Urinary Pyrophosphate Research Articles

Spiropyran-Based Fluorescent Anion Probe and Its Application for Urinary Pyrophosphate Detection

In recent decades, numerous spiropyran derivatives have been designed and utilized for optical sensing of metal ions. However, there is still less research on spiropyran-based anion sensors. In this work, a new spiropyran compound (L) appended with a pendant bis(2-pyridylmethyl)amine was synthesized and used in fluorescent sensing of pyrophosphate ion (PP(i)) in aqueous solution. The molecular recognition and signal transduction are based on the cooperative ligation interactions and the ligation-induced structural conversion of the spiropyran, which leads to a significant change in the photophysical property of the spiropyran. In an ethanol/water solution (30:70, v/v) at pH 7.4, ligation of L with Zn(2+) causes an intense fluorescence emission at 620 nm at the expense of the original fluorescence at 560 nm. Once PP(i) was introduced, interaction between PP(i) and the L-Zn(2+) complex leads to full quenching of the 620 nm band emission which was concomitant with recovery of the 560 nm band emission, and the fluorescence intensity ratio, F(560)/F(620), is proportional to the PP(i) concentration. Under the optimum condition, the L-Zn(2+) complex responds to PP(i) over a dynamic range of 1.0 x 10(-6) to 5.0 x 10(-4) M, with a detection limit of 4.0 x 10(-7) M. The fluorescence response is highly selective for PP(i) over other biologically related substrates, especially the structurally similar anions, such as phosphate and adenosine triphosphate. The mechanism of interaction among L, Zn(2+), and PP(i) was primarily studied by (1)H NMR, (31)P NMR, and HRMS. To demonstrate the analytical application of this approach, the PP(i) concentration in human urine was determined. It was on the order of 3.18 x 10(-5) M, and the mean value for urinary PP(i) excretion by three healthy subjects was 62.4 micromol/24 h.

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 μg/g), struvite and oxalate calculi showed a lower amount (the order was 2.5 and 4.5 μg/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.

Renal handling of calcium and phosphorus in primary Sjogren syndrome

The excretion of inorganic pyrophosphate was studied in daily, fasting and postprandial urine specimens of normocalciuric and hypercalciuric patients with recurrent renal calcium stone disease (40 men and 40 women), and healthy controls (20 men and 20 women). Both populations were subdivided into younger (20 to 40 years old) and older (more than 40 years old) individuals.In general, there was a tendency towards higher urinary pyrophosphate excretion with increasing age (both sexes and all groups studied), and lower excretion in women than in men. The urinary pyrophosphate excretion rate was unchanged in daily and fasting urine specimens of the younger male normocalciuric and idiopathic hypercalciuric stone patients, whereas in the daily and postprandial urine of younger women the median excretion rate was reduced (controls versus normocalciuric plus idiopathic hypercalciuric subjects, 3 versus 1 μmol., p less than 0.05). In contrast, in older men urinary pyrophosphate was reduced in daily specimens (controls versus normocalciuric plus idiopathic hypercalciuric subjects, 55 versus 33 μmol., p less than 0.05) but it was unchanged in fasting urine specimens. In older women no change was detectable in any of the 3 urine portions. Factorization of urinary pyrophosphate for the associated urinary creatinine did not alter these results substantially, and the presence of renal stones did not modify pyrophosphate excretion significantly. Urinary pyrophosphate was correlated significantly with urinary volume, citrate and phosphorus.We conclude that only subclassification of stone patients with respect to sex, age and type of calciuria, and consideration of additional urine portions besides the daily urine may help to uncover states of urinary pyrophosphate deficit. On the basis of the data, we recommend that clinically relevant studies on inhibitory effects of urinary pyrophosphate on the nucleation and growth of crystals and stones should be done preferentially in urine portions with a proved pyrophosphate deficit.

