the effects of sterilization by ethylene oxide and gamma irradiation on the activity of bone morphogenetic protein. Osteoinductivity was reduced considerably after sterilization by gamma irradiation at 2.5 Mrad and by ethylene oxide at 37°C for 4 hours and at 55°C for 1 hour; however, the reduction induced by ethylene oxide at 29°C for 5 hours was about half of the control values. This study showed that ethylene oxide at 29°C for 5 hours can be used clinically for sterilization of bone morphogenetic protein. We also investigated the effect of gamma irradiation on bone morphogenetic protein and the collagen carrier separately and found that collagen was far more labile than bone morphogenetic protein.     

Gamma irradiation and ethylene oxide in the sterilization of native reindeer bone morphogenetic protein extract.

BACKGROUND AND AIMS: For human use, it is necessary to sterilize bone morphogenetic proteins (BMPs), in order to reduce the risk of infections and associated complications. We compared the effects of ethylene oxide and gamma irradiation in the sterilization of native reindeer BMP extract with regard to bone induction in the Balb/C mouse thigh muscle pouch model. MATERIALS AND METHODS: BMP extract, sterilized with ethylene oxide gas (Steri-Vac 4XL, temperature 29 degrees C, exposure time 4 h, ethylene oxide concentration 860 mg/l), or gamma irradiation at doses of 3.15 MRad was administered in implants containing 5 or 10 mg of BMP extract with collagen carrier. Non-sterilized collagen implants served as controls. New bone formation was evaluated based on the incorporation of Ca45 and radiographically three weeks after implantation. RESULTS: The collagen was not able to induce new bone visible in radiographs. The mean Ca45 incorporation in the gamma sterilized group containing 5 mg of BMP extract was 30% (p = 0.04) and that containing 10 mg of BMP extract was 60% (p = 0.02) higher than seen in the corresponding ethylene oxide sterilized groups. The mean new bone areas were 45% higher in the gamma sterilized groups than in the corresponding ethylene oxide sterilized groups, but the differences were not significant. The mean optical density of new bone in the gamma sterilized group containing 5 mg of BMP extract was 75% (p = 0.00) and in that containing 10 mg of BMP extract was 70% (p = 0.00) higher than seen in the corresponding ethylene oxide sterilized groups. CONCLUSION: Native reindeer BMP extract is more sensitive to the effects of ethylene oxide gas sterilization than gamma irradiation. These results suggest that gamma irradiation is recommendable for the sterilization of BMP extracts.     

Lymphopenia in dialysis patients: a preliminary study indicating a possible role of apoptosis

Lymphopenia is a common finding in dialysis patients. Since infection rate and mortality associated with infection are high in dialysis patients, lymphopenia may be one of the contributing factors. In the present study, we evaluated the mechanism responsible for lymphopenia in these patients. Lymphocytes isolated from dialysis patients showed increased apoptosis (p < 0.001) when compared to lymphocytes isolated from healthy subjects (healthy subjects, 0.5 +/- 0.2% vs. dialysis patients, 8.8 +/- 0.7% apoptotic cells/field). Sera from dialysis patients promoted lymphocyte apoptosis in a time- and dose-dependent manner. These sera also enhanced lymphocyte DNA fragmentation into multiple integers of 180 base pairs in the form of a ladder pattern. Cellulose acetate membranes promoted T cell apoptosis when compared to polysulfone membranes and to control. Cellulose acetate dialysis membranes also appear to promote lymphocyte FasL expression. Similarly, dialysis sera enhanced T cell Fas as well as FasL expression. Neither the cellulose acetate nor polysulfone membranes could induce FasL expression on B cells. Similarly, dialysis sera failed to induce FasL expression on B cells. On the other hand, anti-FasL antibodies attenuated dialysis sera-induced apoptosis in T as well as B cells. Interestingly, dialysis serum showed a 5-fold increase in FasL content when compared with control serum. These results suggest that dialysis-associated factors can induce autocrine death in T cells but the help of activated T cells is required to induce death in B cells.     

