Osteoprotegerin and Inflammation in Incident Peritoneal Dialysis Patients

Objectives: Osteoprotegerin (OPG) is a member of the tumor necrosis factor receptor family involved in processes in many inflammatory states. OPG concentration is enhanced in the majority of chronic kidney disease (CKD) patients and those undergoing renal replacement therapy. The aim of the study was to assess the relation of OPG and chronic inflammation in peritoneal dialysis (PD) patients and to evaluate whether OPG concentrations in plasma and dialysate were related to plasma and dialysate levels of proinflammatory mediators (interleukin 6 (IL-6), high-sensitivity C-reactive protein (hsCRP), interleukin 33 (IL-33) and interleukin 1 receptor-like 1IL-1RL1 (IL-1RL1, sST2)). Methods: The study included 37 patients of the Peritoneal Dialysis Center, Department of Nephrology, Transplantology and Internal Medicine, Szczecin, Poland, 4-6 weeks after the onset of peritoneal dialysis therapy. During a peritoneal equilibration test, plasma (at 2 h) and dialysate (at 4 h) OPG, IL-33, 1IL-1RL1 (sST2), IL-6 and hsCRP concentrations were determined. Results: Plasma concentration of OPG did not correlate with dialysate OPG level (Rs = 0.04, p = 0.8). There was a strong positive correlation between plasma OPG concentrations and plasma IL-1RL1 (sST2) (Rs = 0.41; p = 0.01), plasma IL-6 (Rs = 0.38; p = 0.01) and plasma hsCRP (Rs = 0.35; p = 0.02). Dialysate OPG concentrations were positively associated with dialysate IL-1RL1 (sST2) (Rs = 0.37; p = 0.02) and dialysate IL-6 levels (Rs = 0.44; p = 0.005). Multivariate analysis showed that higher IL-1RL1 (sST2) (ß = +0.38, p = 0.006), higher plasma hsCRP (ß = +0.32, p = 0.02) and older age (ß = +0.35, p = 0.01) were independent determinants of higher plasma OPG concentration and that higher concentrations of dialysate IL-6 (ß = +0.37, p = 0.02) were independent determinants of higher dialysate OPG concentration. Conclusions: Both plasma and dialysate OPG levels are associated with the severity of systemic and local inflammation illustrated by the plasma and dialysate concentrations of IL-1RL1 (sST2), hsCRP and IL-6, suggesting that OPG might have a pivotal role in explaining the milieu of systemic and intraperitoneal inflammation.

An Unusual Case of Vulvar Involvement in the Course of Granulomatosis with Polyangiitis

Granulomatosis with polyangiitis is a rare autoimmune disease with the presence of c-ANCA in most cases. It involves necrotizing inflammation in small and medium-sized vessels with multiple granulomas. The disease can affect many systems, but the typical triad of attacked systems are the upper and lower respiratory tracts and kidneys, with varying degrees of severity. Involvement of the respiratory tract may manifest, among other symptoms, as nasal crusting, nosebleeds, and dyspnea. Among patients with granulomatosis with polyangiitis, only less than 1% develop genitourinary system involvement. We present a case study of a 36-year-old woman with an 8-year-long GPA history and a lesion, which, due to its appearance and accompanying symptoms, aroused the suspicion of a neoplasm but was proven to be a granuloma with a nontypical location. The systemic disease was treated with glucocorticosteroids and cyclophosphamide. The lesion on the labium minus was surgically removed. We concluded that the macroscopic picture of GPA of the vulva and vulvar cancer is similar. The patient's medical history may help differentiate GPA and vulvar cancer. Although vulvar GPA is extremely rare, it should be considered in the differential diagnosis of vulvar lesions, especially those suspected to be oncological.

Repeat exit site infection in peritoneal dialysis patient with polycythemia vera - a case report

BACKGROUND

Infectious complications of peritoneal dialysis (PD) remain a common cause of catheter loss and discontinuation of PD. Exit site infection (ESI) constitutes a significant risk factor for PD-related peritonitis and determination of predisposing states is relevant. We here present a case of repeat ESI due to Pseudomonas aeruginosa in a PD patient with skin changes in the course of polycythemia vera (PV).

CASE PRESENTATION

A 73-year-old PD patient with chronic kidney disease secondary to renal amyloidosis and ankylosing spondylitis, presented to the nephrology unit with signs of ESI. In 2006 he was diagnosed with PV and since then has was successfully treated with hydroxyurea; however, he reported recurrent episodes of developing skin nodules in the course of the disease. Exit site swab yielded Pseudomonas aeruginosa and the infection developed in the ulcerated PV nodule that appeared in exit site 2 weeks earlier. Patient was treated with intraperitoneal amikacin and oral ciprofloxacin, however, due to neurological complications, the treatment had to be interrupted and finally catheter was removed. Similar episode of ESI with Pseudomonas aeruginosa developed in the patient two years earlier and also required catheter removal.

CONCLUSION

This is the first case report demonstrating the development of ESI on the polycythemia vera skin lesion in this area. Skin manifestations of PV might be a predisposing factor to ESI in PD patients.

Current epidemiology and practice patterns in prevention and treatment of PD-related infections in Poland

BACKGROUND

Peritoneal dialysis (PD) related infections are associated with technique failure and mortality. The aim of this multicentre study was to examine epidemiology, treatment and outcomes of PD-related infections in Poland as well as practice patterns for prevention of these complications in the context of current ISPD recommendations.

METHODS

A survey on PD practices in relation to infectious complications was conducted in 11 large Polish PD centres. Epidemiology of peritonitis and exit-site infections (ESI) was examined in all patients treated in these units over a 2 year period.

RESULTS

The study included data on 559 PD patients with 62.4% on CAPD. Practice patterns for prevention of infectious complications are presented. The rate of peritonitis was 0.29 episodes per year at risk, with Gram positive microorganisms responsible for more than 50% of infections and 85.8% effectively treated. Diagnosis and treatment followed ISPD guidelines however most units did not provide an anti-fungal prophylaxis. Although neither of the centres reported routine topical mupirocin on catheter exit-site, the rate of ESI was low (0.1 episodes per year at risk), with Staphylococcus aureus as most common pathogen and full recovery in 78.3% of cases.

CONCLUSION

The study shows rewarding outcomes in prevention and treatment of PD-associated infections, mainly due to a thorough compliance with the current ISPD guidelines, although some deviations from the recommendations in terms of practice patterns have been observed. More studies are needed in large numbers of patients to differentiate the importance of specific recommendations and further support the guidelines.

