Biomedical subjects

F Grases

Publications and source records attributed to F Grases.

At least 19 recordsLinked to original sources

PubMed2006

Factors affecting calcium oxalate dihydrate fragmented calculi regrowth.

BACKGROUND: The use of extracorporeal shock wave lithotripsy (ESWL) to treat calcium oxalate dihydrate (COD) renal calculi gives excellent fragmentation results. However, the retention of post-ESWL fragments within the kidney remains an important health problem. This study examined the effect of various urinary conditions and crystallization inhibitors on the regrowth of spontaneously-passed post-ESWL COD calculi fragments. METHODS: Post-ESWL COD calculi fragments were incubated in chambers containing synthetic urine varying in pH and calcium concentration: pH = 5.5 normocalciuria (3.75 mM), pH = 5.5 hypercalciuria (6.25 mM), pH = 6.5 normocalciuria (3.75 mM) or pH = 6.5 hypercalciuria (6.25 mM). Fragment growth was evaluated by measuring increases in weight. Fragment growth was standardized by calculating the relative mass increase. RESULTS: Calcium oxalate monohydrate (COM) crystals formed on COD renal calculi fragments under all conditions. Under pH = 5.5 normocalciuria conditions, only COM crystals formed (growth rate = 0.22 +/- 0.04 microg/mg x h). Under pH = 5.5 hypercalciuria and under pH = 6.5 normocalciuria conditions, COM crystals and a small number of new COD crystals formed (growth rate = 0.32 +/- 0.03 microg/mg x h and 0.35 +/- 0.05 microg/mg x h, respectively). Under pH = 6.5 hypercalciuria conditions, large amounts of COD, COM, hydroxyapatite and brushite crystals formed (growth rate = 3.87 +/- 0. 34 microg/mg x h). A study of three crystallization inhibitors demonstrated that phytate completely inhibited fragment growth (2.27 microM at pH = 5.5 and 4.55 microM at pH = 6.5, both under hypercalciuria conditions), while 69.0 microM pyrophosphate caused an 87% reduction in mass under pH = 6.5 hypercalciuria conditions. In contrast, 5.29 mM citrate did not inhibit fragment mass increase under pH = 6.5 hypercalciuria conditions. CONCLUSION: The growth rate of COD calculi fragments under pH = 6.5 hypercalciuria conditions was approximately ten times that observed under the other three conditions. This observation suggests COD calculi residual fragments in the kidneys together with hypercalciuria and high urinary pH values may be a risk factor for stone growth. The study also showed the effectiveness of specific crystallization inhibitors in slowing calculi fragment growth.

Calcium↗

PubMed2006

Influence of concomitant food intake on the excretion of orally administered myo-inositol hexaphosphate in humans.

myo-Inositol hexaphosphate (InsP6) widely occurs in plant seeds. At present, some important benefits of InsP6 for human health have been described. The purpose of this study was to find the best condition for the optimum absorption of orally administered InsP6, evaluated by InsP6 urinary excretion. The influence of different stomach conditions (empty, empty with an alkalinizing agent, and full stomach) on the effects of oral administration of InsP6 and its urinary excretion was investigated in six healthy subjects on an InsP6-poor diet, given 400 mg of calcium/magnesium salt of InsP6 as a single dose. The basal urinary excretion of InsP6 on an InsP6-poor diet (50.91 +/- 15.09 microg) was significantly lower than that found when an InsP6-normal diet was consumed (100.09 +/- 26.42 microg) (P < .05). No differences were observed in the areas under the curve of accumulated excretion at 8 hours among the three different stomach conditions studied, suggesting that the overall InsP6 absorption took place independently of the stomach state (full or fasted) and indicating that the InsP6 absorption also takes place during the intestinal transit. Thus, if InsP6 supplements of vegetal origin are consumed to maintain the optimum InsP6 levels needed for a healthy status, these supplements can be consumed either during or between meals with the same efficacy.

Absorption↗

PubMed2006

Absorption of myo-inositol hexakisphosphate (InsP6) through the skin in humans.

