Source of a micro-nutrient in a semi-synthetic basal diet as a causative factor in inducing urinary calculi in rats and its inhibition by PSC 833, a potent inhibitor of P-glycoprotein

We report a serendipitous finding of urinary calculi in rats fed a semi-synthetic basal diet. This observation was made during ongoing studies to evaluate the inhibitory effect of PSC 833, a potent inhibitor of P-glycoprotein, on development of tumors in rodent tumor model systems. A large number of specific-pathogen-free (SPF) female Sprague-Dawley and SPF male Fischer 344 rats being fed the diet were euthanized when it became evident clinically that they were uremic. At necropsy, the renal pelvis, ureters, and urinary bladder contained numerous calculi. The presence of urinary calculi was determined to be related to the source of a Food Chemical Codex grade of choline bitartrate. Rats being fed the same basal diet containing the United States Pharmacopia grade of choline bitartrate failed to develop urinary calculi. Interestingly, rats treated with the P-glycoprotein inhibitor were at significantly reduced risk of developing urinary calculi. This finding highlights how something seemingly innocuous as a minor dietary constituent can have a profound impact and, thereby, affect experimental outcome.     

Struvite Urolithiasis in Long–Evans Rats

Struvite urinary calculi, which are composed of magnesium, ammonium, and phosphate, can cause complications including sepsis and renal failure. Struvite calculi were identified within the urinary bladder and renal pelvis of 2 Long-Evans rats that died within days after arrival from a commercial vendor. The remaining rats in the shipment were screened by physical examination, radiography, and ultrasonography, revealing an additional 2 animals that were clinically affected. These rats were euthanized, necropsied, and yielded similar findings to those from the first 2 rats. In addition, urine samples had an alkaline pH and contained numerous bacteria (predominantly Proteus mirabilis), leukocytes, and crystals. All calculi were composed completely of struvite. Another 7 rats in the shipment had alkaline urine with the presence of blood cells; 6 of these rats also had abundant struvite crystals, and P. mirabilis was cultured from the urine of 3 rats. Further investigation by the vendor identified 2 of 100 rats with struvite calculi from the same colony. Although no specific cause could be implicated, the fact that all the affected rats came from the same breeding area suggests a genetic or environmental triggering event; a contribution due to diet cannot be ruled out. Our findings suggest that the affected rats had metabolic disturbances coupled with bacterial infection that predisposed them to develop struvite calculi. During sudden increases of struvite urinary calculi cases in rats, urine cultures followed by appropriate surgical intervention and antibiotic therapy is warranted. Additional factors, including diet, merit attention as well.Struvite, also known as triple phosphate, is a crystalline substance composed of magnesium ammonium phosphate (MgNH₄PO₄• 6 H₂0)¹⁰ that was first identified in the 18th century. This mineral is what consolidates into urinary calculi, or stones, both in humans and animals. Other frequently encountered types of urinary stones include calcium oxalate, calcium phosphate, uric acid, and cysteine.¹⁷ Although only 2% to 3% of stones from humans are composed of struvite,⁴³ struvite calculi are important clinically because they can lead to sepsis and renal failure.⁴³In both humans and animals, stones in the urinary tract can obstruct the urine outflow, with subsequent extreme pain, hydronephrosis, and (possibly) rupture of the urinary bladder. In addition, disruption of kidney function can lead to metabolic imbalances, such as uremia, seizures, depression, anorexia, dehydration, even coma and death.^1,8 Here we present a case study describing the spontaneous presentation of struvite urolithiasis in a recently imported cohort of rats and related significant clinical findings.     

Experimental oxalate urolith formation in rats.

