Inhibitory effect of Incarvillea diffusa Royle extract in the formation of calcium oxalate nephrolithiasis by regulating ROS-induced Nrf2/HO-1 pathway in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Calcium oxalate (CaOx) kidney stones are widely acknowledged as the most prevalent type of urinary stones, with high incidence and recurrence rates. Incarvillea diffusa Royle (ID) is a traditionally used medicinal herb in the Miao Minzu of Guizhou province, China, for treating urolithiasis. However, the active components and the underlying mechanism of its pharmacodynamic effects remain unclear.

AIM OF THE STUDY

This study aimed to investigate the potential inhibitory effect of the active component of ID on the formation of CaOx nephrolithiasis and elucidate the underlying mechanism.

MATERIALS AND METHODS

In vivo, a CaOx kidney stone model was induced in Sprague-Dawley (SD) rats using an ethylene glycol and ammonium chloride protocol for four weeks. Forty-eight male SD rats were randomly assigned to 6 groups (n = 8): blank group, model group, apocynin group, and low, medium, and high dose of ID's active component (IDW) groups. After three weeks of administration, rat urine, serum, and kidney tissues were collected. Renal tissue damage and crystallization, Ox, BUN, Ca2+, CRE, GSH, MDA, SOD contents, and levels of IL-1β, IL-18, MCP-1, caspase-1, IL-6, and TNF-α in urine, serum, and kidney tissue were assessed using HE staining and relevant assay kits, respectively. Protein expression of Nrf2, HO-1, p38, p65, and Toll-4 in kidney tissues was quantified via Western blot. The antioxidant capacities of major compounds were evaluated through DPPH, O2·-, and ·OH radical scavenging assays, along with their effects on intracellular ROS production in CaOx-induced HK-2 cells.

RESULTS

We found that IDW could significantly reduce the levels of CRE, GSH, MDA, Ox, and BUN, and enhancing SOD activity. Moreover, it could inhibit the secretion of TNF-α, IL-1β, IL-18, MCP-1, caspase-1, and decreased protein expression of Nrf2, HO-1, p38, p65, and Toll-4 in renal tissue. Three major compounds isolated from IDW exhibited promising antioxidant activities and inhibited intracellular ROS production in CaOx-induced HK-2 cells.

CONCLUSIONS

IDW facilitated the excretion of supersaturated Ca2+ and decreased the production of Ox, BUN in SD rat urine, and mitigated renal tissue damage by regulating Nrf2/HO-1 signaling pathway. Importantly, the three major compounds identified as active components of IDW contributed to the inhibition of CaOx nephrolithiasis formation. Overall, IDW holds significant potential for treating CaOx nephrolithiasis.

Sodium-Glucose Cotransporter 2 Inhibitors and Nephrolithiasis Risk in Patients With Type 2 Diabetes

Importance

Type 2 diabetes (T2D) is associated with an increased risk of kidney stones. Sodium-glucose cotransporter 2 inhibitors (SGLT2is) might lower the risk of nephrolithiasis by altering urine composition. However, no studies have investigated the association between SGLT2i use and nephrolithiasis risk in patients receiving routine care in the US.

Objective

To investigate the association between SGLT2i use and nephrolithiasis risk in clinical practice.

Design, Setting, and Participants

This new-user, active comparator cohort study used data from commercially insured adults (aged ≥18 years) with T2D who initiated treatment with SGLT2is, glucagon-like peptide 1 receptor agonists (GLP-1RAs), or dipeptidyl peptidase 4 inhibitors (DPP4is) between April 1, 2013, and December 31, 2020. The data were analyzed from July 2021 through June 2023.

Exposure

New initiation of an SGLT2i, GLP-1RA, or DPP4i.

Main Outcomes and Measures

The primary outcome was nephrolithiasis diagnosed by International Classification of Diseases codes in the inpatient or outpatient setting. New SGLT2i users were 1:1 propensity score matched to new users of a GLP-1RA or DPP4i in pairwise comparisons. Incidence rates, rate differences (RDs), and estimated hazard ratios (HRs) with 95% CIs were calculated.

Results

After 1:1 propensity score matching, a total of 716 406 adults with T2D (358 203 pairs) initiating an SGLT2i or a GLP-1RA (mean [SD] age, 61.4 [9.7] years for both groups; 51.4% vs 51.2% female; 48.6% vs 48.5% male) and 662 056 adults (331 028 pairs) initiating an SGLT2i or a DPP4i (mean [SD] age, 61.8 [9.3] vs 61.7 [10.1] years; 47.4% vs 47.3% female; 52.6% vs 52.7% male) were included. Over a median follow-up of 192 (IQR, 88-409) days, the risk of nephrolithiasis was lower in patients initiating an SGLT2i than among those initiating a GLP-1RA (14.9 vs 21.3 events per 1000 person-years; HR, 0.69 [95% CI, 0.67-0.72]; RD, -6.4 [95% CI, -7.1 to -5.7]) or a DPP4i (14.6 vs 19.9 events per 1000 person-years; HR, 0.74 [95% CI, 0.71-0.77]; RD, -5.3 [95% CI, -6.0 to -4.6]). The association between SGLT2i use and nephrolithiasis risk was similar by sex, race and ethnicity, history of chronic kidney disease, and obesity. The magnitude of the risk reduction with SGLT2i use was larger among adults aged younger than 70 years vs aged 70 years or older (HR, 0.85 [95% CI, 0.79-0.91]; RD, -3.46 [95% CI, -4.87 to -2.05] per 1000 person-years; P for interaction <.001).

Conclusions and Relevance

These findings suggest that in adults with T2D, SGLT2i use may lower the risk of nephrolithiasis compared with GLP-1RAs or DPP4is and could help to inform decision-making when prescribing glucose-lowering agents for patients who may be at risk for developing nephrolithiasis.

Association between urinary phthalate metabolites and nephrolithiasis in adults: A cross-sectional analysis with NHANES 2007-2018

Nephrolithiasis is highly prevalent and brings health and economic burdens to patients. The augmentation of nephrolithiasis may be associated with exposure to phthalate metabolites. However, few studies investigated the effect of various phthalates exposure on nephrolithiasis. We analyzed data from 7139 participants aged 20 years or above from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. Serum calcium level-stratified univariate and multivariate linear regression analyses were performed to explore the relationship between urinary phthalate metabolites and nephrolithiasis. As a result, the prevalence of nephrolithiasis was approximately 9.96%. After adjusting for confounding factors, associations were found between serum calcium concentration with monoethyl phthalate (P = 0.012) and mono-isobutyl phthalate (P = 0.003) compared with tertile 1 (T1). In adjusted analysis, nephrolithiasis was positively associated with middle and high tertiles of mono benzyl phthalate (P < 0.05) compare with low tertile group. Furthermore, high-level exposure to mono-isobutyl phthalate had a similar positive association with nephrolithiasis (P = 0.028). Our findings provide evidence that exposure to certain phthalate metabolites (i.e. MiBP and MBzP) may be associated with a high risk of nephrolithiasis depending on serum calcium level.

Gallic acid ameliorates calcium oxalate crystal-induced renal injury via upregulation of Nrf2/HO-1 in the mouse model of stone formation

BACKGROUND

High prevalence and reoccurrence rate of nephrolithiasis bring about serious socioeconomic and healthcare burden, necessitating the need of effective therapeutic agents. Previous study revealed that gallic acid (GAL) alters the nucleation pathway of calcium oxalate (CaOx). On the other hand, it appears protective role against oxidative injury. Whether GAL could protect against crystal-induced lesion in vivo, and its underlying mechanism is yet unsolved.

