Felix Grases

University of the Balearic Islands | UIB · University Institute for Health Sciences Research (IUNICS)

The aim of this paper is to present a protocol for the routine morphocompositional study of kidney stones in a clinical setting, and to demonstrate that it is a simple and useful approach that can reliably determine the etiology of all types of kidney stones. Our routine study of kidney stones consists of a combination of stereoscopic microscopy, s...

Background: Our purpose was to study the relationship of the 3 different types of endoscopic calcifications of the renal papilla (Randall's plaque, intratubular calcification, papillary crater) with the type of stone and urine analysis. Methods: This prospective study examined 41 patients (age range: 18 to 80 years) who received retrograde intra...

Objective To evaluate the urinary levels of inositol phosphates (InsPs) in rats that received different salts of myo-inositol hexaphosphate (InsP6) by gavage or by oral administration. Methods Thirty rats received AIN-76A diet (in which InsPs are undetectable) for 15 days. Then, 12 rats received InsP6 by gavage as a Na salt or a Ca/Mg salt; after...

Background Diverse studies have investigated the relationship between diet and depression. In fact some cross-sectional studies suggested that a healthy diet reduced the risk for depression. The main objective of this study was to assess the relationship of consumption of different food groups with depression. The food groups were selected based o...

We use a simple method for evaluating antioxidative status, by measuring the redox potential of urine, and correlate the findings with measures of anxiety and depression. We include 63 individuals (28 males and 35 females aged between 20 and 65 years). The validated anxiety State-Trait Anxiety Inventory questionnaire and the validated BDI (Beck Dep...

Background Diverse studies have investigated the relationship between diet and depression. In fact some cross-sectional studies suggested that a healthy diet reduced the risk for depression. The main objective of this study was to assess the relationship of consumption of different food groups with depression. The food groups were selected based on...

Background/aim: This study was designed to evaluate the relationship between urinary phytate concentration and risk of fracture at 10 years, determined by using the FRAX model, in women who had undergone menopause within 5 years of the time of enrollment. Materials and methods: Of the 212 postmenopausal women evaluated, 69 were excluded because...

Background The diagnosis and follow-up of stone forming patients is usually performed by analysis of 24-h urine samples. However, crystallization risk varies throughout the day, being higher at night. The main objective of this study is to evaluate the urinary crystallization risk in adults and children by calculating risk indexes based on differen...

Background Fructose intake, mainly as table sugar or high fructose corn syrup, has increased in recent decades and is associated with increased risk for kidney stones. We hypothesized that fructose intake alters serum and urinary components involved in stone formation. Methods We analyzed a previously published randomized controlled study that inc...

The purpose of this study was to determine the effects of consumption of different cocoa-derived products on uric acid crystallization in urine of 20 healthy volunteers. Participants were requested to select the specific diet that they wished to follow during the 12 h prior to collection of urine. The only restriction was that the diet could not in...

Background: High-dose methotrexate (HDMTX) therapy is a key component of many chemotherapy protocols. However, some patients develop HDMTX-induced nephrotoxicity. Carboxypeptidase-G2 (CPDG2) hydrolyses MTX into 2,4-diamino-N10-methylpteroic acid (DAMPA) and glutamic acid, and is used as a rescue agent in patients with nephrotoxicity and delayed el...

Objective To identify in vitro inhibitors of xanthine crystallization that have potential for inhibiting the formation of xanthine crystals in urine and preventing the development of the renal calculi in patients with xanthinuria. Methods The formation of xanthine crystals in synthetic urine and the effects of 10 potential crystallization inhibito...

Myo-inositol hexaphosphate (phytate; IP6) is a natural compound that is abundant in cereals, legumes, and nuts and it has the ability to chelate metal cations. The binding of IP6 to transition metals suggests that it could be used for the treatment of metal-catalyzed protein glycation, which appears to trigger diabetes-related diseases. Our in vitr...

