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Andreas Vychytil

Publications and source records attributed to Andreas Vychytil.

15 recordsLinked to original sources
PubMed2005

Effect of radio contrast media on residual renal function in peritoneal dialysis patients--a prospective study.

BACKGROUND: Residual renal function is an independent predictor of survival in peritoneal dialysis patients. Systemic administration of radio contrast media (CM) may increase the risk of acute renal failure in patients with impaired renal function not on dialysis. There are few data on the influence of CM administration in dialysis patients. METHODS: We investigated residual renal function in 10 continuous ambulatory peritoneal dialysis (CAPD) patients who underwent elective diagnostic intravenous or intra-arterial administration of CM (study group). Iopromide (a iodinated, non-ionic hypo-osmolar CM) was used for all interventions. The median dose of CM given was 107.5 ml/patient. Residual renal function (calculated as the average of renal creatinine and renal urea clearance) was measured on the day before the intervention (baseline), on days 1-7, day 10 and day 30 after intervention. Eight CAPD patients without exposure to CM acted as the control group. RESULTS: There was no significant difference between the two groups in age, gender, diabetes, duration of dialysis and renal clearance at baseline. In the study group, we observed a temporary decline of residual renal clearance after administration of CM (P<0.05; Friedman test). On day 30, clearances were not significantly different from baseline. In the control group, there was no significant change of residual clearance during the observation period. Repeated measures ANOVA revealed no significant difference in the course of residual renal function between study and control groups. The decline of residual renal clearance between baseline and a routine visit after 4 months was comparable between groups. CONCLUSION: Administration of iopromide did not lead to a persistent decline of residual renal function in CAPD patients. Nevertheless, non-ionic hypo-osmolar CM should be given to these patients with the lowest possible dose and only if there is a real clinical indication.

Aged↗
PubMed2005

Asymmetrical dimethylarginine plasma concentrations are related to basal nitric oxide release but not endothelium-dependent vasodilation of resistance arteries in peritoneal dialysis patients.

Vascular dysfunction in chronic renal failure may be linked to reduced nitric oxide (NO) bioactivity and increased circulating concentrations of the endogenous NO synthase inhibitor asymmetrical dimethyl L-arginine (ADMA). The association between ADMA and basal endothelial NO release and endothelium-dependent vasodilation in resistance arteries of chronic renal failure patients is unknown. Forearm blood flow responses to the endothelium-dependent vasodilator acetylcholine, the endothelium-independent vasodilator nitroglycerine, and the endothelium-dependent vasoconstrictor N(G)-monomethyl-L-arginine (L-NMMA) were assessed in 37 peritoneal dialysis patients. L-arginine and ADMA plasma concentrations were measured by HPLC. ADMA (mean +/- SEM: 0.68 +/- 0.02 micromol/L) was associated with basal forearm blood flow (r = -0.33; P < 0.05) and L-NMMA induced vasoconstriction (r = -0.55; P < 0.0005), but not with dilator effects of acetylcholine or nitroglycerine. L-arginine (68 +/- 3 micromol/L) tended to correlate with acetylcholine-induced vasodilation (r = 0.32; P = 0.05) but was not associated with other parameters. ADMA is related to basal but not to acetylcholine-stimulated NO bioactivity in patients on peritoneal dialysis. Impaired endothelium-dependent vasodilation found in chronic renal failure is not explained by elevated circulating NO synthase inhibitors in renal failure.

Arginine↗
PubMed2005

[Automated peritoneal dialysis--actual clinical aspects].