The influence of exposure to immunosuppressive treatment during pregnancy on renal function and rate of apoptosis in native kidneys of female Wistar rats

Pregnancy puts a significant additional strain on kidneys. The aim of our study was to investigate the impact of immunosuppressive drugs on changes in native kidneys in female Wistar rats after exposure during pregnancy. The study was conducted on 32 dams, subjected to immunosuppressive regimens commonly used in the therapy of human kidney transplant recipients (cyclosporine A, mycophenolate mofetil and prednisone; tacrolimus, mycophenolate mofetil and prednisone; cyclosporine A, everolimus and prednisone). The animals received drugs for 2 weeks before pregnancy and during 3 weeks of pregnancy. In all treated dams lower body weight (but not kidney mass) and alterations in serum sodium and chloride ions were found; serum creatinine concentration was increased in dams treated with cyclosporine A, everolimus and prednisone. All treatment groups of dams showed increased apoptosis in the distal tubules. In histological examination the changed intensity of acidophilic or basophilic cytoplasm of epithelial cells was found in kidneys of rats treated with calcineurin inhibitors, mycophenolate mofetil and prednisone. All immunosuppressive regimens caused abnormalities affecting nephron tubules. Regimens containing calcineurin inhibitors and mycophenolate mofetil caused higher rate of apoptosis and more pronounced histopathological changes. Regimen based on everolimus despite the lower rate of apoptosis in the proximal tubules and lower accumulation of kidney injury markers revealed higher serum creatinine concentration. Thus, interpretation which combination of drugs is better or worse for long-lasting functioning of kidneys in pregnant females requires further studies.

The Role of Klotho Protein in Chronic Kidney Disease: Studies in Animals and Humans

The identification of Klotho gene was a major discovery as the gene encodes a protein regulating multiple functions. A defect in Klotho gene expression in mice results in a phenotype of premature aging including shortened life span, growth retardation, hypogonadism, skin and muscle atrophies, vascular calcification, cognition impairment, motor neuron degeneration and others. This phenotype is associated with phosphate balance disorders and underlines the major function of Klotho in mineral metabolism. As another 2 related paralogs were discovered (beta-Klotho, which is involved in bile acid and energy metabolism, and gamma-Klotho, with a yet to be defined function), this led to the revised naming of Klotho as alpha-Klotho. Two forms of alpha-Klotho protein have been reported: a membrane-bound and a soluble one. Membrane Klotho forms a complex with fibroblast growth factor (FGF) receptors and functions as an obligate co-receptor for the FGF-23 phosphatonin in distal tubules. The soluble form of Klotho seems to function as a humoral factor and regulates glycoproteins on the cell surface including ion channels and growth factors. There is data suggesting that soluble Klotho exerts phosphaturic effects independently of FGF-23. Circulating soluble Klotho is produced either by proteolytic cleavage of the extracellular domain of the transmembrane form by two membrane-anchored proteases (ADAM10 and ADAM17) or by alternative mRNA splicing. In animal models Klotho has been shown to exert pleiotropic actions, including cytoprotection, anti-oxidation, anti-apoptosis, protection of vasculature, promotion of angiogenesis and vascularization, inhibition of fibrogenesis and preservation of stem cells. The exact diagnostic and therapeutic role of Klotho in humans is not fully known yet. The article presents the role of Klotho in physiology and different stages of chronic kidney disease (CKD).

The influence of intrauterine exposure to immunosuppressive treatment on changes in the immune system in juvenile Wistar rats

Background

In our study, we assessed the impact of immunosuppressive drug combinations on changes in the immune system of juvenile Wistar rats exposed to these drugs during pregnancy. We primarily concentrated on changes in two organs of the immune system – the thymus and the spleen.

Methods

The study was conducted on 40 (32+8) female Wistar rats administered full and half dose of drugs, respectively, subjected to regimens commonly used in therapy of human kidney transplant recipients ([1] cyclosporine A, mycophenolate mofetil, and prednisone; [2] tacrolimus, mycophenolate mofetil, and prednisone; [3] cyclosporine A, everolimus, and prednisone). The animals received drugs by oral gavage 2 weeks before pregnancy and during 3 weeks of pregnancy.

Results

There were no statistically significant differences in the weight of the thymus and spleen, but changes were found in the results of blood hematology, cytometry from the spleen, and a histologic examination of the examined immune organs of juvenile Wistar rats. In the cytokine assay, changes in the level of interleukine 17 (IL-17) after increasing amounts of concanavaline A were dose-dependent; the increase of IL-17 was blocked after administration of higher doses of immunosuppressive drugs. However, after a reduction of doses, its increase resumed.

Conclusion

Qualitative, quantitative, and morphological changes in the immune system of infant rats born to pharmacologically immunosuppressed females were observed. Thymus structure, spleen composition, and splenocyte IL-17 production were mostly affected in a drug regimen–dependent manner.

Effect of Immunosuppressive Therapy on Proteinogram in Rats

BACKGROUND It has been observed that the use of immunosuppressive drugs in patients after transplantation of vascularized organs may be associated with changes in the concentration of certain fractions of plasma proteins. The concentration of these proteins was correlated with an increased risk of occurrence of stage 3 chronic kidney disease (CKD). This article examines the effect of the most commonly used immunosuppressive drugs on the concentration of plasma proteins in Wistar rats. MATERIAL AND METHODS The study involved 36 rats grouped according to the immunosuppressive regimen used (tacrolimus, mycophenolate mofetil, cyclosporine A, rapamycin, and prednisone). The rats in all study groups were treated with a 3-drug protocol for 6 months. The treatment dose was adjusted based on available data in the literature. No drugs were administered to the control group. The rats were sacrificed and blood samples collected to determine the concentration of plasma proteins using electrophoresis technique. RESULTS Statistically significant differences were observed between protein concentrations within the studied groups. The differences related to the proteins with masses of 195 kDa, 170 kDa, 103 kDa, and 58 kDa. CONCLUSIONS (1) Immunosuppressive drugs caused changes in the proteinogram of plasma proteins. (2) The strongest effect on rat plasma proteins was exerted by a regimen based on rapamycin. Intermediate, weak, and weakest effects were observed in regimens based on cyclosporine A, tacrolimus, and mycophenolate mofetil, respectively.

Birth defects in juvenile Wistar rats after exposure to immunosuppressive drugs during pregnancy

INTRODUCTION

Immunosuppressive drugs and their active metabolites can cross the placental barrier and enter fetal circulation. The adverse effects on the fetus include chromosomal aberrations, structural malformations, organ-specific toxicity and intrauterine growth retardation. The aim of our study was to investigate the impact of "safe" and "contraindicated" immunosuppressive drugs on birth defects in juvenile Wistar rats after exposure of pregnant female rats to these drugs.

MATERIAL AND METHODS

The study was conducted on 32 female Wistar rats, subjected to immunosuppressive regimens most commonly used in therapy of human kidney transplant recipients. The animals received drugs by oral gavage 2 weeks before pregnancy and during 3 weeks of pregnancy.

RESULTS

Treatment with mycophenolate mofetil and everolimus turned out to be toxic. We have noticed a significantly reduced number of live births in all pregnant rats exposed to these drugs in combination with calcineurin inhibitors and prednisone. Malformations and histological changes of fetal organs were confirmed after mycophenolate mofetil exposure during pregnancy.

CONCLUSIONS

Mycophenolate mofetil turned out to be more toxic when used with tacrolimus than with cyclosporin (delivery of live offspring was possible only in the latter group). Everolimus in combination with cyclosporin effectively suppressed the fetal maturation in utero, but did not contribute to the development of malformations.

