What Is Uremia? Retention versus Oxidation

Prevalence of Methicillin-resistant Staphylococcus aureus (MRSA) Carrier in Hemodialysis Patients at Dr. Soetomo Academic General Hospital

Chronic kidney disease (CKD) is now a global epidemic, and the prevalence is increasing worldwide. Hemodialysis    is one of the ways to treat by kidney function replacement. Infection is the number two cause of death in patients with hemodialysis (HD). Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of bacteriemia in patients with dialysis. The epidemiological data of MRSA carriers in CKD in Indonesia are still scarce. This study was to determine the prevalence of MRSA carriers in patients at The Kidney and Hypertension Outpatient-clinic and Hemodialysis Installation at Dr. Soetomo Academic General Hospital, Surabaya Indonesia. The study design was descriptive-analytic with a cross- sectional study design. Sampling was collected consecutively. Data on the general characteristics of the research subjects will be analyzed using a Chi-Squared test. There were 150 CKD stage five patients included in this study, the number  of patients has MRSA carrier were 6 (4%), among them, subjects underwent HD MRSA carrier were 2 subjects(2.7%), while for non-HD patients with MRSA were 4 subjects (5.3 %). There were no significant differences in MRSA carriers between HD and non HD groups (p=0.404). Comorbid factors that accompany MRSA carriers are diabetes mellitus, hypertension, kidney stones, gout, and systemic lupus erythematosus (SLE).  This study found, there were no significant differences in the incidence of MRSA carriers in stage five CKD non HD or HD groups. MRSA colonization exists in stage five CKD sufferers, so awareness of MRSA colonization

[Pleiotropic effects of sevelamer: a model of intestinal tract chelating agent]

The number of patients with chronic kidney disease (CKD) with its associated complications has increased dramatically worldwide in recent years. Therefore, many experimental and clinical studies have examined over the last decade the mechanisms involved, in order to explain the sharp increase in cardiovascular mortality. Hyperphosphatemia is a major problem in these patients especially at advanced stages of CKD, and it is associated with cardiovascular and mineral complications in these patients. Sevelamer is a phosphate binder that allows a better control of hyperphosphatemia, like other phosphate binder agents, but it has additional pleiotropic effects such as correcting certain abnormalities of lipid metabolism and clearance of several uremic toxins. These effects of sevelamer, restricted to the intestinal lumen, underline the importance of intestinal pathway in CKD and open the way to new therapeutic strategies for the management of the CKD and its complications.

Does the adequacy parameter Kt/V(urea) reflect uremic toxin concentrations in hemodialysis patients?

Hemodialysis aims at removing uremic toxins thus decreasing their concentrations. The present study investigated whether Kt/V_urea, used as marker of dialysis adequacy, is correlated with these concentrations. Predialysis blood samples were taken before a midweek session in 71 chronic HD patients. Samples were analyzed by colorimetry, HPLC, or ELISA for a broad range of uremic solutes. Solute concentrations were divided into four groups according to quartiles of Kt/V_urea, and also of different other parameters with potential impact, such as age, body weight (BW), Protein equivalent of Nitrogen Appearance (PNA), Residual Renal Function (RRF), and dialysis vintage. Dichotomic concentration comparisons were performed for gender and Diabetes Mellitus (DM). Analysis of Variance in quartiles of Kt/V_urea did not show significant differences for any of the solute concentrations. For PNA, however, concentrations showed significant differences for urea (P<0.001), uric acid (UA), p-cresylsulfate (PCS), and free PCS (all P<0.01), and for creatinine (Crea) and hippuric acid (HA) (both P<0.05). For RRF, concentrations varied for β₂-microglobulin (P<0.001), HA, free HA, free indoxyl sulfate, and free indole acetic acid (all P<0.01), and for p-cresylglucuronide (PCG), 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF), free PCS, and free PCG (all P<0.05). Gender and body weight only showed differences for Crea and UA, while age, vintage, and diabetes mellitus only showed differences for one solute concentration (UA, UA, and free PCS, respectively). Multifactor analyses indicated a predominant association of concentration with protein intake and residual renal function. In conclusion, predialysis concentrations of uremic toxins seem to be dependent on protein equivalent of nitrogen appearance and residual renal function, and not on dialysis adequacy as assessed by Kt/V_urea. Efforts to control intestinal load of uremic toxin precursors by dietary or other interventions, and preserving RRF seem important approaches to decrease uremic solute concentration and by extension their toxicity.