In this paper, we present a pilot study of the absorption of myo-inositol hexakisphosphate (InsP6) through the skin in humans. We found that, after topical treatment with a 4% InsP6 rich gel, InsP6 urinary excretion increased 54% compared to the control situation (participants submitted to an InsP6-poor diet for 15 days, n = 6), clearly demonstrating that InsP6 is absorbed through the skin of humans. These results demonstrate the topical application as a suitable administration route of InsP6 in humans.

Administration, Topical↗

PubMed2006

Anxiety and stress among science students. Study of calcium and magnesium alterations.

Stress and anxiety of university science students (Chemistry) was evaluated in basal conditions and during exams using validated stress and anxiety questionnaires. The relations between the data obtained and various biochemical markers were established. Results showed that the evaluated students did not experience stress increase as a consequence of exams but suffered a significant increase in anxiety. The psychological findings agree with the urinary biomarkers studied. It is known that anxiety is related to partial magnesium reduction associated with a urinary magnesium excretion increase, as observed in the present data. Nevertheless, stress also correlates with a urinary calcium increase which was not detected in the present study.

Adolescent↗

PubMed2005

An experimental study on residual lithiasis after shock wave lithotripsy.

The main objective of this paper was to study residual lithiasis after extracorporeal shock wave lithotripsy (post-ESWL), with the aim of contributing to the development of effective prophylactic measures. In vivo regrown calcium oxalate monohydrate (COM) post-ESWL residual fragments were studied by stereoscopic microscopy, infrared spectroscopy and scanning electron microscopy with an energy dispersive X-ray analyzer. An in vitro system was also used to study the regrowth of post-ESWL fragments of COM calculi. The regrowth was evaluated as the relative increase in the weight of the fragments. The effects of a calcium oxalate crystallization inhibitor (phytate) were also evaluated. All of the in vivo regrown COM real residual post-ESWL fragments exhibited practically the same internal structural features. The in vitro studies demonstrated that the regrowth of post-ESWL residual fragments, in the absence of crystallization inhibitors, occurred even using normocalciuric/normooxaluric urine and could be detected at 24 h. At 144-240 h, the formation of new COM columnar zones was observed. The presence of 1.5 mg/l of phytate totally blocked the growth process. When hypercalciuric/normooxaluric urine was used, significant amounts of disorganized calcium oxalate dihydrate (COD) crystals were formed. The in vitro regrowth of post-ESWL COM fragments was clearly influenced by the presence of crystallization inhibitors. These data also demonstrate the importance that effective prophylactic therapies could exert on preventing recurrence.

Calcium Oxalate↗

PubMed2005

[Chronic idiopathic lithoptysis].

Broncholiths, which usually arise from calcified peribronchial lymph nodes, can be found by radiography or bronchoscopy. We describe the case of a 19-year-old man who had experienced lithoptysis of bronchial hydroxyapatite calculi for over 6 months and who reported having sandy expectoration since childhood. Exhaustive clinical, radiographic, and endoscopic diagnostic studies detected no calcified lesions in the thorax that could explain the origin of the broncholiths. Therefore, we propose that broncholiths may form by mechanisms similar to those involved in calculi formation in other locations.

Adult↗

PubMed2005

Recurrent vesical calculi, hypercalciuria, and biochemical evidence of increased bone resorption in an adult male with paraplegia due to spinal cord injury: is there a role for intermittent oral disodium etidronate therapy for prevention of calcium phosphate bladder stones?