PURPOSE

This study aims to investigate the protective effects of GAL on the crystal-induced renal injury and its underlying mechanism in the mouse model of stone formation induced by glyoxylic acid.

STUDY DESIGN AND METHODS

The mouse model of stone formation was established via successive intraperitoneal injection of glyoxylate. Proximal tubular epithelial cell line HK-2 treated with calcium oxalate monohydrate (COM) was used as in vitro model. The protective role of GAL on nephrolithiasis was tested by determination of tubular injury, crystal deposition and adhesion, levels of inflammatory cytokines, macrophage infiltration and the redox status of kidney. In vitro, effect of GAL on the ROS level and oxidative tubular injury induced by COM were detected, as well as major antioxidant pathway Nrf2/HO-1.

RESULTS

Administration of GAL alleviates the renal deposition and adhesion of CaOx stone. Meanwhile, GAL ameliorates the inflammation and renal tubular injury. Level of intracellular ROS, osteopontin and CD44 are reduced, either in the mouse model of stone formation or in the COM-treated HK-2 cells after treatment of GAL. Mechanistically, GAL activates Nrf2/HO-1 pathway in HK-2 cells. Silencing Nrf2 abrogates the protective effect of GAL on the oxidative injury and adhesion of COM in HK-2 cells.

CONCLUSION

Taken together, our study demonstrates the protective effect of GAL on the deposition of kidney stone and consequent tubular injury. Induction of the antioxidant pathway Nrf2/HO-1 was found to decrease the level of ROS and oxidative injury, thus implying that GAL could be a potential therapeutic agent for the treatment of nephrolithiasis.

Analysis of Threshold Effect of Urinary Heavy Metal Elements on the High Prevalence of Nephrolithiasis in Men

Exposure to heavy metals in the environment exerts serious effects on kidney health. However, the effects of joint exposure on the kidneys have been rarely studied, particularly in non-occupational exposure high-risk populations. This study provided a reference threshold range of heavy metals in urine and explored the effect of joint exposure on nephrolithiasis in men. The data were obtained from the China Multi-Ethnic Cohort database, and 1502 men were included in the study. A two-piece-wise regression model was used to assess the dose-response relationship between heavy metal exposure and nephrolithiasis. The least absolute shrinkage and selection operator regression model was used to calculate the score of joint exposure to heavy metals. The threshold effect analysis revealed a linear relationship between the concentration of arsenic (As) in the urine and the prevalence of nephrolithiasis, whereas a nonlinear relationship was observed with cadmium (Cd), chromium (Cr), mercury (Hg), and lead (Pb). In addition, As, Cd, Cr, Hg, and Pb may significantly affect the joint exposure effect. Moreover, the final risk of nephrolithiasis increased by 123% (P for trend < 0.001). This study found a threshold relationship between heavy metals (Cd, Cr, Hg, Pb) in male urine and the occurrence of nephrolithiasis. Joint exposure to heavy metals in urine caused a high-risk effect on nephrolithiasis. The study provided a reference threshold value of related studies and indicated that environmental pollution caused by heavy metals should be reduced.

Glycine suppresses kidney calcium oxalate crystal depositions via regulating urinary excretions of oxalate and citrate

An abnormal urine composition is a key reason for kidney stone formation, but little is known about the roles of small metabolites in the urine during kidney stone formation. Here, we found urine glycine in patients with kidney calcium oxalate (CaOx) stone was significantly lower than that in healthy people via 1 H NMR spectra detection, and investigated the role and underlying mechanism of glycine in the regulation of CaOx stone formation. Our results showed that glycine could significantly attenuate ethylene glycol-induced CaOx crystal depositions in rat kidney via decreasing urine oxalate and increasing urine citrate. Mechanism studies revealed that glycine could decrease urine oxalate through downregulating Slc26a6 expression, whereas increase urine citrate via inhibiting Nadc1 expression. Moreover, glycine decreased the protein expression of both Slc26a6 and Nadc1 via increasing the expression of miRNA-411-3p, which directly bound to the 3'-untranslated regions of Slc26a6 and Nadc1 messenger RNAs, in vitro and in vivo. Together, our results revealed a novel role of glycine in the regulation of kidney CaOx crystal formation and provided a potential target for the treatment of kidney CaOx stone.

Vitexin exerts protective effects against calcium oxalate crystal-induced kidney pyroptosis in vivo and in vitro

BACKGROUND

Nephrolithiasis is a common urinary disease with a high recurrence rate of secondary stone formation. Several mechanisms are involved in the onset and recurrence of nephrolithiasis, e.g., oxidative stress, inflammation, apoptosis, and epithelial-mesenchymal transition (EMT). Vitexin, a flavonoid monomer derived from medicinal plants that exert many biological effects including anti-inflammatory and anticancer effects, has not been investigated in nephrolithiasis studies. Moreover, pyroptosis, a form of programmed cell death resulting from inflammasome-associated caspase activation, has not been studied in mice with nephrolithiasis.

PURPOSE

We aimed to investigate the protective effect and underlying mechanisms of vitexin in nephrolithiasis, and the related role of pyroptosis in vivo and in vitro.

METHODS

Mouse models of nephrolithiasis were established via intraperitoneal injection of glyoxylate, and cell models of tubular epithelial cells and macrophages were established using calcium oxalate monohydrate (COM). Crystal deposition and kidney tissue injury were evaluated by hematoxylin and eosin, and von Kossa staining. Renal oxidative stress indexes including malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT), were analyzed. The renal expression of interleukin-1 beta (IL-1β), gasdermin D (GSDMD), osteopontin (OPN), CD44, and monocyte chemotactic protein 1 (MCP-1), and EMT-related proteins in renal tubular epithelial cells was assessed. Cell viability and the apoptosis ratio were evaluated.

RESULTS

In vivo, vitexin alleviated crystal deposition and kidney tissue injury, and decreased the level of MDA, and increased the levels of SOD, GSH, and CAT. Vitexin also reduced the levels of the pyroptosis-related proteins GSDMD, NLRP3, cleaved caspase-1, and mature IL-1β, which were elevated in mice with nephrolithiasis, and repressed apoptosis and the expression of OPN and CD44. Moreover, vitexin mitigated F4/80-positive macrophage infiltration and MCP-1 expression in the kidneys. Furthermore, an in vitro study showed that vitexin increased the viability of HK-2 cells and THP-1-derived macrophages, which was impaired by treatment with COM crystals, decreased the medium lactate dehydrogenase (LDH) level, and inhibited the expression of pyroptosis-related proteins in HK-2 cells and macrophages. Vitexin repressed EMT of HK-2 cells, with increased expression of pan-cytokeratin (Pan-ck) and decreased expression of Vimentin and alpha-smooth muscle actin (α-SMA), and downregulated the Wnt/β-catenin pathway. Moreover, vitexin suppressed tumor necrosis factor-α (TNF-α) and IL-1β mRNA expression, which was upregulated by COM in macrophages.

CONCLUSION

Vitexin exerts protective effects against nephrolithiasis by inhibiting pyroptosis activation, apoptosis, EMT, and macrophage infiltration. In addition, GSDMD-related pyroptosis mediates nephrolithiasis.

