Extracellular matrix-coated polyethersulfone-TPGS hollow fiber membranes showing improved biocompatibility and uremic toxins removal for bioartificial kidney application

In this study, L-3, 4-dihydroxyphenylalanine and human collagen type IV were coated over the outer surface of the custom-made hollow fiber membranes (HFMs) with the objective of simultaneously improving biocompatibility leading to proliferation of human embryonic kidney cells-293 (HEK-293) and improving separation of uremic toxins, thereby making them suitable for bioartificial kidney application. Physicochemical characterization showed the development of coated HFMs, resulting in low hemolysis (0.25 ± 0.10%), low SC5b-9 marker level (7.95 ± 1.50 ng/mL), prolonged blood coagulation time, and minimal platelet adhesion, which indicated their improved human blood compatibility. Scanning electron microscopy and confocal laser scanning microscopy showed significantly improved attachment and proliferation of HEK-293 cells on the outer surface of the coated HFMs, which was supported by the results of glucose consumption and MTT cell proliferation assay. The solute rejection profile of these coated HFMs was compared favorably with that of the commercial dialyzer membranes. These coated HFMs showed a remarkable 1.6-3.2 fold improvement in reduction ratio of uremic toxins as compared to standard dialyzer membranes. These results clearly demonstrated that these extracellular matrix-coated HFMs can be a potential biocompatible substrate for the attachment and proliferation of HEK-293 cells and removal of uremic toxins from the simulated blood, which may find future application for bioartificial renal assist device.

An adsorbent monolith device to augment the removal of uraemic toxins during haemodialysis

Adsorbents designed with porosity which allows the removal of protein bound and high molecular weight uraemic toxins may improve the effectiveness of haemodialysis treatment of chronic kidney disease (CKD). A nanoporous activated carbon monolith prototype designed for direct blood contact was first assessed for its capacity to remove albumin bound marker toxins indoxyl sulphate (IS), p-cresyl sulphate (p-CS) and high molecular weight cytokine interleukin-6 in spiked healthy donor studies. Haemodialysis patient blood samples were then used to measure the presence of these markers in pre- and post-dialysis blood and their removal by adsorbent recirculation of post-dialysis blood samples. Nanopores (20-100 nm) were necessary for marker uraemic toxin removal during in vitro studies. Limited removal of IS and p-CS occurred during haemodialysis, whereas almost complete removal occurred following perfusion through the carbon monoliths suggesting a key role for such adsorbent therapies in CKD patient care.

The effect of achieving a systolic blood pressure of 140 mmHg. A prospective study of ambulatory measurements in type 2 diabetic patients with nephropathy

OBJECTIVES

What is the prognostic significance of achieving a systolic blood pressure of <140 mmHg?

SETTING

Diabetic renal policlinic, university hospital of Lund, Sweden.

SUBJECTS

118 type 2 diabetic patients with micro-macroalbuminuria were followed for four years (range 1-8 years). METHOD AND MAIN OUTCOME MEASURES: The prognostic significance of office, day- and nighttime measurements of blood pressure (BP) for development of cardiovascular complications was studied.

RESULTS

Forty-two percent (n=49) developed one or more of the following cardiovascular endpoints: 23% (n=27) death, 9% (n=10) stroke, 9% (n=11) myocardial infarction, 9% (n=11) heart failure, 31% (n=36) uremia and 17% (n=20) need for dialysis. Reaching the goal for day- and nighttime systolic BP (SBP) at baseline of <140 mmHg was associated with lower risk for developing uremia. Reaching the goal for nighttime SBP was associated with a decreased risk for developing myocardial infarction and need for dialysis treatment. None of these associations was found for office SBP. Patients not achieving the goal for nighttime systolic blood pressure of <140 mmHg had a 12.9 times higher risk of developing myocardial infarction and 3.9 times increased risk of uremia and 2.7 times increased risk for death than patients achieving the goal.

CONCLUSION

Nighttime blood pressure had better prognostic significance for developing cardiovascular and renal complications than office and daytime blood pressure.

Effects of DPP-4 inhibitors on the heart in a rat model of uremic cardiomyopathy

Background

Uremic cardiomyopathy contributes substantially to mortality in chronic kidney disease (CKD) patients. Glucagon-like peptide-1 (GLP-1) may improve cardiac function, but is mainly degraded by dipeptidyl peptidase-4 (DPP-4).

Methodology/Principal Findings

In a rat model of chronic renal failure, 5/6-nephrectomized [5/6N] rats were treated orally with DPP-4 inhibitors (linagliptin, sitagliptin, alogliptin) or placebo once daily for 4 days from 8 weeks after surgery, to identify the most appropriate treatment for cardiac dysfunction associated with CKD. Linagliptin showed no significant change in blood level AUC(0-∞) in 5/6N rats, but sitagliptin and alogliptin had significantly higher AUC(0-∞) values; 41% and 28% (p = 0.0001 and p = 0.0324), respectively. No correlation of markers of renal tubular and glomerular function with AUC was observed for linagliptin, which required no dose adjustment in uremic rats. Linagliptin 7 µmol/kg caused a 2-fold increase in GLP-1 (AUC 201.0 ng/l*h) in 5/6N rats compared with sham-treated rats (AUC 108.6 ng/l*h) (p = 0.01). The mRNA levels of heart tissue fibrosis markers were all significantly increased in 5/6N vs control rats and reduced/normalized by linagliptin.

Conclusions/Significance

DPP-4 inhibition increases plasma GLP-1 levels, particularly in uremia, and reduces expression of cardiac mRNA levels of matrix proteins and B-type natriuretic peptides (BNP). Linagliptin may offer a unique approach for treating uremic cardiomyopathy in CKD patients, with no need for dose-adjustment.

Systemic resistin is increased in type 2 diabetic patients treated with loop diuretics

Increased serum resistin was found in rodent models of obesity and insulin resistance, whereas contradictory results have been obtained in human studies. In humans, resistin is primarily released by monocytes/macrophages, suggesting that soluble levels may be associated with macrophage activation. Here, systemic and monocyte-released resistin levels were found to be similar in type 2 diabetic (T2D) patients, overweight controls and normal-weight controls. When adjusted for body mass index and age, serum resistin modestly correlated with gamma-glutamyltransferase levels, fasting glucose and interleukin-6. Systemic resistin was marginally increased in T2D patients treated with beta-blockers or urate-lowering drugs and was considerably higher in patients treated with loop diuretics. Monocyte-released resistin was even reduced by the loop diuretic furosemide, excluding the possibility that this drug may directly stimulate resistin synthesis. In summary, the current data indicate that changes accompanying renal dysfunction but not obesity or type 2 diabetes are associated with increased serum resistin.

New uremic toxins - which solutes should be removed?

