Kidney stones: an update on current pharmacological management and future directions

Bioguided isolation of anti-inflammatory and anti-urolithiatic active compounds from the decoction of Cissus gongylodes leaves

ETHNOPHARMACOLOGICAL RELEVANCE

The Cissus gongylodes has traditionally been used in the diet of indigenous people in Brazil and in traditional medicine for kidney stone removal and inflammatory diseases. The active compounds responsible for these pharmacological activities are unknown.

AIM OF THE STUDY

This study aims to isolate, for the first time, the compounds in the decoction of C. gongylodes leaves responsible for their anti-inflammatory and anti-urolithiatic ethnopharmacological properties.

MATERIALS AND METHODS

The most active fractions of the C. gongylodes leaf decoction were fractionated using SPE-C18 and the compounds were purified through HPLC-UV-DAD. The decoction fractions and isolated compounds were evaluated for their anti-inflammatory and anti-urolithiatic activities. The anti-inflammatory activity was assessed using an ex vivo assay in human blood induced by LPS and calcium ionophore, measuring inflammatory mediators, PGE2 and LTB4. The anti-urolithiatic activity was evaluated using an in vitro experimental model with human urine to determine the dissolution of the most recurrent calcium oxalate (CaOx) crystals. Additionally, the decoction was chemically characterized through metabolomic analysis using UHPLC-ESI-HRMS.

RESULTS

The isolated compounds from the decoction of C. gongylodes, including rutin, eriodictyol 3'-O-glycoside, and isoquercetin, have demonstrated significant multi-target actions. These components act as anti-inflammatory agents by inhibiting the release of main inflammatory mediators, PGE2 and LTB4. Additionally, they exhibit anti-urolithiatic properties, promoting the dissolution of calcium oxalate (CaOx) crystals. Furthermore, the characterization of the decoction by UHPLC-ESI-HRMS revealed a high content of flavonoids, mainly glycosylated flavonoids.

CONCLUSIONS

The results support the traditional use of C. gongylodes decoction, identifying the compounds responsible for its anti-inflammatory and anti-urolithiatic effects. The decoction fractions and isolated compounds exhibited dual anti-inflammatory activity, effectively inhibiting key inflammatory pathways and potentially presenting fewer adverse effects while also promoting the dissolution of CaOx crystals associated with urolithiasis. The multi-target action displayed by C. gongylodes is particularly desirable in the treatment of urolithiasis, as inflammation and PGE2 production precede and contribute to the formation of CaOx crystals in the kidneys. Based on these actions, C. gongylodes emerges as a potent source of active compounds for the development of new treatments for urolithiasis.

Linoleic Acid Enhances Renal Tubular Epithelial Cells Autophagy Caused by Calcium Oxalate Monohydrate Crystals

High intake of dietary linoleic acid may increase the incidence of many diseases. The aim of this research is to examine the impact of linoleic acid on the damage caused by calcium oxalate kidney stones on renal tubular epithelial cells. Calcium oxalate monohydrate (COM) crystals were prepared and used to treat HK-2 cells, which were further treated with different concentrations of linoleic acid in vitro. Also, a small-interfering RNA lentiviral vector of milk fat globule epidermal growth factor 8 (MFGE8) was constructed and transfected into HK-2 cells. The cell viability, level of intracellular ROS and autophagy were tested. In vivo experiments were also carried out with a rat model for renal urolithiasis treated with linoleic acid. The results indicated that COM crystals promoted crystal deposition and apoptosis, increased levels of intracellular Ca2+ and ROS levels and inhibited the proliferation of HK-2 cells. Linoleic acid exacerbated the damage of COM crystal-treated HK-2 cells and renal tubular epithelial cells of the rat model for renal urolithiasis, which can be partially reversed by downregulation of MFGE8. These results collectively suggest that linoleic acid might enhance the damage of renal tubular epithelial cells caused by COM crystals.

Low daily water intake profile-is it a contributor to disease?

Few previous review articles have focused on the associations between inadequate daily water intake (LOW) or urinary biomarkers of dehydration (UD; low urine volume or high urine osmolality) and multiple diseases. Accordingly, we conducted manual online searches (47 key words) of the PubMed, Embase, and Google Scholar databases with these inclusion criteria: English language, full-text, peer reviewed, no restriction on research design, and three publications minimum. Initially, 3,903 articles were identified based on their titles and abstracts. Evaluations of full length .pdf versions identified 96 studies that were acceptable for inclusion. We concluded that the evidence is insufficient or conflicting for seven disorders or diseases (i.e. suggesting the need for additional clarifying research) and it is lacking for all-cause mortality. Differential characterizations among women and men have been reported in the results of nine studies involving five diseases. Finally, the evidence for associations of LOW or UD is strong for both kidney stones and type 2 diabetes with hyperglycemia. This suggests that great public health value (i.e. reduced disease risk) may result from increased daily water intake-a simple and cost-effective dietary modification.