Changes in the Immune System of Female Wistar Rats After Exposure to Immunosuppressive Treatment During Pregnancy

This experimental study assessed the impact of medications frequently used after kidney transplantation on the immune system of pregnant female Wistar rats. The study evaluates medications, both approved and contraindicated during pregnancy in common therapeutic combinations. The study was conducted on 32 female Wistar rats, subjected to immunosuppressive regimens most commonly used in therapy of human kidney transplant recipients (cyclosporine A, mycophenolate mofetil and prednisone; tacrolimus, mycophenolate mofetil and prednisone; and cyclosporine A, everolimus and prednisone). The animals received drugs by oral gavage 2 weeks before pregnancy and at 3 weeks of pregnancy. We found drug regimen-dependent differences in cytometry from spleen. Many subpopulations of lymphocytes were suppressed in rats treated with cyclosporine A, mycophenolate mofetil and prednisone and tacrolimus, mycophenolate mofetil and prednisone; the number of NK cells was increased in group of rats treated with cyclosporine A, everolimus and prednisone. We also found changes in histological examination of thymus and spleen of all treated dams. In cytokine assay, we noticed increasing levels of IL-17 with increasing doses of concanavalin A in control group and in group of dams treated with cyclosporine A, mycophenolate mofetil and prednisone. This increase was blocked in rats treated with tacrolimus, mycophenolate mofetil and prednisone and cyclosporine A, everolimus and prednisone. Qualitative, quantitative and morphological changes of immune system in pharmacologically immunosuppressed females have been observed. Thymus structure, spleen composition and splenocytes IL-17 production were mostly affected in drug regimen-dependent manner.

Does Immunosuppressive Therapy Affect Markers of Kidney Damage?

BACKGROUND

Markers currently used to detect kidney damage are effective in both early (KIM-1, NGAL) and late (MCP-1, MMP, TIMP) stages of renal tubular damage, indicating the progression of chronic kidney disease. Immunosuppressive drugs may damage the transplanted organ through their direct toxic effects and by contributing to the development of chronic fibrosis and tubular atrophy. The aim of this study was to determine if immunosuppressive drugs per se affect the concentration of kidney damage markers, by using concentrations and doses of immunosuppressive within therapeutic, not toxic, levels in rat blood.

MATERIAL AND METHODS

The study involved 36 rats grouped according to the immunosuppressive regimen used (tacrolimus, mycophenolate mofetil, cyclosporin A, rapamycin, and prednisone). The rats were treated with a 3-drug protocol for 6 months. No drugs were administered to the control group. The blood samples were collected to determine the concentration of kidney damage markers by using enzyme-linked immunosorbent assay (ELISA).

RESULTS

1. In the groups receiving regimens based on cyclosporin A (CyA), significantly higher concentrations of KIM-1 in plasma was observed compared to cases not treated with drugs. 2. The use of tacrolimus was associated with increased concentrations of MCP-1 in plasma and rapamycin was associated with decreased concentrations of MCP-1 in plasma. 3. Rapamycin induces an unfavorable, profibrotic imbalance between metalloproteinase-9 and its inhibitor, TIMP-1.

CONCLUSIONS

Commonly used immunosuppressive drugs influence the concentration of blood markers of kidney damage. This fact should be taken into account when analyzing the association between the concentration of these markers and pathological processes occurring in the transplanted kidney.

The activity of antioxidant enzymes in blood platelets in different types of renal replacement therapy: a cross-sectional study

PURPOSE

The changes in redox status characterise physiological platelet activation. Increased oxidative stress in chronic kidney disease (CKD) associated with uremic toxicity and procedures of renal replacement therapy leads to the impairment of antioxidant properties of platelets. It may contribute to thrombosis and cardiovascular complications increasing morbidity and mortality among the CKD patients. The object of the research was to assess the influence of conservative treatment, peritoneal dialysis and haemodialysis on platelet prooxidative-antioxidative balance.

METHODS

The examined group consisted of 122 patients: 37 on regular haemodialysis (HD), 23 on peritoneal dialysis (PD) and 62 on conservative treatment with CKD stages 3-5 (CKD3-5). The activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione transpherase (GST) in platelets were obtained using kinetic methods. The spectrophotometric method established the concentrations of reduced glutathione (GSH).

RESULTS

SOD activity in PD differs significantly from CKD3-5 (4.96 vs 1.66; p < 0.0001). CAT activity assessed in PD and CKD3-5 was significantly different from HD (0.82 and 0.8 vs 0.52 before and 0.35 after HD, respectively). GST activity reached the highest value in PD (1.62), and it was significantly different from CKD3-5 (0.23) and HD before haemodialysis (0.11). During haemodialysis therapy, there was a considerable increase in GST activity (0.11 vs 0.3; p = 0.02) and decrease in SOD activity (from 3.41 to 2.27; p = 0.01). The highest GSH concentrations were obtained in CKD3-5 and differ significantly from HD (4.12 vs 2.01; p = 0.02).

CONCLUSIONS

The type of treatment, age and duration of renal replacement therapy determined significant changes in platelet antioxidative enzymes activities and concentration of GSH, which may enhance the thrombotic complications. PD is associated with lower platelet oxidative stress.

Oxidative stress and antioxidative enzyme activities in chronic kidney disease and different types of renal replacement therapy

The incidence and diagnosis of chronic kidney disease (CKD) is on the rise all over the world. CKD is related to ageing of the society and high morbidity due to lifestyle diseases like diabetes, atherosclerosis, and hypertension. CKD is associated with increased oxidative stress generated by uremic toxicity, chronic inflammatory state, lack of vitamins and microelements, parenteral iron administration, and dialysis procedure itself. In terms of cellular physiology, erythrocytes and blood platelets in particular have effective enzymatic and non-enzymatic antioxidative system. The most efficient enzymatic antioxidants include superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glucose-6-phosphate dehydrogenase. Glutathione is the leading non-enzymatic free radical scavenger. In CKD, antioxidative defense is impaired and the abnormal activity of the enzymes and glutathione concentration is described in literature. The imbalance between the formation of reactive oxygen species and antioxidative system efficiency takes part in the pathogenesis of cardiovascular complications. It contributes to increased morbidity and mortality in patients with CKD. The severity of these processes depends on the type of renal replacement therapy; haemodialysis (HD) is more predisposing to such disorders than peritoneal dialysis (PD), or even conservative treatment. This can influence the outcome and the possibility of kidney transplantation. Moreover, the early function of kidney allograft seems to be dependent on perioperative antioxidative ability of platelets, which can play a potential protective role in kidney transplantation.

[Nutritional status of patients undergoing peritoneal dialysis]

INTRODUCTION

The main causes of death in patients undergoing dialysis are cardiovascular diseases. Their presence is related to the nutritional status of patients treated with peritoneal dialysis, and has a predicted value in this kind of patient. Long-term therapy entails unfavourable changes, from which a clinically significant complication is protein-energy malnutrition and intensification of inflammatory processes. The aim of the study was to assess the nutritional status of patients with chronic kidney disease treated with peritoneal dialysis based on anthropometric, biochemical parameters analysis, a survey, as well as the determination of changes in measured parameters occurring over time.

MATERIAL AND METHODS

The study involved 40 people undergoing peritoneal dialysis (PD) and 30 healthy people. For dialyzed patients testing material was collected twice, every 6 months. Proteins, albumins, prealbumins, C-reactive protein and glucose levels were measured. Anthropometric measurements included body height, body weight, triceps skinfold and subscapular skinfold thickness. Body mass index (BMI) value and exponent of tissue protein source were calculated. The examined patients completed the questionnaire, which included, among other factors, the daily intake of nutrients, and lifestyle information.