Monocyte apoptosis in dialysis patients is Fas ligand-mediated

BACKGROUND: The mononuclear phagocyte system plays an important role in host defense. Since dialysis patients have been reported to show enhanced leukocytes apoptosis, we evaluated the mechanism of increased apoptosis of monocytes in dialysis patients. METHODS: Apoptotic studies were carried out on monocytes isolated from dialysis patients as well as healthy subjects. The effect of dialysis sera and membranes was evaluated on monocyte apoptosis as well as monocyte expression of proapoptotic proteins such as Fas and FasL. To confirm the role of FasL, we evaluated the effect of activated secretory products on T cell apoptosis. In addition, we studied FasL content of dialysis sera and supernatants of activated monocytes. RESULTS: Monocytes isolated from dialysis patients (MDP) showed a greater magnitude of apoptosis when compared to monocytes isolated from healthy subjects (MHS) (MHS, 3.6 +/- 1.1% vs. MDP, 24.3 +/-1.4%). Sera of hemodialysis patients (SHD) promoted (p < 0.001) apoptosis of MHS when compared to pooled control sera (HPS) (HPS, 0.8 +/- 0.5% vs. SHD, 11.5 +/- 0.5% apoptotic cells/field). Dialysis membranes, cellulose acetate membranes in particular, promoted monocyte apoptosis. Interestingly, anti-FasL antibodies partly inhibited dialysis sera-induced monocyte apoptosis. Dialysis membranes also modulated monocyte expression of both Fas and FasL. Secretory products of activated monocytes also promoted T cell apoptosis. Dialysis sera and activated monocyte secretory products showed increased FasL content. CONCLUSIONS: These results suggest that dialysis patients have an increased rate of monocyte apoptosis, which is mediated through a uremic milieu (serum factors). One of these serum factors seems to be FasL. In addition, dialysis membranes seem to promote apoptosis independent of the uremic milieu. The present study provides a mechanistical insight into the enhanced apoptosis of monocytes in dialysis patients.     

Comparison of blood loss with different high-flux and high-efficiency hemodialysis membranes

Iron deficiency is a common problem in patients on chronic HD. Earlier studies have shown significant blood loss per HD session. To identify whether the new more biocompatible high-flux or high-efficiency membranes are also responsible for significant blood loss during HD, we quantitated the amount of blood loss associated with 4 commonly used membranes (F-50, F-80, CA-210, and CT-190). The residual blood in each compartment of extracorporeal circuit was quantitated after total lysis of the red blood cells (RBC), hemoglobin assay, and calculation of the RBC volume using the patient's hemoglobin and hematocrit concentrations just prior to the study. The average residual RBC volume in different membranes was 0.2-0.3 ml. The residual RBC volume in the dialysis lines (arterial or venous) was 0.1-0.2 ml and did not correlate with the residual RBC volume in the dialysis membranes. The residual RBC volume in the whole extracorporeal circuit (HD membrane, arterial and venous lines) ranged from 0.5 to 0.6 ml. It was significantly higher with F-50 vs. CA-210. The residual RBC volume in the dialysis membrane was significantly higher in the F-80 vs. CA-210 and CT-190 dialyzers. There was also significant difference in the residual RBC volume in the arterial lines of F-50 vs. CT-190, and F-50 vs. F-80 dialyzers. CONCLUSION: Our results demonstrate for the first time that the total RBC loss per HD session is minimal in chronic HD patients.     