Chronic kidney disease (CKD) is characterized by the progressive retention of a myriad of compounds, several of which play a role in cardiovascular damage, a major cause of mortality in CKD. Over the past years, especially protein-bound compounds (e.g. indoxylsulfate and p-cresylsulfate) and/or middle molecules (e.g. AGEs, cytokines and dinucleoside polyphosphates) have been identified as some of the main toxins involved in vascular lesions affecting endothelial cell, leukocyte, platelet and/or vascular smooth muscle cell function in CKD. Many of these solutes, however, are difficult to remove by standard dialysis strategies. The removal of protein-bound solutes remains limited because only the free fraction of the solute is available for, mostly diffusive, removal, while removal of the larger middle molecules (mostly larger peptidic compounds) can be obtained by increasing dialyzer pore size and by applying convective strategies. In addition, new therapeutic strategies pursuing specific removal (e.g. by adsorption) and/ or pharmacological neutralization of the molecular impact of the responsible compounds are explored, aiming at an improved outcome in CKD patients.

Pilot study of probiotic dietary supplementation for promoting healthy kidney function in patients with chronic kidney disease

INTRODUCTION

Uremic syndrome consists of nitrogenous waste retention, deficiency in kidney-derived hormones, and reduced acid excretion, and, if untreated, may progress to coma and eventual death. Previous experience suggests that oral administration of a probiotic formulation of selected microbial strains may extend renoprotection via intraintestinal extraction of toxic waste solutes in patients with chronic kidney disease (CKD)stages 3 and 4. This report presents preliminary data from a pilot study.

METHODS

This was a 6-month prospective, randomized, double-blind, placebo-controlled crossover trial of a probiotic bacterial formulation conducted in four countries, at five institutions, on 46 outpatients with CKD stages 3 an nd 4: USA (n=10), Canada (n=113), Nigeria (n=115), and Argentina (n=8). Outcomes were compared using biochemical parameters:blood urea nitrogen (BUN), serum creatinine, and uric acid. General well-being was assessed as a secondary parameter by a quality of life (QQOL) questionnaire on a subjective scale of 1-10.

RESULTS

Oral ingestion of probiotics (90 billion colony forming units [CFUs]/day) was well tolerated and safe during the entire trial period at all sites. BUN levels decreased in 29 patients (63%, P<0.05), creatinine levels decreased in 20 patients (43%, no statistical significance), and uric acid levels decreased in 15 patients (33%, no statistical significance). Almost all subjects expressed a perceived substantial overall improvement in QOL (86%, P<0.05).

CONCLUSION

The main outcomes of this preliminary trial include a significant reduction of BUN, enhanced well-being, and absence of serious adverse effects, thus supporting the use of the chosen probiotic formulation for bowel-based toxic solute extraction. QOL and BUN levels showed statistically significant differences in outcome (P<0.05) between placebo and probiotic treatment periods at all four sites (46 patients). A major limitation of this trial is the small sample size nd elated inconsistencies.

Amelioration of cisplatin-induced nephrotoxicity by extracts of Hemidesmus indicus and Acorus calamus

Administration of commonly used anticancer drug cisplatin [cis-diamminedichloroplatinum (II)] at pharmacologically relevant concentrations (12 mg/kg body weight) resulted in severe renal toxicity as evidenced from histopathological observations and biochemical alterations in the renal tissue. The extracts of medicinal plants Hemidesmus indicus L. (Apocynaceae) and Acorus calamus L. (Araceae) protected the renal tissue effectively from cisplatin-induced toxicity. Treatment of cisplatin-administered animals with the plant extracts could prevent the drug-induced oxidative damage in the renal tissue as evidenced from the decreased levels of lipid peroxidation and enhanced activities of the antioxidants in the renal tissue. Cisplatin treatment increased serum urea level to 41.3 +/- 2.86 mg/dL and administration of the extracts of H. indicus and A. calamus brought down the level to 34.54 +/- 0.37 and 30.12 +/- 0.95 mg/dL, respectively. Serum creatinine levels were increased to 1.1 +/- 0.02 mg/dL following cisplatin administration, and treatment with extracts of H. indicus and A. calamus brought this down to 0.76 +/- 0.09 and 0.61 +/- 0.06 mg/dL, respectively. The histopathological observations indicated that treatment with the H. indicus and A. calamus extracts restored the cisplatin-induced structural alterations in the renal tissue.

Effect of extract of Withania Somnifera on dehydration-induced oxidative stress-related uremia in male rats

Dehydration or water deprivation in the body decreases urinary excretion and allows urea and other protein waste products to accumulate in the blood. The aim of the present study is to evaluate the association of uremia and oxidative stress by applying the herbal plant Withania somnifera (W. somnifera) (Aswagandha). The study was performed on male Wister strain rats in which, dehydration was achieved by water withdrawal. A total of 18 rats were studied and were randomly divided into three Groups: Group-1, control, Group-2, only dehydration and Group-3, dehydration + administration of aqueous root extract of W. somnifera, orally (50 mg/100 gm body weight/day) for 25 days. After 25 days of treatment, it was observed that the body weight of Group-3 animals had increased significantly, while that in Group-2 had decreased significantly. The liver enzymes in both blood and kidneys did not show any significant change in the three groups implying absence of any toxicity of the root extract. In Group-2 animals, the serum urea and creatinine levels increased sig-nificantly when compared with animals in Groups-1 and 3. The low levels of serum urea and crea-tinine in Group-3 animals indicates the protective effect of the plant extract against renal injury caused by dehydration. Dehydration-induced oxidative stress was established in our study by noting the low activities of super-oxide dismutase and catalase, both important antioxidant enzymes, in Group-2 animals; both enzymes were stabilized in animals of Groups-3 and 1. In conclusion, it is hypothesized that there is an antioxidative role of W. somnifera resulting in reducing the extent of renal injury as a result of oxidative stress.

Substitute treatment and replacement in chronic kidney disease: peritoneal dialysis, hemodialysis and transplant

Chronic dialysis replacement treatments or renal transplants are instituted when the patient's glomerular filtration rate, measured by 24-h urine endogenous creatinine clearance, is <10-15 ml/mm and, as the The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF KDOQI), European and Canadian guidelines point out, when one or two of the following complications occur: "uremic toxicity" symptoms, significant fluid retention that does not respond to loop diuretics, hyperkalemia, chronic anemia (hemoglobin <8 g), metabolic acidosis or acute pulmonary edema. In all patients for whom transplant is indicated, a selected live donor must be sought or, in the absence of contraindications, the patient should be registered with the national cadaver donation waiting list. While waiting for the transplant, patients will be on a chronic dialysis program. There is no national registry of patients undergoing chronic dialysis; only indirect data from the Mexican Kidney Foundation and the dialysis industry are available. However, it is estimated that 40,000-50,000 people are under this treatment and the numbers grow by 11% every year. Overall, it is thought that for every patient receiving chronic dialysis, there is one more patient who dies without access to therapy. Hemodialysis units must comply with the Official Hemodialysis Standard and the General Health Council Hemodialysis Unit Quality Assessment Form.