RESULTS

During the 6 month observation of the PD group a stastically significant increase in the energy value of intake food and amount of calories intake from carbohydrates was found. Analysis of nutritional status dependent on the BMI showed that overweight and obese patients are characterized by higher concentrations of the C-reactive protein and glucose, as well as lower concentrations of prealbumin compared to patients with normal body weight. At the same time, the energy value of food and the amount of protein in the group with BMI > 25 were smaller than in the other groups. During the 6 month observation a decrease the concentration of prealbumin and an increase in C-reactive protein in BMI > 25 group were observed.

CONCLUSIONS

The nutritional status of all patients undergoing peritoneal dialysis was abnormal, which was not reflected by BMI. In overweight and obese patients increased changes over time were observed. This suggests the occurrence of protein-energy malnutrition.

Prooxidative-antioxidative balance of cells in different types of renal replacement therapy

BACKGROUND

Patients suffering from chronic kidney disease (CKD) are exposed to increased oxidative stress and disturbances manifesting in the enzymatic and non-enzymatic antioxidative defence system. The object of the research was to assess the differences between conservative treatment, peritoneal dialysis and haemodialysis in moderating cellular antioxidative agents.

METHODS

The group examined comprised 145 patients. The activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase were obtained using kinetic methods. The spectrophotometric method established the concentrations of reduced glutathione, albumin, uric acid, glucose, total protein and lipids.

RESULTS

The type of treatment determined significant changes in antioxidative enzyme activities and concentrations of non-enzymatic antioxidative compounds.

CONCLUSIONS

Peritoneal dialysis provides better antioxidant protection than other types of therapy in CKD and should be considered as first-choice treatment despite more metabolic disorders.

[Old age--neither sour nor bitter]

The development of medicine involves prolongation of human life. In many cases, however, chronic diseases, quite common in the elderly, make the quality of life very poor. We put the question: why we--the doctors--are not able to cope with the problem and whether the pharmacological treatment actually helps? A common medical practice is the use of proton pump inhibitors for various, often nonspecific disorders of the gastrointestinal tract. Statistics point to the overuse of the drugs from this group, also in the elderly. Despite the belief in the safety of such proceedings, proton pump inhibitors may pose a significant threat to older patients contributing to the symptoms worsening, and significantly affecting the mechanisms of acid-base balance. Inhibition of gastric acid secretion in the stomach is not a golden receipt in the case of dyspeptic symptoms, especially in people with the elderly. In many of them achlorhydria or hipochlorhydria is diagnosed. In others, such treatment, may not bring an expected relief in symptoms, while contributing to disturbances of acid-base balance, and--indirectly--have an adverse effect on renal function. We suggest moderation in the use of proton pump inhibitors to bring patients to a real, and not quasi wellness.

[FGF-23 and Klotho protein - new markers in chronic kidney disease?]

Disorders of calcium and phosphate metabolism are among the major problems in patients with chronic kidney disease (CKD), especially undergoing chronic dialysis. Besides the classic parathyroid-kidney axis, in recent years the existence of an endocrinological bone-kidney axis has been established, which allows better explanation of calcium and phosphate metabolism pathophysiology and secondary hyperparathyroidism in CKD. Fibroblast growth factor 23 (FGF-23) and its co-factor alpha-Klotho protein are the most important factors in the axis. The role of FGF-23 and Klotho protein, their mechanisms of action and significance in CKD have been presented. In ealy stages of CKD the increase of FGF-23 level precedes the decline in vitamin 1.25 (OH)2D3 and the increase of PTH level. Some studies showed correlation between the elevated FGF-23 level and increased mortality from cardiovascular disease in patients with chronic kidney disease. Clinical usefulness of determinations of FGF-23 and Klotho protein in chronic kidney disease is currently investigated.

Solute transport at the start of peritoneal dialysis and the risk of peritonitis

BACKGROUND

In peritoneal dialysis (PD) approximately 40% of ultrafiltration (UF) during hypertonic dwell (mini-PET test) occurs as free water transport (FWT) through water channels, mainly aquaporin-1. Experimental studies have shown that aquaporin-1 plays a role in cell migration and inflammatory response.

OBJECTIVES

The purpose of the study was to evaluate if FWT is associated with the incidence of PD-related peritonitis.

MATERIAL AND METHODS

Standard PET and mini-PET tests were performed on 27 patients at the onset of PD. Clinical data was reviewed and PET transport parameters calculated. The peritonitis rate was assessed and the group of patients was divided into the subgroups of peritonitis-free patients (n = 18) and patients with peritonitis episode (n = 9).

RESULTS

Solute transport, measured as D/P creatinine during the PET test was significantly higher in the group of patients with peritonitis episode than in the group of peritonitis-free patients (0.77 ± 0.12 vs. 0.66 ± 0.11, p = 0.02). In the mini-PET test, there was a tendency to have higher solute transport in the group of patients with peritonitis episode compared to the group of peritonitis-free patients (0.61 ± 0.13 vs. 0.51 ± 0.1, p = 0.07). Ultrafiltration (mL) in the mini-PET test was slightly higher in the group of peritonitis-free patients (642 ± 178 vs. 488.9 ± 161.6, p = 0.06). FWT was not different between the two groups.

CONCLUSIONS

Higher solute transport at the start of PD may be associated with the risk of peritonitis.

Oxidative stress modulates the organization of erythrocyte membrane cytoskeleton

BACKGROUND

Apart from their main role in transporting oxygen and carbon dioxide, erythrocytes play also an important role in organism antioxidative defence. Direct exposure to reactive oxygen species (ROS) results in shortening of their half-life, even by 50%. The presence of glucose, being the substrate in pentose phosphate pathway (PPP) cycle, is one of the factors that can have influence on the level of oxidative stress. The activity of PPP increases during oxidative stress. Glucose guarantees normal PPP functioning with the production of reductive equivalents in the amounts necessary to reproduction of glutathione--nonenzymatic free radical scavenger. In available literature there are no reports regarding the changes in protein contents of erythrocyte cytoskeleton exposed to t-butyl hydroperoxide in relation to glucose presence in incubation medium.

MATERIAL/METHODS

Erythrocytes taken from 10 healthy subjects were used to assess the influence of generated free radicals on erythrocyte proteins and chosen parameters of oxidative stress. Erythrocytes were incubated in the solutions containing deferent concentrations of t-butyl hydroperoxide and glucose. Electrophoresis was performed on polyacrylamide gel in denaturating conditions. The contents of tryptophan in membranes was evaluated spectrofluorometrically.

RESULTS/CONCLUSIONS

In vitro conditions oxidative stress leads to protein damage in erythrocyte cytoskeleton, both in proteins inside the cell as well as having contact with extracellular environment. In consequence, the amount of low-molecular proteins--mainly globin, which bind to cytoskeleton, increases. This process takes place independently of glucose presence in incubation medium. One of the element of protein cytoskeleton, tryptophan, also undergoes degradation. The decrease of its contents is higher during erythrocyte exposure to t-BOOH in environment containing glucose, what can suggest prooxidative influence of glucose in conditions in vitro.

Three clinical cases of nonrespiratory acidosis in kidney transplant recipients receiving anti-CMV therapy

BACKGROUND

To preserve kidney graft function it is necessary to use ganciclovir or valganciclovir as a therapy for fresh CMV infection or prophylaxis in high-risk kidney transplant recipients. Ganciclovir-induced lactic acidosis has thus far not been reported.