Urolithiasis has a high prevalence and recurrence rate, especially in developed countries, and is a major public health issue with a high socioeconomic cost. There are multiple causes of urolithiasis, including urinary tract infection (UTI). Infection stones (mainly composed of struvite) are associated with renal infections by urease-producing bact...

OBJECTIVE To identify in vitro inhibitors of xanthine crystallization that have potential for inhibiting the formation of xanthine crystals in urine and preventing the development of the renal calculi in patients with xanthinuria. METHODS The formation of xanthine crystals in synthetic urine and the effects of 10 potential crystallization inhibito...

Thermodynamic equilibria in urine at 37 °C showed that the inorganic urinary constituents, citrate and oxalate are present as 76 different species. Complexes formed by uric acid and various organic compounds, such as creatinine, proteins, hormones and metabolites, for which the relevant thermodynamic data are not available in the library of the com...

Aims: Previous studies demonstrated a remarkable increase of urinary InsP6 by topical administration. However, the methodology used for InsP6 analysis was not specific. The aim of this paper is to measure urinary inositol phosphates InsPs using more advanced methodologies and to compare the results with those obtained by the non-specific method....

Quantitative analysis of relevant metabolites in biofluids such as urine is often a tedious procedure, since it usually requires extraction, purification or preconcentration. For instance, in the analysis of methylxanthines in urine, a solid-phase extraction is often required. In the current work, a rapid and highly sensitive "dilute-and-shoot" met...

Background The likelihood of a Randall’s plug composed of calcium oxalate monohydrate (COM) forming by the free particle mechanism in a model of kidney with a structure recently described by Robertson was examined at the most favourable conditions for the considered mechanism. Methods The Robertson model of the kidney is used in the following deve...

Mechanism of formation and development of intraluminal concretion, also called Randall's plug, extracted from a female patient forming calcium oxalate dihydrate (COD) calculi was examined. Some of these calculi were connected to the papillary tip, and had connections with the interior of the papilla with finger-like extensions in the collecting duc...

Introduction: a low urine volume is a main etiological factor for renal lithiasis (< 1 ml/kg/h). It is commonly assumed that children who report a high fluid intake have a protective urine volume. The purpose of the present study is to assess the habit of fluid intake in healthy schoolchildren and to evaluate its relation with the urinary volume....

Introduction: a low urine volume is a main etiological factor for renal lithiasis (< 1 ml/kg/h). It is commonly assumed that children who report a high elevated fluid intake have a protective urine volume. The purpose of the present study is to assess the habit of fluid intake in healthy schoolchildren and to evaluate its relation with the urinary...

For decades phytate has been regarded as an antinutrient, as, during gastrointestinal passage, it may inhibit the absorption of some essential trace elements and minerals, which under certain dietary circumstances leads to calcium, iron and zinc deficiencies. In the last 25 years, however, important healthy beneficial properties of phytate have bee...

Phytate, or myo-inositol 1,2,3,4,5,6-hexakis dihydrogen phosphate (InsP6), is a naturally occurring phosphorus compound that is present in many foods, mainly legumes, whole grains and nuts. Patients with chronic kidney disease (CKD) have cardiovascular disease mortality up to 30 times higher than the general population. Vascular calcifications (VCs...

Renal calculi are generally formed as a result of the combination of certain factors, some related to urine composition (concentration of lithogenic substances, deficiency of crystallization inhibitors, presence of heterogeneous nucleants) and others with renal morphology and anatomy (urinary tract stasis, low urodynamic efficiency cavities, morpho...

El fitato o myo-inositol-1,2,3,4,5,6-hexakis dihidrogenofostato (InsP6) es un compuesto fosforado de origen natural que está presente en numerosos alimentos, principalmente en legumbres, cereales integrales y frutos secos. Los pacientes con enfermedad renal crónica (ERC) experimentan una mortalidad por enfermedad cardiovascular hasta 30 veces mayor...