Urinary calculi composed of calcium oxalate were produced in male hooded Wistar rats fed a vitamin B6 deficient diet over 16 weeks. This basic diet was modified by doubling the phosphate content or loading with vitamin C or D3 in three treatment groups. The number of rats developing oxalate stones was not altered by the addition of vitamin D3 or phosphate, but there was a significant increase in total weight of stone formed and histological evidence of extensive renal damage in rats on the high vitamin D3 diet. The addition of vitamin C to the vitamin B6 deficient rats resulted in a reduction in the number of rats with uroliths and a fall in urinary oxalate excretion, while similarly loaded vitamin B6 supplemented controls were free of oxalate calculi. It is concluded that the oxalate urolithiasis induced by vitamin B6 deficiency was exacerbated by added vitamin D3 and reduced by vitamin C.     

Effect of citrate feeding on free radical induced changes in experimental urolithiasis.

Feeding calculi producing diet (CPD) to rats for 4 weeks produced calcium oxaltate stones. Supplementation of sodium citrate to CPD (c-CPD) prevented stone formation. Except oxalate, the excretion of calcium, phosphorus and magnesium was restored to normal in c-CPD fed rats. The CPD fed rats exhibited increase in glycolic acid oxidase (GAO) and lactate dehydrogenase (LDH) activities and only GAO activity was partially restored in c-CPD fed rats. Kidney sub-cellular fractions of calculi producing diet (CPD) fed rats showed increased susceptibility for lipid peroxidation in presence of promotors. Antioxidant enzyme activities of superoxide dismutase (SOD), catalase and glutathione peroxidase and antioxidant concentrations of reduced glutathione, total thiols, ascorbic acid and vitamin E were significantly decreased while the xanthine oxidase activity, and concentrations of hydroxyl radical, diene conjugates and hydroperoxides were significantly increased in CPD fed rats. The susceptibility to lipid peroxidation, activities of antioxidant enzymes, and the concentration of antioxidants were not normalized by feeding citrate.     

Lipids changes in rat tissues in experimental urolithiasis

Total lipids, free and ester cholesterol, triglyceride and phospholipids were determined in plasma, liver, kidney and intestine in control and calculi producing diet (CPD) fed rats. Cholesterol, phospholipids and triglycerides were increased in plasma while they were decreased in all the three tissues of CPD fed rats, compared to that of control. Distribution studies of phospholipids in the tissues of treated rats showed marked decrease in the concentration of the major lipids, i.e., PC, PE, PI and SPH. However, significant increase in absolute concentration as well as percent distribution of phosphatidic acid in kidney of treated rats was observed.     

侧卧位经皮肾微造瘘输尿管镜下取石治疗上尿路结石56例报道

目的:探讨侧卧位施行经皮肾微造瘘输尿管镜下取石(MPCNL)治疗上尿路结石方法及疗效。方法:回顾分析56例上尿路结石侧卧位施行PCNL治疗的临床资料,其中肾铸形结石33例,输尿管上段结石23例。结果:56例均手术成功,无穿刺失败或中转开放手术。一次结石取净率80%,两次手术合计达96%。术中均无输血,无肠道损伤等并发症。结论:侧卧位施行MPCNL手术患者易耐受,手术更安全,术中碎石易排出。效果良好。     

超声诊断对输尿管结石的临床价值探讨

目的探讨超声诊断输尿管结石的临床价值,并对其声像图进行分析。方法分析我院2008年1月-2009年6月确诊的21例输尿管结石患者的超声声像图及诊断符合率情况。结果21例输尿管结石中超声确诊19例,诊断符合率90．48％。结论超声诊断输尿管结石具有方便、无创,诊断符合率高,值得临床推广和应用。     

Asian small-clawed otter (Aonyx cinerea) urolithiasis prevalence in North America

