Marialuisa Caiazzo

New horizon in dialysis depuration: Characterization of a polysulfone membrane able to break the ‘albumin wall’

The uremic syndrome is attributed to the progressive retention of a large number of toxins, which under normal conditions are excreted by the healthy kidneys. Standard dialytic membranes do not purify middle-high molecular weight toxins. Haemodiafiltration with endogenous reinfusion coupled with a highly permeable membrane could break the limit of the ‘albumin wall’ improving the dialytic depuration without loss of important nutrients. The aim of this study was to evaluate the performance of a new polysulfone membrane, Synclear 0.2, to remove uremic molecules. Surface Enhanced Laser Desorption Ionization-Time of Flight was employed to evaluate the proteomic profile of ultrafiltrate and Electrospray Ionization-Quadruple-ToF coupled with on-chip elution was used for proteins identification. A high and specific permeability for middle-high molecular weight molecules was revealed by mass spectrometry for the investigated membrane. The identified proteins are mostly uremic toxins: their relative abundance, estimated in the ultrafiltrate by exponentially modified protein abundance index, showed a high purification efficiency of the new membrane when compared with conventional ones. In conclusion, Synclear 0.2, used as convective membrane in hemodiafiltration with endogenous reinfusion treatment, permits to break the ‘albumin wall’, clearing middle-high molecular weight uremic toxins, improving the dialytic treatment purification efficiency.

Quantification of p-cresol sulphate in human plasma by selected reaction monitoring

AbstractChronic renal failure patients accumulate in the blood molecules that are normally excreted into the urine. p-Cresol Sulphate (pCS), the most representative retained toxin, shows a high level of toxicity. Therefore, its quantification could represent a prediction factor to determine the risk of endothelial dysfunction and cardiovascular complication and response to the haemodialysis treatment. The aim of this study was to evaluate the suitability of the multiple reaction monitoring (MRM) technique in order to improve the sensibility, the selectivity and the timing of pCS detection in a small amount of plasma. Deproteinized plasma of uremic patients was concentrated and dissolved in liquid chromatography (LC) mobile phase solution. pCS was quantified by LC coupled to tandem mass spectrometry (LC-MS/MS) on a triple-quadrupole mass spectrometer. Selective and sensitive detection of pCS was achieved by selecting the specific parent ion and monitoring two specific fragment ions. The MRM assay was carried out using the following transitions: m/z 187 → 80.00 and m/z 187 → 107.00. A good linearity was observed for each calibration curve. The intra-day and inter-day results showed a good precision and repeatability. The percentage recoveries indicate an optimal selectivity of the analytical method. The MRM assay to quantify pCS in a small amount of human plasma is rapid, highly sensitive, selective and with a good repeatability. FigurepCS workflow of the SRM method. The m/z of the precursor ion (selected in Q1) is fragmented in Q2 (not showed) and selected fragment ions are monitored from the detector (after Q3) and quantified by the detector

Adsorption in Extracorporeal Blood Purification: How to Enhance Solutes Removal Beyond Diffusion and Convection

Uremic syndrome is linked to a plethora of uremic toxins circulating in the body in ESRD patients. Their overall spectrum is partly or entirely unexplored despite the need to urgently define the specimens and the patho-physiology beyond their high blood levels to address new or more selective removal strategies. It is generally accepted that convective hemodialysis is the best choice to remove large part of the molecular spectrum, even though it is not fully demonstrated its superiority in terms of clinical outcomes. Then, transport mechanisms can benefit from maximizing all the physi‐ co-chemical principles including diffusion for small solutes, convection for middle mole‐ cules and adsorption for large molecular size uremic toxins. The latter has not been fully adopted in hemodialysis and this transport mechanisms is limited to the intrinsic capability of dialysis membrane to adsorb macromolecules while transporting solutes by diffusion and/or convection. However, poorly has been explored about the use of sorbents to enhance the solute removal in hemodialysis. The purpose of this chapter is to summarize the main contributions of so far published clini‐ cal and technical experiences. The chapter will be structured as follow: first we introduced a summary of the basic princi‐ ples of solutes transport and relative contribution of the different mechanisms to the overall

Radical improvement of signs and symptoms in systemic lupus erythematosus when treated with hemodiafiltration with endogenous reinfusion dialysis.

