In vitro utilization of ferromagnetic nanoparticles in hemodialysis therapy.

The in vitro utilization of biocompatible ferromagnetic nanoparticles (BFNs) in hemodialysis (HD), routinely used today for the treatment of end stage renal disease (ESRD), is introduced in this work. The proposed strategy is termed magnetically assisted hemodialysis (MAHD) and it aims to become a more efficient development of conventional HD. The method is based on the production of biocompatible ferromagnetic nanoparticles-targeted binding substances conjugates (BFNs-TBSs Cs) constructed of BFNs and specifically designed TBSs that should have high affinity and binding capacity for target toxic substances (TTSs) which must be removed from the ESRD patient subjected to HD. Antibodies or even specific proteins could serve as the TBS of the desired BFNs-TBSs Cs. The BFNs-TBSs Cs should be administered to the patient timely prior to the MAHD session so as to bind with the desired TTSs during their free circulation in the vascular network. Eventually, the complete BFNs-TBSs-TTSs structure can be selectively removed during the MAHD session by means of an external inhomogeneous magnetic field that is applied either at the dialyzer or at other collection point(s) along the blood circulation line of the dialysis machine. The advantages of MAHD over conventional HD regarding the patient's comfort and overall health status are discussed in detail among practical issues. To examine this proposition we employed Fe(3)O(4) and bovine serum albumin (BSA) as the BFN and the TBS constituents respectively, since they are both highly biocompatible. By means of x-ray diffraction, atomic force microscopy, circular dichroism spectropolarimetry, UV-vis spectrophotometry, SQUID magnetometry, and nuclear magnetic resonance we evaluated (i) the structural/morphological characteristics, (ii) the magnetic retraction efficiency, and most importantly (iii) the toxin binding affinity and capacity of both bare Fe(3)O(4) BFNs and Fe(3)O(4)-BSA Cs by performing in vitro experiments on specific TTSs. Homocysteine and p-cresol were chosen as representative TTSs and were investigated in great detail. The results obtained prove the in vitro applicability of the proposed MAHD method. Corrections were made to this article on 6 November 2007 (see figure 10 caption and lines 10 and 11 of page 11). The corrected electronic version is identical to the print version.

The use of TWH catheters in CAPD patients: fourteen-year experience in technique, survival, and complication rates.

OBJECTIVE: To evaluate the technique of insertion, complication rates, and survival rates of Toronto-Western Hospital (TWH) peritoneal catheters in continuous ambulatory peritoneal dialysis (CAPD) patients. PATIENTS AND METHODS: A total of 222 TWH catheters were inserted into 203 CAPD patients (113 males and 90 females) with end-stage chronic renal failure during a period of 14 years (1 January 1982 to 31 August 1995). The mean age of the patients was 58.5 years (range 18-86 years). For the first 6 years, the peritoneal cavity approach was performed via a lower midline incision (45 insertions), various other approaches (17 insertions), and, finally, for the last 160 insertions (for approximately 8 years) the transverse paraumbilical incision was exclusively employed. The duration of CAPD ranged between 1 to 151 months (mean time 33.2 months). RESULTS: Regarding early and late complications (namely leakages, obstructions, eviscerations, tunnel infections, herniation, and others), as well as catheter survival, the transverse paraumbilical insertion, compared to other approaches, had the smallest number of complications. Thus, early leakage occurred in 5/222 (2.25%) versus 10/222 (4.5%), obstruction nil versus 2/222 (0.9%), and evisceration nil versus 1/222 (0.45%). In addition, as far as the late complications are concerned: tunnel infections 5/222 (2.22%) versus 13/222 (5.85%), herniations 1/222 (0.45%) versus 16/222 (7.3%), and cuff protrusion nil versus 7/222 (3.1%). Finally, overall peritonitis occurred with a rate of one episode every 21.2 months. Actuarial survival for 1 and 3 years was 75% and 37%, respectively. CONCLUSIONS: The transverse paraumbilical incision seems to be the most advantageous approach in inserting (by "surgical method") theTWH catheters. We found it to be a safe, simple, versatile procedure, giving good results in all parameters concerned.

Factors affecting the lifespan of autologous and synthetic arteriovenous access routes for haemodialysis.

OBJECTIVE: To try and establish a consensus about the ideal secondary access for haemodialysis by assessing factors that affect the longevity of various access routes. DESIGN: Multicentre survey, by questionnaire. SETTING: General hospital, Athens. SUBJECTS: All 1516 patients in the Athens area receiving chronic haemodialysis. MAIN OUTCOME MEASURES: Longevity of present and any previous access routes (n = 2323). Data including type of access, age, sex and the existence of diabetes, hypertension, hyperlipidaemia, or other systematic diseases were recorded. RESULTS: Some 1220 (80%) of the patients were using autologous access, 1049 (69%) arteriovenous (AV) fistulas at wrist and 171 (11%) at elbow. Variables were analysed using Cox's proportional hazard model. Age and female sex were significantly associated with failure of autogenous access (p < 0.001) although not affecting synthetic grafts. Autogenous fistula at the elbow was the only secondary access that was less likely to fail than the initial (baseline) fistula at the wrist. Among the various grafts, straight arm grafts had the best prognosis and straight forearm grafts were the most likely to fail (p < 0.001). CONCLUSION: An AV fistula at the elbow should be considered the second best after the fistula at wrist, but is not always feasible. A synthetic graft is more likely to be needed in elderly patients and women, in whom an autogenous AV fistula is more likely to fail.