Automated peritoneal dialysis (APD) is an important treatment option in PD patients with high peritoneal transport rates, in patients with inadequate small-solute clearances during continuous ambulatory peritoneal dialysis (CAPD) treatment, and in patients with complications associated with high intraperitoneal pressure. Because APD offers better flexibility during the daytime, patients often have a better quality of life and are able to go to work or school. However, APD is more expensive and technically more complex than CAPD and there are controversial results on the course of residual renal function and the risk of peritonitis in the two types of treatment. The increased elimination of antibiotic drugs during cycler therapy has to be considered in patients with peritonitis, especially in those using high treatment volumes. When used during the daytime dwell, polyglucose solution has been shown to improve ultrafiltration and reduce the extracellular fluid volume in PD patients. In comparison with conventional dialysis solutions, treatment with pH-neutral solutions allows better correction of metabolic acidosis and is associated with an increase of CA-125 dialysate concentrations and a reduction of infusion pain. Tidal PD has its place in patients with mechanical outflow problems; however, compared with conventional APD, there is no improvement of clearances when the dialysate flow is kept constant. Continuous-flow PD using a double-lumen catheter is more effective but also more expensive than conventional APD. Most studies report a similar or even better patient survival with APD than with CAPD; however, a selection bias cannot be excluded from these mainly retrospective studies. In summary, APD is an established method of PD treatment that provides several advantages to patients and contributes to decreased technical drop-out rates.

Humans↗
PubMed2005

History of cardiovascular disease is associated with endothelial progenitor cells in peritoneal dialysis patients.

BACKGROUND: It is unknown whether traditional cardiovascular disease risk factors influence the number of endothelial progenitor cells (EPCs) and whether numbers of EPCs correlate with endothelial function in patients with end-stage renal disease. METHODS: In a cross-sectional study of 38 peritoneal dialysis patients, we examined numbers of circulating CD34+/KDR+/CD133+ cells, CD34+ hematopoietic stem cells, and EPCs cultured from peripheral blood. We also assessed conventional cardiovascular disease risk factors, such as history of vascular disease, diabetes, hypercholesterolemia, hypertension, and smoking. We determined endothelial function by measurement of endothelium-dependent and endothelium-independent reactivity of forearm resistance arteries by using strain-gauge plethysmography. RESULTS: Numbers of EPCs cultured from peripheral blood and forearm blood flow reactivity did not differ between erythropoietin-treated peritoneal dialysis patients and healthy individuals. A history of vascular disease was associated with number of cultured EPCs, but other cardiovascular disease risk factors showed no association. Furthermore, there was no association of endothelial-dependent and endothelial-independent forearm blood flow reactivity with EPCs in peritoneal dialysis patients. CONCLUSION: In this first study of EPCs in peritoneal dialysis patients, we found an association between history of vascular disease and EPCs, but no association of EPCs with endothelial function or other cardiovascular disease risk factors.

Aged↗
PubMed2005

Longitudinal membrane function in functionally anuric patients treated with APD: data from EAPOS on the effects of glucose and icodextrin prescription.

BACKGROUND: Peritoneal dialysis is associated with changes in membrane function that can lead eventually to ultrafiltration (UF) failure. Factors driving these changes are thought to include hypertonic glucose exposure, but previously reported associations are confounded by the presence of residual renal function. METHODS: Longitudinal membrane function (solute transport and UF capacity) were measured annually in a prospective cohort of 177 functionally anuric patients as part of the European Automated Peritoneal Dialysis Outcomes Study (EAPOS). Subgroup analysis was performed according to glucose exposure and icodextrin use at baseline. RESULTS: The whole cohort experienced an increase in solute transport and reduction in UF capacity at 12 and 24 months that could not be explained by informative censoring. These changes were accelerated and more severe in patients using either 2.27% or 3.86% glucose, or those not using icodextrin at baseline. These differences could not be explained by age, comorbidity score, previous time spent on renal replacement, differential dropout from the study, peritonitis rates, or, by definition, residual renal function. Patients using icodextrin at baseline had worse membrane function and were more likely to be diabetic. There was an association between membrane function changes and achieved 24-hour ultrafiltration over the 2-year study period. CONCLUSION: Anuric automated peritoneal dialysis (APD) patients experience significant detrimental changes in membrane function over a relatively short time period. Glucose appears to enhance these changes independent of residual renal function. Icodextrin use in these circumstances is associated with less deterioration in membrane function.