Amelioration of lithiatic injury to renal tissue by candesartan and sodium thiosulfate in a rat model of nephrolithiasis

AIM

Nephrolithiasis is a chronic metabolic condition affecting 10% of population worldwide. The present study aimed to investigate the possible protective role of candesartan (CAND) and sodium thiosulfate (STS) in ameliorating ethylene glycol (EG) induced nephrolithiasis.

METHODS

One hundred male Wistar rats were divided into five groups: Normal control group, nephrolithiasis (EG) group (1% EG in drinking water), Cystone (CYS) group (EG + 750 mg/kg CYS, orally, once daily), STS group (EG + 0.4 gm/kg STS, intraperitoneally, 3 times/week) and CAND group (EG + 70 μg/mL CAND in drinking water). Treatments and EG administration commenced on the same day and continued for 28 days. CYS was used as reference drug. Urine, blood, and renal tissues were collected at the end of the experiment for assessment of kidney function tests (serum creatinine and urea), urinary (8-hydroxydeoxyguanosine (8-OHdG), calcium and oxalate), inflammatory and oxdative stress biomarkers (transforming growth factor beta (TGF-β), osteopontin (OPN) and ratio of reduced glutathione to oxidized glutathione (GSH/GSSG)) in renal tissue.

RESULTS

Serum (creatinine and urea), urinary (8-OHdG and oxalate) and renal (OPN and TGF-β) were significantly reduced in CAND and STS groups compared to EG group. Furthermore, renal GSH/GSSG and urinary calcium were significantly increased in CAND and STS groups compared to EG group. Histopathological results support the biochemical findings; CAND and STS groups showed less retention of crystals and necrotic damage in kidney. Also, microscopic examination of urine revealed less crystal for CAND and STS groups.

CONCLUSION

Candesartan and sodium thiosulfate exhibited protective effect against nephrolithiasis.

Proton-pump inhibitors associated with decreased urinary citrate excretion

INTRODUCTION

Proton-pump inhibitors (PPIs) may increase the risk of kidney stone formation, but the mechanism has not been elucidated. There is a paucity of literature evaluating the effects of PPIs on urinary metabolites and urine pH.

METHODS

We performed a retrospective review of nephrolithiasis patients treated at our institution and compared patients who were taking PPIs to those who were not at the time of their 24-h urine collections. Hierarchical multivariate linear regression was used to evaluate the independent relationship between PPI use and urinary mineral composition.

RESULTS

We identified 301 consecutive patients, 88 (29%) of whom were taking PPIs at the time of their 24-h urine collections. Patients taking PPIs were older and more likely to have medical comorbidities associated with metabolic syndrome such as hypertension, diabetes, and dyslipidemia (p < 0.01). Controlling for these factors, patients taking PPIs were found to have 12% lower 24-h urine citrate excretion (β =  - 0.12, ΔF = 4.24, p = 0.04). There were no other differences in urinary mineral composition between the groups.

CONCLUSION

Our findings suggest that patients who take PPIs regularly may be at risk for decreased urinary citrate excretion. The consequent decrease in urinary citrate may become clinically significant for patients with other predisposing factors for hypocitraturia.

[Mesalazine renal lithiasis.]

Mesalazine (5-aminosalicylic acid, 5-ASA),is an anti-inflammatory drug well-established as first-line treatment in the management of inflammatory bowel disease. Nephritic colic has been described as an uncommonside effect, but very few mesalazine nephrolithiasis have been published in the literature, probably due to its underdiagnosis for not using appropriate methodology for calculi analysis. We present two cases of lithiasis in patients treated with mesalazine at high dosage, an adverse effect to betaken into account as a drug lithiasis and which is not even mentioned in the patient information leaflet.

Curcumin ameliorates glyoxylate-induced calcium oxalate deposition and renal injuries in mice

BACKGROUND

Nephrolithiasis is one of the most common and frequent urologic diseases worldwide. Several pathophysiological mechanisms are involved in stone formation, including oxidative stress, inflammation, apoptosis, fibrosis and autophagy. Curcumin, the predominant active component of turmeric, has been shown to have pleiotropic biological and pharmacological properties, such as antioxidant, anti-inflammatory and antifibrotic effects.

PURPOSE

The current study proposed to systematically investigate the protective effects and the underlying mechanisms of curcumin in a calcium oxalate (CaOx) nephrolithiasis mouse model.

METHODS

The animal model was established in male C57BL/6 mice by successive intraperitoneal injection of glyoxylate (100 mg/kg) for 1 week. Curcumin was orally given to mice 7 days before the injection of glyoxylate and for a total of 14 days at 50 mg/kg or 100 mg/kg. Bilateral renal tissue was harvested and processed for oxidative stress index detection, histopathological examinations and other analyses.

RESULTS

Coadministration of curcumin could significantly reduce glyoxylate-induced CaOx deposition and simultaneous tissue injury in mouse kidneys. Meanwhile, curcumin alleviated the oxidative stress response via reducing MDA content and increasing SOD, CAT, GPx, GR and GSH levels in this animal model. Moreover, treatment with curcumin significantly inhibited apoptosis and autophagy induced by hyperoxaluria. Curcumin also attenuated the high expression of IL-6, MCP-1, OPN, CD44, α-SMA, Collagen I and collagen fibril deposition, which were elevated by hyperoxaluria. Furthermore, the results revealed that both the total expression and nuclear accumulation of Nrf2, as well as its main downstream products such as HO-1, NQO1 and UGT, were decreased in the kidneys of mice in the crystal group, while treatment with curcumin could rescue this deterioration.

CONCLUSION

Curcumin could significantly alleviate CaOx crystal deposition in the mouse kidney and the concurrent renal tissue injury. The underlying mechanism involved the combination of antioxidant, anti-apoptotic, inhibiting autophagy, anti-inflammatory, and antifibrotic activity and the ability to decrease expression of OPN and CD44 through the Nrf2 signaling pathway. The pleiotropic antilithic properties, combined with the minimal side effects, make curcumin a good potential choice to prevent and treat new or recurrent nephrolithiasis.

[DRUG-INDUCED BILATERAL NEPHROLITHIASIS IN AN ULCERATIVE COLITIS PATIENT: A CASE REPORT]

A 59-year-old female experienced gross hematuria and right back pain, and she visited our hospital in March 2015. Abdominal computed tomography (CT) showed bilateral renal pelvic calculi; the right stone was 15 mm and the left stone was 18 mm in diameter. She had ulcerative colitis and had been taking salazosulfapyridine (SASP) for about 30 years. Urinalysis showed aciduria and deposition of urate crystals. An abdominal X-ray picture did not show a calculus shadow. We suspected uric acid calculus and started treatment with urinary alkalizer and uric acid production inhibitor.Three months later, abdominal CT showed enlargement of the bilateral renal pelvic calculi; the right stone was 25 mm and the left stone was 24 mm in diameter. She also complained of worse right back pain and underwent transurethral ureterolithotripsy for the right renal pelvic stone. The stone was orange, comparatively soft, and chipped down until it was approximately half of its original size. The stone analysis suggested suspected drug-induced urolithiasis, but not uric acid calculus. Thus, we investigated the stone and SASP using infrared spectroscopy, and the infrared absorption pattern was similar in both. The stone analysis demonstrated drug-induced urolithiasis induced by SASP.The patient's ulcerative colitis therapy was switched to mesalazine, and the amount of urinary alkalizer was increased. Abdominal CT 3 months thereafter showed dissipation of bilateral renal pelvic calculi. The patient did not take any preventative medication, and there was no recurrence of urolithiasis.