Male susceptibility to hepatic damage in acute uremia in rats

OBJECTIVE

To evaluate the role of gender in hepatic oxidative stress response and production of inflammatory cytokines in acute uremia after bilateral nephrectomy. Published studies indicate that the severity of tissue damage in kidney, brain, or heart injury may differ according to gender. We recently demonstrated that acute renal failure after kidney injury or bilateral nephrectomy activates oxidative stress and causes damage to the liver.

METHODS

Male and female rats were subjected to bilateral nephrectomy and euthanized four hours later. Serum and liver tissues were collected and analyzed. To ascertain the role of testosterone and estrogen in hepatic oxidative stress, castration was carried out 15 days before bilateral nephrectomy. In some groups, animals were administrated 17-β-estradiol or vehicle for 2 weeks before bilateral nephrectomy.

RESULTS

Hepatic oxidative stress was significantly pronounced in male rats as determined by increase in malondialdehyde (MDA) levels and decrease in total glutathione (GSH) contents. An increase in proinflammatory cytokine concentration was seen in male rats, whereas the antiinflammatory cytokine level was more elevated in females. Castration reduced hepatic oxidative stress and proinflammatory cytokine concentration, whereas exogenous estradiol after castration did not have an additional effect on these parameters.

CONCLUSIONS

There is a gender difference with regard to the severity of hepatic oxidative stress and inflammatory response in acute uremia after bilateral nephrectomy, with female rats displaying significant protection relative to male rats. We suggest that sex hormones could play an important role in the severity of remote tissue damage in acute kidney failure.

The effect of the uremic toxin cyanate (CNO⁻) on anaerobic cysteine metabolism and oxidative processes in the rat liver: a protective effect of lipoate

Chronic renal failure (CRF) patients have an increased plasma level of urea, which can be a source of cyanate. This compound can cause protein carbamoylation thereby changing biological activity of proteins. Therefore, in renal failure patients, cyanate can disturb metabolism and functioning of the liver. This work presents studies demonstrating that the treatment of rats with cyanate alone causes the following changes in the liver: (1) inhibition of rhodanese (TST), cystathionase (CST) and 3-mercaptopyruvate sulfotransferase (MPST) activities, (2) decrease in sulfane sulfur level (S*), (3) lowering of nonprotein sulfhydryl groups (NPSH) group level, and (4) enhancement of prooxidant processes (rise in reactive oxygen species (ROS) and malondialdehyde (MDA) level). This indicates that cyanate inhibits anaerobic cysteine metabolism and shows prooxidant action in the liver. Out of the above-mentioned changes, lipoate administered with cyanate jointly was able to correct MDA, ROS and NPSH levels, and TST activity. It had no significant effect on MPST and CST activities. It indicates that lipoate can prevent prooxidant cyanate action and cyanate-induced TST inhibition. These observations can be promising for CRF patients since lipoate can play a dual role in these patients as an efficient antioxidant defense and a protection against cyanate and cyanide toxicity.

The effect of uremic toxin cyanate (OCN–) on anaerobic sulfur metabolism and prooxidative processes in the rat kidney: a protective role of lipoate

Cyanate and its active form isocyanate are formed mainly in the process of nonenzymatic urea biodegradation. Cyanate is capable of protein S- and N-carbamoylation, which can affect their activity. The present studies aimed to demonstrate the effect of cyanate on activity of the enzymes implicated in anaerobic cysteine metabolism and cyanide detoxification and on glutathione (GSH) level and peroxidative processes in the kidney. In addition, we examined whether a concomitant treatment with lipoate, a dithiol that may act as a target of S-carbamoylation, can prevent these changes. The studies were conducted in Wistar rats. The animals were assigned to four groups, which received injections of physiological saline, cyanate (200 mg/kg), cyanate (200 mg/kg) + lipoate (100 mg/kg) and lipoate alone (100 mg/kg). The animals were killed 2 h after the first injection, the kidneys were isolated and kept at -80°C until biochemical assays were performed. Cyanate inhibited rhodanese (TST) and mercaptopyruvate sulfotransferase (MPST) activity, decreased GSH level and enhanced peroxidative processes in the kidney. All these changes were abolished by cyanate treatment in combination with lipoate.

