Myo-inositol hexakisphosphate (phytate) inhibits calcium carbonate crystallisation in hard water

A batch system and a flow system with synthetic water were used to study calcium carbonate precipitation and phytate crystallisation inhibitory effects. Afterwards, phytate inhibitory effects on calcium carbonate crystallisation were tested in a real system, working with a cistern filled with hard water. Finally, the effects of phytate on calcium carbonate crystallisation were compared with another phosphate derivative and with a chelating agent. The results obtained with the batch system demonstrated that 1.52 μM of phytate completely avoided calcium carbonate crystallisation when the calcium concentration was less than 7.9 mM and the carbonate concentration was 5.83 mM. The results corresponding to the flow system showed that 3.03 μM of phytate led to a 95% reduction of calcium carbonate scale formation on a copper pipe after 48 h, operating at 30ºC. In addition, in a full-scale system, the dissolved calcium and bicarbonate concentration was increased for a given time when adding phytate to the cistern. Finally, using a batch system, it was demonstrated that phytate effects on calcium carbonate crystallisation reduction were superior to those shown by triphosphate and EDTA. The results presented demonstrate that phytate at very low concentrations can be used to prevent calcium carbonate scale formation without changing the mineral composition of water due to its capacity as a crystallisation inhibitor.Keywords: phytate, inhibition, calcium carbonate, scale formation, water hardnes

Characterization of deposits on double J stents

We have characterized the types of encrustations that form on ureteral stents. The deposit that generates blocks is composed of hydroxyapatite/magnesium ammonium phosphate (44%). Calcium oxalate dihydrate was also detected at a high degree of encrustation (13%). Hydroxyapatite deposits, also of high degree of encrustation (13%) are generated due to their formation as a consequence of persistently high urinary pH values. The formation of large uric acid deposits (31%) must be attributed to the persistence of urinary $\mathrm{pH} < 5.5$. To avoid development of encrustations of ureteral stents, urinary calcium levels and urinary pH control should be carried out, avoiding urinary infections

Characterization of deposits on double J stents

We have characterized the types of encrustations that form on ureteral stents. The deposit that generates blocks is composed of hydroxyapatite/magnesium ammonium phosphate (44%). Calcium oxalate dihydrate was also detected at a high degree of encrustation (13%). Hydroxyapatite deposits, also of high degree of encrustation (13%) are generated due to their formation as a consequence of persistently high urinary pH values. The formation of large uric acid deposits (31%) must be attributed to the persistence of urinary $\mathrm{pH} < 5.5$. To avoid development of encrustations of ureteral stents, urinary calcium levels and urinary pH control should be carried out, avoiding urinary infections

Reduction of ureteral stent encrustation by modulating the urine pH and inhibiting the crystal film with a new oral composition: a multicenter, placebo controlled, double blind, randomized clinical trial

Background: Encrustation of ureteral double J stents is a common complication that may affect its removal. The aim of the proposed study is to evaluate the efficacy and safety of a new oral composition to prevent double J stent encrustation in indwelling times up to 8 weeks. Methods: A double-blinded, multicenter, placebo-controlled trial was conducted with 105 patients with indwelling double J stents enrolled across 9 public hospitals in Spain. The patients were randomly assigned (1:1) into intervention (53 patients) or placebo (52 patients) groups for 3 to 8 weeks and both groups self-monitored daily their morning urine pH levels. The primary outcome of analysis was the degree of stent ends encrustation, defined by a 4-point score (0 - none; 3 - global encrustation) using macroscopic and electron microscopy analysis of crystals, after 3 to 8-w indwelling period. Score was exponentially transformed according to calcium levels. Secondary endpoints included urine pH decrease, stent removal, and incidence of adverse events. Results: The intervention group benefits from a lower global encrustation rate of stent ends than placebo group (1% vs 8.2%; p < 0.018). Mean encrustation score was 85.12 (274.5) in the placebo group and 18.91 (102.27) in the intervention group (p < 0.025). Considering the secondary end points, treated patients reported greater urine pH decreases (p = 0.002). No differences in the incidence of adverse events were identified between the groups. Conclusions: Our data suggest that the use of this new oral composition is beneficial in the context of ureteral double J indwelling by decreasing mean, as well as global encrustation

Internalization of Calcium Oxalate Calculi Developed in Narrow Cavities

We describe the case of a patient with calcium oxalate monohydrate and calcium oxalate dihydrate calculi occluded in cavities. All those calculi were located inside narrow cavities covered with a thin epithelium that permits their visualization. Urinary biochemical analysis showed high calciuria, not hypercalciuria, hypocitraturia, and a ratio [calcium]/[citrate] >0.33. The existence of cavities of very low urodynamic efficacy was decisive in the formation of such calculi. It is important to emphasize that we observed a thin epithelium covering such cavities, demonstrating that this epithelium may be formed after the development of the calculi through a re-epithelialization process. Keywords: Calcium oxalate stones, Calculi occluded in cavitie

Tracheal oxalosis associated with Aspergillus niger tracheobronchitis

Peer reviewe

A Pilot Randomized Crossover Trial Assessing the Safety and Short-Term Effects of Walnut Consumption by Patients with Chronic Kidney Disease

The aim of this study of patients with chronic kidney disease (CKD) is to assess the safety of daily consumption of walnuts on the physiological levels of phosphorous, potassium, parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF23), and to assess the short-term benefits of this intervention on risk factors associated with cardiovascular events. This led us to perform a prospective, randomized, crossover, pilot clinical trial examined 13 patients with CKD. Subjects were randomly assigned to a diet of 30 g of walnuts per day or the control diet. After 30 days, each group was given a 30-day washout period, and then switched to the alternate diet for 30 days. Urinary and serum levels of phosphorous and potassium, multiple vascular risk factors, and urinary inositol phosphates (InsPs) were measured at baseline and at the end of the intervention period. Our results showed that the walnut dietary supplement led to reduced blood pressure, LDL cholesterol, and albumin excretion, but had no effect on the physiological levels of phosphorous, potassium, PTH, and FGF23. This is the first report to show that daily consumption of walnuts by patients with CKD does not alter their physiological levels of phosphorous, potassium, PTH, and FGF23 when included in a sodium-, protein-, phosphate-, and potassium-controlled diet, and it could be an effective strategy for reducing cardiovascular risk in patients with CKD

Phytate Dephosphorylation Products Also Act as Potent Inhibitors of Calcium Oxalate Crystallization

Phytate has been classified as an anti-nutrient, but there are no adverse effects from the consumption of a balanced diet with 1 to 2 g of daily phytate (inositol-hexaphosphate, InsP6) as a calcium magnesium salt, the form naturally present in grains. Furthermore, recent research has shown that phytate consumption may prevent pathological calcifications, such as kidney stones and cardiovascular calcifications. However, many endogenous and exogenous enzymes can hydrolyze phytate to lower inositol phosphates (InsPs) that also have biological activity. We performed a controlled hydrolysis of phytate and identified the products (InsPs) using tandem mass spectrometry (MS/MS). The total level of all InsPs was measured using a non-specific methodology. In addition, we evaluated the effects of the InsP6 hydrolysates on calcium oxalate crystallization using scanning electron microscopy and measuring the time needed for the induction of crystallization. Our results indicate that InsP6 and its hydrolysis products functioned as effective inhibitors of calcium oxalate crystallization. Thus, even though InsP6 is hydrolyzed after consumption, the enzymatic products also have the potential to reduce pathological calcifications. Finally, although it is useful to measure the overall level of InsPs in biological fluids, such as urine, there is a need to develop simple analytical methods to quantify the level of individual InsPs