Progressive Pseudolithiasis Associated with the Intravenous Administration of Ceftriaxone in Patients with Central Nervous System Infections

We report four adult cases of ceftriaxone (CTRX)-induced pseudolithiasis and nephrolithiasis. With the exception of case 1, none of our cases showed abdominal symptoms. Our patients, who had central nervous system (CNS) infections, had been treated with CTRX (4 g/day) for 35-69 days. CTRX-induced pseudolithiasis and nephrolithiasis can appear depending on the total dose of CTRX and the duration for which it is administered. Patients with bacterial CNS infections who are treated with CTRX are typically treated with higher doses for longer periods. It should be recognized that these patients are at higher risk of developing CTRX-induced pseudolithiasis and nephrolithiasis.

Metabolic syndrome contributes to renal injury mediated by hyperoxaluria in a murine model of nephrolithiasis

Metabolic syndrome (MS) individuals have a higher risk of developing chronic kidney disease through unclear pathogenic mechanisms. MS has been also related with higher nephrolithiasis prevalence. To establish the influence of MS on renal function, we designed a murine model of combined metabolic syndrome and hyperoxaluria. Four groups of male Sprague-Dawley rats were established: (1) control group (n = 10) fed with standard chow; (2) stone former group (SF) (n = 10) fed with standard chow plus 0.75% ethylene glycol administered in the drinking water; (3) metabolic syndrome group (MS) (n = 10), fed with 60% fructose diet; (4) metabolic syndrome + stone former group (MS + SF) (n = 10), 60% fructose diet and 0.75% EG in the drinking water. MS group showed a significant injury to renal function when hyperoxaluria was induced. It was demonstrated by a significant decrease of creatinine clearance (p < 0.001), with higher tubular damage (34.3%, CI 95% 23.9-44.7, p < 0.001), produced by deposition of crystals, and increased tubular synthesis of osteopontin as a response to tubular damage. Induction of hyperoxaluria in rats with MS causes severe morphological alterations with a significant impairment of renal function. This impairment is not produced in rats without MS. Therefore, this model can be useful for the study of the influence of MS in stone formation.

Incidence of nephrolithiasis in relation to environmental exposure to lead and cadmium in a population study

Whether environmental exposure to nephrotoxic agents that potentially interfere with calcium homeostasis, such as lead and cadmium, contribute to the incidence of nephrolithiasis needs further clarification. We investigated the relation between nephrolithiasis incidence and environmental lead and cadmium exposure in a general population. In 1302 participants randomly recruited from a Flemish population (50.9% women; mean age, 47.9 years), we obtained baseline measurements (1985-2005) of blood lead (BPb), blood cadmium (BCd), 24-h urinary cadmium (UCd) and covariables. We monitored the incidence of kidney stones until October 6, 2014. We used Cox regression to calculate multivariable-adjusted hazard ratios for nephrolithiasis. At baseline, geometric mean BPb, BCd and UCd was 0.29µmol/L, 9.0nmol/L, and 8.5nmol per 24h, respectively. Over 11.5 years (median), nephrolithiasis occurred in 40 people. Contrasting the low and top tertiles of the distributions, the sex- and age-standardized rates of nephrolithiasis expressed as events per 1000 person-years were 0.68 vs. 3.36 (p=0.0016) for BPb, 1.80 vs. 3.28 (p=0.11) for BCd, and 1.65 vs. 2.95 (p=0.28) for UCd. In continuous analysis, with adjustments applied for sex, age, serum magnesium, and 24-h urinary volume and calcium, the hazard ratios expressing the risk associated with a doubling of the exposure biomarkers were 1.35 (p=0.015) for BPb, 1.13 (p=0.22) for BCd, and 1.23 (p=0.070) for UCd. In conclusion, our results suggest that environmental lead exposure is a risk factor for nephrolithiasis in the general population.

Preventive treatment of calcium oxalate crystal deposition with immortal flowers

ETHNOPHARMACOLOGICAL RELEVANCE

A number of medicinal plants are used for their diuretic, urolithiatic and anti-inflammatory effects on urinary system problems in Turkey and the most common traditional remedy for kidney stones is the tea of immortal flowers. The aim of this study is to evaluate the preventive effect of infusions prepared from capitulums of Helichrysum graveolens (M.Bieb.) Sweet (HG) and Helichrysum stoechas ssp. barellieri (Ten.) Nyman (HS) on formation of kidney stones.

MATERIALS AND METHOD

Sodium oxalate (Ox-70mg/kg intraperitoneally) was used to induce kidney stones on Wistar albino rats. At the same time, two different doses of the plant extracts (HG: 62.5 and 125mg/kg; HS: 78 and 156mg/kg) were dissolved in the drinking water and administered to animals for 5 days. Potassium citrate was used as positive control in the experiments. During the experiment, water intake, urine volume and body weights of the animals were recorded. At the end of the experiments, liver, kidney and body weights of the animals were determined; biochemical analysis were conducted on urine, blood and plasma samples. Histopathological changes in kidney tissues were examined and statistical analysis were evaluated.

RESULTS

HS extract showed the highest preventive effect at 156mg/kg dose (stone formation score: 1.16), whereas a number of kidney stones were maximum in sodium oxalate group (stone formation score: 2.66). Helichrysum extracts decreased urine oxalate and uric acid levels and increased citrate levels significantly. In addition, Helichrysum extracts regulated the negative changes in biochemical and hematological parameters occurred after Ox injection.

CONCLUSIONS

We conclude that Helichrysum extracts could reduce the formation and growth of kidney stones in Ox-induced urolithiasis and can be beneficial for patients with recurrent stones. In addition, this is the first study on the preventive effect of immortal flowers.

[Metabolic therapy of nephrolithiasis in two different rat models of kidney disease]

108 albino male rats were used in two experimental rat models reproducing urolithiasis for the assessment of metabolic drug medicine Remaxol nephroprotective effect upon the development of this disease. "Ethyleneglycol" model consisted of adding 1% ethylene glycol solution in drinking water for 37 days and "fructose-induced" one--of adding 10% fructose solution in drinking water for the same period. Therapy included a 10-day course of daily i.v. injections of Remaxol (14 ml/kg). Both experimental models were successful in producing urolithiasis with considerable disturbances in the structure and functioning of kidneys up to revealing microconcrement formation. The "ethyleneglycol" model proved to cause maximum changes while the "Fructose-induced" model--only moderate ones. Metabolic correction of these changes was successful in nephroprotection effectively normalizing kidney functions and the total protein concentration, eliminating hyperglycemia and reducing creatinine and urea blood plasma concentration in both rat experimental models.

Vitamin D intoxication in two brothers: be careful with dietary supplements

Vitamin D (VitD) intoxication, a well-known cause of hypercalcaemia in children, has renal, cardiac and neurological consequences. Iatrogenic or accidental administrations are the most common causes. We present two cases of hypervitaminosis D due to over-the-counter VitD supplement self-medication. A 12-year-old boy was hospitalised for abdominal pain, constipation and vomiting. Routine biochemistry indicated severe hypercalcaemia and renal failure. Plasma 25-OH VitD level was very high and parathyroid hormone was suppressed. Renal ultrasound showed nephrolithiasis. Hydration, diuretics and prednisone induced a progressive reduction of calcium levels. His brother, who was receiving the same treatment, was hospitalised although asymptomatic. Normal serum calcium and renal function were revealed, while 25-OH VitD was high and parathyroid hormone was suppressed. Renal ultrasound was within the normal range. Examination of the VitD content of the over-the-counter supplement revealed a higher amount than declared. VitD administration implies several risks and must be prescribed only when needed and under strict medical control.