Nephroprotective effect of the HMG-CoA-reductase inhibitor cerivastatin in a mouse model of progressive renal fibrosis in Alport syndrome

BACKGROUND

Alport syndrome is caused by mutations in genes encoding for the alpha3, alpha4 or alpha5 chain of type IV collagen leading to excessive production of fibrotic tissue and end-stage renal failure. HMG-CoA-reductase-inhibitors exhibit pleiotropic effects by which they modulate the production of connective tissue. The aim of this study was to examine the anti-fibrotic effect of the HMG-CoA-reductase-inhibitor, cerivastatin, in COL4A3 knockout mice, an animal model of Alport syndrome with progressive renal fibrosis.

METHODS

Forty homozygous COL4A3 knockout mice received cerivastatin, starting 28 or 49 days after birth. Mice were sacrificed at day 52 or 66 after birth. Immunohistochemistry against laminin and fibronectin was performed. Inflammatory cell infiltration was determined by F4/80- and CD3-staining. Myofibroblasts were identified by an alpha-smooth muscle actin staining. Expression of the profibrotic cytokines, TGF-beta1 and CTGF, were determined by immunoblot.

RESULTS

The lifespan of treated COL4A3 knockout mice was increased by 28% compared with untreated animals (71+/-6 vs 91+/-9 days, P<0.01). Early cerivastatin treatment reduced cholesterol levels (113+/-13 vs 141+/-19 mmol/l in untreated animals, P<0.05) and serum urea (164 vs 235 mmol/l, day 66, P<0.05). Treatment also decreased proteinuria (5.5 vs 12 g/l at day 66, P<0.05). Deposition of laminin and fibronectin, expression of TGF-beta and CTGF was reduced. Infiltration of T-cells and macrophages as well as myofibroblasts appeared to be reduced in kidneys from cerivastatin-treated mice.

CONCLUSION

Cerivastatin prolongs the lifespan of COL4A3 knockout mice, reduces proteinuria and delays uraemia. These effects are associated with decreased renal fibrosis and a reduction of inflammatory cell infiltration.

[From CANUSA to ADEMEX: do we need a new paradigm for definition of peritoneal dialysis adequacy?]

Peritoneal dialysis doses were prescribed out of empirical criteria up to the mid-Ninety Then, the observational CANUSA study and the experimental ADEMEX study helped to define adequacy criteria according to urea kinetics model. This review analyzes the limits of a definition of adequacy grounded exclusively on urea kinetics, as well as the need for new parameters of adequacy. The evidence is presented fostering the hypothesis that the control of extra-cellular fluid excess and of other cardiovascular risk factors may now be considered a new target for adequacy.

Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats

Objective-To determine whether a renal diet modified in protein, phosphorus, sodium, and lipid content was superior to an adult maintenance diet in minimizing uremic episodes and mortality rate in cats with stage 2 or 3 chronic kidney disease (CKD). Design-Double-masked, randomized, controlled clinical trial. Animals-45 client-owned cats with spontaneous stage 2 or 3 CKD. Procedures-Cats were randomly assigned to an adult maintenance diet (n = 23 cats) or a renal diet (22) and evaluated trimonthly for up to 24 months. Efficacy of the renal diet, compared with the maintenance diet, in minimizing uremia, renal-related deaths, and all causes of death was evaluated. Results-Serum urea nitrogen concentrations were significantly lower and blood bicarbonate concentrations were significantly higher in the renal diet group at baseline and during the 12- and 24-month intervals. Significant differences were not detected in body weight; Hct; urine protein-to-creatinine ratio; and serum creatinine, potassium, calcium, and parathyroid hormone concentrations. A significantly greater percentage of cats fed the maintenance diet had uremic episodes (26%), compared with cats fed the renal diet (0%). A significant reduction in renal-related deaths but not all causes of death was detected in cats fed the renal diet. Conclusions and Clinical Relevance-The renal diet evaluated in this study was superior to an adult maintenance diet in minimizing uremic episodes and renalrelated deaths in cats with spontaneous stage 2 or 3 CKD.

Beta2-microglobulin, a uremic toxin with a double meaning

beta(2)M is a strong and independent indicator of hemodialysis patient outcomes and an excellent surrogate for middle molecules, and deserves to be routinely monitored and incorporated into dialysis adequacy targets. beta(2)M has a double meaning, reflecting both dialysis efficacy in terms of solute mass transfer and patient bioactivity. The work of Ward et al. in this issue warrants a study to test the hypothesis that long daily hemodiafiltration treatment would be the optimal renal replacement modality to improve dialysis patient outcomes.

In vivo removal of high- and low-molecular-weight compounds in hemodiafiltration with on-line regeneration of ultrafiltrate

BACKGROUND

Current methods of renal replacement therapy, combining convection and diffusion, are largely unsatisfactory in removing uremic toxins. Adsorption is a third mechanism that has been applied in extracorporeal therapy. This study evaluates the impact of hemodiafiltration with on-line regeneration of ultrafiltrate, a new two-step integrated sorbent system, on in vivo removal of a wide spectrum of solutes with different molecular weights.

METHODS

Pre- and post-dialysis concentrations of small, medium-size, and large molecules were determined in ten patients undergoing regular hemodiafiltration treatments with on-line regeneration of the ultrafiltrate. We also analyzed, at different times of the same dialysis session, the inlet and outlet ultrafiltrate; the latter had been regenerated by the sorbent cartridge and was used as reinfusion liquid. The mean dialysis time was 260 +/- 21.2 min with a blood flow of 361 +/- 33.3 ml/min and a reinjection volume of 3.6 +/- 0.2 l/h.

RESULTS

Urea, creatinine and phosphate reduction ratio were respectively 69.8 +/- 8.2, 61.9 +/- 5.5, and 40.2 +/- 17.3%. Removal of medium-size markers such as calcitonin, osteocalcin, beta2-microglobulin, cystatin C, myoglobin and prolactin varied between 24 and 60%. The percentage of reduction for retinol binding protein and alpha1-microglobulin was negligible and we were unable to demonstrate any removal of alpha1-acid glycoprotein, pre-albumin, and albumin in the regenerated ultrafiltrate.

CONCLUSION

The hemodiafiltration with on-line regeneration of ultrafiltrate is a new hemodialysis system, which allows uremic toxin removal over a wide molecular-weight spectrum.