CASE REPORT

Three cases of nonrespiratory acidosis in kidney transplant recipients receiving ganciclovir or valganciclovir as anti-CMV therapy or prophylaxis are presented. Lactic acidosis developed in 2 patients, and the other patient had nonrespiratory acidosis of unknown origin. The possible mechanism of the development of lactic acidosis in presented cases is explored.

CONCLUSIONS

The analysis of the described cases cannot eliminate the potential negative influence of anti-CMV therapy on acid-base equilibrium, especially with coexisting active viral infection.

Oxidative stress indices in rats under immunosuppression

Immunosuppressants lead to generation of reactive oxygen species (ROS). Oxidative stress (OxS) can initiate chronic allograft nephropathy (CAN). The most active antioxidant enzymes, superoxide dysmutase (SOD) and catalase (CAT), are present in erythrocytes. Glutathione peroxidase (GPx) is produced in the proximal tubules of nephrons. Malonyldialdehyde (MDA) concentrations are a marker of OxS intensity in plasma. In vitro and animal model studies have shown increased or decreased OxS during treatment with tacrolimus (Tac) or cyclosporine (CyA). Results obtained in humans after solid organ transplantation have been contradictory, because of confounding factors such as ischemia-reperfusion injury, donor and recipient ages, endothelial injury, and comorbidity. The aim of this study was to assess the intensity of OxS among rats under chronic immunosuppression (IS) without a transplantation. We examined 49 male Wistar rats. IS started at 12 weeks of age was continued for 6 months: group I were controls (n=7); group II, Tac+sirolimus (Rapamycin [Rapa])+corticosteroids (CS; n=6); group III, CyA+Rapa+CS (n=4 of which 2 died); group IV, Rapa+mycophenolate mofetil (MMF)+CS (n=6); group V, CyA+MMF+CS (n=6); group VI, CsA+MMF+CS for 3 months followed by conversion to Rapa (n=6); group VII, Tac+MMF+CS (n=6 rats); and group VIII, Tac+MMF+CS for 3 months followed by conversion to Rapa (n=6). The drug doses were as follows: Tac 4 mg/kg/d; MMF 20 mg/kg/d; CyA 5mg/kg/d; Rapa 0.5 mg/kg/d; and CS 4 mg/kg/d. Multiple regression analysis revealed that all IS drugs decreased GPx activity (P<.001) except CS, which increased it (P<.0001). Multiple regression analysis showed that CsA and Tac decreased plasma MDA concentrations (P<.01), whereas CS increased them (P<.05). In conclusion, all IS drugs except CS damage proximal tubules of nephrons.

Urinary hepatocyte growth factor indicates ischemia/reperfusion injury after kidney transplantation

INTRODUCTION

Despite the development of immunosuppressive regimens in kidney transplantation, long-term graft survival rates have not increased significantly. One of the causes of long-term graft loss is ischemia-reperfusion insult. Hepatocyte growth factor (HGF) is a regenerative factor produced in response to injury.

OBJECTIVES

Our aim was to assess the effect of HGF and xanthine oxidase (indicators of ischemia/reperfusion insult) on early and late kidney function.

PATIENTS AND METHODS

In 17 patients, HGF levels in urine and xanthine oxidase activity in blood were examined 1, 7, 14, 30 days, 3 and 6 months after kidney transplantation. We also measured 24-hour diuresis and serum creatinine levels after transplantation.

RESULTS

Urinary HGF levels were highest 1 day after transplantation. During the following week, it rapidly decreased and was maintained at similar levels in the later period. Creatinine at 1 day showed a positive correlation with urinary HGF levels at 1 day and at 3 months (R = 0.54, P <0.05 and R = 0.82, P <0.01, respectively). Creatinine at 7 days positively correlated with HGF levels at 6 months (R = 0.82, P <0.05). HGF levels at 1 day and at 6 months positively correlated with xanthine oxidase activity at 1 day (R = 0.73, P <0.001 and R = 0.77, P <0.02, respectively). A negative correlation was observed between HGF levels at 6 months and diuresis 1 and 7 days after transplantation (R = -0.99, P <0.00 001 and R = -0.77, P <0.05, respectively).

CONCLUSIONS

Urinary HGF is a good marker of perioperative kidney damage and may affect long-term graft function.

Does oxidative stress affect the activity of the sodium-proton exchanger?

INTRODUCTION

Accumulation of reactive oxygen species (ROS) takes place in patients with chronic renal failure (CRF). Oxidative stress causes disorders in the activity of the sodium-proton exchanger (NHE). Studies on NHE in CRF produced results that are discrepant and difficult to interpret. The aim of this study was to demonstrate that oxidative stress had an effect on the activity of NHE.

METHODS

We enrolled 87 subjects divided into 4 groups: patients with CRF treated conservatively; patients with CRF hemodialyzed without glucose--HD-g(-); patients with CRF hemodialyzed with glucose--HD-g(+); controls (C). The activity of NHE, the rate of proton efflux V(max), Michaelis constant (Km), and the concentration of thiobarbituric acid-reactive substances (TBARS, an indicator of oxidative stress) in plasma, as well as the concentration of reduced glutathione in blood were determined.

RESULTS

The concentration of TBARS was significantly higher in hemodialyzed patients before and after dialysis and in patients with CRF on conservative treatment in comparison with group C. TBARS in plasma correlated negatively with VpH(i)6.4 in group C and with V(max) and VpH(i)6.4 after HD in group HD-g(-). We found that the concentration of creatinine correlated with TBARS (p < 0.0001; r = +0.51) in the conservatively treated group.

CONCLUSION

We observed a marked oxidative stress and decreased NHE activity when dialysis was done without glucose, whereas patients dialyzed with glucose demonstrated a relatively low intensity of oxidative stress.

Creatinine Clearance after Cimetidine Administration—Is It Useful in the Monitoring of the Function of Transplanted Kidney?

BACKGROUND

Determination of clearance of endogenous creatinine using its plasma and urinary concentration (standard clearance), Cockroft and Gault formula, or MDRD formula (estimated clearance) is commonly performed for assessment of glomerular filtration rate. Although the evaluation of renal function in this way is useful, it is biased with an error resulting from secretion of creatinine in tubules. This error can be reduced by determining the clearance after administration of cimetidine, which competitively blocks creatinine tubular transport.

METHODS

The study was performed in the group of 87 patients after renal transplantation. In this group, estimated clearance and creatinine clearance after cimetidine administration (1000 mg in 75 patients and then 1600 mg in 12 patients with plasma creatinine above 3 mg/dL) were determined.

RESULTS

Analysis of mean percentage differences between clearance values after cimetidine administration and estimated clearance shows increasing contribution of creatinine tubular secretion along with plasma creatinine increase in renal transplant recipients. A higher dose of cimetidine resulted in lower clearance values in renal transplant recipients with plasma creatinine above 3 mg/dL.

CONCLUSIONS

Creatinine clearance after administration of 1000 mg cimetidine seems to be a useful measure of glomerular filtration rate in renal graft recipients with plasma creatinine concentration below 2.5 mg/L. Higher dose of cimetidine would be needed to effectively block tubular excretion at higher concentrations of creatinine. Establishing an efficient but safe dose of cimetidine for such patients needs further investigations. As we have noticed that creatinine clearance calculated according to MDRD formula was similar to the clearance after administration of cimetidine, we propose a strategy of one GFR measurement at baseline using 24h urine collection after cimetidine administration and follow-up with creatinine clearance calculated from MDRD formula during standard check-up visits.

