Urinary pH and renal lithiasis.

Formation of calcium oxalate crystals, either as monohydrate or dihydrate, is apparently unrelated to urinary pH because the solubilities of these salts are practically unaltered at physiologic urinary pH values. However, a urinary pH <5.5 or >6.0 may induce uric acid or calcium phosphate crystals formation, respectively, which under appropriate conditions may induce the development of the calcium oxalate calculi. We assessed the relationship between the urinary pH and the formation of different types of calculi. A retrospective study in 1,478 patients was done. We determined the composition, macrostructure, and microstructure of the calculi and the urinary pH, 50.9% of calcium oxalate monohydrate unattached calculi were present in patients with urinary pH <5.5. We found that 34.1 and 41.5% of calcium oxalate dihydrate calculi were present in patients with urinary pH <5.5 and >6.0, respectively. Infectious calculi were found primarily in patients with urinary pH >6.0 (50.7%). Only calcium oxalate monohydrate papillary calculi were associated with urinary pH between 5.5 and 6.0 (43.1%). Urine of pH <5.5 shows an increased capacity to develop uric acid crystals, which can act as a heterogeneous nuclei of calcium oxalate crystals. In contrast, urine of pH >6.0 has an increased capacity to develop calcium phosphate crystals, which can act as a heterogeneous nuclei of calcium oxalate crystals. Oxalate monohydrate papillary calculi were associated to pH between 5.5 and 6.0 because the injured papilla acts as a heterogeneous nucleant. Consequently, measurement of urinary pH may be used to evaluate the lithogen risk of given urine.

A simple and rapid colorimetric method for determination of phytate in urine.

Phytate is a natural product present in urine and biological fluids that is associated with health benefits, such as the prevention of calcium renal stone formation. The available methods for phytate analysis in urine all require elaborate instrumentation and cannot be routinely applied in clinical laboratories. Here, we describe a simple procedure for urinary phytate determination, employing colorimetric detection. Our method requires purification and preconcentration of phytate via solid-phase extraction prior to colorimetric detection employing Fe(III)-thiocyanate. The working linear range of the assay is 0-5 µM phytate. The limit of detection is 0.055 µM. The relative standard deviation obtained upon assay of samples containing 2 µM phytate was 3.5 %. Several urine samples were analyzed using an alternative method based on the detection of phosphorus; the results of the two assays were comparable. Our novel method of phytate analysis in human urine is simple, rapid (3 h for 10 samples), accurate, precise, reliable, and highly sensitive. The assay can be run in most analytical laboratories and does not require sophisticated instrumentation.

[Update on the current role of plasma cholinesterase]. / Papel de las colinesterasas plasmáticas. Actualización.

The antagonism of steroidal nondepolarizing neuromuscular blockers (NDMBs) moved forward recently with the introduction of sugammadex, the only drug able to immediately reverse the effects of curarization produced by NDMBs. This advance has necessitated reflection on the future role of pseudocholinesterase. In spite of the side effects of succinylcholine and published opinions on its use, this NDMB continues to be used in clinical anesthesia. Pseudocholinesterase is mainly found in the liver, plasma, and nervous system. The enzyme is synthesized in the liver in greater amounts than required although certain conditions lead to deficiency, which is usually asymptomatic. The only clinical expression is the apnea which develops after administration of succinycholine because this NDMB cannot be metabolized. In some patients, slight reductions in the antagonism of succinylcholine lead to rising neuromuscular concentrations of the drug in accordance with the degree and duration of the blockade. We review the various forms of pseudocholinesterase deficiency, including a discussion of genetic variants, clinical manifestations, and management. In addition to discussing the diagnosis of this condition and the clinical implications, we highlight the importance of practice protocols and access to a referral laboratory if one is not available within the immediate hospital.

Anticalculus effect of a triclosan mouthwash containing phytate: a double-blind, randomized, three-period crossover trial.