Anuria↗
PubMed2005

Intravenous iron increases labile serum iron but does not impair forearm blood flow reactivity in dialysis patients.

BACKGROUND: There are concerns about adverse vascular effects of intravenous iron by inducing oxidative stress. We therefore examined the effect of a single high dose of intravenous iron on endothelial function and biochemical markers of iron homeostasis. METHODS: In a randomized, placebo-controlled, double-blind, parallel-group study, forearm blood flow (FBF) was assessed by strain-gauge plethysmography in 38 peritoneal dialysis patients before and after a single intravenous infusion of 300 mg iron sucrose. RESULTS: Iron infusion increased total (Delta 601 microg/100 mL, CI 507, 696) and non-transferrin-bound iron (Delta 237.2 micromol/L, CI 173.6, 300.8) approximately 10-fold, as well as redox-active iron nearly five-fold (Delta 0.76 micromol/L, CI 0.54, 0.98). After iron infusion basal FBF was 59% higher than after placebo. FBF response to acetylcholine before and after iron infusion was 263 +/- 32% and 310 +/- 33%, corresponding to 304 +/- 43% and 373 +/- 29% in the placebo group, respectively. Before and after iron or placebo infusion, glyceryl-trinitrate increased resting FBF to 232 +/- 22% and 258 +/- 21% in the iron group, and to 234 +/- 18% and 270 +/- 30% in the placebo group. L-N-monomethyl-arginine decreased FBF to 70 +/- 4% and 72 +/- 3% before and after iron, and to 74 +/- 4% and 73 +/- 4% before and after placebo infusions, respectively. Despite higher basal FBF after iron infusion, absolute and relative FBF changes in response to vasoactive substances were not significantly different between iron and placebo groups. CONCLUSION: Our data suggest that 300 mg intravenous iron sucrose has a vasodilatory effect, but does not impair vascular reactivity in dialysis patients, despite a significant increase in non-transferrin-bound and redox-active iron.

Adult↗
PubMed2003

Aberrant T cell activation and heightened apoptotic turnover in end-stage renal failure patients: a comparative evaluation between non-dialysis, haemodialysis, and peritoneal dialysis.

Patients in end-stage renal disease (ESRD) have a high incidence of bacterial and viral infections. Fifteen non-dialysed (ND), 15 haemodialysed (HD), 15 patients with peritoneal dialysis (PD), and 15 healthy controls were included. T cell proliferation was measured by [3H]thymidine uptake. Apoptosis and cell phenotype were determined by FACS. sTNF-R1, sCD95, interleukin-1beta-converting enzyme (sICE), and interleukin (IL)-10 were measured by ELISA. PHA and CD3-driven T cell proliferation were significantly decreased in ESRD patients. CD3(+), CD19(+) B cells, and percentage of CD4(+) T cells were significantly reduced. Percent memory T cells (CD45RO(+)) and cells undergoing apoptosis (CD95(+)/Annexin V+) were significantly increased in ESRF. Moreover, sCD95, sTNFRI, and ICE were significantly increased. Serum level of IL-10, a Th2 cytokine, was enhanced. These findings strongly suggest that in ESRD patients Th1 T cells are selectively susceptible to undergo apoptosis. This observation provides an additional pathophysiological concept in the genesis of Th2 dominance.

Aged↗
PubMed2003

Effect of TCN2 776C>G on vitamin B12 cellular availability in end-stage renal disease patients.