Peritoneal dialysis-related peritonitis in the years 2005-2007 among patients of the Peritoneal Dialysis Clinic of the Department of Nephrology, Transplantology and Internal Medicine, Pomeranian Medical University in Szczecin

INTRODUCTION

Peritoneal dialysis-related peritonitis (PDRP) is the most common complication of dialysis in patients undergoing continuous ambulatory peritoneal dialysis.

OBJECTIVES

The study analyzes incidence of PDRP, pathogens responsible for the disease and response to treatment in patients at the Peritoneal Dialysis Clinic of the Department of Nephrology, Transplantology and Internal Medicine of Pomeranian Medical University and the Independent Public University Hospital No 2 in Szczecin in the years 2005-2007.

PATIENTS AND METHODS

Within 36 months, 20 peritonitis incidents have been diagnosed in 18 subjects of 89 patients undergoing peritoneal dialysis.

RESULTS

The incidence of PDRP was 1 episode/32 patient-months with 45% of PDRP episodes caused by Gram-positive bacteria, 40% by Gram-negative bacteria, and 5% by fungi. Staphylococcus aureus was the most common pathogen among Gram-positive bacteria and so were equally Klebsiella oxytoca and Enterobacter cloacae among Gram-negative bacteria. A satisfactory percentage of successful standard therapy (80%) was achieved; in 20% of PDRP cases removal of the Tenckhoff catheter was necessary.

CONCLUSIONS

A higher proportion of PDRP caused by Gram-negative bacteria has been observed as compared to the data from other centers. There was high susceptibility of the isolated strains to third-generation cephalosporins and chinolones. Low incidence of PDRP in the center and bacteriological profile of strains causing the disease confirm high qualifications and training quality of the patients and the correct insertion of dialysis catheters.

Impact of posttransplant diabetes mellitus on graft function in autosomal dominant polycystic kidney disease patients after kidney transplantation

INTRODUCTION

Posttransplant diabetes mellitus (PTDM) remains the significant clinical problem and impairs the quality of life of renal transplant recipients. Negative influence of PTDM on graft function is associated with chronic allograft nephropathy, systemic infectious complications, recurrent infections or urinary tract infections. Some earlier studies suggest that patients with Autosomal Dominant Polycystic Kidney Disease (ADPKD) are at special risk of developing PTDM. The aim of our study was to assess the influence of PTDM on graft function in recipients with ADPKD and other causes of renal failure during 12-month follow-up. Another aim of the study was to answer the question if the etiology of renal failure (ADPKD vs non-ADPKD) and the development of PTDM were independent predictors of graft function and if there was a significant interaction between them.

MATERIAL AND METHODS

98 pairs of kidney recipients from the same cadaveric donor were included into the study, with the ADPKD-related renal failure in one of the recipients, and different reasons for transplant in the other, with exclusion of the diabetic nephropathy. Diabetes was diagnosed according to American Diabetes Association (ADA) criteria. For statistical analysis the following parameters were included: age, sex, development ofposttransplant complications such as: PTDM, acute tubular necrosis (ATN) and early graft rejection, the presence of surgical and infectious complications (urinary tract infections excluded) and urinary tract infections as well as kidney function parameters such as serum urea, creatinine and uric acid concentrations 3, 6 and 12 months after transplantation.

RESULTS

At the time of transplantation ADPKD patients were significantly older than non ADPKD patients (median 49.5 vs 45.3 years, p < 0.00008). There was no significant difference in incidence of PTDM between the study groups (19% in the ADPKD group and 18% in non-ADPKD group, p = 1.0). In ADPKD group no significant differences in serum urea, creatinine and uric acid following transplant were found between PTDM and non-PTDM subgroups. In non-ADPKD group, 3 and 6 months after transplantation, serum urea concentrations (77.5 mg/dL vs 54.0 mg/dL, p = 0.007 and 77.0 mg/dL vs 56.7 mg/dL, p = 0.016) and uric acid concentrations (7.7 mg/dL vs 6.8 mg/dL, p = 0.001 and 7.3 mg/dL vs 6.2 mg/dL, p = 0.034) were significantly higher in PTDM than in non-PTDM subgroup. Serum creatinine concentration was significantly higher in PTDM group 12 months following transplant (1.87 mg/dL vs 1.5 mg/dL, p = 0.035), with borderline significance 6 months following transplant (1.77 mg/dL vs 1.5 mg/dL, p = 0.057). In PTDM subgroup of ADPKD patients the percentage of infectious complications was slightly higher than in non-PTDM subgroup, but the difference was not statistically significant (37% vs 18%, p = 0.12), urinary tract infections were significantly more prevalent in PTDM subgroup (47% vs 18%, p = 0.013). In multivariate analysis no significant influence of ADPKD on any of the parameters of graft function was found. Significant interaction between ADPKD and PTDM presence for their influence on parameters of graft function was not found either what suggests that PTDM had a similar negative effect on these parameters in both ADPKD and non-ADPKD patients.

CONCLUSIONS

1. PTDM has negative influence on graft function independently of ADPKD diagnosis. 2. PTDM presence in ADPKD group significantly predisposes to urinary tract infections.

GNB3 C825T and ACE I/D Polymorphisms on the Sodium–Proton Exchanger and the Prevalence of Essential Hypertension in Males

BACKGROUND

The aim of the study was to verify the hypothesis if the interaction between the G protein beta3 subunit (GNB3) C825T polymorphism and ACE I/D polymorphism could lead to the disclosure of increased activity of sodium-proton exchanger and hypertension.

METHODS

The study included 44 male patients, median age: 40 years. Patients were divided into two groups: 26 patients with essential hypertension (EH), and 18 subjects in the normotensive group (C).

RESULTS

CT + TT genotypes of GNB3 predominated in patients with hypertension (65%) compared to normotensive patients (12%) (p <0.01). No significant differences were observed in the frequency of ACE gene polymorphisms between the examined groups. Significantly higher activity of erythrocyte NHE in patients with EH was observed: median 8.83 (interquartile range 4.27) mmol/l RBC/h, compared to C: median 6.18 (2.80) mmol/l RBC/h, p <0.001. Multiple logistic regression analysis showed that the presence of the T allele increased the risk of hypertension 16-fold (p <0.01) and higher erythrocyte NHE activity 2-fold per each unit of activity (p <0.01). DD genotype of ACE polymorphism did not increase the risk of hypertension. No significant interaction of the influence of GNB3 T allele and ACE DD genotype on the risk of hypertension was observed. In multiple linear regression analysis, none of the examined genotypes and their interactions influenced NHE activity.

CONCLUSIONS

The presence of the T allele of GNB3 polymorphism and increased activity of erythrocyte NHE independently of ACE genotype increase the risk of hypertension.

