Jaromír Eiselt

Brain Natriuretic Peptide and N-Terminal proBNP in Chronic Haemodialysis Patients

Background: Brain natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are released into circulation as a result of congestive heart failure (HF). As HF and water overload are frequent complications in haemodialysis (HD) patients, we decided to study the levels of BNP and NT-proBNP and their changes during HD. Methods: BNP and NT-proBNP levels were determined in 94 HD patients before and after a regular 4-h HD. We followed changes in these peptides during HD depending on age, sex, HF (NYHA classification and left ventricular ejection fraction [LVEF]), duration on HD, presence of hypertension, coronary artery disease, type of membrane used for HD [low-flux (LFx) or high-flux (HFx)] and body mass change during HD. Furthermore, patients´ basic medication and creatinine levels and presence of diabetes mellitus were monitored. Results: Respectively,94% and 100% of the patients had pre-dialysis concentrations of BNP and NT-proBNP above the cut-off values for HF. The marker levels correlated significantly both before and after HD (r = 0.903 and 0.888, respectively, p < 0.001). BNP levels significantly decreased (p < 0.0001), whereas NT-proBNP significantly increased (p < 0.0001) during HD on LFx membranes. HD on HFx membranes caused greater decrease of BNP (compared to LFx membranes, p < 0.001), but also a decrease of NT-proBNP (p < 0.001).We did not find any significant differences in marker levels for HF and non-HF patients (NYHA classification). However, both peptides reached higher levels in the group with LVEF ≤50% (p < 0.001 for both peptides). Body mass change during HD negatively correlated only with the change of NT-proBNP (r = –0.27, p < 0.05). In the multiple regression model, the change of both peptides during HD was significantly influenced by membrane type (p = 0.003 for BNP and p = 0.001 for NT-proBNP). NT-proBNP change during HD was further significantly influenced by LVEF (p = 0.012), sex (p = 0.002) and duration on HD (p = 0.006). Conclusions: Both BNP and NT-proBNP levels were significantly increased in HD patients prior to dialysis. The change in concentrations of both peptides during HD is influenced by membrane type. HD probably triggers increased production of both peptides and this increase is emphasized by impaired LVEF. This fact can be clinically observed only on NT-proBNP levels, because BNP levels are biased by significant removal of this protein during HD.

Cell-Free Plasma DNA during Peritoneal Dialysis and Hemodialysis and in Patients with Chronic Kidney Disease

The mechanisms of clearance of circulating plasma DNA are not fully understood, and so we aimed to examine it in patients with impaired renal function compared with healthy individuals. We also assessed the effect of peritoneal dialysis and hemodialysis on circulating plasma cell‐free DNA (cfDNA) in our treated patients. Overall, 20 healthy volunteers, 20 patients with chronic kidney disease (CKD), 18 patients undergoing peritoneal dialysis (PD), and 17 patients on hemodialysis (HD; high‐flux polysulfone membrane) were examined. Cell‐free DNA levels were determined using real‐time GADPH gene sequence amplification. The levels of cfDNA in all groups of our patients did not differ significantly from those of healthy volunteers. In HD patients, cfDNA levels were significantly increased compared with those of CKD patients (P < 0.05) and PD‐treated patients (P < 0.01). In PD‐treated patients, cfDNA was detectable in overnight effluent, with its levels correlating inversely with the duration of PD treatment (r=−0.619, Spearmans coefficient, P= 0.008). Factors contributing to these differences may include changes in the quality and quantity of the cell population of the peritoneum, highlighting the need for additional studies clarifying the dynamics of cfDNA during PD. The plasma levels of cfDNA do not seem to be dramatically altered even in CKD patients or those on PD or HD (as long as they are measured prior to the procedure in the latter two). Our data suggest renal elimination is not the main mechanism of circulating cfDNA clearance.

Asymmetric dimethylarginine in hemodialysis, hemodiafiltration, and peritoneal dialysis.

Asymmetric dimethylarginine (ADMA) is a mediator of endothelial dysfunction. Production and elimination of ADMA may be affected by the type of renal replacement therapy used and oxidative stress. Plasma ADMA, advanced glycation end products (AGE), and homocysteine were assessed in 59 subjects: 20 hemodialysis (HD) patients, 19 patients undergoing peritoneal dialysis (PD), and 20 controls. Results were compared between the groups. The effect of 8 weeks of HD and high-volume predilution hemodiafiltration (HDF) was compared in a randomized study. HD patients showed higher ADMA (1.20 [0.90-1.39 micromol/L]) compared to controls (0.89 [0.77-0.98], P < 0.01), while ADMA in PD did not differ from controls (0.96 [0.88-1.28]). AGE and homocysteine were highest in HD, lower in PD (P < 0.01 vs. HD), and lowest in controls (P < 0.001 vs. HD and PD). PD patients had higher residual renal function than HD (P < 0.01). The decrease in ADMA at the end of HD (from 1.25 [0.97-1.33] to 0.66 [0.57-0.73], P < 0.001) was comparable to that of HDF. Switching from HD to HDF led to a decrease in predialysis homocysteine level in 8 weeks (P < 0.05), while ADMA and AGE did not change. Increased ADMA levels in patients undergoing HD, as compared to PD, may be caused by higher oxidative stress and lower residual renal function in HD. Other factors, such as diabetes and statin therapy, may also be at play. The decrease in ADMA at the end of HD and HDF is comparable. Switching from HD to HDF decreases in 8 weeks the predialysis levels of homocysteine without affecting ADMA.