BACKGROUND: Transcobalamin II is a serum protein that transports vitamin B12 from the intestine to the tissues. This complex, holo-transcobalamin II, may reflect vitamin B12 availability in the body. Conflicting data exist with regard to the effect of a polymorphism in the gene coding for transcobalamin II, TCN2 776C>G, on transcobalamin II levels in the general population, which in turn may affect holo-transcobalamin II, vitamin B12, as well as total homocysteine (tHcy) plasma levels. The effect of TCN2 776C>G on vitamin B12 cellular availability in dialysis patients is unknown. METHODS: We examined the effect of TCN2 776C>G on holo-transcobalamin II, vitamin B12, and tHcy plasma concentrations in 120 dialysis patients. RESULTS: Holo-transcobalamin II levels were normal or supranormal in all patients and showed a linear association with albumin (r = 0.205, P = 0.025) and with vitamin B12 (r = 0.778, P = 0.001), but not with age, creatinine, body mass index, tHcy, ln-tHcy, vitamin B6, plasma folate, and red blood cell folate concentration. TCN2 776C>G showed no effect on holo-transcobalamin II, vitamin B12, and tHcy concentration [one-way analysis of variance (ANOVA), post-hoc Scheffe test]. Multiple linear regression analyses showed that albumin and B12 are independently associated with holo-transcobalamin II, whereas TCN2 776C>G and MTHFR 677C>T had no effect. Independent predictors of ln-tHcy included creatinine, red blood cell folate, and the MTHFR 677TT genotype. There was also an effect of the TCN2 776CC genotype on ln-tHcy levels in this multivariate analysis, however, that deserves cautious interpretation because there was no effect of TCN2 genotypes by ANOVA and Scheffe test [median ln-tHcy concentrations according to TCN2 genotypes (micromol/L): CC, 3.22; CG, 3.30; GG, 3.23]. CONCLUSION: TCN2 776C>G does not influence holo-transcobalamin II or vitamin B12 levels, and has no major effect on tHcy concentrations of end-stage renal disease patients.

Adult↗
PubMed2003

Acute effect of amino acid peritoneal dialysis solution on vascular function.

BACKGROUND: Oral ingestion of proteins or amino acids is associated with endothelial dysfunction. The effect of commercial amino acid peritoneal dialysis solutions on vascular function is unknown. OBJECTIVE: We compared the acute effect of intraperitoneal amino acid administration with that of intraperitoneal glucose administration on vascular function in peritoneal dialysis patients. DESIGN: In an open-label randomized, controlled, crossover and observer-blinded trial, we examined the acute effect of an intraperitoneal application of 2 L commercial 1.1% amino acid solution compared with that of a 2.27% glucose solution in 13 peritoneal dialysis patients. The primary endpoint was the change in forearm reactive hyperemia 6 h after instillation of either dialysis solution. RESULTS: After 6 h of dwell time, reactive hyperemia was substantially impaired after administration of the amino acid solution compared with the glucose solution (median difference: 202%; 95% CI: 57%, 368%; P = 0.007). In a comparison of differences between values at 6 h and those before treatment, reactive hyperemia significantly decreased during the dwell with the amino acid dialysis solution compared with that with the glucose dialysis solution (median difference: 242%; 95% CI: 53%, -457%; P = 0.013). In an analysis of smoking and nonsmoking patients separately, the difference in forearm blood flow between the 2 treatments was still statistically significant. CONCLUSIONS: One 6-h dwell with a commercial amino acid dialysis solution acutely impairs forearm reactive hyperemia in smoking and nonsmoking peritoneal dialysis patients. Because endothelial dysfunction is associated with increased morbidity and mortality, the long-term use of these solutions may increase the risk of cardiovascular disease.

Adult↗
PubMed2003

Personal dialysis capacity (PDC(TM)) test: a multicentre clinical study.