Establishing the relationship between complement activation and stimulation of phagocyte oxidative metabolism in hemodialyzed patients: a randomized prospective study

The present prospective study was conducted in order to establish the relationship between complement activation and stimulation of phagocyte oxidative metabolism observed in long-term hemodialysis (HD) patients during the early phase of dialysis with cellulosic membranes. Two groups of 10 randomized (HD) patients treated with cellulosic (Cuprophan, CUP) or synthetic polyacrilonitrile (PAN AN-69) membranes were studied. Leukocyte counts, C3a antigen plasma concentration and whole blood basal and stimulated chemiluminescence (CL) production were determined in blood samples drawn from the fistula before dialysis (T0) and from both the afferent and efferent lines of the dialyser at 15 min (T15) and at the end (Tend) of the dialysis session. This study confirms that, coincident with the nadir of leukopenia observed at T15, dialysis with CUP but not PAN membranes induces a marked rise in C3a antigen levels and profound alterations in whole blood CL production consisting of a dramatic increase in basal CL and a significant loss in CL response capacity to stimulating agents. It further demonstrates that a direct relationship exists between the variations in C3a antigen plasma levels and whole blood CL production observed in the CUP group of patients from T0 to T15 (delta 15) of dialysis. This relationship is characterized by a positive correlation between delta 15 C3a and delta 15 basal CL levels in afferent and efferent lines, and a negative correlation between delta 15 C3a and delta 15 CL response capacity values in the efferent but not afferent line. In contrast, no significant correlation with the type of dialysis membrane could be demonstrated between the variations in polymorphonuclear neutrophil counts and C3a antigen levels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Is dialysis membrane type responsible for increased circulating adhesion molecules during chronic hemodialysis?

BACKGROUND: Patients with chronic renal failure under maintenance hemodialysis (HD) present with numerous adverse effects including immunologic alterations. Serious abnormalities of neutrophil function have been reported to be associated with disturbed cell adhesiveness. These adhesion processes are mediated by cytokines and different adhesion molecules. PATIENTS AND METHODS: In this study, serum concentrations of the intercellular adhesion molecule ICAM-1, vascular cell adhesion molecule VCAM-1 and endothelial leukocyte adhesion molecule E-selectin were investigated during employment of different dialysis membranes (cuprophane: n = 23, cellulose: 8, polysulfone: 26, acrylonitrile: 7). These adhesion parameters from 64 patients before and after a hemodialysis session were investigated parallel to the serum levels of circulating cytokines and their inhibitors. RESULTS: Circulating ICAM-1 levels were not elevated in low-flux membranes and most of the high-flux HD membranes, except for one high-flux polysulfone membrane. cVCAM-1 levels were significantly elevated both in low- and high-flux dialysis membranes, whereas cE-selectin was not increased. cICAM-1 levels were not different before and after hemodialysis in the entire study group. In contrast, cVCAM-1 and cE-selectin levels increased significantly during HD in the entire study group (both p < 0.001). Serum levels did not correlate with the duration of end-stage renal failure and hemodialysis. Levels of circulating cytokine antagonists/inhibitors (Il-lra, Il-2R, TNFsRp55/75) were significantly increased in all patients before and after HD, whereas the serum concentrations of the corresponding circulating cytokines (I1-1beta, Il-1, TNF-alpha) were within normal ranges. CONCLUSION: Increased levels of cVCAM-1 which suggest an important role for immunological alterations in HD and cytokine-independent changes during HD sessions in all membranes without alterations of cICAM-1 in most membranes and unchanged cE-selectin indicate that processes such as uremia are responsible for these effects rather than membrane characteristics. The level of circulating adhesion molecules does not serve as an appropriate marker of membrane biocompatibility.     