Calcium nephrolithiasis induced by topiramate

Topiramate is an approved drug to treat seizures, but its indications have been extended to other diseases of the nervous system and as an adjuvant to chronic pain. We present four cases of topiramate-induced nephrolithiasis from 2006-2012 in women whose treatment was prescribed for pain control and as a mood stabilizer at doses of 250-300 mg/day. In two cases, the lithiasis was caused by calcium phosphate (patite) and in the other two cases by oxalate and calcium phosphate. The most common metabolic alteration was an alkaline pH, followed by hypocitraturia. The drug was discontinued in two patient; it was reduced in one and was maintained in the fourth. An increase in fluid and potassium citrate intake was prescribed. In patients starting treatment with topiramate, an adequate control and prevention of nephrolithiasis should be performed due to the risk of mixed tubular acidosis and hypocitraturia. to the risk of mixed tubular acidosis and hypocitraturia.

Calcium oxalate nephrolithiasis and expression of matrix GLA protein in the kidneys

OBJECTIVES

Polymorphism of the gene for matrix GLA protein (MGP), a calcification inhibitor, is associated with nephrolithiasis. However, experimental investigations of MGP role in stone pathogenesis are limited. We determined the effect of renal epithelial exposure to oxalate (Ox), calcium oxalate (CaOx) monohydrate (COM) or hydroxyapatite (HA) crystal on the expression of MGP.

METHODS

MDCK cells in culture were exposed to 0.3, 0.5 or 1 mM Ox and 33, 66 or 133-150 μg/cm(2) of COM/HA for 3-72 h. MGP expression and production were determined by Western blotting and densitometric analysis. Enzyme-linked immunosorbent assay was performed to determine MGP release into the medium. Hyperoxaluria was induced in male Sprague-Dawley rats by feeding hydroxyl-L-proline. Immunohistochemistry was performed to detect renal MGP expression.

RESULTS

Exposure to Ox and crystals led to time- and concentration-dependent increase in expression of MGP in MDCK cells. Cellular response was quicker to crystal exposure than to the Ox, expression being significantly higher after 3-h exposure to COM or HA crystals and more than 6 h of exposure to Ox. MGP expression was increased in kidneys of hyperoxaluric rats particularly in renal peritubular vessels.

CONCLUSION

We demonstrate increased expression of MGP in renal tubular epithelial cells exposed to Ox or CaOx crystals as well as the HA crystals. The most significant finding of this study is the increased staining seen in renal peritubular vessels of the hyperoxaluric rats, indicating involvement of renal endothelial cells in the synthesis of MGP.

Clinical practice. Calcium supplements and fracture prevention

This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the author’s clinical recommendations. A 62-year-old healthy woman presents for routine care. She has no history of fracture, but she is worried about osteoporosis because her mother had a hip fracture at 72 years of age. She exercises regularly and has taken over-the-counter calcium carbonate at a dose of 1000 mg three times a day since her menopause at 54 years of age. This regimen provides 1200 mg of elemental calcium per day. She eats a healthy diet with multiple servings of fruits and vegetables and consumes one 8-oz serving of low-fat yogurt and one glass of low-fat milk almost every day. She recently heard that calcium supplements could increase her risk of cardiovascular disease and wants your opinion about whether or not she should receive them. What would you advise?

Ritonavir-boosted darunavir is rarely associated with nephrolithiasis compared with ritonavir-boosted atazanavir in HIV-infected patients

Background

Although ritonavir-boosted atazanavir (ATV/r) is known to be associated with nephrolithiasis, little is known about the incidence of nephrolithiasis in patients treated with ritonavir-boosted Darunavir (DRV/r), the other preferred protease inhibitor.

Methods

In a single-center cohort, the incidence of nephrolithiasis was compared between HIV-infected patients who commenced DRV/r-containing antiretroviral therapy and those on ATV/r. The effects of ATV/r use over DRV/r were estimated by univariate and multivariate Cox hazards models.

Results

Renal stones were diagnosed in only one patient (0.86 per 1000 person-years) of the DRV/r group (n=540) and 37 (20.2 per 1000 person-years) of the ATV/r group (n=517). The median [interquartile (IQR)] observation period in the DRV/r group was 27.1 months (IQR 18.1-38.4 months), and 40.6 months (IQR 17.5-42.7) for the ATV/r group. The total observation period was 1,163.6 person-years and 1,829.6 person-years for the DRV/r group and for the ATV/r group, respectively. In the 37 patients on ATV/r who developed nephrolithiasis, the median time from commencement of ATV/r to diagnosis was 28.1 months (IQR 18.4–42.7), whereas nephrolithiasis in the single patient of the DRV/r group occurred 11.2 month after the introduction of DRV/r. ATV/r use over DRV/r was significantly associated with nephrolithiasis by uni- and multivariate analyses (HR=26.01; 95% CI, 3.541–191.0; p=0.001) (adjusted HR=21.47; 95% CI, 2.879–160.2; p=0.003).

Conclusion

The incidence of nephrolithiasis was substantially lower in patients on DRV/r than those on ATV/r. The results suggest that DRV/r should be selected for treatment of HIV-infected patients at risk of chronic kidney disease.

Prophylactic effects of Orthosiphon stamineus Benth. extracts on experimental induction of calcium oxalate nephrolithiasis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Orthosiphon stamineus (OS) popularly known as "diuretic agent" are traditionally used in folk medicine in the treatment of hyperuricemia, rheumatism, gout, nephritis, nephrolithiasis, urethritis and cystitis.

AIM OF THE STUDY

To evaluate prophylactic potentials of total flavonoids, total phenolics and polysaccharides from OS on experimental induction of calcium oxalate (CaOx) nephrolithiasis in rats.

MATERIALS AND METHODS

Nephrolithic rats were induced by treating with 1.0% ethylene glycol and 1.0% ammonium chloride for 7 days. Rats in the treated groups were also given OS extracts at the doses of 80 mg/kg and 160 mg/kg. Urine samples (4h) and serum samples were collected at 7th day for biochemical analysis. Kidney tissues were stained with H.E. and analyzed by light microscopy. Expressions of OPN protein were detected by immunohistochemistry. Rates of nucleation and aggregation of calcium oxalate crystals were derived from 20-min time-course measurements of optic density at 620 nm after mixing solutions containing calcium chloride, sodium oxalate and OS extracts at 37°C, pH 5.7.

RESULTS

Polysaccharides exhibited the most significant prophylactic effects by reversing BUN and S(cr) levels, ameliorating histopathological changes, increasing urine C(2)O(4)(2-) and Ca(2+) excretion and down-regulating OPN protein expression of kidney in the model rats in comparison with those effects of total flavonoids and total phenolics. Polysaccharides could also significantly inhibit both nucleation and aggregation of CaOx crystals.

CONCLUSIONS

Polysaccharides were the main therapeutic materials in OS. It had impressive prophylactic effects on CaOx stones in nephrolithic rats, playing a role as a regulator of OPN protein expression to increase urine C(2)O(4)(2-) and Ca(2+) excretion and also as an inhibitor of CaOx crystallization.

