SNF472, a novel inhibitor of vascular calcification, could be administered during hemodialysis to attain potentially therapeutic phytate levels.

BACKGROUND: Cardiovascular calcification (CVC) is a major concern in hemodialysis (HD) and the loss of endogenous modulators of calcification seems involved in the process. Phytate is an endogenous crystallization inhibitor and its low molecular mass and high water solubility make it potentially dialyzable. SNF472 (the hexasodium salt of phytate) is being developed for the treatment of calciphylaxis and CVC in HD patients. We aimed to verify if phytate is lost during dialysis, and evaluate SNF472's behaviour during dialysis. METHODS: Dialyzability was assessed in vitro using online-hemodiafiltration and high-flux HD systems in blood and saline. SNF472 was infused for 20 min and quantified at different time points. RESULTS: Phytate completely dialyzed in 1 h at low concentrations (10 mg/l) but not when added at 30 or 66.67 mg/l SNF472. In bypass conditions, calcium was slightly chelated during SNF472 infusion but when the system was switched to dialysis mode the calcium in the bath compensated this chelation. CONCLUSION: Phytate dialyses with a low clearance. The administration of SNF472 as an exogenous source of phytate allows to attain supra-physiological levels required for its potential therapeutic properties. As SNF472 is infused during the whole dialysis session, the low clearance would not affect the drug's systemic exposure.

A novel pharmacodynamic assay to evaluate the effects of crystallization inhibitors on calcium phosphate crystallization in human plasma.

Cardiovascular calcification (CVC) is a progressive complication of chronic kidney disease and a predictor of CV events and mortality. The use of biomarkers to predict CV risk and activities of potential or current treatment drugs in these patients could have a crucial impact on therapeutic approaches. Our aim was to develop a novel assay for measurement of the rate of calcium phosphate crystallization in human plasma and provide a tool to evaluate the effects of crystallization inhibitors. The efficacy of inhibitors was determined by adding inhibitory compounds (polyphosphates, fetuin-A, sodium thiosulfate or citrate) to control samples. The assay was additionally validated for SNF472, an experimental formulation of phytate being developed for the treatment of calciphylaxis and CVC in patients with end-stage renal disease (ESRD) undergoing hemodialysis (HD). The method was repeatable and reproducible. The plasma crystallization rate was reduced up to 80% in a concentration-dependent manner following treatment with inhibitors in vitro, among which SNF472 was the most potent. This method appears beneficial in evaluating and discriminating between inhibitory activities of compounds such as polyphosphates on calcium phosphate crystallization, which present a novel therapeutic approach to treat CVC in ESRD patients.

Evolutionary history of Podarcis tiliguerta on Corsica and Sardinia.

BACKGROUND: Podarcis tiliguerta is a wall lizard endemic to the Mediterranean islands of Corsica and Sardinia. Previous findings of high mtDNA and morphological diversity have led to the suggestion that it may represent a species complex. Here, we analysed mitochondrial and nuclear markers (mtDNA, 3110 bp; 6 nDNA loci, 3961 bp) in P. tiliguerta sampled from thirty-two localities across Corsica and Sardinia. RESULTS: We find much greater intraspecific genetic divergence than between sister species of other Mediterranean island Podarcis, i.e., between P. lilfordi and P. pityusensis. We detected three mtDNA clusters in Corsica (North, South-East and South-West) and either two or three in Sardinia (North vs. South) depending on the clustering method. Only one or two nDNA groups were identified within each main island (again, depending on the method). A Bayesian time-calibrated multispecies coalescent tree was obtained from mtDNA and provided statistical support for a Miocene origin of the species (13.87 Ma, 95% HPD: 18.30-10.77 Ma). The posterior mean divergence time for the Corsican and Sardinian lineages was 12.75 Ma ago (95% HPD: 16.94-9.04 Ma). CONCLUSION: The results support the evolutionary distinctiveness of Corsican and Sardinian populations and also indicate a lack of post-divergence migration despite periods of contact being possible. Further to this, species delimitation analyses of Corsican and Sardinian lineages provided statistical support for their recognition as distinct (sister) taxa. Our results provide new insights into the biogeography of the Mediterranean biodiversity hotspot, and contribute important findings relevant to the systematics and evolution of this speciose lizard genus.

Fibromuscular dysplasia presenting with asymptomatic bilateral renal infarctions.

Fibromuscular dysplasia (FMD) is a noninflammatory nonatherosclerotic vascular disease. It is the second cause of renovascular hypertension after atherosclerosis. Although FMD usually has a good prognosis, renal infarctions and artery dissections have been described. We present the case of a 38-year-old woman with hypertension and asymptomatic bilateral renal infarctions. Bilateral FMD of segmental branches of the renal arteries was diagnosed by digital subtraction angiography after an exhaustive study. Previous intake of nonsteroidal anti-inflammatory drugs may also have played a significant role in the development of renal infarctions. To our knowledge, bilateral renal infarctions complicating FMD have been reported in only four previous cases; only in one of those cases, renal infarctions were asymptomatic.

Anemia associated with pegylated interferon-alpha2a and alpha2b therapy in hemodialysis patients.

AIMS: Anemia is a well-known side effect of interferon therapy since interferons are potent inhibitors of erythropoiesis. The aim of this study was to compare the anemia associated with pegylated interferon (PEG-IFN) (alpha2a versus alpha2b therapy in hemodialysis patients (HD) with chronic hepatitis C. METHODS: In order to study the anemia, doses of erythropoietic growth factors (EGF), hemoglobin (Hb) and erythropoietin resistance index (ERI) were compared at baseline and after PEG-IFN-alpha2a or alpha2b therapy in 16 HD patients with chronic C hepatitis. Pharmacokinetic studies were performed in 4 of those treated with PEG-IFN-alpha2b and 2 patients treated with PEG-IFN-alpha2a. Secondary end-points were viral response and serious adverse events. RESULTS: At 4-6 months after the beginning of therapy, both PEG-IFN-alpha induced a significant increment in the erythropoietin resistance index. This increment was significantly higher in patients treated with PEG-IFN-alpha2a when compared with alpha2b (45 vs 9.9, p = 0.012). The pharmacokinetics of PEG-IFN-alpha2a and alpha2b in HD patients were different, the C(max), C(min) and the area under the serum concentration time curve, were all higher in patients treated with PEG-IFN-alpha2a compared with PEG-INF-alpha2b. Discontinuation of therapy occurred in 2 (28.5%) of the 7 patients in the PEG-IFN-alpha2a group and in 4 (44%) of the 9 patients in the PEG-IFN-alpha2b group. Three (42%) subjects in the alpha2a group and 5 (55%) in the alpha2b group had a response at the end of the 48 weeks of therapy. In 4 (44.4%) of the 9 patients treated with alpha2b the viral response was sustained. CONCLUSIONS: In summary, patients treated with PEG-IFN-alpha2a have a major inhibitory effect on erythropoiesis. This could be explained by the different pharmacokinetic properties of PEG-IFN-alpha2a and alpha2b. Further studies are needed to clarify how these findings influence the efficacy, safety and cost-effectiveness of the PEG-IFN-alpha2.