1967 THE INFLUENCE OF ERYTHROCYTE BAND III ANION TRANSPORTER ON THE OXALATE TRANSPORT OF CALCIUM OXALATE MONOHYDRATE STONE FORMERS VS. NORMAL CONTROLS

Normal urine inhibits both the growth and the aggregation of calcium oxalate monohydrate (COM) crystals but the molecules that inhibit aggregation are not well defined. We have developed a spectrophotometric assay method to measure the aggregation of COM crystals in vitro under conditions that avoid simultaneous crystal growth. At pH 7.2 and 90 mM NaCl, Tamm-Horsfall glycoprotein (THP) and nephrocalcin (NC), a major urinary inhibitor of COM crystal growth, inhibit COM crystal aggregation at concentrations as low as 2 X 10(-9) and 1 X 10(-8) M, respectively. When increasing NaCl to 270 mM or lowering pH to 5.7, inhibition by both glycoproteins, but more markedly by THP, is decreased. Urinary NC from calcium oxalate renal stone formers (SF NC) and NC isolated from calcium oxalate renal stones (stone NC) both inhibit COM crystal aggregation 10-fold less than NC from normal urine. Citrate is ineffective even at millimolar concentrations. Thus THP and NC are two major inhibitors of COM crystal aggregation in normal urine; SF NC and stone NC are defective aggregation inhibitors.

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Sat1 is dispensable for active oxalate secretion in mouse duodenum

AJP Cell Physiology ◽

10.1152/ajpcell.00385.2011 ◽

2012 ◽

Vol 303 (1) ◽

pp. C52-C57 ◽

Cited By ~ 12

Author(s):

Narae Ko ◽

Felix Knauf ◽

Zhirong Jiang ◽

Daniel Markovich ◽

Peter S. Aronson

Keyword(s):

Calcium Oxalate ◽

Basolateral Membrane ◽

Complete Removal ◽

Calcium Oxalate Stones ◽

Anion Transporter ◽

Oxalate Secretion ◽

In Series ◽

Disulfonic Stilbene ◽

Oxalate Transport

Mice deficient for the apical membrane oxalate transporter SLC26A6 develop hyperoxalemia, hyperoxaluria, and calcium oxalate stones due to a defect in intestinal oxalate secretion. However, the nature of the basolateral membrane oxalate transport process that operates in series with SLC26A6 to mediate active oxalate secretion in the intestine remains unknown. Sulfate anion transporter-1 (Sat1 or SLC26A1) is a basolateral membrane anion exchanger that mediates intestinal oxalate transport. Moreover, Sat1-deficient mice also have a phenotype of hyperoxalemia, hyperoxaluria, and calcium oxalate stones. We, therefore, tested the role of Sat1 in mouse duodenum, a tissue with Sat1 expression and SLC26A6-dependent oxalate secretion. Although the active secretory flux of oxalate across mouse duodenum was strongly inhibited (>90%) by addition of the disulfonic stilbene DIDS to the basolateral solution, secretion was unaffected by changes in medium concentrations of sulfate and bicarbonate, key substrates for Sat1-mediated anion exchange. Inhibition of intracellular bicarbonate production by acetazolamide and complete removal of bicarbonate from the buffer also produced no change in oxalate secretion. Finally, active oxalate secretion was not reduced in Sat1-null mice. We conclude that a DIDS-sensitive basolateral transporter is involved in mediating oxalate secretion across mouse duodenum, but Sat1 itself is dispensable for this process.

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Evidence that nephrocalcin and urine inhibit nucleation of calcium oxalate monohydrate crystals

AJP Renal Physiology ◽

10.1152/ajprenal.1991.261.5.f824 ◽

1991 ◽

Vol 261 (5) ◽

pp. F824-F830 ◽

Cited By ~ 1

Author(s):

J. Asplin ◽

S. DeGanello ◽

Y. N. Nakagawa ◽

F. L. Coe

Keyword(s):

Calcium Oxalate ◽

Calcium Oxalate Monohydrate ◽

Calcium Oxalate Crystals ◽

Constant Composition ◽

Oxalate Crystals ◽

Pump Delivery ◽

Consumption Rates ◽

Supersaturated Solutions ◽

Normal Controls

Human urine, and nephrocalcin (NC), a glycoprotein of probable kidney cell origin, greatly reduce consumption of calcium and oxalate from metastably supersaturated solutions seeded with calcium oxalate crystals, a phenomenon usually referred to as inhibition of crystal growth. We seeded metastably supersaturated calcium oxalate solutions with calcium oxalate monohydrate crystals under conditions of ion clamping to maintain constant composition and measured ion consumption from pump delivery rates. Consumption rates increased continuously with time as if the solutions were autocatalytic. After incubation, the seeds were covered with innumerable crystallites, which were also free and numerous in the solution, reflecting self-nucleation. The addition of 20% whole, dialyzed urine, or purified NC reduced ion consumption rates markedly, and the only crystals observed at the end of incubation were the large original seeds. Crystals precoated with concentrated dialyzed urine or NC also showed reduced ion consumption. Urine and NC from patients with nephrolithiasis inhibited nucleation less than normal controls. Self-nucleation seems to be the preferred response in sparsely seeded, ion-clamped, supersaturated solutions, such as exist in the nephron. Urine and NC suppress self-nucleation in vitro by adsorbing to the surface of calcium oxalate crystals.

