Alterations of erythrocyte structure and cellular susceptibility in patients with chronic renal failure: effect of haemodialysis and oxidative stress.

The aim of this study was to investigate erythrocytes rheological behaviour, membrane dynamics and erythrocytes susceptibility to disintegration upon strong oxidative stress induced by dialysis or by external H(2)O(2) among patients with CRF. EPR spectrometry was used to investigate alterations in physical state of cellular components. Generated ROS production induced: (1) significant increase of membrane fluidity in CRF erythrocytes treated with H(2)O(2) (p<0.005) and at 60 min of haemodialysis (p<0.05), (2) significant decrease of cytoskeletal protein-protein interactions (p<0.005) and (3) cellular osmotic fragility (p<0.0005). H(2)O(2) exacerbated these changes. Erythrocytes from CRF patients have changed rheological behaviour and present higher susceptibility to disintegration. Erythrocytes membrane characteristics indicate that CRF patients possess younger and more flexible cells, which are more susceptible to oxidative stress. This may contribute to the shortened survival of young erythrocytes in CRF patients.

[Blood serum and neutrophil amino acid concentrations during hemodialysis]. / Stezenia aminokwasów w osoczu i granulocytach obojetnochlonnych u pacjentów przewlekle dializowanych.

The abnormal amino acid profile and altered distribution of some amino acids between the extra- and intracellular compartments is currently recognized as a part of metabolism abnormalities in hemodialyzed uremic patients associated with prognosis. The aim of this study was to investigate the pattern of HD influence on the extra- and intracellular amino acid concentrations in neutrophil homogenates and in blood serum. Before HD, the concentrations of arginine (64 vs 33 micromol/l) and cysteine (70 vs 40 micromol/l) were significantly higher in the uremic blood serum, but the concentrations of five amino acids, i.e. serine, threonine, alanine, proline, and valine, were significantly decreased in the uremic serum. The concentrations of arginine (7.95 vs 5.2 micromol/l), tyrosine (14.3 vs 12.5 micromol/l) and phenylalanine (10.7 vs 9.5 micromol/l) were significantly elevated in neutrophil homogenate from uremic patients before HD and after HD for arginine (8.73 micromol/l). We found a substantial increase of blood serum arginine concentration at all evaluated time points of HD from 64 to 191 micromol/l. The concentration of 8 amino acids were found to be significantly decreased in blood serum during HD. We may assume amino acid concentration changes in chronic uremia partly attributed to malnutrition, may be actually associated with inflammatory pathomechanisms, the hypothesis worth verifying in further studies.

[Physiopathology of advanced age]. / Fizjopatologia wieku podeszlego.

The paper presents basic changes in the cell structure and function and organ dysfunctions related to advanced age.

Increased hydrogen peroxide in the exhaled breath of uraemic patients unaffected by haemodialysis.

BACKGROUND: Uraemia is accompanied by conditions favouring the rise of H2O2 activity in body fluids. This results from the increased release of H2O2 by polymorphonuclear leukocytes and decreased plasma glutathione peroxidase activity. The purpose of this study was to determine if patients on chronic haemodialysis (HD) exhale more H2O2 than healthy individuals, and if dialysis affects breath H2O2 content. METHODS: We studied 29 chronic HD patients (mean age 49 +/- 11 years) and 40 healthy persons (mean age 44 +/- 9 years). H2O2, which is volatile, was measured fluorimetrically with the homovanillic acid method in the exhaled breath condensate (EBC) of the study cohort. EBC was collected immediately before and after the HD session and also at 20 and 60 min of HD treatment (n = 14) and once in controls. Peak expiratory flow (PEF), white blood cell (WBC) count, PaO(2) and circulatory cyclic guanosine monophosphate (cGMP), Il-6 and Il-8 concentrations were measured concomitantly. Finally, H2O2 diffusion through the dialyser cuprophane membrane was determined in an in vitro experiment. RESULTS: At baseline, EBC H2O2 concentration was 22 times higher in HD patients than in controls (2.92 +/- 4.64 vs 0.16 +/- 0.13 microM, P < 0.001). Although the maximum decrease in PEF (431 +/- 52 vs 398 +/- 56 l/min, P < 0.01) and WBC count (6.72 +/- 1.02 vs 3.82 +/- 1.51 x 10(3)/ microl, P < 0.01) occurred at 20 min after the start of HD, no significant changes in breath H2O2 levels were noted throughout the session. Plasma IL-6 and IL-8 levels remained unchanged whereas cGMP rose 1.3 times at 60 min (P < 0.01). In vitro, H2O2 rapidly diffused through the cuprophane membrane. CONCLUSION: Chronic HD patients exhale more H2O2 than healthy subjects. Although no change of breath H2O2 concentration was observed during HD, as H2O2 easily diffuses through the dialyser membrane, it is not possible to rule out that HD stimulates H2O2 generation.

Left atrial function in patients with renal transplantation.