STUDY DESIGN: Clinical case report with comments by colleagues from Sweden, Poland, Spain, Brazil, Japan, Belgium and Switzerland. OBJECTIVES: To discuss the role of disodium etidronate therapy for prevention of calcium phosphate vesical calculi in persons with spinal cord injury, who have hypercalciuria and biochemical evidence of increased bone resorption. SETTING: Regional Spinal Injuries Centre, Southport, UK. METHODS: A 21-year-old male sustained paraplegia (T-10; ASIA scale: A) in a road traffic accident in June 2001. He had an indwelling urethral catheter until the end of August 2001, when he started self-catheterisation. He developed bladder stones and electrohydraulic lithotripsy (EHL) was performed in May 2002. All stone fragments were removed. Recurrence of vesical calculi was noted in October 2002. These stones were fragmented by lithoclast lithotripsy in two sessions, in December 2002 and February 2003; all stone fragments were removed at the end of the second session. This patient reverted to indwelling catheter drainage when vesical calculi recurred. In September 2003, X-ray of the abdomen showed recurrence of vesical calculi. By February 2004, the stones had increased in size and number. EHL of vesical calculi was again performed in April 2004. Complete clearance was achieved. RESULTS: A 24-h urinalysis detected hypercalciuria--18.7 mmol/day (reference range: 2.5-7.5). Biochemical analysis of vesical calculus revealed calcium phosphate (85%) and magnesium ammonium phosphate (15%). Plasma C-terminal telopeptide (CTX) was increased - 1.06 ng/ml (reference range: 0.1-0.5 ng/ml). Free deoxypyridinoline/creatinine ratio (fDPD/Cr) in urine was also increased - 20.2 (reference range: 2.3-5.4). In April 2004, this patient was prescribed disodium etidronate 400 mg day. Nearly 3 months after commencing therapy with etidronate, plasma CTX decreased to 0.87 ng/ml. fDPD/Cr in urine also decreased to 12.4. After 4 months of etidronate therapy, 24-h urinary calcium excretion had decreased to 6.1 mmol/day. CONCLUSION: Etidronate (400 mg daily) is a very effective inhibitor of calcium phosphate crystallisation. Etidronate decreased urinary excretion of calcium, an important factor in prevention of calcium phosphate bladder stones. Etidronate therapy is not a substitute for other well-established methods for prevention of vesical calculi in spinal cord injury patients, for example, large fluid intake, avoiding long-term catheter drainage. Intermittent therapy with etidronate may be considered in selected patients, in whom hypercalciuria persists after instituting nonpharmacological therapy for an adequate period, for example, early mobilisation, weight-bearing exercises, and functional electrical stimulation. However, possible side effects of etidronate, and the fact that etidronate is not licensed in United Kingdom for prevention of urolithiasis, should be borne in mind.

Adult↗

PubMed2005

Study of a myo-inositol hexaphosphate-based cream to prevent dystrophic calcinosis cutis.

BACKGROUND: Calcinosis cutis is a disorder caused by abnormal deposits of calcium phosphate in the skin and is observed in diverse disorders. Myo-inositol hexaphosphate (InsP(6)) is a diet-dependent molecule found in all mammalian fluids and tissues, which exhibits an extraordinary capacity as a crystallization inhibitor of calcium salts. OBJECTIVES: To establish the effects of topically administered InsP(6) cream on artificially provoked dystrophic calcifications in soft tissues. METHODS: Fourteen male Wistar rats were randomly assigned into two groups: control and treated groups. Rats were fed with an InsP(6)-free or phytate diet. Plaque formation was induced by subcutaneous injection of 0.1% KMnO(4) solution. From 4 days before plaque induction to the end of the experiment, control rats were treated topically with a standard cream, whereas treated rats were treated with the same cream with 2% InsP(6) or phytate (as sodium salt). Calcification of plaques was allowed to proceed for 10 days. InsP(6) in urine was determined. The plaques were excised and weighed. RESULTS: It was found that when InsP(6) was administered topically through a moisturizing cream (2% InsP(6)-rich), the plaque size and weight were notably and significantly reduced compared with the control group (1.6 +/- 1.1 mg InsP(6)-treated, 26.7 +/- 3.0 mg control). The InsP(6) urinary levels for animals treated with the InsP(6)-enriched cream were considerably and significantly higher than those found in animals treated topically with the cream without InsP(6) (16.96 +/- 4.32 mg L(-1) InsP(6)-treated, 0.06 +/- 0.03 mg L(-1) control). CONCLUSIONS: This demonstrates the important capacity of InsP(6) as a crystallization inhibitor and also demonstrates that it is possible to propose topical use as a new InsP(6) administration route.