Probiotic amelioration of azotemia in 5/6th nephrectomized Sprague-Dawley rats

The present study was to test the hypothesis that selected bacteria instilled into the gastrointestinal tract could help in converting nitrogenous wastes accumulated due to renal insufficiency into nontoxic compounds; thereby, ameliorating the biochemical imbalance. Herein we describe a prospective, blinded, placebo-controlled pilot study, using 5/6^th nephrectomized Sprague Dawley rat as a chronic renal failure model. The study group consisted of 36 nephrectomized and 7 non-nephrectomized (control) rats. After two-week nephrectomy stabilization, cohorts of six nephrectomized rats were fed casein-based diet plus one of the following regimens: (A) Control, (B) Placebo (casein-based diet without probiotics), (C) Bacillus pasteurii, (D) Sporolac®, (E) Kibow cocktail, (F) CHR Hansen Cocktail, and (G) ECONORM^TM. Subsequently, blood (retro-orbital) and urine (collected for measurements of blood urea-nitrogen and creatinine respectively), body weight and bacterial counts (feces) were obtained at regular intervals. The study end-points were to determine if any of the probiotic dietary supplements facilitated, (1) decreased blood concentrations of uremic toxins, (2) altered renal function, and (3) prolonged survival. After 16 weeks of treatment, regimens C and D significantly prolonged the life span of uremic rats, in addition to showing a reduction in blood urea-nitrogen levels, concluding that supplementation of probiotic formulation to uremic rats slows the progression of azotemia, which may correlate with prolonged life span of uremic rats. Derivative trials of probiotic treatment of larger animals and humans will further assess the potential role of probiotic formulations in delaying the onset and clinical severity of clinical illness at different stages of renal failure.

Hochdosierte Vitamingabe zur Verhinderung einer Porphyria cutanea urämica?

50 Patients with chronic renal failure undergoing hemodialysis with or without porphyria cutanea tarda (PCT)-like skin changes were investigated. The total porphyrin amount in erythrocytes, plasma and dialysate and the distribution of porphyrin metabolites in plasma and dialysate were measured. In plasma, the group of patients with skin changes (referred as PCU = porphyria cutanea uremica) showed significantly increased uroporphyrin levels as compared to the non-symptomatic group. In addition, significant differences concerning the ratio uro-/coproporphyrin in plasma were shown: non-symptomatic patients with 0.87, as opposed to the PCU group with 3.7. Considerable differences between the level of vitamin ingestion were identified between the groups. Patients with PCU took distinctly less vitamins C, E and B than patients without symptoms.

An analysis of the effectiveness and benefits of peritoneal dialysis and haemodialysis using Nigerian made PD fluids

Haemodialysis (HD) and peritoneal dialysis (PD) remains the cornerstone of management of patients with renal failure in developing countries as renal transplantation is just developing in most. Although both HD and PD are cost intensive, specific advantages and disadvantages have been identified with either of them. Comparative assessment of their effectiveness, benefits and cost will assist in providing a rational basis for preference of one or the other especially in third world countries where renal replacement therapy remains unaffordable and therefore relatively inaccessible to majority of patients. We therefore conducted this prospective randomised study to compare the effectiveness, benefits, cost and complications of acute or intermittent PD (IPD) and HD using locally manufactured PD fluids. Two groups of twenty patients with renal failure matched for age and clinical diagnosis were managed with IPD and HD and the effectiveness, costs and complications of both modalities compared. We found that both were comparably effective in the control of uraemia with significant reductions in the serum urea, creatinine and potassium from 29.2 +/- 7.2 mmol/L, 1693.7 +/- 580.5micromol/L and 4.8 +/- 1.2 mmol/L to 13.2 +/- 4.6 mmol/L, 796.0 +/- 458.0micromol/ L and 3.3 +/- 0.6 mmol/L respectively for IPD (P<0.05) and 34.4 +/- 9.0mmol/L, 1536.0 +/- 832.5 micromol/L and4.8 +/- 1.3 mmoV L to 14.6 +/- 7.5 mmol/L, 830.0 +/- 570.7 micromol/L and 3.9 +/- 0.8 mmol/L respectively for HD (P<0.05). In addition, there were significant improvements in serum bicarbonate in both groups. There was no significant difference in percentage reduction in serum urea, creatinine and serum potassium in both groups (P>0.05). However, HD managed patients required more blood transfusion (P<0.05). There were also comparably significant reductiohs in systolic, diastolic and mean arterial blood pressures in both groups (P<0.05). The costs of dialysis as well as the total cost of hospitalization were found to be significantly lower in patients managed with IPD (P<0.05). The commonest complication observed in patients managed with IPD was peritonitis while in patients managed with HD it was dialysis-induced hypotension. The clinical outcome was equally good in all the ARF patients as all of them recovered irrespective of the treatment modality; CRF patients did not fare as well with 37.5% mortality observed. We conclude that IPD and HD are effective renal replacement therapies with the former being significantly cheaper. IPD should be encouraged in our patients with ARF or acute exacerbation of chronic renal failure.

Citrate anticoagulation in pediatric continuous venovenous hemofiltration

Regional citrate anticoagulation has become a common alternative to systemic heparinization in adult continuous venovenous hemofiltration (CVVH) practice. We report our experience with the technique in critically ill children. We carried out a retrospective chart review of a 22-bed pediatric intensive care unit. CVVH with pre-filter citrate and systemic calcium replacement infusions was performed according to a strict protocol in nine consecutive critically ill children. All charts were reviewed for patient characteristics and CVVH circuit parameters, including filter survival. All complications were noted. Nurse specialists were interviewed about the practical management of citrate anticoagulation. All patient measurements of blood urea nitrogen, creatinine, sodium, ionized calcium (iCa), potassium, and bicarbonate were collected over the CVVH period. In seven patients, 12 simultaneous citrate measurements were taken from patient blood, pre-filter blood, and hemofiltrate fluid. Nine patients (mean age 8.8+/-6.8 years) were treated with CVVH and regional citrate anticoagulation for 1-14 days (mean 5.2+/-4.0 days). Of 19 filters used, 15 were replaced non-electively (mean filter survival 55.6+/-22.0 h). Control of azotemia and hyperkalemia was good. Sodium and iCa levels were well maintained. Bicarbonate levels were elevated in four patients without adverse effects. The mean systemic citrate level at equilibrium was 1.6+/-0.23 mmol/l. No systemic bleeding complications were observed. In children, regional citrate anticoagulation provides equivalent filter survival to heparin without bleeding complications. With good staff preparation, it is simple to perform and safe with respect to metabolic side effects.

Pre-dilution vs. post-dilution during continuous veno-venous hemofiltration: impact on filter life and azotemic control

BACKGROUND/AIMS

To determine the impact of replacement fluid infusion site on filter life and azotemic control during continuous veno-venous hemofiltration (CVVH).

