A polymorphism of matrix Gla protein gene is associated with kidney stones

PURPOSE: Matrix Gla protein, a potent calcification inhibitor in arterial vessels, is also expressed in the kidney and is up-regulated following the administration of ethylene glycol, a precursor of oxalate. Considering the analogous characteristics between arterial calcification and kidney stones, we identified variants of the human matrix Gla protein gene and investigated whether there is an association between MGP genetic polymorphisms and kidney stones. MATERIALS AND METHODS: We studied single nucleotide polymorphisms in matrix Gla protein in 122 kidney stone cases and 125 controls. We resequenced the human genomic MGP gene, including the 1,000 bp promoter 5'-untranslated region, 4 exons and 3'-untranslated regions, and we performed systematic genetic analysis. A single nucleotide polymorphism was genotyped using a fluorescent 5'endonuclease assay and its association with kidney stones was analyzed. RESULTS: We observed 19 polymorphisms. A single nucleotide polymorphism was associated with kidney stones (OR 0.51, 95% CI 0.30-0.87; p = 0.012). The G allele carrier had a 2-fold decreased kidney stone risk compared with A allele carriers in single nucleotide polymorphism 11 (OR 0.55, 95% CI 0.31-1.00, p = 0.047). We found no association between the polymorphism and kidney stone clinical characteristics. CONCLUSIONS: Our findings show that an MGP gene polymorphism is associated with kidney stones and influences genetic susceptibility to kidney stones. In the future functional assays of the polymorphism should permit better understanding of the role of matrix Gla protein genetic variants and kidney stones.     

Calcitonin receptor gene polymorphism: a possible genetic marker for patients with calcium oxalate stones.

OBJECTIVES: The formation of urinary stones is hypothesized to be associated with calcitonin receptors. The most commonly seen polymorphism is C/T at the 1377th nucleotide. Hence, these polymorphisms are being used as a genetic marker in the search for the cause of urolithiasis. METHODS: A normal control group of 105 healthy people and 102 patients with recurrent calcium oxalate stones were examined. The polymorphism was detected following a polymerase chain reaction-based and restriction analysis by AluI. An uncuttable length is 228 bp (CC) whereas two fragments of 120 and 108 bp are shown as cuttable lengths (TT). RESULTS: The results revealed significant differences between the normal individuals and the stone patients (p<0.01). The distribution of leucine (cuttable) homozygote in the stone group (2.0%) was higher than in the control group (0.0%). The odds ratio for the leucine allele of the calcitonin receptor gene in calcium oxalate stone disease is 5.634 (95% CI: 2.286--13.885). CONCLUSIONS: Results show that the polymorphism in the calcitonin receptor gene could be a genetic marker for urinary stone disease and therefore it is worthwhile pursuing further studies of the leucine allele of calcitonin receptor gene due to it is strongly correlated with stone disease.     

A coding polymorphism in the 12-lipoxygenase gene is associated to essential hypertension and urinary 12(S)-HETE

The arachidonic acid-derived metabolite 12-(S)hydroxyeicosatetraenoic acid (12(S)-HETE), catalyzed by 12-lipoxygenase (12-LOX, ALOX12), exhibits a variety of biological activities with implications in cardiovascular disease. Previous studies have shown higher urinary excretion of this metabolite in essential hypertension. The aim of this study was to analyze the association of polymorphisms in ALOX12 with hypertension and urinary levels of 12(S)-HETE. We studied 200 patients with essential hypertension (aged 56+/-1 years, mean+/-s.e.m., 97 males) and 166 matched controls (aged 54+/-1 years, 91 males). Out of six polymorphisms in the coding region of ALOX12, only R261Q determined a nonconservative amino-acid change and was evaluated by polymerase chain reaction and restriction digestion. Urinary 12(S)-HETE was measured in Sep-Pack-extracted samples using specific enzyme-linked immunosorbent assay. The distribution of genotypes of the R261Q polymorphism was significantly different between patients and controls: patients 92 (0.46) GG, 84 (0.42) GA, 24 (0.12) AA vs controls 56 (0.34) GG, 78 (0.47) GA, 32 (0.19) AA (P=0.030). On the contrary, no association was observed for two intronic polymorphisms. The urinary excretion of 12(S)-HETE (ng/mg creatinine) was significantly higher in GG homozygous patients (13.0+/-1.5) than in GA (8.2+/-1.8) or in AA (8+/-1.5) patients (P=0.018). These results indicate that a nonsynonymous polymorphism in ALOX12 is associated to essential hypertension and to urinary levels of 12(S)-HETE, thus suggesting a role for this gene in this disease.     