Dinucleoside polyphosphates: newly detected uraemic compounds with an impact on leucocyte oxidative burst

BACKGROUND

Dinucleoside polyphosphates (Np(n)N) have pathophysiologic roles in cardiovascular disease and are newly detected uraemic retention solutes. They were retrieved in human plasma, tissues and cells. Although their impact on several cell systems involved in vascular damage (endothelium, smooth muscle cells and thrombocytes) has been evaluated, their effect on different types of leucocytes has never been studied.

METHODS

This study evaluates, for the first time, the impact of Np(n)N on monocyte, granulocyte and lymphocyte oxidative burst activity at baseline and after stimulation with N-formyl-methionine-leucine-phenylalanine (fMLP) and phorbol 12-myristate 13-acetate (PMA) in whole blood. Diadenosine triphosphate (Ap(3)A) to diadenosine hexaphosphate (Ap(6)A) were tested to investigate the effect of the number of phosphate groups on reactive oxygen species (ROS) production. The effect of the type of nucleoside was evaluated by comparing adenosine guanosine tetraphosphate, diguanosine tetraphosphate, uridine adenosine tetraphosphate (Up(4)A) and diadenosine tetraphosphate (Ap(4)A).

RESULTS

This study demonstrated that lymphocytes are especially susceptible to intracellular diadenosine polyphosphates. Depending on the phosphate chain length, different effects were observed. At baseline and with fMLP, Ap(4)A, Ap(5)A and Ap(6)A enhanced lymphocyted-free radical production. In addition, Ap(3)A, Ap(4)A and Ap(5)A increased PMA-stimulated ROS production in lymphocytes. Monocytes and granulocytes parallel the lymphocyte response albeit with an inhibition of Ap(6)A on granulocytes. Considering Np(n)N with four phosphate groups, Up(4)A showed the most important stimulatory effects on monocytes and Ap(4)A on lymphocytes.

CONCLUSIONS

Np(n)N mainly have a leucocyte-activating impact, most significant for Ap(4)A, considering phosphate chain length, and for Up(4)A, considering the type of nucleosides. These results suggest that the pro-inflammatory effects of Np(n)N can contribute to the development of atherosclerosis, probably in the early stages of chronic kidney disease, but their chemical composition affects their activity.

Procalcitonin values after dialysis is closely related to type of dialysis membrane

BACKGROUND

Infections account for considerable morbidity and mortality in patients with chronic renal failure undergoing hemodialysis (HD). Diagnosis of infection in HD patients is challenging because the most used laboratory parameters may be increased even in the absence of infection. In this setting, procalcitonin (PCT) could be useful for detection of systemic bacterial infections.

METHODS

We measured high sensitivity C Reactive Protein (hsCRP) and PCT serum levels before and immediately after dialysis in 44 HD patients (22 treated with high- and 22 with low-flux membranes), without history of infections.

RESULTS

Patients on HD by high-flux membranes, but not by low-flux membranes, displayed mean PCT values significantly decreased after dialysis (high-flux: 0.50 vs. 0.26 ng/mL, p=0.005; low-flux: 0.41 vs. 0.42 ng/mL, p=0.863). HsCRP levels were unchanged. HsCRP correlated with PCT values both before and after HD only in patients on HD by low-flux membranes (r=0.51 and 0.47 before and after HD respectively; p<0.05).

CONCLUSIONS

Although PCT is considered a sensitive and specific diagnostic and prognostic marker of systemic bacterial infection, we suggest that specific reference ranges might be developed in patient with impaired renal function, also showing that and its clinical usefulness might be limited in patients undergoing HD with high-flux membranes.

The HSP72 stress response of monocytes from patients on haemodialysis is impaired

BACKGROUND

Induction of heat shock proteins (HSP), i.e. of the major family member HSP70, is an important cytoprotective-resistance mechanism for monocytes/ macrophages (Mphi). Patients on haemodialysis present with a high infectious morbidity and enhanced carcinoma incidence. Renal insufficiency-related alteration of microbicidal and tumoricidal functions of Mphi, major effectors of the immune system, might promote these diseases.

