Proteomic analysis of peritoneal fluid of patients treated by peritoneal dialysis: effect of glucose concentration.

BACKGROUND: Depending on both membrane composition and solute transport rate across the membrane, protein composition of the dialysate of patients receiving peritoneal dialysis (PD) has recently become of great interest. Unfortunately, thus far few studies have focused on dialysate characterization, and further investigations are required to better understand the biological mechanisms influencing PD efficiency. METHODS: Different classical proteomic approaches were combined with advanced mass spectrometric (MS) techniques to analyse peritoneal fluid (PF) protein composition of adult patients receiving PD. Characterization was performed by using 1D gel electrophoresis combined with nano-RP-HPLC-ESI-MS/MS and shotgun proteomics, while comparative analyses were performed coupling 2D gel electrophoresis with MALDI-TOF MS. RESULTS: The study allowed the identification of 151 different proteins from PF, which are mainly of plasmatic origin. Comparison of PD effluents characterized by different glucose concentrations demonstrated four proteins (apolipoprotein A-IV, fibrinogen beta chain, transthyretin and alpha-1-antitrypsin) to be under-expressed in the highest osmolar solution having 4.25% compared to others having 1.5% and 2.5% glucose. All of them were found to be involved in the inflammatory processes. CONCLUSIONS: This study provides a possible platform for future diagnostic and therapeutic applications in the field of PD and allowed the identification of potential targets to be used in preventing inflammatory processes induced by the exposure to dialysis solutions.

Vascular access for hemodialysis: the impact on morbidity and mortality.

BACKGROUND: In chronic hemodialysis (HD), central venous catheter (CVC) use seems associated with an increased risk of death. This study, using registry data, evaluated the morbidity and mortality risk associated with the use of different permanent vascular access (VA) in a HD patient cohort. METHOD: We evaluated hospitalization and death rate in prevalent and incident HD patients recorded in the uremic registry of Campania (southern Italy) for 2001. Patients were divided into three groups: CVC, artero-venous graft (AVG) and artero-venous fistula (AVF). RESULTS: One hundred and eleven dialysis units in the Campania region (69%) provided data. A total of 2201 out of 3387 prevalent HD patients were included: 92 patients (4.2%) were on CVC, 24 patients (1.1%) were on AVG and 2085 patients (94.7%) were on AVF. In comparison with AVF, the CVC group had a greater prevalence of female gender, old age, diabetes, comorbidities, hypoalbuminemia, anemia, erythropoietin (EPO) resistance, and less frequent synthetic membrane use, but had a similar dialysis duration (hr/week). Similar data were collected in the 635 incident patients registered in 2001. During the study, in both prevalent and incident CVC patients, either hospitalization or death rates were enhanced; however, the difference in the relative risk (RR) of death disappeared after correction for age, gender, malnutrition, diabetes, hemoglobin, albumin and comorbidity. Among incident patients, survival analysis was performed in patients remaining on the same VA type throughout the follow-up period; while a similar survival between groups was demonstrated in the 1st year of follow-up, survival was worse in the CVC group during the 2nd year of follow-up; however, this difference also disappeared in the adjusted analysis. CONCLUSION: This cohort study demonstrates that in chronic dialysis patients CVC choice, with respect to AVF, is mainly associated with female gender, advanced age and worse clinical conditions at baseline, and a worst outcome in both prevalent and incident CVC patients compared to AVF patients. Hospitalization, mortality rate and RR of death increased significantly; however, differences disappeared after correction for comorbidity. Therefore, these data suggest that CVC use per se is not associated with increased mortality risks with respect to AVF.

Intra- and post-dialytic changes of haemoglobin concentrations in non-anaemic haemodialysis patients.

BACKGROUND: Non-anaemic haemodialysis (HD) patients are potentially more prone to the adverse effects of ultrafiltration-induced haemoconcentration. No study, however, has assessed the effects of dialytic session on haemoglobin (Hb) levels in these patients. METHODS: The levels of Hb and total protein before, at the end (T0) and up to 120 min (T120) after the third HD session of the week were compared in non-anaemic (Hb >13 g/dl, n = 14, NOR) and anaemic (Hb = 11-12 g/dl, n = 18, LOW) HD patients. RESULTS: The intradialytic weight loss was similar in the two groups (4.0 +/- 0.9 and 4.1 +/- 0.9% body weight). During the treatment, Hb levels increased to the same extent in both groups (from 14.4 +/- 1.2 to 16.3 +/- 1.9 g/dl in NOR, and from 11.4 +/- 0.8 to 12.7 +/- 0.9 g/dl in LOW) in the presence, presumably, of a smaller plasma volume in NOR, whereas the increment of total protein was greater in NOR (from 7.1 +/- 0.2 to 9.6 +/- 0.5 g/dl) than in LOW (from 7.3 +/- 0.6 to 8.7 +/- 0.8 g/dl) (P < 0.0001). At T120, the Hb decline in NOR was almost double that measured in LOW (-9.2 +/- 3.0 vs -4.7 +/- 2.4%, P < 0.001). Consequently, Hb concentration did not differ from the pre-dialytic value in NOR (P = 0.10), but persisted higher in LOW (P < 0.005). The extent of the post-dialytic decrement of Hb was inversely related to the total protein values at T0 (r = -0.547, P = 0.0012). CONCLUSIONS: This study indicates that in NOR: (i) the extent of intradialytic increment of Hb is limited by a greater intradialytic plasma refilling; (ii) the greater plasma refilling persists after the end of dialysis, with the restoration of pre-dialytic Hb levels within the initial 2 h; and (iii) the force driving this phenomenon resides mainly in the larger changes of total protein concentration.