Hydrochlorothiazide compared to chlorthalidone in reduction of urinary calcium in patients with kidney stones

Prevention of recurrent calcium stone disease includes treatment with thiazide and thiazide-type diuretics to reduce urinary calcium (UCa) levels, with the reduction in UCa correlating with risk of stone recurrence. There has been a recent trend of using lower doses of these medications and change from chlorthalidone (CTL) use to hydrochlorothiazide (HCTZ) use. It is unknown whether low doses of HCTZ are effective in lowering UCa levels to target levels. We hypothesize that HCTZ is associated with less reduction in UCa than is CTL when comparing currently used doses. Retrospective observational study of stone-formers was seen in metabolic stone clinic during a 3 years period. Data included patient demographics, co-morbidities, and 24 h urine electrolyte composition. Primary outcome was the change in 24 h UCa. 322 patients were identified with 112 meeting criteria and used in analysis. The majority were placed on HCTZ (n = 42) or CTL (n = 47) 25 mg QD. Patients on CTL 25 mg had a greater reduction in UCa (164 mg; 41 %) than those on HCTZ (85 mg; 21 %), p = 0.01. Neither CTL nor HCTZ at 12.5 mg QD significantly lowered UCa. There was a decrease in serum [K] of 0.5 Meq/L (p = 0.001) in patients on CTL 25 mg daily, but no significant difference in severe hypokalemia or arrhythmia compared to HCTZ. Our data show that CTL is associated with greater reduction in 24 h UCa compared to similarly dosed HCTZ.     

Vickers hardness studies of calcium oxalate monohydrate and brushite urinary stones

PURPOSE: To measure the hardness of two types of urinary stones: calcium oxalate monohydrate (COM; CaC2O4 . H2O) and dicalcium phosphate dihydrate (brushite; CaHPO4 . 2H2O). MATERIALS AND METHODS: The composition of 28 calcium oxalate monohydrate and 22 brushite stones was characterized by infrared spectroscopy (FT-IR). Stone specimens were embedded in crystallographic resin, polished, and subjected to indentation tests using a Vickers tester. The hardness was calculated from measuring the diagonal lengths of the residual indentation on the specimen using the appropriate equation. RESULTS: The COM stones showed hardness values ranging from 15.3 to 64.2 HV with a mean of 35.8 +/- 13.3, while brushite stones ranged from 10.1 to 46.1 HV with a mean of 26.5 +/- 15.1. The results of ANOVA showed that there were significant differences (P < 0.05) between the two stone types. CONCLUSIONS: Calcium oxalate monohydrate stones exhibited greater hardness than brushite stones when assessed with Vickers studies.     

Elevated urinary albumin excretion is not linked to the angiotensin I-converting enzyme gene polymorphism in clinically healthy subjects

An elevated urinary albumin excretion (UAE) in non-diabetic subjects without renal or cardiovascular disease has been shown to be predictive of ischaemic heart disease. An insertion (I)/deletion (D) polymorphism in the angiotensin I-converting enzyme (ACE) gene has been identified and the D allele may be associated with cardiovascular disease. The aim of this study was to find a potential linkage between this polymorphism and elevated UAE. For studies of UAE and cardiovascular pathophysiology, a highly selected population sample has been identified comprising all clinically healthy subjects aged 40-65 years with elevated UAE in a dipstick negative urinary sample (n = 27) from The Copenhagen City Heart Study. Neither the ACE genotype distribution (p = 0.12) nor the D and I allele frequencies (p = 0.69) differed significantly between subjects with elevated UAE and a matched normoalbuminuric control group (n = 46). Elevated UAE in clinically healthy subjects is not linked to the ACE gene polymorphism.     

Klotho基因多态性与新疆地区维吾尔族特发性草酸钙肾结石的相关性研究

目的:探讨Klotho基因rs1207568与新疆地区维吾尔族特发性草酸钙肾结石的相关性。方法:选择400例维吾尔族草酸钙肾结石患者(病例组)和410例维吾尔族健康体检者(对照组),应用SNaPshot方法对Klotho基因rs1207568进行基因检测,并分析其与特发性草酸钙肾结石发病的相关性以及对血脂、血生化的影响。结果:对照组的基因型分布均符合Hardy-Weinberg平衡。病例组和对照组rs1207568基因型比较差异有统计学意义(P<0.01),且病例组携带等位基因C的风险高于对照组(OR=1.295,95%CI:1.019～1.645,P<0.05)。CC基因型患者的血钙、血磷、血氯、尿素氮、尿酸均高于CT+TT基因型,差异有统计学意义(P<0.05),而二者血镁、血钾、血钠水平比较差异无统计学意义。在血脂方面,二者甘油三酯(TG)、总胆固醇(TC)比较差异有统计学意义(P<0.05)。结论:Klotho基因rs1207568在维吾尔族人群中与特发性草酸钙肾结石发病风险显示有相关性,rs1207568C等位基因是其危险因素。     