BACKGROUND: Chronic renal failure leads to structural changes and cardiac functional abnormalities known as uremic cardiomyopathy. Eliminating excess water and improving the composition of the inner environment leads to at least partial cardiac function improvement, which is reflected primarily in favorable changes in left ventricular indices. The aim of our study was to evaluate left atrial function in patients after renal transplantation and compare them with clinically healthy subjects. MATERIAL/METHODS: 10 renal transplant patients (2 women, 8 men; mean age 47.8 +/- 6.4 years), treated before transplantation with repeated hemodialysis, were subjected to standard transthoracic echocardiographic examination. Atrial function was evaluated in M-mode and 2D projections and by cross-sectional Doppler echocardiography. The results obtained were compared with 16 healthy controls (9 women, 7 men; mean age 39.7 +/- 9.4 years). RESULTS: Maximal left atrial dimension (LAmax), left atrial dimension obtained in M-mode of the long axis in parasternal projection (LAa), ejection time (ETlp) and pre-ejection period (PEPlp) were significantly higher in renal transplant patients than in healthy subjects. In both investigated groups there were no differences in minimal left atrial dimensions (LAmin), PEPlp/Etlp ratio, P wave time (P), left atrial fiber shortening fraction (FS%lp), passive evacuate fraction (FBOlp), total left atrial fraction (FClp), or IElp ratio. CONCLUSIONS: Abnormal function of the left atrium in the course of uremia treated with repeated hemodialysis is not fully corrected after renal transplantation despite the elimination of many cardiovascular complications observed in chronic renal disease.

Effects of uraemia and haemodialysis on neutrophil apoptosis and expression of apoptosis-related proteins.

BACKGROUND: In haemodialysis (HD) patients, it is unclear whether increased apoptosis of neutrophils is due to uraemia or HD itself. The purpose of the current study was to assess the effect of uraemia and HD on the rate of apoptosis and apoptosis-related protein expression in whole blood neutrophils. METHODS: We employed a whole-blood micromethod to test spontaneous apoptosis and expression of apoptosis-regulating proteins in cultured neutrophils from uraemic patients (pre-HD), HD patients and healthy controls. Blood samples were drawn before, after 20 min and after 4 h of haemodialysis, and were then cultured for 20 h. We evaluated the rate of apoptosis from annexin V and propidium iodide staining, and examined bcl-2, Fas/Apo-1 and p53 expression in the cultured neutrophils. RESULTS: Fas/APO-1 expression and total percentage of apoptotic whole blood neutrophils of pre-HD and HD patients before HD were significantly higher than controls. There was a transient but significant decrease in the percentage of apoptotic neutrophils and Fas/APO-1 expression after 20 min of dialysis. The expression of bcl-2 protein was significantly lower from neutrophils in HD patients compared with controls, and HD significantly downregulated bcl-2 expression. The p53 protein content in HD patients before HD was significantly higher than in pre-HD patients. CONCLUSIONS: These findings suggest that uraemia accelerates neutrophil apoptosis by increasing Fas/Apo-1, and that HD does not affect neutrophil apoptosis more than uraemia. In addition, HD produces only in a transient sequestration of potentially apoptotic neutrophils.

Blood serum and neutrophil L-arginine concentrations and nitric oxide release by neutrophils in chronic uremic patients and healthy persons.

BACKGROUND: Plasma levels of L-arginine have previously been evaluated in several studies to reveal either down- or up-regulation of the L-arginine/NO pathway in chronic uremia. MATERIAL/METHODS: We studied L-arginine plasma levels along with intracellular neutrophil concentration and NO release by peripheral blood neutrophils in patients with chronic uremia. RESULTS: The L-arginine plasma concentration was found to be significantly higher (64.4 +/- 12.0 micromol/L) in chronic uremic patients (n=25) than in healthy controls (33.0? +/- 10.0 micromol/L; n=25). Neutrophil homogenate L-arginine levels were substantially increased in uremic patients (7.95? +/- 1.10 nmol/10(8) cells) as compared with controls (5.22 +/- 0.46 nmol/10(8) cells). The in vitro release of NO by unstimulated neutrophils was lower in uremic patients (0.14? +/- 0.05? micromol s(-1)) than in healthy persons (0.48 +/- 0.20 micromol s-1). The NO release after uremic neutrophil stimulation with 10(-6) M fMLP was 21.42 +/- 2.13 micromol s(-1), while after PMA it was 31.01 +/- 1.99 micromol s(-1). NO release after normal neutrophil stimulation with 10(-7) M fMLP was 19.52 +/- 2.32 micromol s(-1), and after PMA was 28.63 +/- 3.06 micromol s(-1). CONCLUSIONS: In chronic uremic patients plasma and neutrophil concentrations of L-arginine were significantly higher. However, there were no significant differences in NO release between normal and uremic neutrophils after stimulation. Our findings may have implications for the impact of the L-arginine-nitric oxide signaling pathway on the pathophysiological changes in the L-arginine: NO pathway seen in chronic uremia.