Lipid peroxidation and antioxidant enzymes in children on maintenance dialysis

End-stage renal disease (ESRD) is associated with numerous complications, which may partly result from excessive amounts of reactive oxygen species and/or decreased antioxidant activity. The aim of the study was to evaluate lipid peroxidation (LP) in plasma and erythrocytes, erythrocyte antioxidant enzyme activity (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GSH-Px), and concentrations of Cu and Zn as cofactors of SOD and Se as a cofactor of GSH-Px in erythrocytes, plasma and in dialysis fluid in children with ESRD. In particular, we analyzed whether the modality of dialysis could modify oxidative stress parameters in children. To determine the influence of hemodialysis (HD) on oxidative stress, the measurements were also performed on HD children 20 min after the beginning of the dialysis session. Thirty-one patients participated in the study: group I with 10 children on continuous ambulatory peritoneal dialysis (CAPD), and group II with 21 on HD. The erythrocyte malondialdehyde concentrations (E-MDA), plasma MDA (P-MDA) and plasma organic hydroperoxide (OHP) in children from both groups were higher than in controls. E-MDA and P-MDA in HD before the session was lower compared to the values after 20 min of HD session (time T²⁰). The activity of SOD, GSH-Px, CAT, concentrations of erythrocyte and plasma Se, Cu, Zn were lower in children with ESRD than in controls. In the HD group, the activity of GSH-Px, CAT, and levels of trace elements in erythrocytes and in plasma were diminished at time T²⁰. In conclusion, increased oxidative stress occurs in children on maintenance dialysis, independent of dialysis modality. The activity of the enzymatic antioxidant defence system is highly reduced in red blood cells of pediatric dialysis patients. Children with ESRD exhibit lower trace element (Se, Cu, Zn) levels in plasma and erythrocytes as compared to healthy subjects. Oxidative stress is aggravated during every single HD session in children.     

Elective haemodialysis increases exhaled isoprene.

BACKGROUND: Uraemic odour is a characteristic feature of patients with end-stage renal disease (ESRD). However, few investigations have been carried out into the composition of exhaled air in ESRD patients undergoing haemodialysis (HD). Increases of exhaled isoprene levels by a factor of up to 2.7 following HD have been reported. METHODS: We attempted to confirm these findings in 50 patients undergoing HD using haemophan (n=23) or polysulphone (n=27) dialysis membranes. Parallel evaluation of ambient air, calorie intake, medication and haemodynamic variables was performed. Samples were analysed using proton transfer reaction-mass spectrometry (PTR-MS). RESULTS: Significant changes in breath isoprene concentration were observed when comparing patients before [39.14+/-14.96 parts per billion (ppbv)] and after (63.54+/-27.59 ppbv) dialysis (P<0.001). The quotient of values before and after dialysis was 1.84 (SD 1.41). No significant differences in isoprene kinetics were found between the use of haemophan and polysulphone membranes. No significant correlations were observed between isoprene quotients and variations in blood pressure during HD, calorie intake, ingestion of lipid-lowering drugs or serum lipid levels. CONCLUSIONS: Isoprene concentration was higher in the exhaled air of patients after HD as compared with values before HD. Large interindividual variability existed in isoprene kinetics. Oxidative stress appears to be an unlikely cause for this rise. An alternative hypothesis is an influence of respiratory variables on isoprene exhalation based upon Henry's law constant. We therefore propose to perform online monitoring of isoprene exhalation by PTR-MS during the HD session to investigate the possible influence of respiratory variables.     

The Effects of a Polyacrylonitrile Membrane and a Membrane Made of Regenerated Cellulose on the Plasma Concentrations of Erythropoietin During Hemodialysis

In vitro studies have shown that some dialysis membranes significantly adsorb erythropoietin (EPO), a fact that might have an effect on anemia in long-term hemodialysis (HD) patients and on anemia treatment with recombinant human EPO. The purpose of the study was to determine whether the ability of adsorption demonstrated in vitro also has an effect on EPO concentrations in vivo. In a crossover study, the plasma concentrations of EPO were examined in 11 patients on chronic HD during HD using a polyacrylonitrile (AN69) membrane (high in vitro adsorption) plus EPO administered subcutaneously after the HD session, HD using a Cuprophan membrane (low in vitro adsorption) plus EPO administered subcutaneously after the HD session, HD using an AN69 membrane plus EPO administered subcutaneously after the HD session plus EPO administered intravenously immediately before HD, or HD using a Cuprophan membrane plus EPO administered subcutaneously after the HD session plus EPO intravenously immediately before HD. The intradialysis plasma concentrations of EPO (not detectable in the dialysate) determined at the dialyzer inlet and outlet at Minutes 5 and 240 of the procedure did not differ significantly after its subcutaneous administration from its predialysis concentrations with either the Cuprophan or AN69 membrane. A comparison of EPO concentrations between AN69 and Cuprophan did not reveal marked differences either. The course of concentrations after additional EPO intravenous administration was similar with no statistically demonstrable difference between the 2 membranes. In conclusion, under clinical conditions, AN69 and Cuprophan membranes do not differ in their effects on plasma EPO concentrations. The differences in EPO adsorption between AN69 and Cuprophan, demonstrated in vitro, do not seem to be of clinical importance.     