Vascular endothelial growth factor gene polymorphism is associated with calcium oxalate stone disease

Growth factor-related genes regulate cell growth, differentiation and apoptosis in the kidney in response to cellular injury. One of the theories of stone formation is that cellular injury, and thus growth factors, play a role. We therefore investigated the association between growth factor genes and calcium oxalate stone disease. The most frequently seen polymorphism of the vascular endothelial growth factor (VEGF) gene is Bst U I C/T, which is located upstream at the -460th nucleotide. Other growth factor-related gene polymorphisms include the cytochrome P450c17alpha enzyme (CYP17) gene MspA I C/T polymorphism at the 5'-UTR promoter region, the epidermal growth factor receptor (EGFR) gene Bsr I polymorphism (A to T) at position 2,073, and the insulin-like growth factor-2 (IGF-2) gene Apa I A/G at exon 9. All four polymorphisms were used as genetic markers in this study in the search for an association between stone disease and growth factor related genes. A normal control group of 230 healthy people, and 230 patients with calcium oxalate stone, were examined. The polymorphism was seen following polymerase chain reaction based restriction analysis. The result revealed a significant difference between normal individuals and stone patients (P=0.0003, Fisher's exact test) in the distribution of the VEGF gene polymorphism as well as an odds ratio of 1.30 (95% confidence interval=0.993-1.715) per copy of the "T" allele. Whereas, the IGF-2, EGFR and CYP17 gene polymorphisms did not reveal a significant association with stone disease. We conclude that the VEGF gene Bst U I polymorphism is a suitable genetic marker of urolithiasis.     

Two cases of ammonium acid urate urinary stones related to anorexia nervosa and laxative abuse

We report two cases of urolithiasis related to anorexia nervosa and laxative abuse. Case 1: A 21-year-old woman was referred to our hospital because of left flank pain. A left ureteral stone, 10 x 6 mm in size, was successfully fragmented by extracorporeal shock-wave lithotripsy (ESWL), but she experienced repetitive formation of bilateral urinary stones and double J stent encrustation which required 13 sessions of ESWL, one session of transurethral ureterolithotripsy and one session of cystolithotripsy over a period of 5 years. All stones were comprised of pure ammonium acid urate. It was later revealed that she was diagnosed with anorexia nervosa at 15 years old and had suffered from laxative abuse (bisacodyl, 300-500 mg/day) ever since. Case 2: A 18-year-old woman was referred to our hospital because of left lower abdominal pain. A left renal stone, 15 x 10 mm in size, was successfully fragmented by ESWL, but she had double J stent encrustation which was managed by cystolithotripsy. All stones were comprised of pure ammonium acid urate. She was later diagnosed with anorexia nervosa and it turned out that she had suffered from an eating disorder and laxative abuse (bisacodyl, 200 mg/day) since the age of 15 years. Both patients had marked decrease in urine volume, hyponatremia and hypokalemia. Anorexia nervosa and laxative abuse should be suspected whenever a woman has an ammonium acid urate stone in sterile urine because the treatment of these disorders is crucial to the prevention of repetitive formation of urinary stones.     

Osteocalcin gene Hind III polymorphism is not correlated with calcium oxalate stone disease

The formation of urinary stones is presumed to be associated with polymorphism of the osteocalcin gene. The most frequently seen polymorphism is the Hind III type located at the promoter region. This polymorphism has been used as a genetic marker in the search for a correlation between urolithiasis and normal subjects. In our study, a normal control group of 105 healthy people and 102 patients with calcium oxalate stones were examined. The polymorphism was seen following polymerase chain reaction-based restriction analysis. The results revealed no significant differences between normal individuals and stone patients (P=0.978), and distribution of the TT homozygote in the control group (42.9%) was similar to that in the patient group (42.2%). Further categorization of the stone patients into normocalciuric and hypercalciuric groups also revealed no statistical differences from controls. We conclude that Hind III polymorphism of the osteocalcin gene is not a suitable genetic marker of urinary stone disease. Further searches for other polymorphisms on this gene correlated with stone disease are suggested. Received: 25 August 2000 / Accepted: 27 December 2000     