Administration, Cutaneous↗

PubMed2004

Dietary myo-inositol hexaphosphate prevents dystrophic calcifications in soft tissues: a pilot study in Wistar rats.

Myo-inositol hexaphosphate (InsP6) is an abundant component of plant seeds. It is also found in significant levels in blood and mammalian tissues, but they are totally dependent on their dietary intake. In the present paper, we describe studies on the effect of InsP6 on a model of dystrophic calcification, which was chemically induced by subcutaneous injection of a 0.1% KMnO4 solution. Male Wistar rats were randomly divided into four groups for treatment over 31 days. A: animals consuming a purified diet in which InsP6 was absent but to which 1% of InsP6 (as sodium salt) was added. In this group, the InsP6 plasma levels (0.393 +/- 0.013 microM) were similar to those observed in rats consuming a standard diet. B: animals consuming only the purified diet in which InsP6 was absent. In this case the InsP6 plasma levels decreased (0.026 +/- 0.006 microM); C: animals consuming the same purified diet as group B but received daily subcutaneous injections of 50 microg kg(-1) etidronate during the last 14 days. In this case the InsP6 plasma levels were also very low (0.025 +/- 0.007 microM); D: animals consuming the same diet as group B but a 6% of carob germ (InsP6 rich product) was added. The InsP6 plasma levels (0.363 +/- 0.035 microM) were also similar to those observed in rats consuming a standard diet. After 21 days plaque formation was induced. Calcification plaques were allowed to proceed for 10 days, after which the plaque material present was excised, dried and weighed. It was found that the presence of myo-inositol hexaphosphate (phytate) in plasma at normal concentrations (0.3-0.4 microM) clearly inhibited the development of dystrophic calcifications in soft tissues. These results demonstrates that myo-inositol hexaphosphate acts as an inhibitor of calcium salt crystallization.

Administration, Oral↗

PubMed2004

Determination of myo-inositol in biological samples by liquid chromatography-mass spectrometry.

Due to the absence of HPLC methods to determine myo-inositol using mass detection and considering its sensitivity and selectivity, a high performance liquid chromatography-mass spectrometry method for the analysis of myo-inositol is described and applied to its direct determination in urine and saliva samples. Successful resolution of myo-inositol and its related substances was achieved with a stationary phase Aminex HPX-87C Column with milli-Q water as mobile phase and 5 mM ammonium acetate added post-column. The detector counted positive ions by monitoring m/z = 198, which corresponds to the myo-inositol adduct with ammonium cation. Urine and saliva samples were previously purified by passing through an anion-exchange resin. Concentrations as low as 138 and 461 microg/l in saliva and urine could be respectively quantified. Intra-day R.S.D. ranged from 0.83 to 1.02%, whereas inter-day R.S.D. was between 1.54 and 3.58%.

Chromatography, High Pressure Liquid↗

PubMed2004

Effect of phytate on element bioavailability in the second generation of rats.

In this paper the relation between long term consumption of a high dose of sodium phytate and the mineral status of the organism is evaluated in rats. For this purpose, element concentrations (Ca, Mg, Fe, Zn, Mn) were determined in liver, heart, testicle, bone and urine of a second generation of Wistar rats, treated with a phytate free diet (AIN-76A) and with the same diet plus 1% phytate as sodium salt. The most significant differences were observed between bone zinc contents of male and female rats. The zinc content of rats fed a 1% phytate as sodium salt diet resulted clearly lower than that found in no-phytate treated rats. Hence, it is concluded that when up to 1% of phytate as sodium salt is consumed together with an equilibrated purified diet (free of phytate), no decrease in mineral bioavailability is observed in second generation rats, except for an indication of lower zinc availability by lower zinc concentrations in some organs, mainly bone. However, using this purified diet, the zinc concentration in bone resulted around 10 times higher than found in rats fed with a common non purified rat chow.

Animals↗

PubMed2004

Study of potassium phytate effects on decreasing urinary calcium in rats.

