Juan Gabriel March

Learn More
Phytate (inositol hexaphosphate; InsP6) was determined in rat tissues fed on diets with different phytate contents, using a GC-mass detection methodology that permitted the evaluation of the total amount of this substance present in such tissues. The highest InsP6 concentrations were found in brain 5.89 x 10(-2)(SE 5.7 x 10(-3)) mg/g DM), whereas the(More)
The phytate urinary levels in a group of active calcium oxalate stone formers were studied and compared with those found in healthy people. Urinary phytate was significantly lower for stone formers. If deficit of the capacity to inhibit crystallization of calcium salts is considered an important factor related to calcium stone formation, the excretion of(More)
The effects of vitamin A deficiency on urolithiasis were investigated in male rats. A vitamin A-deficient diet caused important changes in the composition of the urine of the treated rats when compared with controls. One of the main effects was a decrease in the concentration of urinary glycosaminoglycans and zinc in the rats receiving the vitamin(More)
The interaction between calcium and glycosaminoglycans (GAGs) was studied using a calcium ion-selective electrode. The Ca-binding capacity of GAGs involved 16% of total calcium in the presence of chondroitin sulphate and 28% in the presence of pentosan polysulphate. The action of GAGs on the nucleation of uric acid and sodium urate was examined and(More)
A study of the pharmacokinetic profile (oral absorption and renal excretion) of inositol hexaphosphate or phytate (IP(6)) is presented. Seven healthy volunteers were following a IP(6) poor diet (IP(6)PD) in a first period, and on IP(6) normal diet (IP(6)ND) in a second one. When following the IP(6)PD they become deficient in IP(6), the basal levels found in(More)
Phosphates precipitating from artificial urine in the pH range 6-8 were identified using X-ray diffraction, chemical analysis and scanning electron microscopy. The influence of magnesium and citrate on phases precipitating from urine was established. From urine containing a normal quantity of magnesium (around 70 ppm), brushite accompanied by hydroxyapatite(More)
In this paper a thorough study on the composition and structure of calcium oxalate monohydrate (COM) papillary calculi is presented. In 86.4% of these calculi, small amounts of phosphates were detected and generally located at the calculi core. This demonstrates the importance of phosphates as the heterogeneous nucleus of 'pure' COM calculi. Study of the(More)
We have studied the early stages of calcium oxalate monohydrate (COM) crystallization, mainly heterogeneous nucleation, on fixed particles. Experiments were performed using a flow system that closely simulates the human renal conditions related to COM heterogeneous nucleation. The effects of citrate, phytate, aescin and glycyrrhinic acid in the COM(More)
OBJECTIVE To study the initial steps of calcium oxalate monohydrate (COM) stone formation and the influence of the inhibitor substances citrate and phytic acid, using an in vitro model. MATERIALS AND METHODS Experiments were performed using a device to simulate renal stone formation in conditions similar to those found in humans. RESULTS COM crystal(More)
The relation between the dietary phytate (InsP6), mineral status and InsP6 levels in the organism, using three controlled diets (AIN-76A, AIN-76A + 1% phytate, AIN-76A + 6% carob seed germ), are studied. AIN-76A is a purified diet in which InsP6 is practically absent. No important or significant differences in the mineral status (Zn, Cu, Fe) of blood,(More)