METHODS

Pre-dilution CVVH was conducted from February 2001 to December 2001 and then practice was changed to post-dilution (from January 2002 to July 2002). Filter life was prospectively observed and the following data obtained for each filter: starting date and time, ending date and time, heparin use, heparin dose and protamine use. Daily creatinine, urea, INR, APTT and platelet count were also collected.

RESULTS

Forty-eight patients were studied (33 in pre-dilution and 15 in post-dilution) for a total of 309 filters (202 in pre-dilution and 107 in post-dilution). The median filter life was significantly shorter in the post-dilution period (18.0 vs. 13.0 h, p = 0.021). Multivariate linear regression analysis showed that pre-dilution was a significant independent predictor of increased filter life (p = 0.029), together with platelet count (p = 0.0035) and heparin dose (p = 0.046). There was no significant improvement in daily creatinine and/or urea reduction in the post-dilution period (% Delta creatinine: 7.9 vs. 10.2%/day, p = 0.99, urea: 5.4 vs. 9.7%/ day, p = 0.78).

CONCLUSIONS

Post-dilution was associated with reduced filter life without any beneficial effect on daily changes in urea and creatinine levels. Pre-dilution appears a preferable technical approach to CVVH.

[Influence of arginine on the renal functional condition of rats in sublimate nephropathy]

On a background of sublimate nephropathy there was studied the influence of arginin introduction on renal functional condition of white rats. Is established, that the dosage of arginin chloride 300 mg/kg of body weight at in 24 hours after sublimate introduction decreases the kidneys damage and expression of retention azotemia. The positive arginin action in sublimate nephropathy is shown the increasing of glomerular filtration rate and proteinuria decrease. Arginin does not influence on expression of sublimate infringement of kidney Na-transport, and increases it filtrate a charge and renal excretion of present cation.

New insights in uremic toxins

The retention in the body of compounds, which normally are secreted into the urine results in a clinical picture, called the uremic syndrome. The retention compounds responsible for the uremic syndrome are called uremic toxins. Only a few of the uremic retention solutes fully conform to a true definition of uremic toxins. Uremic patients develop atheromatotic vascular disease more frequently and earlier than the general population. The classical risk factors seem to be less important. Other factors have been suggested to be at play, and among those uremic toxins are mentioned as potential culprits. The identification, classification and characterization of the solutes responsible for vascular problems seems of utmost importance but is far from complete due to a lack of standardization and organization. The European Uremic Toxin Work Group (EUTox) has as a primary aim to discuss, analyze and offer guidelines in matters related to the identification, characterization, analytical determination and evaluation of biological activity of uremic retention solutes. The final aim remains the development of new strategies to reduce the concentration of the most active uremic solutes. These activities will at first be concentrated on reducing factors influencing cardiovascular morbidity and mortality.

Oxidant stress in hemodialysis patients: what are the determining factors?

Oxidant stress contributes to morbidity in hemodialysis patients. Three possible causes of oxidant stress have been suggested: the uremic state, the dialyzer membrane, and bacterial contaminants from the dialysate. Oxidant stress occurs in uremia before dialysis therapy is initiated, as evidenced by increased production of reactive oxygen species, increased levels of oxidized plasma proteins and lipids, and decreased antioxidant defenses. It has been proposed that increased production of reactive oxygen species during hemodialysis is also an important contributor to oxidant stress. Hemodialysis is associated with a transient increase in production of reactive oxygen species, particularly with cellulose membranes. In addition, surveys have shown widespread contamination of dialysate by endotoxin, which may cross membranes and prime production of reactive oxygen species by phagocytic cells. Recent studies, however, show a decrease in protein oxidation from pre- to post-dialysis and a normalization of neutrophil reactive oxygen species production. Taken together, these data suggest that uremia, per se, is the most important cause of oxidant stress in hemodialysis patients. Dialysate quality may also contribute to oxidant stress, but evidence that the dialyzer membrane plays a role is weak.

Survival of hemodialysis patients and uremic toxin removal

Uremic toxin removal based on diffusion and/or convection allows eliminating solutes with negative metabolic impact. Uremic solutes can be classified as small and water-soluble compounds, larger "middle" molecules, or protein bound solutes. The question arises whether more removal of each of these solute classes affects patient survival. Kt/V of urea is currently used as a surrogate for small water-soluble solute removal. There is ample evidence that Kt/V and survival are correlated, but the threshold Kt/V remains a matter of debate. Probably, the actually proposed threshold of 1.2 is too low. This impact of Kt/V is in contradiction with the low toxicity of urea and points to a role for other water-soluble solutes, e.g., potassium. More removal of middle molecules results in a lower morbidity and also in a lower mortality. In addition, a relationship has been demonstrated between the use of membranes with large pore size and a decrease of inflammatory status, by itself an important factor related to mortality. One of the problems is that large pore membranes are at the same time more biocompatible and reflect more dialysate impurities, compared to many small pore membranes, whereas they also reflect more dialysate impurities. It remains uncertain which one of these factors, if any, has a predominant effect. Recent studies point to a separate effect of pore size but await confirmation. Protein bound toxins inhibit several biochemical functions. Their removal pattern is totally different from that of classical markers such as urea. In analogy with drugs, it is essentially the free unbound fraction that exerts biological action; this free fraction is inversely related to serum albumin, another inflammatory marker related to survival. In a final section of this presentation, attention will be drawn to the relationship in uremic patients between inflammation, malnutrition, cardiovascular disease, and mortality, and some of the potential culprits are discussed. Virtually all of these molecules have a high molecular weight or are protein bound. It is concluded that both small and middle molecule removal have an impact on survival, so that more than urea removal alone should be pursued.

Preemptive ramipril therapy delays renal failure and reduces renal fibrosis in COL4A3-knockout mice with Alport syndrome

BACKGROUND

Alport syndrome (AS) is a common hereditary cause of end-stage renal failure in adolescence due to defects in type IV collagen genes. Molecular genetics allows early diagnosis, however, no preventive strategy can be offered. Using the COL4A3 -/- mouse, an animal model for human AS, we evaluated therapy with ramipril in mice.

METHODS

One hundred and twenty-two Alport-mice were treated with 10 mg/kg/day ramipril added to drinking water. Proteinuria, serum-urea and lifespan were monitored. Renal matrix was characterized by immunohistochemistry, light- and electron microscopy, and Western blot.

RESULTS

Untreated COL4A3 -/- mice died from renal failure after 71 +/- 6 days. Early therapy starting at four weeks of age and continuing to death delayed onset and reduced the extent of proteinuria. Uremia was postponed by three weeks in treated animals. Lifespan increased by more than 100% to 150 +/- 21 days (P < 0.01). In parallel, decreased deposition of extracellular matrix and lessened interstitial fibrosis as well as reduced amounts of renal transforming growth factor-beta1 (TGF-beta1) could be demonstrated. Late therapy starting at seven weeks decreased proteinuria, however, lifespan did not increase significantly.

