[Selective adsorption of homocysteine using HFR-on line technique]. / Estrazione di omocisteina in corso di HFR on-line.

Homocysteine (Hcy) is grossly elevated in hemodialysis (HD) patients. Treatment with folic acid and/or vitamin B12 fails to normalize Hcy levels in the majority of patients. Treatment with various dialyzers with different flux characteristics has produced contrasting results. Hemodiafiltration reinfusion (HFR) on-line (double chamber hemodiafiltration (HDF) with regenerated ultrafiltrate reinfusion) is a novel method combining the processes of diffusion, convection and absorbance. The ultrafiltrate is regenerated through a charcoal-resin device. Our aim was to observe the effect of the HFR on-line technique on removing Hcy. We investigated the effect of this treatment on Hcy levels in 10 patients with a mean Hcy level of 57.6 micromol/L (range 24.1-119.7). We measured Hcy, folate and vitamin B12 pre- and post-dialysis and in the ultrafiltrate pre- and post-cartridge at 10, 120 and 240 min. Mean Hcy levels were 57.6 and 35.3 micromol/L (range 9.9-80.3) (p=0.005) pre- and post-dialysis, respectively, while folate and vitamin B12 were unchanged. Pre- and post-cartridge Hcy levels were 11.6 vs 2.5 (p=0.005), 9.3 vs 3.9 (p=0.005), 7.7 vs 4.6 micromol/L (p=0.012) at three time points considered, while folate and vitamin B12 were essentially undetectable. These preliminary data, which need confirmation in a long-term study, seem to indicate that HFR on-line reduces Hcy levels, not only through a possible reduction in uremic toxins, but also through the actual removal of Hcy by absorbance on the charcoal-resin cartridge.

Influence of the human paraoxonase polymorphism (PON1 192) on the carotid-wall thickening in a healthy population.

BACKGROUND: Serum paraoxonase (PON1) is a high-density lipoprotein-bound enzyme that can prevent oxidation of low-density lipoprotein and thus exert an anti-atherogenic effect. A polymorphism at codon 192 (Gln/Arg) of the PON1 gene gives rise to two isoforms that differ in substrate-dependent activity. OBJECTIVE: To determine any independent contribution of this polymorphism to the variability of intimal-medial thickness (IMT) of the common carotid artery for a sample of asymptomatic adult subjects from southern Italy by ultrasonography. METHODS: We studied 196 unrelated asymptomatic subjects (mean age 55.1 years), drawn from participants in a cardiovascular-disease-prevention campaign. Plasma levels of lipids and glucose were measured by routine methods. PON1 polymorphism was determined by polymerase chain reaction. IMT was measured from high-resolution B-mode echo-Doppler ultrasonography images. RESULTS: Prevalences of alleles A (Gln) and B (Arg) were 0.68 and 0.32, respectively. We found no significant difference with regard to plasma levels of lipids and glucose and other variables among the PON1 genotypes, although subjects with BB had higher levels of triglycerides and lower levels of high-density lipoprotein cholesterol. Common carotid artery IMT was slightly greater in subjects with BB, although no significant association between PON1 genotypes and common carotid artery IMT was found, even after adjustment for confounding variables. CONCLUSIONS: Our findings demonstrate that there is no significant association between PON1 gene polymorphism at codon 192 and common carotid artery IMT for an Italian population. However, the fact that we found slightly greater IMT in subjects with genotype BB would suggest that the study should be performed again with a larger sample.

Extraction and determination of oxybutynin in human bladder samples by reversed-phase high-performance liquid chromatography.

A reversed-phase high-performance liquid chromatography method is described for the determination of oxybutynin (OXB) in human bladder samples. Following homogenization, tissue samples underwent double extraction with hexane and eventually were concentrated by freeze-drying before analysis. Chromatographic separation was performed with a mobile phase of acetonitrile-water-1 M ammonium acetate, pH 7.0 (85:13:2, v/v/v) at a flow-rate of 0.5 ml/min and double (electrochemical and UV) detection was applied. The retention time of oxybutynin eluting peak was around 18 min. Using a standard curve range of 10 to 500 ng/ml the quantification limit with electrochemical detection was 5 ng/ml with an injection volume of 100 microl. Within-day and day-to-day relative standard deviation values were 4.9 and 9.81%, respectively, while a 94% accuracy and a 72% recovery was attained. We applied this method to compare the OXB levels into bladder wall tissue samples after passive diffusion and after electromotive drug administration (EMDA), using a two-chambered poly(vinyl chloride) diffusion cell designed and developed in our laboratory. The results obtained show that EMDA enhanced OXB penetration into bladder wall and that this novel way of local drug administration can be potentially used in patients with neurogenic bladder dysfunction or urinary incontinence.