BACKGROUND AND OBJECTIVE: Dental calculus occurs as a consequence of supersaturation of saliva with respect to calcium phosphates. This mineralization of dental plaque can be delayed by the presence of crystallization inhibitors, such as pyrophosphate or bisphosphonates. Phytate inhibits brushite and hydroxyapatite crystallization and has the potential to prevent dental calculi formation. The aim of the present study was to examine the effects of phytate and zinc, administered in a mouthwash solution, to prevent the formation of dental calculus. MATERIAL AND METHODS: Healthy dental plaque-forming volunteers (n = 25) took part in a randomized, double-blind, three-period crossover clinical study to assess the efficacy of a phytate-containing mouthwash in relation to control and placebo effects. Subjects rinsed their mouths for 1 min, twice each day, with 20 mL of the test solution, without ingestion. Mouthwash efficacy was assessed through quantification of the amounts of calcium, phosphorus and magnesium present in the residues obtained by dental cleaning, performed by a single trained examiner. RESULTS: A good correlation was found among total calcium, magnesium and phosphorus in calcified dental plaque residues, indicating that any of these variables is adequate for evaluating the reduction of plaque crystallization as calcium phosphate. A statistically significant decrease in total calcium, magnesium and phosphorus was found in the phytate-treatment period compared with control and placebo periods, demonstrating the efficacy of the proposed treatment in reducing dental calculus formation. CONCLUSION: The high efficacy of phytate in reducing dental calculus formation suggests that this substance may be an effective treatment for preventing the development of calculus deposits.

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 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.

Intracellular and extracellular myo-inositol hexakisphosphate (InsP6), from rats to humans.

The presence of myo-inositol hexakisphosphate (InsP6) in biological fluids (blood, urine, saliva, interstitial fluid) of mammalians has been clearly demonstrated. The existence of intracellular InsP6 in mammalian cells has also been established. Further, significant extracellular and intracellular functions of this molecule have been found. The relationship between InsP6 ingestion and the InsP6 distribution in various tissues of mammalians is discussed. It was found that the majority of the extracellular InsP6 found in organs, tissues and biological fluids of mammalians has a dietary origin and is not a consequence of endogenous synthesis, whereas the intracellular InsP6 probably originates in the cell. Little absorption of dietary InsP6 takes place during intestinal transit and depletion of extracellular InsP6 occurs at high rates when InsP6-poor diets are consumed. From these results, it can be deduced that health benefits linked to extracellular InsP6 must be related to dietary InsP6.

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.

Effect of dietary fatty acids on jejunal and ileal oleic acid uptake by rat brush border membrane vesicles.

To test the effect of dietary fatty acids on fatty acid uptake, the influx kinetics of a representative long-chain fatty acid, 3H-oleic acid, in both the jejunum and ileum of rats has been studied using brush border membrane vesicles (BBMV). Animals were fed with semipurified diets containing 5 g fat/100 g diet, as corn oil (control group), safflower oil (unsaturated group) and coconut oil hydrogenated (saturated group). With increasing unbound oleate concentration in the medium, the three dietary groups showed saturable kinetics in both jejunal and ileal BBMV (controls: Vmax = 0.15 +/- 0.01 nmol x mg protein-1 x 5 min-1 and Km = 136 +/- 29.1 nmol for jejunum, and Vmax = 0.23 +/- 0.03 nmol x mg protein-1 x 5 min-1 and Km = 196 +/- 50.3 nmol for ileum; unsaturated: Vmax = 0.28 +/- 0.05 nmol x mg protein-1 x 5 min-1 and Km = 242.7 +/- 91.8 nmol for jejunum, and Vmax = 1.29 +/- 0.06 nmol x mg protein-1 x 5 min-1 and Km = 509.8 +/- 97.5 nmol for ileum; saturated: Vmax = 0.03 +/- 0.01 nmol x mg protein-1 x 5 min-1 and Km = 124.5 +/- 72.6 nmol for jejunum, and Vmax = 0.04 +/- 0.01 nmol x mg protein -1.5 min-1 and Km = 205.6 +/- 85.3 nmol for ileum). These results support the theory that feeding an isocaloric diet containing only unsaturated fatty acids enhanced oleic acid uptake, and feeding an isocaloric diet containing only saturated fatty acids decreased oleic acid uptake. The results obtained in the present work also show the adaptative ability of jejunum and ileum to the type of dietary fat.