The prevalence of urolithiasis in the North American Asian small-clawed otter (Aonyx cinerea) population was determined through a retrospective survey. A questionnaire regarding diet and radiographic or necropsy evidence of urolithiasis was sent to the 16 North American institutions or individuals listed in the Asian Small-Clawed Otter North American Regional Studbook. Completed forms were returned by 75% of questionnaire recipients. Individual surveys or necropsy reports were received for 79.8% of the living or dead animals listed as comprising the North American population. Renal calculi were detected in 66.1%, and cystic calculi in 23.2%, of the captive adult population that had been radiographed or necropsied. All otters with cystic calculi also had renal calculi. Bilateral renal calculi occurred in 83.8% of affected otters. Both males (61.2%) and females (72%) were frequently affected. The prevalence of urolithiasis in wild-born otters was 76.7%, and in adult (≥1 year) captive-born otters it was 53.8%. The higher prevalence in wild-born otters may be a reflection of the older mean age at which they were first evaluated. In the overwhelming majority of otters with renal calculi, the calculi were multiple and diffusely distributed throughout the renal parenchyma. Renal and cystic calculi analyzed were primarily composed of calcium oxalate or urates. Glucosuria was infrequently reported. Necropsies of dependent neonates (≤ 2 months old) that died revealed cystic calculi in one animal. Renal disease was the cause of, or a contributing factor in, the deaths of all older animals whose necropsy reports were reviewed. The captive diet may be a contributing factor to urolith formation and progression.     

Drug-induced urinary calculi

Urinary calculi may be induced by a number of medications used to treat a variety of conditions. These medications may lead to metabolic abnormalities that facilitate the formation of stones. Drugs that induce metabolic calculi include loop diuretics; carbonic anhydrase inhibitors; and laxatives, when abused. Correcting the metabolic abnormality may eliminate or dramatically attenuate stone activity. Urinary calculi can also be induced by medications when the drugs crystallize and become the primary component of the stones. In this case, urinary supersaturation of the agent may promote formation of the calculi. Drugs that induce calculi via this process include magnesium trisilicate; ciprofloxacin; sulfa medications; triamterene; indinavir; and ephedrine, alone or in combination with guaifenesin. When this situation occurs, discontinuation of the medication is usually necessary.     

Restoration of antioxidants in liver by methionine feeding in experimental rat urolithiasis.

The effect of methionine or citrate on antioxidant defense system has been studied in urolithic rat. Liver weight and its protein concentration did not change in the rats fed with calculi producing diet (CPD) when compared to normal diet fed rats. Feeding rats along with citrate (c-CPD) or methionine (m-CPD) improved their body weight gain. Liver microsomes and mitochondria fractions of CPD and c-CPD fed groups showed increased susceptibility for lipid peroxidation in presence of ascorbate and t-butyl hydroperoxide when compared to either control or m-CPD fed groups. Increased superoxide dismutase and xanthine oxidase activities, decreased catalase, glutathione peroxidase and glucose-6-phosphate dehydrogenase activities, decreased concentrations of reduced glutathione, total thiols, ascorbic acid and vitamin-E and increased formation of hydroxyl radical, hydroperoxides and diene conjugates were observed in the liver of both CPD fed group as well as c-CPD fed group. Except SOD and xanthine oxidase, all other parameters were normalized in m-CPD fed group. This suggested that feeding methionine reduced the susceptibility for lipid peroxidation by restoration of the level of free radical scavengers.     

Prevalence of renal urolithiasis in a large, captive white-tailed deer herd

Prevalence of renal urolithiasis in a large, captive white-tailed deer (Odocoileus virginianus) herd was examined over a two-year period of time. In 1973, 1.3% of 225 deer examined had calculi in the renal pelvis and 4.4% had kidney lesions, either independent or in combination with the calculi. In 1974, prevalence increased and 5.9% of 354 deer had calculi and 6.5% had kidney lesions. Calculi and lesions affected all sex and age-classes. Involvement was both unilateral and bilateral with 23.8% having stones in both kidneys and 30.4% having lesions in both kidneys. Lesions and calculi occurred together in 42.8% of cases. Etiology is unknown, but possible relationships are discussed.     