Urinary Pyrophosphate in Patients with Recurrent Calcium Urolithiasis and in Healthy Controls: A Re-Evaluation

The excretion of inorganic pyrophosphate was studied in daily, fasting and postprandial urine specimens of normocalciuric and hypercalciuric patients with recurrent renal calcium stone disease (40 men and 40 women), and healthy controls (20 men and 20 women). Both populations were subdivided into younger (20 to 40 years old) and older (more than 40 years old) individuals.In general, there was a tendency towards higher urinary pyrophosphate excretion with increasing age (both sexes and all groups studied), and lower excretion in women than in men. The urinary pyrophosphate excretion rate was unchanged in daily and fasting urine specimens of the younger male normocalciuric and idiopathic hypercalciuric stone patients, whereas in the daily and postprandial urine of younger women the median excretion rate was reduced (controls versus normocalciuric plus idiopathic hypercalciuric subjects, 3 versus 1μmol., p less than 0.05). In contrast, in older men urinary pyrophosphate was reduced in daily specimens (controls versus normocalciuric plus idiopathic hypercalciuric subjects, 55 versus 33μmol., p less than 0.05) but it was unchanged in fasting urine specimens. In older women no change was detectable in any of the 3 urine portions. Factorization of urinary pyrophosphate for the associated urinary creatinine did not alter these results substantially, and the presence of renal stones did not modify pyrophosphate excretion significantly. Urinary pyrophosphate was correlated significantly with urinary volume, citrate and phosphorus.We conclude that only subclassification of stone patients with respect to sex, age and type of calciuria, and consideration of additional urine portions besides the daily urine may help to uncover states of urinary pyrophosphate deficit. On the basis of the data, we recommend that clinically relevant studies on inhibitory effects of urinary pyrophosphate on the nucleation and growth of crystals and stones should be done preferentially in urine portions with a proved pyrophosphate deficit.

Pyrophosphate does not influence calcium oxalate or calcium phosphate crystal formation in concentrated whole human urine.

1) Low pyrophosphate urine was generated by passage through a nylon coil bearing immobilised inorganic pyrophosphatase. High pyrophosphate urine was made by addition of inorganic pyrophosphate. 2) Urine samples of low, normal, and high pyrophosphate content were rapidly evaporated at 37 degrees C to 1,050 or 1,250 mosmol/L and the crystals formed studied by microscope, isotope and chemical methods. 3) Urinary pyrophosphate level had no significant effect upon calcium oxalate crystals formed in whole urine at pH 5.3 or 6.1, or calcium phosphate crystals formed at pH 6.8.

Urinary pyrophosphate excretion in renal stone formers with normal and impaired renal acidification

A recently described method for analysis of inorganic pyrophosphate (PPi) was used to investigate urinary excretion of PPi in renal calcium stone formers with normal (n=44) or impaired renal acidification capacity (RTA; n=13) as well as in controls (n=22) of corresponding sex and age. The mean values of the 24 h urinary PPi excretion were lower in stone-forming groups than in the control group. There was no statistical difference in the mean 24-h PPi excretion between stone-forming groups with normal and with defective urinary acidification, but there was an overrepresentation of low values for PPi excretion in the latter subject group. Positive relationships existed in all subject groups between the urinary excretion of phosphate and PPi when pooled data from various conditions of phosphate intake (fasting, non-fasting, oral phosphate loading) were examined. In the fasting state the PPi excretion was similar in stone formers and controls. Oral orthophosphate loading after phosphate deprivation with aluminium hydroxide invariably caused a rise in urinary PPi excretion in all subjects, with no difference between stone formers with normal acidification, RTA stone patients and controls. The increment in urinary PPi was positively correlated to the increment in urinary phosphate but not to changes in serum phosphate. In conclusion, these results suggest that renal stone formers may have a lower daily PPi excretion compared with controls. This was most pronounced in patients with impaired renal acidification capacity and may be due to a generalized disturbed tubular function.

Enzymic measurement of urinary pyrophosphate with a centrifugal analyzer.