Relationship between serum vitamin D and 24-hour urine calcium in patients with nephrolithiasis

OBJECTIVE

To examine the relationship between serum 25-OH vitamin D and 24-hour urine calcium in patients with nephrolithiasis.

METHODS

A retrospective review was performed. Patients evaluated in 2 metabolic stone clinics were included for analysis. Multivariate linear regression models were adjusted for known risk factors for stone disease (age, gender, body mass index, hypertension, diabetes mellitus, gout, relevant medications, and 24-hour urine composition).

RESULTS

One-hundred sixty-nine patients were included in the study. Female to male ratio was 69:100, mean age was 50.9 years (SD 13.7), and mean body mass index was 27.4 (SD 6.4). Vitamin D deficiency (25-OH vitamin D <20 ng/mL) was present in 18.9% of patients, vitamin D insufficiency (>20, <30 ng/mL) was present in 34.9% of patients, and vitamin D was within normal limits (≥ 30 ng/mL) in 46.1% of patients. On age-adjusted and multivariate linear regression, serum 25-OH vitamin D was not related to 24-hour urine calcium (age adjusted β = -0.31 m 95% CI -1.9 to 1.3; multivariate adjusted β = 0.08, 95% CI -1.3 to 1.5).

CONCLUSION

Although 25-OH vitamin D is involved in the body's calcium homeostasis, our study does not show a relationship between serum vitamin D level and 24-hour urine calcium excretion in stone-formers. This information may have implications regarding the safety of vitamin D repletion in patients with nephrolithiasis.

Liver involvement in melamine-associated nephrolithiasis

It is currently believed that melamine ingestion can lead to insoluble crystals in an animal's urinary system with subsequent physical obstruction or bladder carcinoma. However, whether melamine can cause injury of other tissues and organs in humans is yet unknown. In this study, we encountered 3 affected children with liver lesions, 2 males and 1 female, and detailed their clinical characterizations. Their ages were respectively 2, 6, and 10 months. Among the 3 patients with liver lesions, only 1 exhibited symptoms of gradual progressive jaundice, abdominal distention, hepatic intumesce, and bilirubin abnormality; the other 2 were asymptomatic. The mechanism associated with liver lesion may, at least in part, be due to physical deposition and blockage of the biliary tract system. Disturbance of the acid-base equilibrium may be another reason that accelerates stone formation in human tissues.

Preventive and curative effects of Achyranthes aspera Linn. extract in experimentally induced nephrolithiasis

The present study was undertaken to evaluate the efficacy of Achyranthes aspera in preventing and reducing the growth of calcium oxalate stones in ethylene glycol induced nephrolithiatic model. Hyperoxaluria was induced in rats using ethylene glycol (EG, 0.4%) and ammonium chloride (1%) for 15 days and was then replaced with EG (0.4%) only. Upon administration of cystone (750 mg/kg body wt.), aqueous extract of A. aspera (500 and 1000 mg/kg body wt.), levels of renal injury markers (lactate dehydrogenase and alkaline phosphatase) were normalized with a decrease in serum urea and serum creatinine. Concurrent treatment reduced changes in the architecture of renal tissue and also decreased the size of crystals thereby helping in quick expulsion of the crystals. The present results indicated that Achyranthes aspera had an ability to maintain renal functioning and reduced renal injury.

[Anti-lithogenic effect of meloxicam in experimental nephrolithiasis]

Experiments performed on 23 male rats, were divided into 2 groups. Animals in the control received group 1% solution of ethylene glycol (EG) as a drink during 6 weeks. In the test group, EG was also introduced for 6 weeks, and meloxicam was administered in a dose of 2.5 mg/kg from the 4th week. Every 7 days, daily urine was analyzed for the concentrations of oxalate, phosphate, and calcium and for the activity of urothelium injury marker enzymes includng lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), and N-acetyl-beta-D-glucose aminidase (NAG). In addition, sections of the rats kidney were used to detect calcium deposits by histochemical Van Koss method. The treatment of experimental nephrolithiasis by meloxicame led to simplification of pathology, as indicated by a significant reduction in the urine oxalate and calcium concentrations and a pronounced decrease in the activity of all marker enzymes (LDH, GGT, NAG).This was confirmed by morphological studies, which detected very significant reduction in both number and size of calcium deposits.

Experimental induction of calcium oxalate nephrolithiasis in mice

PURPOSE

The availability of various transgenic and knockout mice provides an excellent opportunity to better understand the pathophysiology of calcium oxalate stone disease. However, attempts to produce calcium oxalate nephrolithiasis in mice have not been successful. We hypothesized that calcium oxalate nephrolithiasis in mice requires increasing urine calcium and oxalate excretion, and experimentally induced hyperoxaluria alone is not sufficient. To provide evidence we induced hyperoxaluria by administering hyperoxaluria inducing agents in normocalciuric and hypercalciuric mice, and investigating various aspects of nephrolithiasis.

MATERIALS AND METHODS

We administered ethylene glycol, glyoxylate or hydroxyl proline via diet in male and female normocalciuric B6 mice, and in hypercalciuric sodium phosphate co-transporter type 2 a -/- mice for 4 weeks. We collected 24-hour urine samples on days 0, 3, 7, 14, 21 and 28, and analyzed them for pH, creatinine, lactate dehydrogenase calcium and oxalate. Kidneys were examined using light microscopy. Urine was examined for crystals using light and scanning electron microscopy.

RESULTS

Hypercalciuric mice on hydroxyl proline did not tolerate treatment and were sacrificed before 28 days. All mice on ethylene glycol, glyoxylate or hydroxyl proline became hyperoxaluric and showed calcium oxalate crystalluria. No female, normocalciuric or hypercalciuric mice showed renal calcium oxalate crystal deposits. Calcium oxalate nephrolithiasis developed in all mice on glyoxylate and in some on ethylene glycol. In all mice the kidneys showed epithelial injury. Male mice particularly on glyoxylate had more renal injury and inflammatory cell migration into the interstitium around the crystal deposits.

CONCLUSIONS

Results confirm that hyperoxaluria induction alone is not sufficient to create calcium oxalate nephrolithiasis in mice. Hypercalciuria is also required. Kidneys in male mice are more prone to injury than those in female mice and are susceptible to calcium oxalate crystal deposition. Perhaps epithelial injury promotes crystal retention. Thus, calcium oxalate nephrolithiasis in mice is gender dependent, and requires hypercalciuria and hyperoxaluria.

Pharmacological and toxicological effects of Paronychia argentea in experimental calcium oxalate nephrolithiasis in rats

AIM OF THE STUDY

Renal protection and antiurolithiasic effects of two extracts of Paronychia argentea (PA), a traditional Algerian plant commonly known as Algerian tea, were evaluated. This study was carried out to determine whether the aqueous extract (APA) or the butanolic extract (BPA) of aerial parts could prevent or reduce calculi aggregation in experimental calcium oxalate (Ox) nephrolithiasis in Wistar rats.

MATERIALS AND METHODS

The two extracts (APA and BPA) were administrated orally and daily, during 28 days to nephrolithiasic treated rats at the dose of 250, 500 mg/kg b.w. and 10, 20mg/kg b.w. respectively. Body weight, renal index, liver index, serum level of creatinine, uric acid, urea, K(+), Ca(2+), Mg(2+), Na(+) and transaminase (alanine aminotransferase, ALT; aspartate aminotransferase, AST), phosphatase alkaline activity (PAL) were evaluated following the 28 days treatment in rats. In addition histopathological changes in kidney and liver were stained in hematoxylin eosin (HE).