BACKGROUND: Phytate as sodium salt has been used at high doses to treat stone-former patients with idiopathic hypercalciuria. The experimental and clinical hypocalciuric effects of dietary fiber have also been assigned to the presence of phytate as calcium-magnesium salt (phytin). As a consequence of the additional interest in phytate due to its capacity as crystallization inhibitor, now a study of the effects of potassium phytate on urinary calcium excretion is presented and compared with the effects caused by other phytate salts. METHODS: To study the effect of calcium-magnesium phytate, 36 Wistar rats (6 groups) were fed with a purified diet in which phytate was practically absent (4068.02 Reference Diet). Three groups were fed with increasing calcium amounts and with the same amount of phytin, each one corresponding to one control group. To study the effects of magnesium-potassium, sodium and potassium phytate salts, 48 Wistar rats (8 groups) were fed with UAR-A04 diet (a standard diet which contains 0.8% of phytin). Two control groups fed with low and high calcium amounts and 6 treated groups were formed. The effect of the dose of potassium phytate on urinary calcium was carried out using 2 additional groups of 6 Wistar rats each one fed with UAR-A04 diet and increasing amounts of potassium phytate. RESULTS: No significant changes in urinary calcium were observed when phytin (calcium-magnesium phytate) was supplied. The urinary calcium was clearly reduced by the three phytate salts assayed (magnesium-potassium, sodium, potassium), but the most significant decrease was noticed when the potassium phytate salt was administered. Phytate administration, independently of the salt or dose used, did not significantly affect the urinary oxalate. CONCLUSION: It can be clearly deduced that the effects of phytate on the urinary parameters, mainly calcium, fundamentally depend on the type of salt used. Thus, the most remarkable effects on urinary calcium reduction were caused by the potassium salt. Obviously, these findings must be confirmed in human studies.

Animals↗

PubMed2001

Determination of phytic acid by gas chromatography-mass spectroscopy: application to biological samples.

A GC-MS method is reported for the determination of phytic acid based on purification by anion-exchange chromatography, enzymatic hydrolysis of phytic acid to myo-inositol and derivation to trimethylsilyl derivative, with scyllo-inositol as an internal standard. Analytical features of the method are: limit of detection 9 microg l(-1) phytic acid, linear working range 18-500 microg l(-1) phytic acid, and coefficient of variation 1.9%. The method has been successfully applied to a variety of biological samples: various rat organs (kidney, liver, brain and bone), human plasma and urine and kidney stones. A comparative study of sample treatments, including deproteization, lipid extraction and the presence of a chelator, is also reported. Phytic acid amounts found in rat organs ranged from 1.07 g kg(-1) for bone to 32.0 g kg(-1) for brain. Phytic acid in human plasma was of the order of 0.14 mg l(-1). In kidney stones, phytic acid was found in calcium containing stones.

Animals↗

PubMed2001

Determination of phosphate in urine by sequential injection analysis.

Two simple turbidimetric methods for the determination of phosphate in urine are presented and compared. One method is based on the calcium phosphate crystallisation, and the other one on the inhibitory action of phosphate on the calcium carbonate crystallisation. The analytical features of both methods were: linear range = 0.2-1.5 g L-1, LOD = 14 mg L-1 and RSD 1.1-2.0% for the calcium phosphate method, linear range = 0.1-1.8 mg L-1, LOD = 0.01 mg L-1 and RSD 0.97-1.90% for the inhibitory method. Urines with high calcium content (> or = 400 mg L-1) can interfere the method based on the crystallisation of calcium phosphate. This interference was solved using a cation exchange resin as a part of the manifold. Considering the low toxicity of used reagents, these methods can be considered as a contribution to Green Analytical Chemistry.

Calcium Carbonate↗

PubMed2001

Absorption and excretion of orally administered inositol hexaphosphate (IP(6) or phytate) in humans.