A case of a patient who developed multiple calcium oxalate dihydrate calculi, some of them connected to intratubular calcifications (Randall's plugs), is presented. Randall's plugs were isolated and studied. The mechanism of Randall's plug development is also suggested.

Objective: The aim of this study was to evaluate the relationship between physiological levels of myo-inositol hexaphosphate (phytate) and cardiovascular (CV) calcification in patients with chronic kidney disease (CKD). Design and methods: This was a prospective cross-sectional study conducted from December 2012 to June 2013. Subjects: Sixty-n...

Renal lithiasis is a complex multifactorial disease in which recurrence is common. Thus, simple and reliable procedures are needed to evaluate patients with previous kidney stones to determine the risk of recurrence. In this paper we review simple biochemical procedures that can be used to determine the risk for renal stone formation when the stone...

Phytate is a natural substance present in urine and biological fluids that is associated with health benefits. Existing methods for the determination of phytate are not applicable to routine measurements in urine by clinical laboratories. This study describes a new method for measuring urinary phytate. Following its purification and preconcentratio...

Mesoamerican nephropathy (MeN), an epidemic in Central America, is a chronic kidney disease of unknown cause. In this article, we argue that MeN may be a uric acid disorder. Individuals at risk for developing the disease are primarily male workers exposed to heat stress and physical exertion that predisposes to recurrent water and volume depletion,...

Diverse enzymatic and non-enzymatic antioxidants provide protection against reactive oxygen species in humans and other organisms. The nonenzymatic antioxidants include low molecular mass molecules such as plant-derived phenols. Aim of study This study identified the major phenolic compounds of a grape seed extract by HPLC and analyzed the effect o...

Pathological calcification generally consists of the formation of solid deposits of hydroxyapatite (calcium phosphate) in soft tissues. Supersaturation is the thermodynamic driving force for crystallization, so it is believed that higher blood levels of calcium and phosphate increase the risk of cardiovascular calcification. However several factors...

to determine the reasons behind the lower prevalence of kidney stones in children by assessing urinary lithogenic parameters in healthy children, healthy adults, and three groups of stone former patients. The study subjects included 75 healthy adults, 105 healthy children, 62 patients with previous calcium oxalate monohydrate papillary stones, 120...

To validate a simple method of urinary theobromine determination, to assess urinary theobromine levels in 80 healthy children and to relate these levels to consumption of cocoa products. Urine samples were diluted, directly injected into an HPLC system, separated by gradient elution on a C18 column, and detected by UV spectrometry. The method was v...

The main aim of this study is to describe the relationship between serum levels of atazanavir, renal toxicity, and lithiasis. This is a prospective observational study of patients being treated with atazanavir (ATV) at Son Espases Teaching Hospital, Palma de Mallorca, between 2011 and 2013. The study includes 98 patients. Sixteen were found to have...

The main aim of the current study was to evaluate the effectiveness of mixtures of magnesium, citrate and phytate as calcium oxalate crystallization inhibitors. A turbidimetric assay in synthetic urine was performed to obtain induction times for calcium oxalate crystallization in the absence and presence of different mixtures of inhibitors. The mor...

Nephrolithiasis is a complex disease that results from a combination of factors related to both urine composition and kidney morphoanatomy. Development of calcium oxalate monohydrate papillary calculi is linked to initial subepithelial calcification of renal papilla. Progressive tissue calcification depends on preexisting injury and involves reacti...

Calcific tendinopathy of the tendons of the rotator cuff is common in adults. These calcifications tend to be reabsorbed after a period of acute pain. This study evaluated the morphologic characteristics of calcific deposits and the participation of phytate and osteopontin (OPN) in their development.Calcific deposits were removed from 21 patients w...

Purpose To assess the capacity of methylxanthines (caffeine, theophylline, theobromine and paraxanthine) to inhibit uric acid crystallization, and to evaluate their potential application in the treatment of uric acid nephrolithiasis. Materials and Methods The ability of methylxathines to inhibit uric acid nucleation was assayed turbidimetrically....