CONCLUSIONS

The results indicate an antiproteinuric and antifibrotic nephroprotective effect of ramipril in COL4A3 -/- mice is mediated by down-regulation of TGF-beta1. This effect in mice is enhanced by initiation of therapy during pre-symptomatic disease. The data in COL4A3 -/- mice as an animal-model for Alport syndrome suggest that ramipril might as well delay renal failure in humans with AS. Early diagnosis and preemptive treatment also may be crucial in humans.

Continuous renal replacement therapy: does technique influence azotemic control?

BACKGROUND AND OBJECTIVES

Different techniques of continuous renal replacement therapy (CRRT) might have different effects on azotemic control. Accordingly, we tested whether continuous veno-venous hemodiafiltration (CVVHDF) or continuous veno-venous hemofiltration (CVVH) would achieve better control of serum creatinine and plasma urea levels.

DESIGN

Retrospective controlled study.

SETTING

Two tertiary Intensive Care Units.

PATIENTS

Critically ill patients with acute renal failure (ARF) treated with CVVHDF (n = 49) or CVVH (n = 50).

INTERVENTIONS

Retrieval of daily morning urea and creatinine values before and after the initiation of CRRT for up to 2 weeks of treatment.

MEASUREMENTS AND RESULTS

Before treatment, serum urea and creatinine concentrations were significantly lower in the CVVH group than in CVVHDF group (urea: 31.0 +/- 15.0 mmol/L for CVVHDF and 24.7 +/- 16.1 mmol/L for CVVH, p = 0.01, creatinine: 547 +/- 308 micromol/L vs. 326 +/- 250 micromol/L, p < 0.0001). These differences were still significant after 48 h of treatment (urea: 20.1 +/- 8.3 mmol/L vs. 14.1 +/- 6.1 mmol/L; p = 0.0003, creatinine: 360 +/- 189pmol/L vs. 215 +/- 118 micromol/L; p < 0.0001). Throughout the duration of therapy, mean urea levels (22.3 +/- 9.0 mmol/L for CVVHDF vs. 16.7 +/- 7.8 mmol/L for CVVH, p < 0.0001) and mean creatinine levels (302 +/- 167 vs. 211 +/- 103 micromol/L, p < 0.0001) were better controlled in the CVVH group.

CONCLUSIONS

CRRT strategies based on different techniques might have a significantly different impact on azotemic control.

Clinical evaluation of dietary modification for treatment of spontaneous chronic renal failure in dogs

OBJECTIVE

To determine whether a diet used for dogs with renal failure (renal food [RF]) was superior to an adult maintenance food (MF) in minimizing uremic crises and mortality rate in dogs with spontaneous chronic renal failure.

DESIGN

Double-masked, randomized, controlled clinical trial.

ANIMALS

38 dogs with spontaneous chronic renal failure.

PROCEDURE

Dogs were randomly assigned to a group fed adult MF or a group fed RF and evaluated for up to 24 months. The 2 groups were of similar clinical, biochemical, and hematologic status. The effects of diets on uremic crises and mortality rate were compared. Changes in renal function were evaluated by use of serial evaluation of serum creatinine concentrations and reciprocal of serum creatinine concentrations.

RESULTS

Compared with the MF, the RF had a beneficial effect regarding uremic crises and mortality rate in dogs with mild and moderate renal failure. Dogs fed the RF had a slower decline in renal function, compared with dogs fed the MF.

CONCLUSIONS AND CLINICAL RELEVANCE

Dietary modifications are beneficial in minimizing extrarenal manifestations of uremia and mortality rate in dogs with mild and moderate spontaneous chronic renal failure. Results are consistent with the hypothesis that delay in development of uremic crises and associated mortality rate in dogs fed RF was associated, at least in part, with reduction in rate of progression of renal failure.

Retinoic acid exacerbates experimental radiation nephropathy

Studies have shown that angiotensin-converting enzyme inhibitors and an angiotensin II receptor blocker can delay, but cannot reverse, the progression of experimentally induced radiation nephropathy. In an effort to find a method for reversing injury, three agents were tested in a rat model of radiation nephropathy. Pirfenidone (a phenyl-pyridone antifibrotic) and thiaproline (an inhibitor of collagen deposition) were not capable of retarding the development of radiation nephropathy. However, all-trans retinoic acid (an anti-inflammatory agent) exacerbated radiation nephropathy. We speculated that the detrimental effects of retinoic acid might be the result of stimulation of renal cell proliferation. However, retinoic acid had no effect on tubular or glomerular cell proliferation in normal animals and did not enhance radiation-induced proliferation. A recent report that retinoic acids inhibit nitric oxide production suggested an alternative mechanism, since inhibition of production of nitric oxide is known to exacerbate radiation nephropathy. Experiments demonstrated that retinoic acid exacerbated the radiation-induced drop in renal production of nitric oxide, suggesting that the detrimental effect of all-trans retinoic acid might be explained by inhibition of renal nitric oxide activity. Particularly in view of the recent clinical report of enhancement of radiation nephropathy by retinoic acid in patients receiving bone marrow transplantation, the combination of retinoic acid and renal irradiation should be carried out with great caution.

Alterations of non-enzymatic biochemistry in uremia, diabetes, and atherosclerosis ("carbonyl stress")

Aging is accompanied by a progressive and irreversible non-enzymatic modification of protein by carbohydrates, eventually yielding the advanced glycation end products (AGEs). Age generation (Maillard reaction) is markedly augmented in diabetes with sustained hyperglycemia but also in normoglycemic uremia and atherosclerosis. Recent studies have brought new insights into broad derangements in non-enzymatic biochemistry involving not only carbohydrates but also lipids, present in diabetes, uremia, and atherosclerosis. The latter have in common increased levels of reactive carbonyl compounds (RCOs) with attendant protein modifications ("carbonyl stress"). Carbonyl stress might be derived from 1) hyperglycemia (lipemia), 2) oxidative stress, and/or 3) impaired detoxification of RCOs. Manipulation of carbonyl stress in diabetes, uremia and atherosclerosis opens new therapeutic approaches including redox modulation, RCO detoxification, and carbonyl stress inhibition. The first generation of carbonyl stress inhibitors such as aminoguanidine trap RCOs with its hydrazine group. Unfortunately, aminoguanidine (AG) traps pyridoxal as well as noxious RCOs, so that its long-term administration in animals results in vitamin B6 deficiency and neurotoxicity. Fortunately, newer compounds devoid of such side effects, have opened exciting prospects. Widely used hypotensive agents, such as angiotensin converting enzyme (ACE) inhibitor and angiotensin II receptor antagonist, but not calcium blockers, prove more effective than AG in attenuating the production of AGEs. Unlike AG, they do not act as RCO trapping agents, but impact upon the production of RCO precursors by scavenging a variety of radicals and altering oxidative stress, a mechanism similar to that involved in the inhibitory action of nitric oxide on AGE formation. These results provide a new framework to assess families of compounds according to their mechanisms of action.