METHODS

Freshly isolated Mphi from Sprague-Dawley rats 2 weeks after 5/6-nephrectomy and from patients on intermittent haemodialysis (IHD) were stimulated by heat shock (HS) and compared to stimulated Mphi of control rats or healthy volunteers (CTR). Expression of HSP72 (inducible HSP70) was assessed by RT-PCR, and/or flow cytometry. Apoptosis of Mphi was detected by flow cytometry (CD14/annexin V-labelling).

RESULTS

In rat Mphi, baseline HSP72 expression was similar in both groups, but its induction was significantly impaired in renal insufficiency (214 +/- 68% less HSP70-mRNA versus CTR, n = 6). In patients, HSF-1-mRNA and HSP72-mRNA/protein response to HS was significantly lower, but not affected by dialysis session itself. In parallel, apoptosis of Mphi of patients was enhanced (+83 +/- 29% constitutive apoptotic Mphi versus CTR, n = 8), and HS-dependent protection from apoptosis with and without serum depletion (48 h depletion: HS, +275 +/- 37% apoptotic Mphi versus CTR, n = 6; full medium: +166 +/- 62% versus CTR, n = 8, P < 0.05) was inferior.

CONCLUSIONS

Impaired HSP72 stress response of Mphi in patients on haemodialysis might contribute to the observed immune dysfunction and, therefore, to the increased susceptibility to infection and malignancy. Stress impairment is not restricted to uraemia but is already present in a rat model of chronic kidney disease.

Arginine, scurvy and Cartier's "tree of life"

Several conifers have been considered as candidates for "Annedda", which was the source for a miraculous cure for scurvy in Jacques Cartier's critically ill crew in 1536. Vitamin C was responsible for the cure of scurvy and was obtained as an Iroquois decoction from the bark and leaves from this "tree of life", now commonly referred to as arborvitae. Based on seasonal and diurnal amino acid analyses of candidate "trees of life", high levels of arginine, proline, and guanidino compounds were also probably present in decoctions prepared in the severe winter. The semi-essential arginine, proline and all the essential amino acids, would have provided additional nutritional benefits for the rapid recovery from scurvy by vitamin C when food supply was limited. The value of arginine, especially in the recovery of the critically ill sailors, is postulated as a source of nitric oxide, and the arginine-derived guanidino compounds as controlling factors for the activities of different nitric oxide synthases. This review provides further insights into the use of the candidate "trees of life" by indigenous peoples in eastern Canada. It raises hypotheses on the nutritional and synergistic roles of arginine, its metabolites, and other biofactors complementing the role of vitamin C especially in treating Cartier's critically ill sailors.

Timing of renal replacement therapy in critically ill patients with acute kidney injury

PURPOSE OF REVIEW

Timing of renal replacement therapy in critically ill patients with acute kidney injury is highly subjective, and may influence outcome. We discuss renal and nonrenal criteria for timing considering the recent literature.

RECENT FINDINGS

Two randomized and four nonrandomized controlled trials investigated the effects of timing on patient outcome. All but one randomized controlled trial indicated better outcome with early renal replacement therapy but had poor methodological quality. The heterogeneity of timing definition, study population and mode of therapy, however, hampered comparison among studies.

SUMMARY

In the absence of large randomized controlled trials we can make no firm recommendations for timing of renal replacement therapy in acute kidney injury. Since rapid recovery of renal function is unlikely when other organ failure persists and the consequences of acute kidney injury may be more severe in critically ill patients, we suggest other organ failure is also considered. Patients with acute kidney injury, persisting shock and poorly recovering functions of other organs may benefit from early therapy. For future studies, we recommend describing renal replacement therapy timing according to the 'RIFLE' classification, as modified by the Acute Kidney Injury Network, and quantifying the severity of other organ failure. Biomarkers may refine acute kidney injury and timing definitions in the future.