Oleic acid uptake by jejunal and ileal rat brush border membrane vesicles.

In previous works, a membrane fatty acid transport system has been identified in brush border membrane vesicles, but no different intestinal regions were considered in these studies. To test the existence of a proximal-to-distal gradient of fat absorption along the small intestine, transmembrane influx kinetics of a representative long-chain fatty acid, 3H-oleic acid, in both jejunum and ileum of rat has been studied using brush border membrane vesicles (BBMV). With increasing concentration of unbound oleate in the medium, both jejunal and ileal BBMV showed saturable uptake kinetics (Vmax = 0.15 +/- 0.01 nmol.mg protein-1 x 5 min-1 and Km = 136 +/- 29.1 nmol for jejunum, and Vmax = 0.23 +/- 0.03 nmol.mg protein-1 x 5 min1 and Km = 196 +/- 50.3 nmol for ileum). These results support the hypothesis that oleic acid uptake occurs via a carrier-mediated transport mechanism in both jejunum and ileum. Furthermore, the existence of a proximal-to-distal gradient for fat absorption was apparent with a higher density of transport units (Vmax) in ileum compared to jejunum.

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.

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.

Phytate prevents tissue calcifications in female rats.

The AIN-76 A, a purified rodent diet, has a propensity to cause kidney calcifications in female rats which is not observed with non-purified rodent diets, suggesting a nutritional factor that avoids these calcifications. One candidate is phytate, which inhibits crystallisation of calcium salts and is practically absent in purified diets. Therefore, the effects on calcification of kidney tissue of phytate addition to the AIN-76 A diet using female Wistar rats were studied. The rats were assigned to three groups: AIN-76 A, AIN-76 A + 1% phytate and standard nonpurified chow. Urinary phytate of the AIN-76 A fed group was undetectable. Urinary phytate of AIN-76 A + 1% phytate and standard fed groups did not differ and was significantly higher than in the AIN-76 A group. The concentrations of calcium and phosphorus in kidneys were greater in the AIN-76 A group than in AIN-76 A + 1% phytate and standard groups. Only rats of the AIN-76 A group displayed mineral deposits at the corticomedullary junction. These findings demonstrated that the absence of phytate in the AIN-76 A diet is one of the causes of renal calcification in female rats.

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.

In vitro models for studying renal stone formation: a clear alternative.

This paper discusses the limitations of using laboratory animals for direct in vivo observation of the development of renal stones. In fact, the majority of hypotheses related to mechanisms of stone formation have been based on the results of in vitro experiments. The relevance of in vitro experiments that allow the study of urolithiasis depends upon the degree of correspondence between the experimental conditions and those prevailing in the stone-forming kidney in vivo. For this reason, several in vitro experimental systems that attempt to reproduce the conditions found in vivo have been developed in order to study renal stone formation, which have been classified into two main groups: a) models to study papillary stone formation; and b) models to study "sedimentary" stone formation. These models are briefly described in this paper, and the information obtained was compared with that resulting from a study of the fine structure of real human renal calculi, in order to prove the validity of the models. It was concluded that the experimental in vitro models can closely reproduce the renal conditions under which human calculi are developed. This allows important data to be obtained about the aetiology of renal lithiasis, which is of great relevance to the development of effective treatments for this disease. Therefore, experimental in vitro models constitute a clear alternative to the use of laboratory animals.

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.

Changes in intestinal alpha-methyl-D-glucoside uptake due to pregnancy and lactation in rats.

Uptake of alpha-methyl-D-glucoside, a nonmetabolizable glucose analogue, by everted intestinal sleeves was studied in virgin, pregnant and lactating rats. The animals showed an increase in jejunal and ileal tissue mass, mucosal mass, nominal surface area, and enzymatic activities. No changes were observed in the carrier affinity throughout the breeding stages. Nevertheless there was a significant increase in glucose carrier density (Vmax) per unit of length of jejunum and ileum in pregnant and lactating animals. Integrating the results obtained, and increased overall ability to transport hexoses by nonspecific adaptation can be observed in breeding stages.