BACKGROUND: The assessment of the peritoneal membrane capacity and physiology of the individual patient is becoming increasingly important. It allows the prescription of an individualized peritoneal dialysis (PD)-regimen, and the monitoring of peritoneal membrane function over time. The PDC(TM) program offers the possibility to evaluate the peritoneal membrane characteristics and to predict solute and water removal by simulation of different treatment regimens. METHODS: This study evaluates the relevance of the PDC(TM) program when routinely used. The PDC(TM) data of 336 patients from nine different centres in Europe were evaluated. RESULTS: The area parameter was 20 985+/-7578 cm/1.73 m(2) (mean+/-SD). The reabsorption of fluid after dissipation of glucose, Jv(AR), was 1.97+/-1.00 ml/min/1.73 m(2). The large pore fluid flux, Jv(L), was 0.11+/-0.07 ml/min/1.73 m(2). A multivariate model for prediction of serum albumin included dialysate protein loss, Jv(L), Jv(AR), nPCR, A(0)/deltaX, BMI and gender (R(2)=0.81, P<0.001). Total clearance fell with increasing PD duration (P<0.001). A negative relation between A(0)/deltaX and ultrafiltration (rho=-0.26, P<0.05), a positive relation between A(0)/deltaX and peritoneal creatinine clearance (rho=0.52, P<0.05) and urea clearance (rho=0.36, P<0.05), and a positive relation between measured peritoneal creatinine and urea clearance (rho=0.64, P<0.01) was observed. CONCLUSIONS: In summary, the present study shows that the PDC(TM) program is a robust, accurate method to describe the peritoneal membrane transport characteristics. Analysis of PDC(TM) data of large groups of patients, especially if followed up over time, can give interesting information on the physiology of the peritoneal membrane and the impact of different parameters on it.

Aged↗
PubMed2003

Effect of glutamate carboxypeptidase II and reduced folate carrier polymorphisms on folate and total homocysteine concentrations in dialysis patients.

This study was designed to examine the effect of two single nucleotide polymorphisms in the reduced folate carrier 1 (RFC1 80G>A) and the glutamate carboxypeptidase 2 (GCP2 1561C>T) gene on total homocysteine (tHcy) plasma level and folate status in 120 chronic dialysis patients. Red blood cell folate concentration was higher in patients with the GCP2 CT or TT genotype (ANOVA, P = 0.04). Among patient groups with different RFC1 genotypes, red blood cell folate level was not significantly different. A multivariate analysis confirmed that the GCP2 1561C>T genotype (P = 0.011) had a significant influence on the red blood cell folate concentration. Overall, serum folate, creatinine, and the GCP2 polymorphism explained nearly 50% of the variance of red blood cell folate. A linear multivariate regression analysis showed that red blood cell folate (P < 0.001), creatinine (P < 0.001), and the 5,10-methylenetetrahydrofolate reductase (MTHFR) 677T allele (P = 0.013) are independent predictors of tHcy plasma level explaining 49% of the variance of tHcy plasma concentration. GCP2 1561C>T and RFC1 80G>A showed no effect on tHcy and folate plasma level. In conclusion, GCP2 1561C>T, but not RFC1 80G>A, is a predictor of red blood cell folate level in chronic dialysis patients. Both polymorphisms have no major effect on tHcy plasma concentration in end-stage renal disease patients.

Adult↗
PubMed2002

Riboflavin is a determinant of total homocysteine plasma concentrations in end-stage renal disease patients.

The effect of thiamine (vitamin B(1)) or riboflavin (vitamin B(2)) availability on fasting total homocysteine (tHcy) plasma levels in end-stage renal disease patients is unknown. A cross-sectional study was performed in a population of non-vitamin supplemented patients maintained on continuous ambulatory peritoneal dialysis. Red blood cell availability of thiamine (alpha-ETK) and of riboflavin (alpha-EGR), along with other predictors of tHcy plasma levels, was considered in the analysis. There was a linear association of alpha-EGR with tHcy plasma concentrations (P = 0.009), which was not observed for alpha-ETK. Among red blood cell vitamins, alpha-EGR was the only predictor of tHcy levels (P = 0.035), whereas alpha-ETK, red blood cell pyridoxal-5-phosphate supply (alpha-EGOT) and red blood cell folate levels had no effect. The risk for having a high tHcy plasma levels within the fourth quartile (plasma tHcy >38.3 micromol/L) was increased by an alpha-EGR > median (odds ratio, 4.706; 95% confidence interval, 1.124 to 19.704; P = 0.026). By way of contrast, alpha-ETK had no effect in these analyses. Independent predictors of tHcy plasma levels were serum albumin, alpha-EGR, red blood cell folate, and certain MTHFR genotypes. A logistic regression analysis showed that the MTHFR genotype is a predictor for having a tHcy plasma concentration within the fourth quartile. In summary, riboflavin availability, as measured by alpha-EGR, is a determinant of fasting tHcy plasma levels in peritoneal dialysis patients. This finding may have implications for tHcy lowering therapy in individuals with end-stage renal disease.