The Effect of Intravenous Iron on Oxidative Stress in Hemodialysis Patients at Various Levels of Vitamin C

Background/Aims: Vitamin C levels decrease during hemodialysis (HD), which deteriorates antioxidant defense. Vitamin C may also act pro-oxidatively, via reduction in Fe(III). We sought to determine whether intravenous iron (Fe_iv)-induced oxidative stress differs in HD patients with low and physiological vitamin C levels and whether intravenous vitamin C (C_iv) administration during HD would change the response to Fe_iv. Patients and Methods: Twenty patients with vitamin C deficiency (median 15.7 µmol/l, range 8.0–22.7) received Fe_iv (100 mg iron sucrose between 150 and 180 min of HD). After 4 weeks of oral supplementation, the levels of vitamin C were comparable with those of controls (60.1 µmol/l, range 47.4–70.9). Patients were subsequently treated with (1) Fe_iv, (2) Fe_iv and continuous 2 mg/min C_iv throughout HD, (3) saline (S), and (4) S+C_iv. Plasma thiobarbituric acid reacting substances (TBARS) and vitamin C were assessed before, during and after FE_iv(S), and 15, 30 and 60 min after infusion. Results: Fe_iv induced a comparable rise in TBARS in patients with vitamin C deficiency (before Fe_iv, 1.9 µmol/l, range 1.4–1.9; after Fe_iv, 2.6 µmol/l, range 2.3–2.9; p < 0.01) and in those with normal vitamin C (before Fe_iv, 1.9 µmol/l, range 1.7–2.1; after Fe_iv, 2.6 µmol/l, range 2.5–2.9; p < 0.01). Fe_iv+C_iv resulted in a greater increase in TBARS (after Fe_iv, 3.1 µmol/l, range 2.8–3.2) compared with Fe_iv (p < 0.01). Conclusion: Iron sucrose-induced oxidative stress is comparable in HD patients with vitamin C deficiency and in those with normal vitamin C. We documented a pro-oxidative effect of vitamin C during Fe_iv+C_iv administration.

Fibrinolysis Defect in Long-Term Hemodialysis Patients with Type 2 Diabetes mellitus and Its Relation to Metabolic Disorders

Background/Aims: Patients with chronic renal failure (CRF) secondary to diabetes mellitus show a high incidence of atherosclerosis with its thrombotic complications. Both CRF and type 2 diabetes mellitus (DM2) results in fibrinolysis defects causally related to atherogenesis and thrombogenesis. It is not well known whether or not and, if so, how fibrinolysis is altered in patients with both CRF and DM2. Our study was designed (1) to identify the fibrinolysis defect present in patients with DM2-mediated CRF and treated by long-term hemodialysis (DM2HD), and (2) to establish whether the fibrinolysis defect is related to the metabolic abnormalities observed in CRF or DM2. Methods: Sixteen DM2HD patients and 23 healthy individuals (HI) had their euglobulin clot lysis time (ECLT), and tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) activities (act) and concentrations (ag) assessed before and after standard fibrinolytic stimulus (i.v. administration of 0.4 µg/kg BW 1-deamino-8-D-arginine vasopressin, DDAVP) along with metabolic status markers. Results: DDAVP caused a significant shortening of ECLT, rises in tPA act and ag, and a significant decrease in PAI-1 act. PAI-1 ag declined significantly in HI, but not in DM2HD. A comparison of responses to DDAVP revealed the groups differed significantly in the change in PAI-1 ag. Whereas, in HI, PAI-1 ag decreased by 11.8 ng/ml, no decrease was seen in DM2HD (0.0 ng/ml) (p < 0.0001; medians given; unpaired Wilcoxon’s test). Stepwise regression analysis showed the change in PAI-1 ag was highly group-specific (DM2HD vs. HI, regression coefficient 21.22; partial correlation 0.58; p < 0.0001) and, also dependent on the serum concentrations of apolipoprotein A-I (–32.41; –0.46; p < 0.01) and homocysteine (0.35; 0.36; p < 0.05). Conclusions: Patients with type 2 DM and CRF on long-term hemodialysis have a fibrinolysis defect manifesting itself after standard fibrinolytic stimulus by an insufficient decrease in PAI-1 concentrations. The defect is related to decreased serum levels of apolipoprotein A-I and increased serum levels of homocysteine. The defect might be a factor contributing to accelerated atherosclerosis and thrombotic complications in these patients.