We describe a simple, rapid, and fully automated technique for measuring urinary pyrophosphates with a centrifugal analyzer (the ENI GEMSAEC). This technique depends on the enzymic magnesium-dependent reaction with UDPG pyrophosphorylase (UTP: alpha-D-glucose-1-phosphate uridylyl transferase, EC 2.7.7.9) and spectrophotometry of the NADPH formed in a combined system of phosphorylation and reduction. Many samples of urine can be analyzed quickly without pretreatment, with high sensitivity (1.3 mA/mumol of substrate) and good reproducibility. The mean within-run coefficient of variation for a 50 mumol/L pyrophosphate solution was 1.4%. We determined the optimum enzyme and magnesium concentrations necessary for use in a 4-min reaction. Because there is no inhibitory effect of chloride and phosphate ions, pyrophosphate can be measured directly in urine, without prior extraction. With this technique, the mean value (and SD) for urinary pyrophosphate excretion by 30 healthy subjects was 39.3 (SD 17.2) mumol/24 h.

Metabolic investigations after xylitol infusion in human subjects

Evidence has been sought for minor degrees of thiamin and pyridoxine deficiency in patients undergoing surgery who have been infused with xylitol as a parenteral nutrient. Some metabolic changes which are associated with this practice have been studied; the findings are compared with those obtained in similar patients infused with glucose solutions. The thiamin status of all of the subjects was normal. Some of the patients showed slight biochemical evidence of pyridoxine deficiency, but there were no untoward effects of xylitol infusion. The concentration of oxalate in the blood and the excretion of oxalate in the urine did not exceed the normal range in any patient. The plasma and urine orthophosphate and urinary pyrophosphate levels decreased in association with the infusion of both xylitol and glucose. Plasma pyrophosphate and calcium levels, and the urinary calcium level, were essentially unaltered. A detailed quantitative study of the urinary organic acid excretion by means of gas chromatography/mass spectrometry showed that there was an abnormal glycolic aciduria and tetronic aciduria associated with xylitol infusion, but not with glucose infusion. There was no evidence of increased oxalate excretion in any patient by this method. The biochemical and clinical significance of these findings is discussed.

Hydrochlorothiazide therapy in nephrolithiasis. Effect on the urinary activity product and formation product of brushite.

The effect of hydrochlorothiazide on the formation of renal stones containing calcium was evaluated by the quantitative assessment of the propensity of urine for the nucleation of brushite (nidus of calcium stones). In 6 patients with renal stones, the urinary activity product ratio (APR) and the formation product ratio (FPR) of brushite were measured before, during, and following treatment with hydrochlorothiazide (50 mg twice a day orally) for from 5 days to 1 month. The urinary APR (the state of saturation with respect to brushite) decreased in the majority of cases primarily as the result of a fall in urinary calcium. The urinary FPR (lowest state of supersaturation at which nucleation is initiated) usually increased, probably as a result of a rise in urinary pyrophosphate. Both changes reduced the propensity for the formation of the nidus of brushite, and may therefore account for the improvement reported after thiazide therapy in nephrolithiasis.

Effects of cellulose phosphate and sodium phosphate on formation product and activity product of brushite in urine

The crystal nidus of brushite (nidus of renal stones containing calcium) cannot form when the activity product (state of saturation) of brushite in urine is less than the formation product (the lowest state of supersaturation supporting nucleation). Treatment measures should therefore be directed at reducing the activity product or increasing the formation product. The response to treatment with cellulose phosphate and with sodium phosphate was evaluated according to this criterion. Cellulose phosphate decreased the activity product while slightly increasing or not significantly affecting the formation product. Sodium phosphate increased both the activity product and the formation product of brushite. The formation product increased largely as the result of the increase in urinary pyrophosphate. In most patients, the increase in the activity product during treatment with sodium phosphate was fully compensated by the increase in the formation product.