Serum malondialdehyde and prevalent cardiovascular disease in hemodialysis.

BACKGROUND: Oxidative stress has been proposed as a mechanism by which the accelerated rate of cardiovascular disease (CVD) observed in maintenance hemodialysis (HD) patients may be explained. This study examined the effects of HD and CVD on serum malondialdehyde (MDA) levels as a marker of oxidative stress in HD patients with and without prevalent CVD. Serum MDA levels and CVD prevalence in HD were modeled. METHODS: Serum MDA was determined using spectrophotometry in HD patients (N = 76, 53 men and 23 women, mean age 63.8 years) immediately prior to and at the conclusion of one midweek HD treatment. Traditional CVD risk factors, including serum lipids, lipoproteins, apolipoproteins, and fibrinogen, were also measured, as were serum chemistry and dialysis adequacy. RESULTS: Mean serum MDA levels were significantly elevated in HD patients with prevalent CVD compared with those without, whereas serum lipoprotein and plasma fibrinogen levels did not differ between the two groups. Patients in the highest compared with the lowest tertile of postdialysis MDA were nearly four times as likely to have prevalent CVD, and serum MDA was the single strongest predictor of prevalent CVD in this patient population. CONCLUSIONS: These findings indicate the presence of oxidative stress in HD patients, and are consistent with the theory of oxidative stress as a factor in accelerated CVD in this population.     

Procalcitonin serum levels in children undergoing chronic haemodialysis

Infections account for considerable morbidity and mortality in patients requiring haemodialysis (HD). Procalcitonin (PCT)—a low molecular weight protein of 13 kDa—helps one to distinguish viral from bacterial infections and to evaluate the severity of bacterial infections. We investigated (1) PCT baseline levels in eight children undergoing chronic HD with high-flux membranes and (2) changes in the serum levels of PCT, C-reactive protein (CRP) and beta-2-microglobulin (β2-MG)—a peptide with biochemical characteristics similar to those of PCT—before and after haemodialysis sessions. Blood sampling was performed three times in the mid-week session. Serum PCT of the seven uninfected children before HD sessions was increased (0.75±0.07 ng/ml), whereas CRP levels were normal. PCT after dialysis decreased significantly by 40% (P<0.0001) compared with initial values, whereas CRP levels before and after HD were not different. β2-MG decreased by 70%, probably due to different biochemical proprieties of both proteins. PCT serum levels 15 min and 60 min after the HD session remained unchanged in comparison with those at the end of the HD session, suggesting accumulation of PCT between HD sessions rather than HD-induced production to be responsible for the increased baseline PCT serum levels. We concluded that CRP serum levels were not affected by HD in our group. Moderately elevated baseline PCT serum levels that are presumably due to reduced renal clearance and uraemia and dialysability of PCT should be taken into consideration. However, increase of serum PCT in patients with severe bacterial infections is generally massive (10-fold to 1,000-fold), suggesting a low risk for false negative results in such cases.     

Impairment of glutathione biosynthetic pathway in uraemia and dialysis.