High Ferritin, but Not Hepcidin, Is Associated with a Poor Immune Response to an Influenza Vaccine in Hemodialysis Patients

Background: The immune response to vaccination in hemodialysis (HD) patients can be influenced by disorders of iron metabolism, iron overload or chronic inflammatory state. Elevated levels of hepcidin are considered a new marker of iron metabolism impairment and anemia of inflammation in HD patients. Methods: We studied the effects of hepcidin, other markers of iron status and intravenous iron (Feiv) on the response to an influenza vaccine (Influvac® subunit 2008/2009) in 40 HD patients. The immune response of HD patients was compared with that of 46 controls without renal disease according to serum antihemagglutinin antibody titer (anti-HA). Results: A total of 31 HD patients (responders) attained seroconversion (at least a 4-fold increase in anti-HA) to at least 1 of 3 vaccine strains; 9 patients (nonresponders) did not respond to any strain. Responders did not differ from nonresponders in hepcidin [99 µg/l (36–200) vs. 97 µg/l (23–216), p = 0.97]. Responders had lower ferritin (571 ± 291 vs. 821 ± 309 µg/l, p = 0.031) and were administered higher doses of Feiv within the last 12 weeks prior to vaccination [625 mg (312–625) vs. 312 mg (0–625), p = 0.029]. The seroconversion to A(H1N1), A(H3N2) and B strains was noted in 20, 52 and 40% of HD and in 11, 39 and 48% of controls, respectively (HD vs. controls, p = nonsignificant). The rates of seroprotection (anti-HA ≧40) to vaccine strains in HD (27, 85 and 95%) and controls (24, 96 and 98%) were also comparable. Conclusion: Antibody production following influenza vaccination in HD patients may be suppressed by very high ferritin levels. Hepcidin does not correlate with immune response and high levels of hepcidin may reflect its retention in HD patients. Feiv administration was not associated with a poorer immune response. The immunogenicity of the A(H1N1) strain was inadequate in HD patients and controls alike.

Asymmetric dimethylarginine and progression of chronic kidney disease: a one-year follow-up study.

Background/Aims: Asymmetric dimethylarginine (ADMA) is a prognostic factor in patients with chronic kidney disease (CKD). However, the relationships among factors influencing the metabolism of ADMA and the CKD progression are not fully understood. Methods: Serum ADMA, and variables related to the metabolism of ADMA were measured in 181 non-dialysis patients (CKD stages 3-5) and in 46 controls. Patients were assessed at baseline, and 6 and 12 months after the initiation of the study. Results: Patients had increased baseline ADMA, advanced glycation end products (AGE), and advanced oxidation protein products (AOPP) compared with controls (P<0.001). In a total of 164 patients who completed a one-year study, the estimated GFR (eGFR) declined from 23.5 (17.7-36) mL/min/1.73m2 to 21 (14.7-31.5) (P=0.018), AGE rose from 1.58 (1.38-1.90) μmol/L to 1.76 (1.52-2.21) (P<0.001), while ADMA, AOPP, tubular function, and proteinuria remained stable. In a multiple regression model (adjusted R2 = 0.49, P<0.0001), the interaction of relatively higher baseline eGFR, i.e. > 25 mL/min/1.73m2, with higher ADMA (P=0.02) and higher AOPP (P=0.04) predicted the severest decrease in eGFR per year. Other predictors of progression were higher baseline AGE (P<0.001), proteinuria (P=0.003), hypertension (P=0.01), and higher baseline eGFR (P=0.03). Conclusion: Elevated ADMA and markers of oxidative stress were strong predictors of progression in patients with eGFR between 25-40 mL/min/1.73m2 , i.e. at the borderline of CKD stages 3-4.

Previous Vaccination and Age are More Important Predictors of Immune Response to Influenza Vaccine than Inflammation and Iron Status in Dialysis Patients

Background/Aims: The immune response to influenza vaccine may be influenced by many factors, e.g. age, comorbidities or inflammation, and iron status. Methods: We studied the vaccine-induced production of hemagglutination-inhibition antibodies (HI) in 133 hemodialysis patients (HD) and 40 controls. To identify variables associated with the immune response, uni- and multivariate regression analyses were performed with seroconversion in HI titers as a dependent variable, with demographics, comorbidities, previous vaccination, inflammation, and iron status as independent variables. Results: Seroconversion rates were lower in HD than in controls [43% versus 73% (H1N1 strain; p < 0.05); 43% versus 53% (H3N2; P=NS); 36% versus 62% (B; p < 0.05)]. In both HD and control groups, the predictors of the inferior HI production were pre-vaccination seroprotection, vaccination in the previous season, and old age. We did not find associations between seroconversion rates and inflammation and iron status in the studied populations. This was also true for a subanalysis of patients without pre-vaccination seroprotection. Conclusion: The influenza vaccine-induced antibody production was lower in HD than in controls and was independent of inflammation and iron status in both groups. Besides dependence on dialysis, the variables associated with inferior seroconversion rates included pre-vaccination seroprotection, previous vaccination, and old age.