Long-term ammonium chloride or sodium bicarbonate treatment in two models of polycystic kidney disease

Administration of ammonium chloride aggravates, while short-term administration of sodium or potassium bicarbonate lessens the development of polycystic kidney disease in Han:SPRD rats. We have conducted studies to determine whether the protection afforded by the administration of sodium bicarbonate is sustained and prevents development of uremia during chronic administration and whether the effects of the administration of ammonium chloride and sodium bicarbonate are also observed in a different model of polycystic kidney disease, the CD1-pcy/pcy mouse. We found that chronic administration of 200 mM sodium bicarbonate to Han:SPRD rats inhibited cystic enlargement and prevented the subsequent development of interstitial inflammation, chronic fibrosis, and uremia. We also found that, while the administration of ammonium chloride has similar effects in Han:SPRD rats and CD1-pcy/pcy mice, the administration of sodium bicarbonate is only protective in the Han:SPRD rats. This probably reflects differences in these models (predominately involvement of proximal tubules in Han:SPRD rats and of collecting ducts and distal tubules in pcy/pcy mice) and the different location and nature of the renal metabolic responses to the administration of acid or alkaline load.

Relationship between insulin resistance and uremic toxins in the gastrointestinal tract

The relationship between insulin resistance and local uremic toxins was examined using an oral adsorbent. Fourteen rats demonstrating a diabetic state underwent two-thirds, nephrectomy and were divided into two groups. The control group was fed standard rat chow, and the test group was fed standard rat chow containing 5% AST-120. The target level of blood glucose was achieved by controlling the dosage of exogenous insulin. All rats were sacrificed at week 6. Body weight, blood glucose level, and renal function at week 6 were not significantly different between both groups. However, the mean blood glucose level and the mean dose of exogenous insulin in the AST-120-fed group were significantly reduced as compared with the control group. The results of the present study indicate that administration of an oral adsorbent in diabetic nephropathy decreases the doses of exogenous insulin and improves insulin resistance, and that uremic toxins which exist in the gastrointestinal tract play important roles.

Urea is the best molecule to target adequacy of peritoneal dialysis

For hemodialysis, a large base of data shows the validity of modelling the dialysis dose and reliably estimating protein intake from equilibrated Kt/V urea (eKt/VU), the total dialyzer urea clearance provided during each treatment divided by the urea distribution volume. An eKt/VU of 1.05 thrice weekly is judged adequate, but is still under study. In continuous ambulatory peritoneal dialysis (CAPD), two dosage criteria are widely recognized: continuous ("standard") Kt/VU (stdKt/VU = 2.0 weekly), and total creatinine (Cr) clearance normalized to body surface area (KCrT = 70 L/week/1.73 m2). The CANUSA study concluded that a stdKt/VU of 2.1 and a KCrT of 70 L/week/1.73 m2 gave equivalent clinical outcomes. The Dialysis Outcomes Quality Initiative (DOQI) recommends values of 2.0 and 60 L/week/1.73 m2 respectively. An analysis of these two parameters for males and females over a wide range of body surface areas (BSAs) was done and the analysis showed: (1) The U and Cr dose criteria are incommensurable--that is, they can virtually never be achieved simultaneously in anephric patients. (2) The Cr criterion varies widely with the sex of the patient and with the BSA-dependent variation in stdKt/VU over a range of 2.1 to 3.0. (3) The U criterion always produces a KCrT < 60 L/week/1.73 m2 in females and 60-70 L/week/1.73 m2 in males. With respect to U and Cr, the CANUSA results were concluded to be valid in patients with substantial residual renal function, but probably not applicable to anephric patients where the doses are clearly incommensurable.

Tiopronin protects against the nephrotoxicity of cisplatin in the rat

1. Tiopronin (N-(2-mercaptopropionyl)-glycine) is a drug with a free thiol (sulphydryl) group that is used clinically. We have reported previously that tiopronin protects rat kidney slices in vitro from the nephrotoxic effects of cisplatin and does not reduce the antitumour activity of cisplatin. Tiopronin has been investigated therefore for its protective effects in rats in vivo. 2. The extent of kidney damage was studied 5 days after the administration of cisplatin. A single injection (i.p.) of cisplatin (6 mg/kg; 20 micromol/kg) to female Wistar albino rats caused a sustained decrease in body weight and, after 5 days, plasma urea, creatinine and kidney weight were increased. Tiopronin (2.5 mmol/kg, p.o.) ameliorated cisplatin nephrotoxicity when given 1 h before cisplatin. Tiopronin provided marked protection against cisplatin-induced increases in urea (from 237+/-19 mg to 48+/-23 mg/100 ml; control: 17+/-1) and creatinine (from 6.5+/-0.5 to 1.7+/-0.5 mg/100 ml control: 1.0+/-0.1). Tiopronin did not, prevent the body weight loss caused by cisplatin. In addition, an intraperitoneal dose (1 mmol/kg) of tiopronin afforded similar protection to that of an oral dose. Rats that received an i.p. mixture of cisplatin (6 mg/kg) and tiopronin (65 mg/kg) displayed generally less toxicity, as indicated by a small fall in body weight and smaller increases in urea and creatinine and kidney weight. 3. The results show that tiopronin protects against cisplatin-induced nephrotoxicity. Oral administration of tiopronin may be a clinically useful way to prevent cisplatin nephrotoxicity.

Changing acute renal failure treatment from intermittent hemodialysis to continuous hemofiltration: impact on azotemic control

BACKGROUND

Continuous renal replacement therapy is increasingly used in the management of acute renal failure in critically ill patients. The advantages of continuous renal replacement therapy (CRRT) over intermittent hemodialysis (IHD), however, are not yet fully documented. In particular, it is unknown whether continuous veno-venous hemodiafiltration (CVVHDF) provides better control of azotemia than IHD.

OBJECTIVES

To study the effect on azotemic control of changing acute renal failure treatment from IHD to CVVHDF.

SETTINGS

Tertiary intensive care unit.

PATIENTS

Forty seven consecutive critically ill patients with multiorgan failure and acute renal failure treated with IHD and 47 similar patients treated with CVVHDF.

METHODS

Analysis of daily morning urea and creatinine concentrations over the period of renal replacement therapy in the ICU. Statistical comparison of data.