High urinary pyrophosphate excretion in the acute phase of pseudogout

High urinary pyrophosphate excretion in the acute phase of pseudogout

Basal urinary pyrophosphate excretion in pseudogout.

AbstractUrinary pyrophosphate excretion was measured in 4 patients with calcium pyrophosphate crystal deposition disease, and was found to be in the low normal range reported by others. A more strictly controlled diet may account for the relatively low values obtained.

Biochemical studies of the urine in urinary calculi, with special reference to hypercalciuria and urinary phosphates

In one hundred and fourteen cases of normal subjects, and in eighty-six patients with upper urinary kcalculi, daily excretions of urinary calcium, orthophosphate, pyrophosphate, cirtic acid, magnesium, creatinine, uric acid and alkaline phosphatase activity were estimated. The results of urine analysis in both groups were respectively compared.In the calculous patient group, significantly higher levels of urinary pyrophosphate and citric acid, but significantly lower levels of urinary magnesium were demonstrated. Urinary excretions of the remaining compositions, especially urinary calcium levels showed no significant differences between both groups. But idiopathic hypercalcinuria, in which over 300mg of calcium are excreted in the 24 hour urine with normal serum levels of calcium and phosphorus, was found in 11 percent of normal subjects over 20 years old, whereas the group of calculous patients showed higher incidence of 19 percent hypercalcinuria. Also it is interesting that hypercalcinuria is not demonstrated in thirty-nine normal subjects under twenty years old.The inhibitor index proposed by Fleisch, H. et al., which is expressed in the ratio of pyrophosphate: calcium×orthophosphate, showed significantly higher value in the calculi group. This difference was more distinctly observed in the comparison between calculous patients with hypercalcinuria and normal subjects. Moreover, the chronological values of the ratio in the control group show the interesting variations, which conversely correspond to the age distribution of the urinary calculus. These findings are supposed to indicate that the ratio possibly correlates to the formation of the urinary calcareous stone.In eleven cases of calculous patients and five cases of normal adults, orthophosphates (Na2HPO4+KH2PO4) in daily dosis of 2gm were administered by mouth. Before and after administration the consecutive biochemical analysis was performed and was compared. The results definitely demostrated that the administration of the phosphates preparation caused significant increase of urinary citric acid, pyrophosphate and the inhibitor index expressed in the ratio of pyrophosphate: calcium×orthophosphate, but significant decrease of urinary calcium and magnesium. These changes of urine compositions caused by administration of phosphates, suggests that orthophosphates have clinical usefullness in prevention of the formation of the urinary calcareous stone.

Excretion of Pyrophosphate in Disorders of Bone Metabolism

Measurements of urinary inorganic pyrophosphate in clinical disorders characterized by increased turnover of bone have demonstrated significant pyrophosphaturia. Pyrophosphate excretion paralleled the hydroxyprolinuria noted in each instance and was unrelated to total urinary inorganic orthophosphate. These observations suggest that urinary pyrophosphate excretion may reflect the abnormal patterns of bone resorption and remodeling in clinical disorders of bone metabolism.

Isolation from urine of pyrophosphate, a calcification inhibitor.

The minimum value of the product, Ca X P, necessary for calcium phosphate precipitation to occur, was determined in vitro. The addition of 2.2% urine to the solutions raised the mean product from 53 to 105 (mg/100 ml)2, which shows that the urine contains inhibitors to hydroxyapatite precipitation. One of these was isolated and purified. Its characteristics are those of inorganic pyrophosphate. The mean level of urinary pyrophosphate was 2.24 mg P/liter, sufficient to inhibit precipitation of hydroxyapatite. Pyrophosphate is one of the substances permitting urine to be supersaturated with calcium and phosphate; other urinary inhibitors are still to be identified. It is suggested that the phosphate compound present in the plasma which inhibits hydroxyapatite precipitation is pyrophosphate. In bone, pyrophosphatase would act by locally destroying this calcification inhibitor, thus allowing the apatite crystals to form.