Urolithiasis associated with experimental lymphocytic choriomeningitis virus inoculation in Lewis rats

A high frequency of struvite urolithiasis, hydronephrosis, and other urinary tract lesions developed in a group of Lewis rats inoculated intracranially with lymphocytic choriomeningitis virus (LCMV). Initially, clinically ill rats were referred to necropsy: 30 rats over 3 years. These rats had high frequency of urolithiasis (8/30, 27%), hydronephrosis (12/30, 40%), cystitis (9/30, 30%), transitional cell carcinoma (4/30, 13%), and pyelonephritis (19/30, 63%). Lesions were more common in LCMV-inoculated rats. After this trend was noted, all rats on this protocol were necropsied as part of a cohort study (n = 144). Although the apparent frequency of disease was lower due to increased sampling, there still was a high number of urolithiasis (9/144, 6%) and hydronephrosis (40/144, 28%) cases. All cases of urolithiasis developed in rats inoculated with LCMV (9/44, 20%), as did most cases of hydronephrosis (31/44, 70%). Although sham-injected and uninoculated control rats also had high frequency of hydronephrosis (6/57 [11%] and 3/43 [7%], respectively), LCMV-inoculated rats had a significantly higher frequency of disease than did sham inoculated (P < 0.0001) and uninoculated (P < 0.0001) controls. These results suggest that Lewis rats may be predisposed to developing lesions of the urinary tract, and that intracranial inoculation of rats with LCMV augments this tendency, leading to formation of struvite calculi and associated urinary tract disease.     

钙敏感受体(CaSR)基因986、990多态性与尿石症的相关性研究

目的:探讨钙敏感受体(Ca SR)基因单核昔酸多态性与泌尿系结石的关系。方法:选取90例黑龙江地区的泌尿系结石患者及90例健康对照者外周血标本中的基因组DNA,采用PCR(聚合酶链反应)结合DNA测序,检测并分析Ca SR基因的单核苷酸多态性位点的分布。结果:泌尿系结石组和对照组Ca SR基因第986位、990位频率分布符合Hardy-Weinberg定律,其基因型分布频率在泌尿系结石患者和健康对照者中差异无统计学意义(P0.05),但在泌尿系结石患者组内Ca SR第990位GG纯合子和RG杂合子出现频率明显偏高,差异有统计学意义(P0.05)。结论:Ca SR基因第7外显子第986、990多态性位点与泌尿系结石的形成无直接相关性,但第7外显子第990位A/G单核苷酸多态性可能与泌尿系结石的形成密切相关。     

Methionine feeding prevents kidney stone deposition by restoration of free radical mediated changes in experimental rat urolithiasis

Feeding calculi producing diet (CPD) to rats for 4 weeks produced calcium oxalate stones deposition. Supplementation of methionine to CPD (m-CPD) prevented the stone deposition. However the urine pH and excretion of oxalate and calcium in m-CPD-fed rats was still as high as in CPD-fed groups compared to that of the control group. The CPD-fed rats exhibited an increase in liver oxalate synthesizing enzymes and glycolic acid oxidase (GAO) and lactate dehydrogenase (LDH), and these activities were not restored in m-CPD-fed rats. Similarly, the elevated LDH activity and oxalate concentration observed in the kidney of CPD-fed rats were not restored by methionine supplementation. Kidney sub-cellular fractions of CPD-fed rats showed increased susceptibility for lipid peroxidation in presence of iron, ascorbate, and t-butyl hydroperoxide. Antioxidant enzyme activities of superoxide dismutase (SOD), catalase, and glutathione peroxidase and antioxidant concentrations of reduced glutathione, total thiols, ascorbic acid, and vitamin E were significantly decreased, while the xanthine oxidase activity and concentrations of hydroxyl radical, diene conjugates, and hydroperoxides were significantly increased in CPD-fed rats. The susceptibility to lipid peroxidation, activities of antioxidant enzymes, and the concentration of antioxidants were normalized in m-CPD—fed rats, thus suggesting that methionine feeding prevents the stone formation by neutralizing the free radical induced changes.     