RESULTS

The two groups of patients were comparable for mean age (55 years for IHD vs. 60 years for CVVHDF; NS) and number of failing organs prior to therapy (mean of 4.2 for IHD vs. 3.7 for CVVHDF; NS). Severity of illness at admission as assessed by APACHE II score, however, was greater for patients receiving CVVHDF (29.4 vs 25.7; p<0.003). CVVHDF was associated with a significantly lower plasma urea (p < 0.0001) and serum creatinine (p < 0.01) level at 24 hours of treatment despite similar levels at the start of therapy Throughout the duration of therapy, mean urea levels (35.0 mmol/L for IHD vs 23.4 mmol/L for CVVHDF) and mean serum creatinine levels (513 micromoles/L for IHD and 263 micromoles/L for CVVHDF) showed significantly (p <0.0001) better control of uremia with CRRT.

CONCLUSIONS

Changing the form of renal replacement therapy from intermittent hemodialysis to continuous hemofiltration is associated with improved control of azotemia. The superior adequacy of small solute clearance achieved during CVVHDF provides additional support for its preferential use in the management of acute renal failure in the ICU.

Timely initiation of dialysis: a urea kinetic approach

The traditional approach of initiating dialysis when the patient begins to manifest uremic symptoms may result in the development of significant malnutrition with detrimental effects on subsequent morbidity and mortality. The recently issued Dialysis Outcome Quality Initiative guidelines suggest that dialysis be initiated when the Kt/V from residual renal function decreases to less than 2.0. We have used the urea kinetic model to show how dialytic dose can be titrated to compensate for declining renal function while maintaining a constant total dose of delivered therapy (Kt/V = 2.0). For hemodialysis (HD), we show that initiating dialysis with once-weekly therapy may be a viable option only for a few months, being replaced by twice-weekly and subsequently with the more typical regimen of thrice-weekly HD. We recommend that the patient be directly initiated with twice-weekly HD to minimize wide swings in the serum concentrations of small-molecular-weight solutes. With continuous ambulatory peritoneal dialysis (CAPD), a hypothetical average-sized patient with high-average transport can be maintained for approximately 8 months with a single 2.5-L nocturnal exchange and from 8 to 17 months with two nocturnal exchanges of 2.5 L each. The use of nocturnal exchanges allows more normal daytime activities and is less intrusive on patient lifestyle. We have shown that both HD and CAPD regimens can be successfully adjusted to achieve a constant total Kt/V of 2.0 for 5 or more years, although CAPD may provide a smoother transition from no dialysis to a complete 10-L regimen.

[Uremia after hemorrhages in the upper digestive tract]

Haemorrhages in the upper GI tract may lead to severe uraemia and, in patients with liver failure, to hyperammonaemia. The cause of this is not yet sufficiently clear. Recently we observed a decrease in arterial isoleucine levels after intragastric blood administration in pigs. This contrasted with elevated levels of most other amino acids, ammonia and urea. After an isonitrogenous control meal in these pigs all amino acids including isoleucine increased, and urea increased to a lesser extent, suggesting a relationship between the arterial isoleucine decrease and uraemia after gastrointestinal (GI) haemorrhage. Analysis of blood protein showed a complete absence of the essential amino acid isoleucine, making it a protein of low biological value. In additional porcine experiments, uraemia after intragastric blood administration could be prevented by simultaneous intravenous isoleucine administration. This led to the hypothesis that there was a causal relationship between the absence of isoleucine in blood protein and the uraemia and hyperammonaemia observed after GI bleeding. Similar results were seen in patients with intact and with impaired liver functions. These results support the hypothesis that the absence of isoleucine in blood protein causes decreased plasma and tissue isoleucine levels after GI haemorrhage. This might inhibit protein synthesis, and may contribute to uraemia and hyperammonaemia in patients with normal and impaired liver function, respectively. Intravenous isoleucine administration after GI haemorrhage could be beneficial.

Uraemic autonomic neuropathy

Uraemia leads to the damage of autonomic nervous system and the emergence of uraemic autonomic neuropathy. Consequences of uraemia may be dangerous for life, therefore its early diagnosis and prevention is essential.

[Perioperative management of uremia and fluid balance in patients with compromised renal function undergoing open heart surgery]

Five patients with renal dysfunction underwent coronary artery bypass grafting (CABG). Three patients were in cardiogenic shock with acute myocardial infarction for whom CABG was carried out on emergent basis. Immediate preoperatively these patients were in almost anuria which was derived from sustained renal dysfunction plus decreased renal perfusion due to low cardiac output. The other two patients were operated on electively, and hemodynamic instability and artificial perfusion (cardiopulmonary bypass) affected their chronic renal disease (polycystic kidney and nephrosclerosis, respectively) so unfavorably that intraoperative anuria took place. In all patients intraoperative control of fluid balance and prevention of azotemia were accomplished by intraoperative hemofiltration (HF), in which 10 litters of body fluid was filtered out through a hemofiliter incorporated into the cardiopulmonary bypass circuit, and replaced with saline solution. In emergent cases (three patients) complete anuria was sustained and continuous hemodialysis/hemofilitration (CHDF) was successively performed to control water balance and to prevent exacerbation of uremia. Although they all were in profound low cardiac output state necessitating intraaortic balloon counterpulsation (IABP) and infusion of considerable amount of catecholamines, there was no hemodynamic instability occurred throughout the period of CHDF. In four cases renal function recovered significantly along with the recover from their cardiogenic shock so that they could wean from the hemodialysis therapy. In the remaining case intermittent hemodialysis was necessary in chronic phase. There were no hospital death nor late mortality. From this experience we might conclude that the combined use of intraoperative HF and successive postoperative CHDF is an effective method for controlling fluid balance and preventing uremia in cardiac surgical patients with severe renal dysfunction along with considerable hemodynamic instability.

Nephron sparing by partial median nephrectomy for treatment of renal hemangioma in a dog

A 6-year-old neutered male Golden Retriever was admitted for evaluation of intermittent hematuria of 2 months' duration. A 3-cm heterogeneous mass causing distortion of the caudomedial aspect of the left kidney was detected via ultrasonography. Histologic examination of a renal tissue sample obtained by ultrasound-guided biopsy revealed a telangiectatic vascular plexus of unknown origin. Low glomerular filtration rate was identified by a modified exogenous creatinine clearance test. Excretory urography revealed a filling defect in the medial aspect of the caudal pole of the kidney, near the hilus. Because total renal function was low, a decision was made to perform nephron-sparing surgery involving resection of centrally located renal parenchymal and pelvic tissue by en bloc resection in the median plane, instead of radical nephrectomy. After surgery, the hematuria resolved and further decrease in renal function was not evident. Nephron-sparing surgery is a viable option for dogs with compromised renal function when there is concern that radical nephrectomy may precipitate uremia.