BACKGROUND: Glutathione (GSH), the predominant intracellular antioxidant, reportedly has been shown to be decreased in chronic renal failure patients, which renders these patients more susceptible to oxidative damage by free radicals. To our knowledge, the ability of erythrocytes to normalize the GSH level by de novo synthesis in uraemic and dialysis patients has not been studied previously. The main goal of the present study was to measure the activities of the enzymes that are responsible for de novo GSH generation, namely gamma-glutamylcysteine synthetase (gamma-GCS) and glutathione synthetase (GSH-S), in erythrocytes from uraemic and dialysis patients. METHODS: Erythrocyte total GSH level and gamma-GCS and GSH-S activities as well as plasma malondialdehyde (MDA) levels were measured in 19 non-dialysis patients (ND), 34 haemodialysis patients (HD), 22 continuous ambulatory peritoneal dialysis patients (CAPD) and 21 normal healthy controls. The effect of a single haemodialysis session was determined in 16 HD patients. RESULTS: Significant decreases in GSH levels and gamma-GCS activity but not GSH-S were observed in ND, HD and CAPD patients compared with controls. However, GSH levels as well as gamma-GCS and GSH-S activities were not different among the ND, HD and CAPD patients. The decrease in GSH was strongly and positively correlated with the decrease in gamma-GCS in ND, HD and CAPD patients (r = 0.717, P<0.001; r = 0.854, P<0.001; and r = 0.603, P<0.01, respectively). In addition, plasma MDA was negatively correlated with gamma-GCS in ND, HD and CAPD patients (r = 0.721, P<0.001; r = 0.560, P<0.01; and r = 0.585, P<0.01, respectively). A single dialysis session had no effect on GSH level or on gamma-GCS and GSH-S activities. Only a significant reduction in MDA was observed at the end of dialysis. CONCLUSIONS: The activity of the rate-limiting enzyme in GSH biosynthesis, gamma-GCS, was significantly decreased in uraemic and dialysis patients, which explains, at least in part, frequent reports of reduced GSH levels in these patients. The decrease in gamma-GCS activity may have been secondary to inhibitory effects from uraemic factors that are not removed by standard dialysis. However, this assumption does not exclude the possibility of down-regulation of gamma-GCS protein expression and further studies in this context are recommended.     

Effect of an increase in C-reactive protein level during a hemodialysis session on mortality

The prevalence of chronic inflammation is high in dialysis patients. Moreover, it is associated with an increased mortality risk, yet the origin of chronic inflammation in dialysis patients remains unclear. The aim of this study was to determine the effect of a hemodialysis session (HD) on C-reactive protein (CRP) levels and to study the relation with survival. As part of a large, prospective, multicenter study in the Netherlands (Netherlands Cooperative Study on the Adequacy of Dialysis), patients who were started on dialysis treatment between September 1997 and May 1999 were included. Demographic data, clinical data, and serum samples were collected at regularly timed intervals. From this cohort, a random sample of patients was taken. CRP levels were determined before and after an HD session and before the next session. Date of death or censoring was recorded until September 2002. A total of 186 HD patients were included. Mean age was 65 yr (SD, 13); 56% were male. A total of 71 patients had a CRP level below the detection limit (3 mg/L), 68 patients showed no increase in CRP during an HD session (no-increase group), and 47 (25%) patients showed an increase in CRP level during an HD session (increase-group). No statistically difference in mean CRP levels before the dialysis session was found between the increase group (22.3 mg/L) and the no-increase group (19.4 mg/L). In the subsequent interdialytic period, CRP levels returned to the levels of the initial CRP value. Two-year survival was 44% in the increase group and 66% in the no-increase group (P = 0.09). Independent of CRP level before the session and adjusted for age, comorbidity, nutritional status, and primary kidney disease, a raise of 1 mg/L CRP during a session was associated with a 9% increased mortality risk (adjusted hazard ratio, 1.09; 95% CI, 1.02 to 1.16). The present study showed an increase in CRP level during a single dialysis session in 25% of the patients; during the succeeding interdialytic period, CRP level returned to its original value. More important, however, an increase in CRP level during an HD session was independently associated with a higher mortality risk.