80例血液透析患者上尿路结石患病率及危险因素分析

摘要 目的：分析血液透析患者上尿路结石的患病率及其危险因素,为早期干预提供依据。方法：回顾性分析2017年1月至2018年12月我院肾内科收治的CKD 5期持续性血液透析患者（血液透析组）上尿路结石的患病情况,并与健康体检者80名（对照组,n=80）、CKD1~3期患者（非血液透析组,n=80）进行比较。比较血液透析患者中结石和非结石者人口学资料、血清白蛋白、血糖、血脂、肾功能等生化指标,并记录二者透析时间及24 h尿量。采用多因素logistic回归分析上尿路结石的患病情况的危险因素。结果：血液透析组上尿路结石患病率为25.0%,显著高于非血液透析组13.8%、对照组10.0%(P<0.05);非血液透析组、对照组上尿路结石患病率比较,差异无统计学意义(P>0.05)。结石与非结石患者在性别、透析时间、TG、TC、UA、ALB、24 h尿量方面比较,差异均有统计学意义（P<0.05）。多因素logistic回归分析显示,透析时间、UA、TC是血液透析患者发生上尿路结石的独立危险因素,而ALB则是保护性因素（P<0.05）。结论：血液透析患者上尿路结石的患病率较高,对血脂代谢异常、高血UA、低血清ALB及长期透析者应早期筛查,并纠正脂代谢紊乱和低蛋白血症。     

Urinary calculi in Lewis and Wistar rats

A high incidence (8/892) of urinary tract calculi was encountered during a study involving rats being fed diets supplemented with retinoids. When the incidence was compared to that observed in earlier studies without retinoid supplements and spanning several years (2/2998), the incidence in the current study was significantly higher. Possible causative factors such as age, sex, strain, diet and carcinogen or retinoid treatment have been analyzed without a clear explanation for the increased incidence. The data suggest that retinoid treatment increased the risk of stone formation, but that retinoids were less important than some other unidentified factor(s) that operated during the recent period.     

胆道镜结合微爆破碎石治疗复杂性胆道结石

目的:探讨微爆破碎石用于治疗复杂胆道结石的治疗体会。方法:在胆道镜直视下,分别在术中和术后对158例复杂的胆道结石患者进行微爆破碎石,然后用取石网取出碎石,泥沙状结石随液体流出或让其自行流入肠道。结果:158例患者156例取石成功。取石成功率98.73%。明显提高了胆道取石的成功率。无1例出现胆道穿孔、瘘道穿孔及胆道出血等严重并发症。结论:在胆道镜下,采用微爆破碎石术治疗复杂的胆道结石是一种安全、可靠、高效的方法,可以明显提高结石的取净率。     

胆道镜结合微爆破碎石治疗复杂性胆道结石

目的：探讨微爆破碎石用于治疗复杂胆道结石的治疗体会。方法：在胆道镜直视下,分别在术中和术后对158例复杂的胆道结石患者进行微爆破碎石,然后用取石网取出碎石,泥沙状结石随液体流出或让其自行流入肠道。结果：158例患者156例取石成功。取石成功率98.73%。明显提高了胆道取石的成功率。无1例出现胆道穿孔、瘘道穿孔及胆道出血等严重并发症。结论：在胆道镜下,采用微爆破碎石术治疗复杂的胆道结石是一种安全、可靠、高效的方法,可以明显提高结石的取净率。     

Urolithiasis in ferrets (Mustela putorius).

Urinary calculi was observed frequently in ferrets which were from a group used for influenza research. They were submitted for necropsy with various clinical signs. The calculi were composed of magnesium ammonium phosphate hexahydrate and were found in the pelvis of the kidney, urinary bladder and urethra. Crystals of undetermined nature occasionally were observed in the kidneys.