2022 Recommendations of the AFU Lithiasis Committee: Medical management - from diagnosis to treatment

The morphological-compositional analysis of urinary stones allows distinguishing schematically several situations: dietary, digestive, metabolic/hormonal, infectious and genetic problems. Blood and urine testing are recommended in the first instance to identify risk factors of urinary stone disease in order to avoid recurrence or progression. The other objective is to detect a potential underlying pathology associated with high risk of urinary stone disease (e.g. primary hyperparathyroidism, primary or enteric hyperoxaluria, cystinuria, distal renal tubular acidosis) that may require specific management. Lifestyle-diet measures are the basis of the management of all stone types, but pharmacological treatments may be required. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendation (CPR) method and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU 2022] and their adaptability to the French context.

A critical appraisal of urolithiasis clinical practice guidelines using the AGREE II instrument

Background

The Appraisal of Guidelines for Research and Evaluation II (AGREE II) instrument was developed to improve the methodological quality of clinical practice guidelines (CPGs). High-quality guidelines can provide reliable recommendations for different clinical issues. Currently, there is no quality appraisal of CPGs for urolithiasis. This study evaluated the quality of evidence-based CPGs for urolithiasis and provided new insights into improving guideline quality on urolithiasis.

Methods

Systematic reviews were conducted to identify urolithiasis CPGs in PubMed, electronic databases, and websites of medical associations from January 2009 to July 2022. The quality of included CPGs was evaluated by four reviewers using the AGREE II instrument. Subsequently, the scores of all domains in the AGREE II instrument were calculated.

Results

A total of 19 urolithiasis CPGs were identified for review: seven from Europe, six from USA, three from international union, two from Canada, and one from Asia. The agreement among reviewers was rated good [intraclass correlation coefficient (ICC), 0.806; 95% CI: 0.779-0.831]. The domains with the highest scores were scope and purpose (69.7%, 54.2-86.1%) and clarity of presentation (76.8%, 59.7-90.3%). The domains of stakeholder involvement (44.9%, 19.4-84.7%) and applicability (48.5%, 30.2-72.9%) gained the lowest score. Only five guidelines (26.3%) were considered "strongly recommended".

Conclusions

The overall quality of the eligible CPGs was relatively high; however, future work is still needed in the domains of rigor of development, editorial independence, applicability, and stakeholder involvement.

Hormonal and molecular characterization of calcium oxalate stone formers predicting occurrence and recurrence

The purpose of the study is to investigate the role of sex hormones, androgen receptors (ARs) and miRNA/CSF-1 in occurrence and recurrence of calcium oxalate (CaOx) renal urolithiasis. In this prospective study, 74 patients with CaOx stones; stone formers group (SFG) and 40 healthy subjects; control group were compared. SFG includes both de novo and recurrent cases. Steroid sex hormone plasma assay including testosterone, free testosterone, dihydrotestosterone, estradiol, and sex hormone binding globulin was analyzed. ARs, miRNA-185-5p and CSF-1 expression were compared between the groups. SFG showed significant higher ARs and miRNA-185-5p expression (3.7 ± 1.3, 1.8 ± 0.4, respectively) than control group (1 ± 0.08 and 1 ± 0.07, respectively) (p < 0.05). However, CSF-1 expression was significantly lower in stone formers than control group (0.4 ± 0.19 vs 1 ± 0.1, respectively) (p < 0.05). No differences were detected between de novo and recurrent SFG regarding sex hormones, AR, miRNA or CSF-1 expression. Our data suggest the important role of AR, miRNA and CSF-1 signaling in human nephrolithiasis pathogenesis.

In Vivo Prediction of Kidney Stone Fragility Using Radiomics-Based Regression Models

Introduction: The surgical technique for urinary stone removal is partly influenced by its fragility, as prognosticated by the clinician. This feasibility study aims to develop a linear regression model from CT-based radiomic markers to predict kidney stone comminution time in vivo with two ultrasonic lithotrites. Materials and Methods: Patients identified by urologists at our institution as eligible candidates for percutaneous nephrolithotomy were prospectively enrolled. The active engagement time of the lithotrite in breaking the stone during surgery denoted the comminution time of each stone. The comminution rate was computed as the stone volume disintegrated per minute. Stones were grouped into three fragility classes (fragile, moderate, hard), based on inverse of the comminution rates with respect to the mean. Multivariable linear regression models were trained with radiomic features extracted from clinical CT images to predict comminution times in vivo. The model with the least root mean squared error (RMSE) on comminution times and the fewest misclassification of fragility was finally selected. Results: Twenty-eight patients with 31 stones in total were included in this study. Stones in the cohort averaged 1557 (±2472) mm3 in volume and 5.3 (±7.4) minutes in comminution time. Ten stones had nonmoderate fragility. Linear regression of stone volume alone predicted comminution time with an RMSE of 6.8 minutes and missed all 10 stones with nonmoderate fragility. A fragility model that included stone volume, internal morphology, shape-based radiomics, and device type improved RMSE to below 3.3 minutes and correctly classified 20/21 moderate and 6/10 nonmoderate stones. Conclusions: CT metrics-based fragility models may provide information to surgeons regarding kidney stone fragility and facilitate the selection of stone removal procedures.