Face-specific incorporation of osteopontin into urinary and inorganic calcium oxalate monohydrate and dihydrate crystals

Our aim was to examine the attachment to, and incorporation of intact, highly phosphorylated osteopontin (OPN) into inorganic (i) and urinary (u) calcium oxalate monohydrate (COM) and dihydrate (COD) crystals. uCOM and uCOD crystals were precipitated from ultrafiltered (UF) urine containing human milk OPN (mOPN) labelled with Alexa Fluor 647 fluorescent dye at concentrations of 0.1–5.0 mg/L. iCOM and iCOD crystals were generated in aqueous solutions at concentrations of 0.01–0.5 mg/L. Crystals were demineralised with EDTA and the resulting extracts analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis and western blotting, or examined by fluorescent confocal microscopy and field emission scanning electron microscopy before and after washing to remove proteins bound reversibly to the crystal surfaces. Binding of mOPN to pre-formed iCOM crystals was also studied in phosphate-buffered saline (PBS) and ultrafiltered (UF) urine. mOPN attached to the {100} faces and to the {010} sides of the {100}/{010} edges of iCOM crystals was removed by washing, indicating that it was not incorporated into the mineral bulk. In both PBS and urine, mOPN was attached to the {021} faces of pre-formed iCOM crystals as well as to the {100}/{010} edges, but was concentrated at the intersection points of the {100} and {121} faces at the crystal tips. Attachment in UF urine appeared to be greater than in PBS and stronger at higher calcium concentrations than lower calcium concentrations. In uCOM crystals, the distribution of fluorescence and patterns of erosion after washing suggested attachment of mOPN to the four end faces, followed by interment within the mineral phase. Fluorescence distributions of mOPN associated with both iCOD and uCOD crystals were consistent with uniform binding of the protein to all equivalent {101} faces and concentration along the intersections between them. Persistence of fluorescence after washing indicated that most mOPN was incarcerated within the mineral phase. We concluded that attachment of mOPN to calcium oxalate crystals is face-specific and depends upon the anatomical and genetic source of the protein and whether the crystals are (1) COM or COD; (2) pre-formed or precipitated from solution, and (3) precipitated from urine or aqueous solutions. Our findings emphasise the need for caution when drawing conclusions about possible roles of OPN or other proteins in urolithiasis from experimental data obtained under inorganic conditions.     

Interleukin-4 gene intron-3 polymorphism is associated with transitional cell carcinoma of the urinary bladder

OBJECTIVE: To evaluate whether polymorphism of the interleukin-4 gene exon 3, and of the interleukin-1beta gene exon 5 and promoter region, are associated with transitional cell carcinoma (TCC) of the urinary bladder, as cytokines are hypothesized to be important in cancer formation. PATIENTS, SUBJECTS AND METHODS: The study included 138 patients with TCC of urinary bladder and 105 healthy controls living in the same area. Each genetic polymorphism was typed using polymerase chain reaction-based restriction analysis. Genotype distribution and allelic frequencies between patients and controls were compared. RESULTS: There were significant differences in genotype and allelic distribution of intron 3 RP1/RP2 polymorphism (P < 0.001), but no significant difference in genotype distribution or allelic frequencies of the interleukin-1beta gene polymorphism between patients with bladder cancer and controls. CONCLUSION: The interleukin-4 gene intron 3 polymorphism is associated with bladder cancer and is a potential genetic marker in screening for the possible causes of bladder cancer.     

The severity of infection stones compared to other stones in the upper urinary tract

A retrospective study of the case records of 391 adult patients with spontaneously passed or surgically removed concrements from the upper urinary tract during the period 1982-1983 was performed. According to chemical analysis, 66% of the stones were calcium stones, 30% were infection stones, 4% were uric acid/urate stones and 1% were cystine stones. Of the infection stones 12 (10%) were staghorn calculi. The infection stones placed a greater strain on the patients than the calcium stones. Thus, infection stones were significantly more often recurrent stones and required surgery significantly more often than the calcium stones. Only 6% of the patients with infection stones had proved abnormalities predisposing to upper urinary tract infection. Urinary tract infection with a urease-producing microorganism was detected in only 52% of the patients with infection stones. As infection with a urease-producing microorganism is a prerequisite for the formation of infection stones in the urinary tract a careful microbiological investigation to find and treat the infection responsible for the stone formation is mandatory.