Lupus nephritis is one of the most serious complications of systemic lupus erythematosus (SLE). In the kidney, immune complexes and autoantibodies activate mesangial cells that secrete cytokines that can further amplify inflammatory processes. We present the case of a 42-year-old woman with lupus nephritis accompanied by periods of exacerbation of SLE, with necrotic-like skin lesions, psoriatic arthritis without skin psoriasis, purpura of the lower limb, petechial rash, joint pain, fever, eyelid edema with bilateral conjunctival hyperemia and itching. The patient underwent a dialytic treatment of hemodiafiltration with endogenous reinfusion. The technique uses the super-high-flux membrane Synclear 02 (SUPRA treatment) coupled with an adsorbent cartridge that has affinity for many toxins and mediators. Fever and joint pain were immediately reduced after treatment and, subsequently, there was a notable reduction of the skin damage. Prednisone and immunosuppressive drugs were gradually reduced until complete suspension. High-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometer was performed for identification of proteins captured by a resin bed during a dialysis session of the patient. This technique identified several biomarkers of kidney injuries, uremic toxins, fragments of immunoglobulins, antigens involved in antiphospholipid syndrome and a new marker (α-defensin) that correlated significantly with disease activity. The removal of these different proteins could possibly provide an explanation of the improvement in the patients symptoms and the normalization of her SLE. SUPRA coupled with an adsorption may be a promising new technique for the treatment of lupus nephritis.

Development of a degenerated TaqMan real‐time Q‐PCR for detection of bacteria‐free DNA in dialysis fluid

Bacterial‐derived DNA fragments (BDNAs) have been shown to be present in a dialysis fluid, to pass through dialyzer membranes, and to induce interleukin 6 (IL‐6) in mononuclear cells. DNA fragments are thought to be derived from microorganisms inhabiting hemodialysis water and fluid. The primary aim of the present study was to develop two degenerated TaqMan real‐time quantitative‐PCR (Q‐PCR) for detection of a broad range of bacterial DNA that specifically detect 16S ribosomal DNA (rDNA) (862 and 241 bp) and evaluate the efficiency of the Bellco Selecta resin to capture the BDNAs in the dialysis fluid. For this purpose, we decided to compare measurements of unfragmented samples (9.8 × 105 Escherichia coli genome) with artificially fragmented DNA samples. We assessed two broad‐range real‐time PCR targeting bacterial 16S rRNA genes for detection of fragmented and unfragmented bacterial DNA in the dialytic fluid and demonstrated that Bellco Selecta resin is capable of retaining these types of bacterial DNA.

Erratum to: Proteomic analysis of protein extraction during hemofiltration with on-line endogenous reinfusion (HFR) using different polysulphone membranes [JMater Sci:MaterMed, 25, (2014) 2691-2698, DOI 10.1007/s10856-014-5290-5]

In end-stage renal disease patients, extracorporeal dialytic therapy is not able to prevent the accumulation of toxins related to the uremic syndrome, a severe complication that increases morbidity and mortality rate. In this paper, hemoFiltration with on-line Reinfusion (HFR) architecture is used to evaluate the effect of a more permeable membrane on the extraction of medium–high molecular weight molecules. The aim of this study was to compare two polysulphone membranes for convective chamber: polyphenylene High Flux (pHF) and polyphenylene Super High-Flux (pSHF). Fourteen patients were subjected to HFR with pHF and pSHF membranes and ultra filtrate (UF) samples were collected to evaluate molecular weight cut-off (MWCO) and to identify extracted proteins. Furthermore, image analysis software was used in order to evaluate change in protein extraction during the dialysis. The quantification of four proteins by immunoassay demonstrates a higher permeability of pSHF membrane. Two-dimensional electrophoresis (2-DE) gels showed, for both membranes, the greater number of protein spots at 235 min. Some of the identified proteins, involved in nephropathic disease complications, were compared to assess differences in extraction during dialytic treatment by PDQuest analysis. UF proteomic analysis demonstrated a different behavior for the two membranes; pHF membrane was more permeable at the beginning of HFR treatment (15 min), while pSHF membrane at the end of treatment (235 min). Proteomic analysis is a suitable approach to investigate the behavior of different membranes during dialysis. Results indicated that pSHF membrane offers the higher permeability, and showed higher efficiency in removal of middle molecules related to uremic syndrome.