RESULTS

The effect of the extracts could be advantageous in preventing urinary stone retention by reducing renal necrosis and thus inhibit crystal retention. In contradiction with APA, the two doses of BPA attenuated elevation in the serum creatinine (p<0.01) and blood urea levels (p<0.01) (nephroprotective effect). However, the increase in ALT (27%) and PAL (31-51%) serum levels and in the relative liver weights (p<0.01) in the groups treated with doses of APA may indicate that this extract has not a hepatoprotective effect against oxalate toxicity.

CONCLUSIONS

The presented data indicate that administration of the butanolic extract of aerial parts to rats with NaOx induced lithiasis, and reduced and prevented the growth of urinary stones in experimental calcium oxalate nephrolithiasis in Wistar rats.

The risk of melamine-induced nephrolithiasis in young children starts at a lower intake level than recommended by the WHO

We investigated 683 children with nephrolithiasis and 6,498 children without nephrolithiasis aged <3 years. Nephrolithiasis was diagnosed by renal ultrasonography in hospitals in Beijing in September/October 2008. In addition, data was collected on current and past formula feeding and on other possible risk factors for nephrolithiasis. Daily intake of melamine per kilogram of body weight was calculated for each individual. In general, the adjusted odds ratios between melamine dose and nephrolithiasis increased with an increasing daily level of melamine intake per kilogram of body weight. The risk of nephrolithiasis also increased with the increasing duration of exposure. Preterm infants, urinary malformation, and parents with a history of urinary stones were independent risk factors. In children exposed to melamine levels <0.2 mg/kg per day, the adjusted odds ratio expressing the risk for nephrolithiasis was still 1.7 times higher than in those without melamine exposure. These findings suggest that the risk of melamine-induced nephrolithiasis in young children starts at a lower intake level than the levels recommended by the World Health Organization.

Non-drug-induced nephrotoxicity

Several drugs and other compounds can induce acute and/or chronic nephrotoxicity. The goal of this study was to review clinical features of nephrotoxicity induced by 'atypical' or 'unconventional' agents, such as environmental agents (metals, minerals, animals), food agents (mushrooms, aristolochic acid, medicinal traditional herbals, dietary supplements, melamine), drugs, and other products (ethylene glycol). Nephrotoxicity varies according to local background, dependent on different food and cultural customs, as well as to differences in local fauna and flora. The incidence of such a phenomenon is not well known. Many different pathophysiological pathways are involved, and the spectrum of renal lesions is rather wide. 'Epidemic nephrotoxicity' may occur, as recently illustrated by the melamine epidemics in Chinese infants receiving powdered milk formulas; a rapid reaction to unusual increased frequency of acute kidney injury and nephrolithiasis in young children has led to a rapid analysis from international experts, with subsequent recommendations for diagnosis and care. Nephrotoxicity should be considered when there is any unexplained renal impairment, especially in children.

Antiretroviral nephrotoxicities

With the introduction of combination antiretroviral therapy, there have been substantial declines in both morbidity and mortality associated with human immunodeficiency virus (HIV)-1 infection. However, data increasingly indicate that HIV-1-infected individuals are faced with accelerated rates of chronic diseases that afflict the general population such as diabetes mellitus, hypertension, and dyslipidemia, as well as cardiovascular, liver, and kidney diseases. Furthermore, this population is exposed to a variety of adverse effects from long-term use of antiretroviral medications, which may cause clinically important renal toxicities. However, it often is challenging to distinguish antiretroviral-related renal toxicity from either direct effects of HIV-1 on the kidney or from a multitude of non-HIV-related kidney diseases. A timely and coordinated effort by the HIV primary provider and a nephrologist is likely to facilitate the evaluation of HIV-1-infected patients with new kidney problems.

Effects of low-molecular-weight polyguluronate sulfate on experimental urolithiasis in rats

Urinary macromolecules, especially glycosaminoglycans (GAGs), have attracted great interest as promising inhibitors of urinary stone formation. As an analogue of GAGs, low-molecular-weight polyguluronate sulfate (LPGS) with strong polyanionic nature was prepared by chemical modification of brown algae extract. The effects of LPGS both on ethylene glycol-induced nephrolithiasis and Zinc disc implant-induced urinary bladder stone formation in Wistar rats were evaluated, and its acute toxicity in Kunming mice and Wistar rats were also investigated. The contents of renal oxalate and calcium in ethylene glycol-induced nephrolithiasic rats were decreased significantly from 5.01 +/- 0.96 to 3.26 +/- 1.31 mumol/g kidney (P < 0.01) and 20.11 +/- 4.60 to 11.83 +/- 3.54 mumol/g kidney (P < 0.01), respectively, after oral administration of LPGS at dose-level of 100 mg/kg. The renal crystal depositions and histopathological changes were reduced also. The formation of zinc disc implant-induced urinary bladder stones in rats was inhibited considerably after oral administration of LPGS at dose-levels of 50 mg/kg (P < 0.05) and 100 mg/kg (P < 0.01). The intravenous LD(50) and the oral maximum tolerance value of LPGS in mice are 6.29 and 25 g/kg, and in rats are 2.25 and 10 g/kg, respectively. These data show that LPGS has significant prevention effects both on nephrolithiasis and urinary bladder stone formation in rats, and negligible oral toxicity both in mice and rats. LPGS is a safe and promising drug candidate for the prevention of urolithiasis.

Dietary oxalate and calcium oxalate nephrolithiasis

PURPOSE

Patients with calcium oxalate kidney stones are advised to decrease the consumption of foods that contain oxalate. We hypothesized that a cutback in dietary oxalate would lead to a decrease in the urinary excretion of oxalate and decreased stone recurrence. We tested the hypothesis in an animal model of calcium oxalate nephrolithiasis.

MATERIALS AND METHODS

Hydroxy-L-proline (5%), a precursor of oxalate found in collagenous foods, was given with rat chow to male Sprague-Dawley rats. After 42 days rats in group 1 continued on hydroxy-L-proline, while those in group 2 were given chow without added hydroxy-L-proline for the next 21 days. Food and water consumption as well as weight were monitored regularly. Once weekly urine was collected and analyzed for creatinine, calcium, oxalate, lactate dehydrogenase, 8-isoprostane and H(2)O(2). Urinary pH and crystalluria were monitored. Rats were sacrificed at 28, 42 and 63 days, respectively. Renal tissue was examined for crystal deposition by light microscopy.

RESULTS

Rats receiving hydroxy-L-proline showed hyperoxaluria, calcium oxalate crystalluria and nephrolithiasis, and by day 42 all contained renal calcium oxalate crystal deposits. Urinary excretion of lactate dehydrogenase, 8-isoprostane and H(2)O(2) increased significantly. After hydroxy-L-proline was discontinued in group 2 there was a significant decrease in urinary oxalate, 8-isoprostane and H(2)O(2). Half of the group 2 rats appeared to be crystal-free.

CONCLUSIONS

Dietary sources of oxalate can induce hyperoxaluria and crystal deposition in the kidneys with associated degradation in renal biology. Eliminating oxalate from the diet decreases not only urinary oxalate, but also calcium oxalate crystal deposits in the kidneys and improves their function.