Ethnomedicinal Plants Used for Treatment of Urolithiasis in India: A Review

Background:

The kidney stone is the most commonly observed and painful disease of the urinary tract in human being. Numerous intrinsic and extrinsic factors are responsible for the formation of kidney stone, for instance, age, sex, heredity (intrinsic factors) and climate, dietary, geography, mineral composition, and water intake (extrinsic factors). The kidney stones are categorized into calcium, struvite or magnesium ammonium phosphate, uric acid or urate, cystine and other types of stones based on chemical composition and pathogenesis. Due to the multifactorial nature of kidney stone disease, the patient may need to rely on complex synthetic medication. However, in ancient Indian history, there are several pieces of evidence where natural resources such as plants were used to remediation this lethal disease.

Objective:

The present review attempts to provide exhaustive information of ethnomedicinal and ethnopharmacological information of medicinal plants used for kidney stone in India.

Result:

Hitherto, there are a total of 258 ethnomedicinal plants from 90 different families reported using for kidney stone application. The majority of the plant species are associated with three important families: Asteraceae, Amaranthaceae, and Fabaceae. Most of the plants are from Andhra Pradesh (43 plants), followed by East Bengal (38), Jammu & Kashmir (36), Uttarakhand (31), Panjab (27), Mizoram (23), Karnataka (20), Maharashtra (20) and Assam (18). The commonly used plant parts for the herbal preparation are roots (21.22 %) followed by leaves/leaf (20.15 %), and sometimes complete plant (17.77 %) is used. The most commonly used method for the formulation is decoction (46.41 %) followed by powder (18.66 %) and then extracts (15.78 %) of different aerial and non-aerial parts of the plant. To date, the in-vitro and in-vivo activities against the kidney stone assessed for more than sixty ethnomedicinal plants.

Conclusion:

The present review epitomizes the ethnomedicinal information of medicinal plants used for kidney stone and pharmacological evidence for anti-urolithiasis activity. Most reported medicinal plants are not yet scientifically explored and need immediate attention before we lose some important species due to excessive deforestation for farming and industrial needs.

Appraising the potency of small molecule inhibitors and their graphene surface-mediated organizational attributes on uric acid-melamine clusters

Uric acid (UA) and melamine (MM) crystallization in humans is associated with adverse medical conditions, including the germination of kidney stones, because of their low solubility. The growth of kidney stones, usually formed on renal papillary facades, is accomplished on the matrix-coated surface by the aggregation of preformed crystals or secondary crystal nucleation. Therefore, the effects of inhibitors such as theobromine (TB) and allopurinol (AP) on MM-UA aggregation are investigated by employing classical molecular dynamics simulations on a graphene surface. This impersonates the exact essence of the precipitation of kidney stones. The interaction between MM-UA is very intense and, thus, large clusters are formed on the surface. The presence of TB and AP will, however, substantially inhibit their aggregation. TB and AP significantly impede UA aggregation in particular. Therefore, lower order UA clusters are formed. These smaller UA clusters then pull a lower number of MM towards themselves, resulting in a smaller order UA-MM cluster. MM and UA aggregation on a 2D graphene surface is found to be spontaneous. There is no difference in these molecules' adsorption with a change in the force field parameters (i.e., GAFF and OPLS-AA) for graphene. Moreover, the greater the surface area of graphene, the more molecules are absorbed. The solute-surface van der Waals interaction energy plays a driving force in the adsorption of solute molecules on the surface. In addition, interactions like hydrogen bonding and π-stacking over the graphene surface involve binding all like molecules. These aggregated solute molecules strongly attract more like molecules until all solute molecules are adsorbed on the graphene surface, as estimated by enhanced sampling. The molecular origin of graphene exfoliation by MM is also described here. The present work helps to design novel kidney stone inhibitors.

Anti-urolithiatic activity of Bryophyllum pinnatum Lam. hydroalcoholic extract in sodium oxalate-induced urolithiasis in rats

Background and Aim

Despite advances in modern medicine, the development and growth of calculi continues to be a source of concern for mankind, as there is no effective treatment for kidney stones. In the present study we investigated antiurolithiatic activity of Bryophyllum pinnatum Lam against sodium oxalate (NaOx) induced urolithiasis in rats.