This report describing a previously healthy young patient, who experienced crystalluria and non-cholestatic acute liver injury after a single intravenous dose of 400mg. The nuclear magnetic resonance spectra confirmed that the urinary sediment in our patient was formed by pure ciprofloxacin. The nuclear magnetic resonance spectra (1H NMR) of the ur...

Calcium oxalate monohydrate (COM) papillary calculi can be initiated by subepithelial calcification of the renal papillae. Hydroxyapatite disruption of the papillary epithelial layer can become the nidus of a COM papillary calculus. This study evaluated the causes of papillary tissue calcifications in 60 patients with calcium oxalate lithiasis, 30...

We use a simple method for evaluating antioxidative status, by measuring the redox potential of urine, and correlate the findings with measures of anxiety and depression. We include 63 individuals (28 males and 35 females aged between 20 and 65 years). The validated anxiety State-Trait Anxiety Inventory questionnaire and the validated BDI (Beck Dep...

Purpose Urinary pH is an important factor linked to renal stone disease and a useful marker in the treatment of urolithiasis. Although the gold standard for measuring urinary pH utilizes a glass electrode and a pH meter, at present dipstick testing is largely used to estimate urinary pH. However, the accuracy and precision of this method may be ins...

Although the incidence of urolithiasis is lower in children than in adults, the number of children with urolithiasis is increasing. Phytate, a naturally occurring compound present in legumes, nuts, and whole meals, has antilithiasic activity. The aim of this study was to assess, for the first time, the urinary levels of phytate in children and to c...

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 [cal...

Improving knowledge about normal urine composition in children is important for early prevention of lithiasis. We describe urinary excretion values of calcium (Ca), magnesium (Mg), phosphate (P), citrate (Cit), uric acid (Ur), and oxalate (Ox) in healthy children with and without a family history of lithiasis, using a 12-h urine collection protocol...

Synthetic calcium phosphate (CaP) concretions in the form of hemispheres formed under carefully controlled conditions (pH 7.4, 37 °C, no evaporation) from stagnant simulated body fluid on anionic polymeric substrate (laminin) were observed by scanning and transmission electron microscopy and atomic force microscopy. The hemispheres with diameter be...

At present, beneficial properties of phytate have been observed. However, due to the special characteristics of this molecule and its low concentrations in physiological samples, the analytical determination of phytate in these samples becomes a complex and tedious problem. Therefore, the aim of this paper was to develop a simple and reliable metho...

Myo-inositol hexakisphosphate (phytate, IP6) is a naturally occuring compound whose determination in biological matrices is chanllenging. Several benefitial properties have been attributed to IP6 in parallel with the development of suitable analytical methodologies for its analytical determination in urine and some tissues. However, there is a lack...

The objective of this study is to determine in a case series (four patients) how calcified deposits in renal papillae are associated with the development of calcium oxalate monohydrate (COM) papillary calculi. From the recently collected papillary calculi, we evaluated retrospectively patients, subjected to retrograde ureteroscopy, with COM papilla...

The present invention relates to the use of myo-inositol hexaphosphate or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the prevention or treatment of a disease associated with the dissolution of crystals of calcium salts, in particular osteoporosis. These compounds may be utilized in the manufacture of function...

Background: The prevalence of lithiasis is increasing at all ages. This study aimed to assess the crystallization risk in urine from healthy school children and to determine urinary parameters that are most associated with it. Methods: Urine samples were obtained from 184 children aged 5-12 years: a spot sample collected in the afternoon, and a...

Objective To perform a multivariate statistical analysis of epidemiological, clinical and biochemical factors that make it possible to identify the variables that can independently predict the course of renal lithiasis, thus defining a group at risk of worse evolution.Material and methodsA retrospective, descriptive and analytic study was in a coho...