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Citrate and calcium effects on Tamm-Horsfall glycoprotein as a modifier of calcium oxalate crystal aggregation

AJP Renal Physiology ◽

10.1152/ajprenal.1993.265.6.f784 ◽

1993 ◽

Vol 265 (6) ◽

pp. F784-F791 ◽

Cited By ~ 12

Author(s):

B. Hess ◽

L. Zipperle ◽

P. Jaeger

Keyword(s):

Calcium Oxalate ◽

Healthy Volunteers ◽

Calcium Oxalate Monohydrate ◽

Calcium Oxalate Crystal ◽

Crystal Aggregation ◽

Stone Formers ◽

Stone Former ◽

Calcium Effects ◽

Citrate Inhibition

We measured the effects of Tamm-Horsfall glycoprotein (THP) on calcium oxalate monohydrate (COM) crystal aggregation (Ac) in vitro as well as intrinsic viscosities (Vi) of THP at pH 5.7 and 200 mM NaCl and studied the effects of calcium and citrate on these parameters. THP were isolated from 24-h urines of seven male recurrent calcium stone formers (RCSF) and eight age-matched male healthy volunteers (N, normal). At basal conditions, RCSF-THP inhibited Ac by 28 +/- 10% and normal THP by 60 +/- 6% (P = 0.028). In the presence of calcium, increasing THP concentrations from 16 to 28 and 40 mg/l progressively lowered inhibition by RCSF-THP, but not by N-THP. At 40 mg/l, inhibition by N-THP was 27 +/- 9% vs. -43 +/- 8% by RCSF-THP (P = 0.001), i.e., all stone former THP promoted Ac. With an additional 3.5 mM of citrate, inhibition of Ac was 56 +/- 5% by normal and 34 +/- 6% by stone former THP (P = 0.021), and all seven stone former THP again inhibited Ac. Vi of RCSF-THP was higher than that of N at basal conditions (162 +/- 21 vs. 93 +/- 15 ml/g, P = 0.021) and in the presence of 5 mM calcium (352 +/- 54 vs. 118 +/- 17 ml/g, P = 0.001), i.e., RCSF-THP were more self-aggregated, but not when citrate was added (185 +/- 29 vs. 123 +/- 19 ml/g). (ABSTRACT TRUNCATED AT 250 WORDS)

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Daily Green Tea Infusions in Hypercalciuric Renal Stone Patients: No Evidence for Increased Stone Risk Factors or Oxalate-Dependent Stones

Nutrients ◽

10.3390/nu11020256 ◽

2019 ◽

Vol 11 (2) ◽

pp. 256 ◽

Cited By ~ 5

Author(s):

Julie Rode ◽

Dominique Bazin ◽

Arnaud Dessombz ◽

Yahia Benzerara ◽

Emmanuel Letavernier ◽

...

Keyword(s):

Risk Factors ◽

Calcium Oxalate ◽

Green Tea ◽

Calcium Oxalate Monohydrate ◽

Infrared Analysis ◽

Metabolic Evaluation ◽

Stone Composition ◽

Calcium Oxalate Dihydrate ◽

Cross Sectional ◽

Stone Formers

Green tea is widely used as a ‘’healthy’’ beverage due to its high level of antioxidant polyphenol compounds. However tea is also known to contain significant amount of oxalate. The objective was to determine, in a cross-sectional observational study among a population of 273 hypercalciuric stone-formers referred to our center for metabolic evaluation, whether daily green tea drinkers (n = 41) experienced increased stone risk factors (especially for oxalate) compared to non-drinkers. Stone risk factors and stone composition were analyzed according to green tea status and sex. In 24-h urine collection, the comparison between green tea drinkers and non-drinkers showed no difference for stone risk factors such as urine oxalate, calcium, urate, citrate, and pH. In females, the prevalence of calcium oxalate dihydrate (COD) and calcium phosphate stones, assessed by infrared analysis (IRS) was similar between green tea drinkers and non-drinkers, whereas prevalence of calcium oxalate monohydrate (COM) stones was strikingly decreased in green tea drinkers (0% vs. 42%, p = 0.04), with data in accordance with a decreased oxalate supersaturation index. In males, stone composition and supersaturation indexes were similar between the two groups. Our data show no evidence for increased stone risk factors or oxalate-dependent stones in daily green tea drinkers.

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