Analysis of Variance↗
PubMed2002

Hepatitis B and C in peritoneal dialysis patients.

In most countries the prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in peritoneal dialysis (PD) patients is lower than in hemodialysis (HD) patients. Besides a history of blood transfusions, previous HD is an important risk factor for developing HCV infection in PD patients. Many HCV-positive patients already are anti-HCV-positive before initiation of PD. Seroconversion to HCV during PD treatment is, therefore, a rare event. HCV RNA in serum is positive in 53% to 84% of anti-HCV-positive patients. Routine screening for HBV and HCV by using a second- or third-generation enzyme-linked immunosorbent assay (ELISA) should be performed in PD patients every 6 months. Asymptomatic HBV and HCV infection may be detected by elevation of transaminases, but lower cut-off levels should be preferred in PD patients. Prophylactic strategies include hygienic measures and HBV vaccination. The staff should be aware of the infectiousity of the PD effluent, especially in hepatitis B surface antigen (HBsAg)-positive patients. Because of the smaller number of required blood transfusions and the increased use of home therapy, which reduces the risk for environmental contamination, PD is considered to be an important strategy for prevention of hepatitis in end-stage renal disease patients.

Cross Infection↗
PubMedDate not supplied

Efficacy of a low-dose intravenous iron sucrose regimen in peritoneal dialysis patients.

OBJECTIVE: Sufficient iron substitution leads to a decrease in the required recombinant human erythropoietin (rHuEPO) dose and/or an increased hematocrit in dialysis patients. Intravenous (i.v.) application of larger doses of iron sucrose may be associated with hyperferritinemia, appearance of catalytically free iron, and impaired phagocyte function. Therefore, we investigated the effectiveness of a low-dose i.v. iron regimen in peritoneal dialysis (PD) patients. PATIENTS AND INTERVENTIONS: Forty-five PD patients were followed over a period of 1 year. Serum ferritin, serum transferrin saturation, and hemoglobin were measured monthly. In cases of absolute iron deficiency (serum ferritin < 100 microg/L), 50 mg iron sucrose was given i.v. every second week. In cases of functional iron deficiency (ferritin > or = 100 microg/L and transferrin saturation < 20%) and in iron repleted patients (ferritin > or = 100 microg/L and transferrin saturation > or = 20%), 50 mg i.v. iron sucrose was applied monthly. Iron therapy was stopped in cases of acute infection (until complete recovery) and when serum ferritin level was > or = 600 microg/L. RESULTS: To analyze the influence of iron substitution on erythropoiesis and rHuEPO requirements, the EPO resistance index (ERI; quotient of rHuEPO dose in units/kilogram/week and hemoglobin in grams per deciliter) was calculated every 3 months. The ERI decreased significantly during the course of the study in the whole patient group (p = 0.009) as well as in the subgroup of 21 patients with absolute iron deficiency (p = 0.01). A nonsignificant decrease in the ERI was observed within the group of 14 iron repleted patients (p = 0.5). There was no significant change in the ERI in 10 patients with functional iron deficiency (p = 0.6). CONCLUSION: The low-dose i.v. iron regimen used in this study substantially decreased rHuEPO requirements in patients with absolute iron deficiency and was effective in maintaining iron stores in iron repleted patients. However, in the absence of significant hyperparathyroidism, aluminum toxicity, or inadequate dialysis, it did not improve the ERI in patients with functional iron deficiency.

Adult↗