Combined proteomic and metabonomic studies in three genetic forms of the renal Fanconi syndrome

The renal Fanconi syndrome is a defect of proximal tubular function causing aminoaciduria and low-molecular-weight proteinuria. Dent's disease and Lowe syndrome are defined X-linked forms of Fanconi syndrome; there is also an autosomal dominant idiopathic form (ADIF), phenotypically similar to Dent's disease though its gene defect is still unknown. To assess whether their respective gene products are ultimately involved in a common reabsorptive pathway for proteins and low-molecular-mass endogenous metabolites, we compared renal Fanconi urinary proteomes and metabonomes with normal (control) urine using mass spectrometry and (1)H-NMR spectroscopy, respectively. Urine from patients with low-molecular-weight proteinuria secondary to ifosfamide treatment (tubular proteinuria; TP) was also analyzed for comparison. All four of the disorders studied had characteristic proteomic and metabonomic profiles. Uromodulin was the most abundant protein in normal urine, whereas Fanconi urine was dominated by albumin. (1)H-NMR spectroscopic data showed differences in the metabolic profiles of Fanconi urine vs. normal urine, due mainly to aminoaciduria. There were differences in the urinary metabolite and protein compositions between the three genetic forms of Fanconi syndrome: cluster analysis grouped the Lowe and Dent's urinary proteomes and metabonomes together, whereas ADIF and TP clustered together separately. Our findings demonstrate a distinctive "polypeptide and metabolite fingerprint" that can characterize the renal Fanconi syndrome; they also suggest that more subtle and cause-specific differences may exist between the different forms of Fanconi syndrome that might provide novel insights into the underlying mechanisms and cellular pathways affected.

Pleiotropic effects of the non-calcium phosphate binder sevelamer

The number of chronic kidney disease (CKD) patients and related adverse outcomes has dramatically increased worldwide in the past decade. Therefore, numerous experimental and clinical studies have recently addressed the underlying mechanisms, in particular the marked increase in cardiovascular mortality. Hyperphosphatemia is a major problem in these patients with advanced stage of CKD. Its control by calcium-containing phosphate binders is effective, but at the price of potentially noxious calcium overload. Sevelamer hydrochloride is a phosphate binder that offers an effective control of hyperphosphatemia as calcium-rich binders but without increase of calcium load. Beyond the control of phosphate, sevelamer seems to exert pleiotropic effects which include the correction of lipid abnormalities and the clearance of some uremic toxins.

Phagocyte-derived oxidants and plasma antioxidants in haemodialysed patients

OBJECTIVE

Oxidative stress is one of the important complications occurring in haemodialysis. The aim of the study was to determine haemodialysis-induced changes in oxidative burst of phagocytes and the antioxidative properties of plasma.

METHODS

Twenty-seven patients and 50 healthy controls were examined. Oxidative burst of phagocytes and plasma antioxidative potential were measured luminometrically. Concentrations of major plasma antioxidants (vitamin E, bilirubin and uric acid) were also determined.

RESULTS

Phagocyte chemiluminescence was higher in patients before haemodialysis compared with that in controls and decreased after haemodialysis compared with predialysis status. A significant increase in plasma antioxidative potential and uric acid was found in patients before haemodialysis. These parameters decreased after haemodialysis compared with both predialysis and control values.

CONCLUSIONS

The higher generation of phagocyte-derived oxidants and the decline in plasma antioxidative properties after haemodialysis confirm insufficient antioxidant defence in patients with chronic renal failure.

Oxidatively-modified and glycated proteins as candidate pro-inflammatory toxins in uremia and dialysis patients

End stage renal disease (ESRD) patients accumulate blood hallmarks of protein glycation and oxidation. It is now well established that these protein damage products may represent a heterogeneous class of uremic toxins with pro-inflammatory and pro-oxidant properties. These toxins could be directly involved in the pathogenesis of the inflammatory syndrome and vascular complications, which are mainly sustained by the uremic state and bioincompatibility of dialysis therapy. A key underlying event in the toxicity of these proteinaceous solutes has been identified in scavenger receptor-dependent recognition and elimination by inflammatory and endothelial cells, which once activated generate further and even more pronounced protein injuries by a self-feeding mechanism based on inflammation and oxidative stress-derived events. This review examines the literature and provides original information on the techniques for investigating proteinaceous pro-inflammatory toxins. We have also evaluated therapeutic - either pharmacological or dialytic - strategies proposed to alleviate the accumulation of these toxins and to constrain the inflammatory and oxidative burden of ESRD.