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 plasma (0.07+/- 0.01 mg/L) being clearly lower than those found when IP(6)ND was consumed (0.26+/- 0.03 mg/L). During the restriction period the maximum concentration in plasma were obtained 4 h after the ingestion of a single dose of IP(6), observing almost the same renal excretion profiles for the three different commercial sources and doses. After the IP(6) restriction period, volunteers were on IP(6)ND, reaching normal plasma and urinary IP(6) values in 16 days. Thus, the normal plasma and urinary concentrations, can be obtained either by consumption of a IP(6)ND taking a long time or in a short period by IP(6) supplements.

Absorption↗

PubMed2001

Determination of pyrophosphate in renal calculi and urine by means of an enzymatic method.

An enzymatic method for the determination of pyrophosphate which has been applied to renal calculi is described. The method involves the preconcentration of pyrophosphate using anionic exchange resin and development of the enzymatic reactions with the pyrophosphate retained on the resin. The study of calculi treatment according to calculi composition is also reported. The pyrophosphate content was dependent on the calculi composition. The highest amount of pyrophosphate was found in hydroxyapatite calculi (of the order of 10 microg/g), struvite and oxalate calculi showed a lower amount (the order was 2.5 and 4.5 microg/g, respectively) and was not detected in uric acid and cystine stones. The method was also successfully applied to the determination of pyrophosphate in human urine. For urinary pyrophosphate determination, a modification based on a clean-up of urine using activated carbon has been proposed. Pyrophosphate in human urine was of the order of 4 mg l(-1).

Algorithms↗

PubMed2001

Dietary phytate and mineral bioavailability.

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, kidneys, liver, brain and bone, were observed, except iron in the brain. Thus, the amounts of iron found in the brain of rats fed AIN-76A + 1% InsP6 were significantly inferior to those found in rats fed AIN-76A diet. The amounts of InsP6 found in organs of rats fed AIN-76A diet became very low or even undetectable while the ones found in rats fed diets that contained 1% and 0.12% (AIN-76A + 6% carob seed germ) InsP6, were considerably higher and similar. Moreover the majority of rats fed AIN-76A diet exhibited calcifications at the corticomedullary junctions, whereas no calcifications were detected in rats fed the other two diets. From these results, it can be deduced that there was no important adverse effects on mineral status as a consequence of the presence of InsP6 in the studied diets. Besides, considering that a 0.12% InsP6 contained in the AIN-76A purified diet through the addition of a 6% of carob seed germ to this diet, produced the same beneficial effects as the direct addition of a 1% of InsP6 and no negative effects on mineral status was observed, it can be concluded that the value of the presence of InsP6 at adequate amounts in the diet is remarkable and must be favourably considered.

Analysis of Variance↗

PubMed2001

Variation of InsP(4),InsP(5) and InsP(6) levels in tissues and biological fluids depending on dietary phytate.

Due to the increasing interest of InsP(6) on human health, the aim of this paper is to compare the levels of highly phosphorilated inositols (InsP(4), InsP(5) and InsP(6)) in organs and biological fluids of rats and to study the influence of the presence and absence of InsP(6) in diets. Thus, for this purpose, the variation of InsP(4), InsP(5) and InsP(6) levels in organs and biological fluids of rats submitted to two different diets were studied. In the AIN-76A diet no InsP(6) was present, yet the other was a 1% InsP(6) modified diet (AIN-76A + 1% InsP(6)). The highest InsP(4), InsP(5) and InsP(6) levels were found to be 10-fold superior in the brain than those found in the kidney. When the InsP(6) was eliminated from the diet, the InsP(6) levels decreased dramatically (97.2% in kidney, 89.8% in brain, 100% in bone, 90.5% in plasma and 98.1% in urine), the InsP(5) levels showed an important decrease (61.2% in kidney, 45.5% in brain, 28.1% in bone, 30% in plasma and 88.6% in urine) and the InsP(4) levels in organs only changed slightly. From these results, it can be deduced that the majority of InsP(6) present in the organism is of dietary origin and its endogenous synthesis is not important. According to the results, it can be evidenced that the endogenous synthesis of InsP(5) can occur, besides InsP(6) can be transformed by enzymatic dephosphorilation in InsP(5).

Journal Article↗