Atazanavir-associated nephrolithiasis: cases from the US Food and Drug Administration's Adverse Event Reporting System

The risk of nephrolithiasis associated with atazanavir is not well characterized. The US Food and Drug Administration's Adverse Event Reporting System was searched for reports of nephrolithiasis in HIV-infected patients taking an atazanavir-based regimen. Thirty cases were identified. Many patients required hospitalization for management, including lithotripsy, ureteral stent insertion, or endoscopic stone removal. Some cases of nephrolithiasis resulted in atazanavir discontinuation. Healthcare professionals and patients should be informed that nephrolithiasis is a possible adverse event with atazanavir.

Oxalate intake and the risk for nephrolithiasis

Most kidney stones consist of calcium oxalate, and higher urinary oxalate increases the risk for calcium oxalate nephrolithiasis. However, the relation between dietary oxalate and stone risk is unclear. This study prospectively examined the relation between oxalate intake and incident nephrolithiasis in the Health Professionals Follow-up Study (n = 45,985 men), the Nurses' Health Study I (n = 92,872 older women), and the Nurses' Health Study II (n = 101,824 younger women). Food frequency questionnaires were used to assess oxalate intake every 4 yr. Cox proportional hazards regression was used to adjust for age, body mass index, thiazide use, and dietary factors. A total of 4605 incident kidney stones were documented over a combined 44 yr of follow-up. Mean oxalate intakes were 214 mg/d in men, 185 mg/d in older women, and 183 mg/d in younger women and were similar in stone formers and non-stone formers. Spinach accounted for >40% of oxalate intake. For participants in the highest compared with lowest quintile of dietary oxalate, the relative risks for stones were 1.22 (95% confidence interval [CI] 1.03 to 1.45; P = 0.01 for trend) for men and 1.21 (95% CI 1.01 to 1.44; P = 0.05 for trend) for older women. Risk was higher in men with lower dietary calcium (P = 0.08 for interaction). The relative risks for participants who ate eight or more servings of spinach per month compared with fewer than 1 serving per month were 1.30 (95% CI 1.08 to 1.58) for men and 1.34 (95% CI 1.10 to 1.64) for older women. Oxalate intake and spinach were not associated with risk in younger women. These data do not implicate dietary oxalate as a major risk factor for nephrolithiasis.

Ceftriaxone associated nephrolithiasis: a prospective study in 284 children

Urinary tract calculi have been reported to account for between 1 in 1,000 and 1 in 7,600 hospital admissions in children in the USA. The annual incidence of urolithiasis in patients older than 10 years is 109 per 100,000 of the population in men and 36 per 100,000 of the population in women in Minnesota. The use of various medications is considered to be one of the etiologic factors of nephrolithiasis. Ceftriaxone is a widely used third-generation cephalosporin that is generally considered very safe, but complications such as biliary pseudolithiasis, and rarely, nephrolithiasis have been reported in children. There is limited information about urolithiasis as a side effect of ceftriaxone. The aim of this study was evaluation of the incidence of nephrolithiasis following ceftriaxone therapy in children. This quasi-experimental before and after study was conducted in Mofid Children's Hospital between 2003 and 2005. All patients were treated with 75 mg/kg intravenous ceftriaxone. Diagnosis of pyelonephritis was based on standard criteria. The first renal ultrasonography was performed on the first or second day of admission and was repeated on the last day of treatment. We also evaluated complicated patients for the third time with renal ultrasonography 3 months after treatment. Stone-forming patients underwent metabolic kidney stone risk factor evaluation. We evaluated 284 patients with pyelonephritis, 185 girls and 99 boys. The first ultrasonography was normal in all of our patients. On the second ultrasonography renal stones were reported in 4 out of 284 cases (1.4% and CI=0.96-1.83%). Underlying metabolic risk factors could not be identified in stone-forming patients. Follow-up ultrasonography 3 months later was normal. The results of our study suggest that ceftriaxone-treated patients may be at an increased risk of kidney stone formation. Stones passed spontaneously in all affected patients so the use of this effective drug can be safely continued. Close monitoring of ceftriaxone-treated patients with regard to kidney stone formation is recommended.

Indinavir Trough Concentration as a Determinant of Early Nephrolithiasis in HIV-1-Infected Adults

Indinavir plasma levels are associated with antiretroviral efficacy; however, little data are available regarding toxicity. We assessed the relationship between indinavir pharmacokinetic (PK) characteristics and severe nephrolithiasis as well as other severe or serious adverse reactions. Patients included in the ANRS CO8 APROCO-COPILOTE cohort and receiving 800 mg indinavir three times daily as a first-line protease inhibitor were eligible for this study. To be included in the analysis, their plasma sample at month 1 (M1) had to be available (n = 282) to estimate using population PK modeling, indinavir PK characteristics, ie, maximum (Cmax) and trough plasma (Cres) concentrations, area under the curve (AUC), and observed/predicted concentration ratio (CR). A Cox model was used to estimate the independent effect of Cmax, Cres, AUC, and CR on the hazard of severe nephrolithiasis and serious adverse reactions. At M1, median Cmax was 6205 ng/mL, Cres 631 ng/mL, AUC 24,242 ng . h/mL, and CR 0.6. After a median follow up of 12 months, 11% of patients (30 of 282) had experienced at least one serious adverse reaction among which 12 were nephrolithiasis. In the multivariate analyses, early high indinavir Cres (ie, >/=1000 ng/mL at M1) was associated with a higher rate of severe nephrolithiasis (hazard ratio = 6.7; 95% confidence interval = 1.8-25.2; P < 0.01) and was also associated with a higher rate of all serious adverse reactions but only when nephrolithiasis were included among those cases. Prospective and early indinavir Cres determination should be recommended in the patient's care management and dosage adjustments.

Successful formation of calcium oxalate crystal deposition in mouse kidney by intraabdominal glyoxylate injection

The establishment of an experimental animal model would be useful to study the mechanism of kidney stone formation. A calcium kidney stone model in rats induced by ethylene glycol has been used for research; however, to investigate the genetic basis affecting kidney stone formation, which will contribute to preventive medicine, the establishment of a kidney stone model in mice is essential. This study indicates the optimum conditions for inducing calcium oxalate stones in normal mouse kidney. Various doses of oxalate precursors, ethylene glycol, glycolate and glyoxylate, were administered either by free drinking or intraabdominal injection for 2 months as a preliminary study. Stone formation was detected with light microscopy, polarized light optical microscopy and electron microscopy. Stone components were detected with X-ray diffraction analysis. The expression of osteopontin (OPN), a major stone-related protein, was detected with immunohistochemical staining, in situ hybridization and quantitative reverse transcriptase polymerase chain reaction. Kidney stones were not detected in ethylene glycol- or glycolate-treated groups even at the highest dose of LD(50). Whereas, numerous kidney stones were detected in glyoxylate-treated mice (more than 60 mg/kg) at 3, 6 and 9 days after glyoxylate were administered intraabdominally. However, the number of kidney stones decreased gradually at day 12, and was hardly detected at day 15. The stone component was further analyzed as calcium oxalate monohydrate. A dramatic increase in the expression of OPN was observed by the administration of glyoxylate. We established a mouse kidney stone experimental system in this study. The difficulty of inducing kidney stones suggested that mice have greater intrinsic ability to prevent stone formation with hyperoxaluric stress than rats. The differing response to hyperoxaluric stress between mice and rats possibly contributes to the molecular mechanism of kidney stone formation and will aid preventive medicine in the future.