Copper modifies the activity of sodium-transporting systems in erythrocyte membrane in patients with essential hypertension

The aim of the study was to verify the hypothesis if copper could influence the activity of sodium-transporting systems in erythrocyte membrane that could be related to essential hypertension. The examined group of patients consisted of 15 men with hypertension. The control group was 11 healthy male volunteers. The Na+/H+ exchanger (NHE) activity in erythrocytes was determined according to Orlov et al. The activity of transporting systems (ATP-Na+/K+; co-Na+/K+/Cl-; ex-Na+/Li+; free Na+ and K+ outflow [Na+, K+-outflow]) was determined according to Garay's method. The concentration of copper in plasma was assessed using atomic absorption spectrometry. The activity of ATP-Na+/K+ (micromol/L red blood cells [RBCs]/h) in hypertensive patients was 2231.5 +/- 657.6 vs 1750.5 +/- 291 in the control (p < 0.05), the activity of co-Na+/K+/Cl- (micromol/L RBCs/h) in hypertensives was 171.3 +/- 77.9 vs 150.7 +/- 53.9 in the control (NS). Na+-outflow (micromol/L RBCs/h) in hypertensives was 118.3 +/- 51.6 vs 113.3 +/- 24.4 in the control (NS). The K+-outflow (micromol/L RBCs/h) in hypertensives was 1361.7 +/- 545.4 vs 1035.6 +/- 188.3 in the control (NS). The activity of ex-Na+/Li+ (micromol/L RBCs/h) in hypertensive patients was 266.1 +/- 76.1 vs 204.1 +/- 71.6 in the control (p < 0.05). NHE activity (mmol/L RBCs/h) in hypertensives was 9.7 +/- 2.96 vs 7.7 +/- 1.33 in the control (p < 0.05). In hypertensive patients, negative correlation was found between the activity of Na+/K+/Cl- co-transport and plasma copper concentration (Rs = -0.579, p < 0.05) and between the activity of ex-Na+/Li+ and plasma copper concentration (Rs = -0.508, p < 0.05). Plasma copper concentration significantly influences the activity of sodium transporting systems in erythrocyte membrane. Copper supplementation could be expected to provide therapeutic benefits for hypertensive patients.

Renal handling of uric acid in patients with type 1 diabetes in relation to glycemic control

BACKGROUND

The aim of the study was to compare the renal handling of uric acid (UA) in 16 patients with type 1 diabetes without renal failure (age 34.8 +/- 13.3 years) and in 15 healthy subjects (age 34.9 +/- 12.6 years).

METHODS

Creatinine clearance (Cr-Cl), clearance of uric acid (UA-Cl), fractional excretion of uric acid (UA-FE), and 24-h urinary UA excretion (UA-U) were determined. Glycemic control was assessed using fasting glucose, glycated hemoglobin and fructosamine tests.

RESULTS

Patients with diabetes had significantly (p < 0.0001) lower serum UA concentrations compared to control group (2.8 +/- 0.7 vs. 5.7 +/- 0.8 mg/dl), and higher urinary UA excretion (813 +/- 107 vs. 423 +/- 40 mg/day), UA clearance (21.9 +/- 7.1 vs. 5.2 +/- 0.9 mL/min) and fractional UA excretion (17.1 +/- 5.5 vs. 4.8 +/- 1.3%), with higher creatinine clearance (129 +/- 16 vs. 111 +/- 12 mL/min, p < 0.005). In patients with diabetes there was a strong negative correlation between serum UA concentration and UA 24-h excretion (R = -0.79; p < 0.001). Fractional UA excretion correlated with fasting glycemia and HbA1c (R = +0.51 and +0.53; p < 0.05).

CONCLUSIONS

In type 1 diabetes there is significant UA renal clearance increase, which is higher with poor glycemic control. It leads to hypouricemia despite an approximately twofold UA excretion increase and therefore despite increased UA synthesis.

Plasma Prekallikrein as a Risk Factor for Diabetic Retinopathy

BACKGROUND

The aim of the study was to verify the hypothesis that in diabetes there is an increased activation of coagulation system leading in consequence to diabetic retinopathy.

METHODS

Thirty three healthy subjects (controls, 16 males and 17 females) and 35 patients with diabetes type 1 (15 males and 20 females) were examined. We monitored plasma prekallikrein (PPK), glycemia, fructosamine, glycosylated hemoglobin, activated partial thromboplastin time (PTT), INR, fibrinolysis in euglobulins time (FET), level of antithrombin III (AT III), fibrinogen (Fb) and fibrinogen degradation products (FDP).

RESULTS

In diabetic patients without retinopathy, PKK concentration was 16% higher (p <0.005), in patients with background retinopathy 33% higher (p <0.001), and in patients with proliferative retinopathy PKK concentration was 50% higher (p <0.001) than in controls. In the subgroup of patients with proliferative retinopathy PTT was significantly shorter (p <0.001), and FET was significantly longer (p <0.001) than in control. In patients with diabetes higher FDP concentrations were found than in controls (p <0.05). Significant correlations were found between PPK and fructosamine levels in all diabetic patients (R(S)=+0.57 p <0.001), in diabetic patients without retinopathy (R(S)=+0.61, p <0.05), and in diabetic patients with retinopathy (R(S)=+0.62, p <0.005). We found negative correlation between PPK concentration and PTT (R(S)=-0.43, p <0.001) and positive correlation between PPK concentration and FET (R(S)=+0.59, p <0.00001) in the entire study group.

CONCLUSIONS

The occurrence of diabetic retinopathy is connected with higher levels of plasma prekallikrein.

Do trace elements modify the activity of erythrocyte sodium-proton exchanger in hemodialyzed patients?

The kinetics (Vmax and Km) of the erythrocyte Na+-H+ exchanger was studied in a group of 21 patients undergoing regular hemodialysis (HD) and in 21 control subjects. The activity of antioxidative enzymes--superoxide dismutase and glutathione peroxidase--as well as the concentrations of their cofactors--zinc, copper, and selenium--in plasma and in erythrocytes were determined. The thiobarbituric acid-reactive substances (TBARS) concentration served as an indicator of oxidative stress intensity in plasma and erythrocytes. It was found that in the control group the concentration of copper in erythrocytes was positively correlated with Km and Vmax. When the concentration of copper increased, the shape of the kinetic curve changed from sigmoidal to hyperbolic. In the control group, the concentration of zinc in erythrocytes also correlated with Km. However, the results obtained for the group of hemodialyzed patients were the opposite: when the erythrocyte concentration of copper increased, a Km decline was observed and the shape of the curve changed from hyperbolic to sigmoidal. In the group of hemodialyzed patients, we also found a positive correlation between Km and the concentration of selenium in erythrocytes, and a negative correlation between Km and erythrocyte TBARS.

The Influence of Angiotensin-Converting Enzyme Gene of Donor and Recipient on the Function of Transplanted Kidney

One of the genes that is supposed to influence renal graft function is the one encoding angiotensin I-converting enzyme (ACE). It shows polymorphism in the presence (I allele) or absence (D allele) of a 287-base pair fragment. The question arises whether ACE gene polymorphism of the recipient and donor influences renal graft survival. This prospective study included 94 recipients who underwent ACE genotyping (DD, DI, II) and measured their creatinine clearance after cimetidine administration. These factors were correlated with the occurrence of acute or chronic rejection and of pharmacologic treatment of hypertension. In 27 recipients it was possible to obtain the ACE genotype of the donor. Among the recipients, 36 proved to be DD genotype, 38 ID, and 20 II. Among the donors, 10 proved to be DD genotype, 10 ID, and 7 II. The changes in creatinine clearance after cimetidine administration were not significantly different among any of the genotype subgroups. Significantly higher creatinine concentrations were found among recipients with II genotype compared to the combined group of ID and DD among patients not treated with ACE inhibitors, but not among those receiving ACE I after kidney transplantation. No differences were found in the frequency of rejection episodes among the subgroups with different ACE genotypes. No significant influence of donor ACE genotype on renal graft function was observed. In summary, the I/D genotype was not an independent prognostic factor for renal graft survival in the first 4 years after transplantation. Possibly the use of ACE I alters the influence of genotype on some parameters.

