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 μg/mg·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 μg/mg·h and 0.35 ± 0.05 μg/mg·h, respectively). Under pH = 6.5 hypercalciuria conditions, large amounts of COD, COM, hydroxyapatite and brushite crystals formed (growth rate = 3.87 ± 0. 34 μg/mg·h). A study of three crystallization inhibitors demonstrated that phytate completely inhibited fragment growth (2.27 μM at pH = 5.5 and 4.55 μM at pH = 6.5, both under hypercalciuria conditions), while 69.0 μM 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

Metabolic diagnosis and medical prevention of calcium nephrolithiasis and its systemic manifestations: a consensus statement

Background: Recently published guidelines on the medical management of renal stone disease did not address relevant topics in the field of idiopathic calcium nephrolithiasis, which are important also for clinical research. Design: A steering committee identified 27 questions, which were proposed to a faculty of 44 experts in nephrolithiasis and allied fields. A systematic review of the literature was conducted and 5216 potentially relevant articles were selected; from these, 407 articles were deemed to provide useful scientific information. The Faculty, divided into working groups, analysed the relevant literature. Preliminary statements developed by each group were exhaustively discussed in plenary sessions and approved. Results: Statements were developed to inform clinicians on the identification of secondary forms of calcium nephrolithiasis and systemic complications; on the definition of idiopathic calcium nephrolithiasis; on the use of urinary tests of crystallization and of surgical observations during stone treatment in the management of these patients; on the identification of patients warranting preventive measures; on the role of fluid and nutritional measures and of drugs to prevent recurrent episodes of stones; and finally, on the cooperation between the urologist and nephrologist in the renal stone patients. Conclusions: This document has addressed idiopathic calcium nephrolithiasis from the perspective of a disease that can associate with systemic disorders, emphasizing the interplay needed between urologists and nephrologists. It is complementary to the American Urological Association and European Association of Urology guidelines. Future areas for research are identified

Internet Daters’ Body Type Preferences: Race–Ethnic and Gender Differences

Employing a United States sample of 5,810 Yahoo heterosexual internet dating profiles, this study finds race–ethnicity and gender influence body type preferences for dates, with men and whites significantly more likely than women and non-whites to have such preferences. White males are more likely than non-white men to prefer to date thin and toned women, while African-American and Latino men are significantly more likely than white men to prefer female dates with thick or large bodies. Compatible with previous research showing non-whites have greater body satisfaction and are less influenced by mainstream media than whites, our findings suggest Latinos and African Americans negotiate dominant white idealizations of thin female bodies with their own cultures’ greater acceptance of larger body types

Raised transmembrane oxalate flux in red blood cells in idiopathic calcium oxalate nephrolithiasis.

Red-blood-cell transmembrane oxalate flux was measured in a group of patients with idiopathic calcium oxalate nephrolithiasis and in normal controls. The mean transmembrane oxalate flux rate was significantly higher in stone-forming patients than in controls (0.93 +/- SD 0.31/min vs 0.29 +/- 0.11/min). 80% of stone-forming patients showed raised (greater than 2SD above the mean in controls) transmembrane oxalate flux. Anomalous cellular oxalate transport may be an important pathogenetic factor in calcium oxalate nephrolithiasis

[Abnormalities in the erythrocyte membrane transport of oxalate in calcium oxalate lithogenesis].

The high incidence of a family history and the observation of abnormally high intestinal absorption and urinary excretion of oxalate suggest to consider idiopathic calcium oxalate nephrolithiasis as a metabolic disease characterized by a disorder in oxalate transport. To test this hypothesis, the flux of 14C Oxalate through the membrane of red blood cells was investigated in 24 calcium oxalate stone formers; 18 of the 24 "idiopathic" calcium oxalate stone formers showed an increased oxalate self exchange (75%). Our data seem to support the possibility that "idiopathic" calcium oxalate nephrolithiasis may be considered as a metabolic disease marked by a defect in transmembrane transport of oxalate