Impaired Synthesis Is Not the Reason for Decreased Activity of Extracellular Superoxide Dismutase in Patients with Diabetes

BACKGROUND

The aim of the study was to find the cause of decreased activity of extracellular superoxide dismutase (EC SOD) in patients with diabetes-is it the decreased synthesis or increased glycation?

METHODS

Total EC SOD activity, the activity of its fractions (A, B, and C) and its glycated form were determined in basal state and 30 min after intravenous (i.v.) administration of 50 mg of heparin. Patients were given i.v. heparin at a dose of 10,000 IU (100 mg) each 6 h for at least 3 days, and the activity of EC SOD was determined before the first heparin administration, just before each subsequent administration, and 30 min after heparin administration.

RESULTS

Pre- and postheparinic activities of EC SOD and its fraction C in the group of patients with diabetes were significantly lower (p <0.001) than in control group. Preheparinic activities of EC SOD did not differ between the examined groups of patients. The postheparinic activities were different during the first 18 h of treatment. They were significantly lower in the group of patients with diabetes. During the following hours, after subsequently administered doses, there were no differences in the activity of EC SOD between the examined groups. Decline of EC SOD activity was observed after administration of repeated doses of heparin both in the examined and in the control groups.

CONCLUSIONS

The decrease of extracellular superoxide dismutase activity in diabetes develops due to excessive glycation but not due to impaired synthesis. Therefore, appropriate glycemic control can lead to normalization of EC SOD activity.

The influence of oxidative stress on permeability of capillary vessels in the cheek pouch of hamsters with alloxan-induced diabetes

Background: The aim of the study was to assess the influence of oxidative stress on the increase of permeability of capillary vessels in animals with alloxan-induced diabetes. Material and methods: The studies were performed in microcirculation system of hamster cheek pouch. After the blockade of histamine receptors and administration of diamine oxidase (DAO) and histamine into circulation fluorescein angiography was done. In addition, the influence of superoxide dismutase, aminoguanidine (DAO inhibitor) and trascolan (protease inhibitor) on vascular permeability caused by superoxide radical generation in DAO/histamine system was assessed. Results: The number of extravasal leakages in the group receiving HA and DAO was significantly higher (p < 0.001) than in the groups receiving potential vascular "sealers", e.g. SOD, aminoguanidine or trascolan. In the group receiving aminoguanidine the number of leakages was significantly lower (p < 0.05) compared to the group receiving SOD or trascolan. Conclusions: The protective effect of aminoguanidine, superoxide dismutase or trascolan decreasing the vascular permeability, suggests that the increased vascular permeability is a result of superoxide radical generation by diamine oxidase.

Methods of GFR determination--creatinine clearance after cimetidine administration in clinical practice

Determination of clearance of endogenous creatinine using its plasma and urinary concentration (standard clearance) or Cockroft and Gault equation (estimated clearance) is commonly performed for assessment of glomerular filtration rate. Although evaluation of renal function in this way is useful, it is biased with an error resulting from secretion of creatinine in tubules. This error can be reduced by determining the clearance after administration of cimetidine. This study enrolled 40 patients who were divided into two groups--the first group consisted of 12 healthy subjects and the second group joined healthy subjects and patients with chronic renal failure. The second group was divided into three subgroups in relation to creatinine serum concentration (intervals: creatinine < 1 mg/dL - 9 subjects, creatinine 1-2 mg/dL - 7 subjects, creatinine > 2 mg/dL - 10 subjects). Estimated and standard creatinine clearance, clearance after cimetidine administration and inulin clearance were assessed. Analysis of mean percentage differences between clearance value after cimetidine administration and estimated or standard clearance shows increasing contribution of tubular creatinine secretion with increase in plasma creatinine concentration. This study suggests that determination of creatinine clearance after cimetidine administration can be used in precise evaluation of renal function.

[Diagnostic value of fasting glucose, fructosamine, and glycated haemoglobin HbA(1c) with regard to ADA 1997 and who 1998 criteria for detecting diabetes and other glucose tolerance abnormalities]

New diagnostic criteria for diabetes mellitus proposed by the American Diabetes Association in 1997 and the World Heath Organization Consultation Report in 1998 recommend lowering of the fasting plasma glucose (FPG) to 7.0 mmol/L. This change in the diagnostic FPG cut-off point was based on the results of well-documented epidemiological studies showing that increased risk of microangiopathy starts at values closer to 7.0 than 7.8 mmol/L used in the past. To facilitate the diagnosis, ADA Expert Committee recommends using FPG as the main diagnostic tool and eliminating OGTT from routine clinical practice. In contrast to ADA, WHO Consultation Group strongly recommended keeping OGTT in routine use. Due to the inconvenience, poor reproducibility, non-physiological character and labour-intensiveness of OGTT, an alternative test has been sought. The aim of this study was to determine whether fasting capillary glucose (FCG) along with fructosamine and glycated haemoglobin (HbA(1c)) perform better for the detection of glucose tolerance abnormalities than FCG alone. OGTT was performed in 1528 patients. Serum fructosamine was determined in 480 and glycated haemoglobin in 234 of these patients. To assess the value of FCG, fructosamine and glycated haemoglobin in predicting post-load glycaemia and detecting glucose tolerance abnormalities, multiple linear regression analysis and Receiver Operating Characteristics analysis were done. Fructosamine correlated stronger with 2h-postload glucose concentrations than with fasting glucose. HbA(1c) correlated stronger with FCG than with 2h-postload glucose. Combined use of fructosamine and FCG predicted 2h-postload glucose better than combined use of FCG and HbA(1c). Receiver Operating Characteristics curve analysis showed that FCG was the best criterion in discriminating diabetes. Combined use of FCG and fructosamine slightly improved the ability to discriminate glucose tolerance abnormalities from normal glucose tolerance. The following conclusions were drawn: (1) FCG is the most effective predictor of 2h-postload glucose and the best criterion for discriminating diabetes and other glucose tolerance abnormalities from normal glucose tolerance. (2) Because of the limited sensitivity and specificity of fasting glucose, fructosamine and glycated haemoglobin tests, OGTT is irreplaceable in the identification of patients with glucose tolerance abnormalities. Nevertheless, fructosamine is a potentially useful post-load glycaemia index.

Chronic hypokalaemia--how to establish a diagnosis?

We present three cases of patients with symptomatic, chronic, diagnosis-resistant hypokalaemia. Differential diagnosis of renal potassium loss between Gitelman's syndrome, Bartter's syndrome and loop diuretic abuse was made. Key elements in differential diagnosis of chronic hypokalaemia are blood pressure assessment, acid base equilibrium, serum calcium concentration, 24-hour urine potassium and calcium excretion.