Experimental procedure

In rats with renal calculi caused by sodium oxalate (NaOx, 70 mg/kg, i.p.); the antiurolithiatic action of Bryophyllum pinnatum hydroalcoholic extract (BPHE) was studied. BPHE was given every day orally at doses of 50, 200 mg/kg for 14 days to rats to examine activity against sodium oxalate (NaOx) mediated urolithiasis, with Cystone (500 mg/kg, p.o.) as a reference standard. The effect of the extract on urine oxalate, creatinine and phosphate retention and excretion in the kidney, as well as serum and biochemical analysis of kidney homogenate and histopathological examinations were studied.

Results and conclusion

Oral administration of BPHE at doses of 50,100, and 200 mg/kg to rats with sodium oxalate-mediated renal calculi showed dose-dependent substantial (P<0.05) antiurolithiatic potential, with notable reversal of NaOx-induced ion excretion and urinary CaOx concentration. These findings justify the traditional use of Bryophyllum pinnatum hydroalcoholic extract (BPHE) in the treatment of renal calculi.

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Supporting its traditional use in renal calculi.

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Demonstrated dose-dependent antiurolithiatic capacity.

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A notable reversal of NaOx-induced ion excretion.

Determination of the etiology of pediatric urinary stone disease by multigene panel and metabolic screening evaluation

INTRODUCTION

Urinary tract stone disease (UTSD) is seen with increasing frequency in children, and genetic, metabolic and environmental factors are known to play a role in its etiology. Since it is a genetically heterogeneous disease, we investigated the multigene panel and metabolic evaluation together.

MATERIAL AND METHOD

Forty-eight pediatric patients that underwent surgery for UTSD and were followed up in the Department of Urology of Çukurova University Faculty of Medicine between March 2016 and July 2019 were included in the study. Children with known metabolic diseases were excluded.A detailed history was taken from each patient, and presence of a positive family history was questioned. Blood and urine samples were obtained, and metabolic evaluation was performed. In addition, 2 cc peripheral blood samples were collected from selected patients to perform DNA isolation at Çukurova University Adana Genetic Diseases Diagnosis and Treatment Center. The analysis of the obtained sequence data was performed.

RESULTS

Of the 48 children included in the study, 29 (60.4%) were male and 19 (39.6%) were female. The mean age was 60 ± 50 (12-192) months. It was observed that 28 (58.3%) of the patients included in the study had a positive family history.As a result of the next-generation sequencing studies conducted with the multigene panel, a total of 21 clinically significant variants in eight different genes were identified with the bioinformatics analysis on the data on which quality control was performed. The weighted distribution of the 21 variants according to the genes was as follows: five variants (23.8%) in the SLC3A1 gene, four (19%) in SLC6A20, and three (14.3%) in SLC7A9 and SLC26A1. The clinical reporting of the disease etiology and/or variants with prognostic significance determined as a result of the performed analyses was completed by field experts in accordance with international standards. The visuals of the detected variants are presented in Summary figure.

CONCLUSION

In pediatric cases with UTSD, it is important to determine the underlying metabolic and genetic risk factors in order to prevent recurrence and apply the most effective treatment.

The Impact of Diet on Urinary Risk Factors for Cystine Stone Formation

Despite the importance of dietary management of cystinuria, data on the contribution of diet to urinary risk factors for cystine stone formation are limited. Studies on the physiological effects of diet on urinary cystine and cysteine excretion are lacking. Accordingly, 10 healthy men received three standardized diets for a period of five days each and collected daily 24 h urine. The Western-type diet (WD; 95 g/day protein) corresponded to usual dietary habits, whereas the mixed diet (MD; 65 g/day protein) and lacto-ovo-vegetarian diet (VD; 65 g/day protein) were calculated according to dietary reference intakes. With intake of the VD, urinary cystine and cysteine excretion decreased by 22 and 15%, respectively, compared to the WD, although the differences were not statistically significant. Urine pH was significantly highest on the VD. Regression analysis showed that urinary phosphate was significantly associated with cystine excretion, while urinary sulfate was a predictor of cysteine excretion. Neither urinary cystine nor cysteine excretion was affected by dietary sodium intake. A lacto-ovo-vegetarian diet is particularly suitable for the dietary treatment of cystinuria, since the additional alkali load may reduce the amount of required alkalizing agents.

Medical evaluation and pharmacotherapeutical strategies in management of urolithiasis

Treatment of urolithiasis depends on several important factors which include stone location, size, composition, and patient symptoms. Although significant advancements have been made in the surgical management of urolithiasis in the last decade, pharmacotherapy which can prevent the formation of new stones and decrease the recurrence of urolithiasis has not experienced the same level of success. Currently, urolithiasis is regarded as a complicated syndrome that is determined by numerous factors, and any treatment plan for urolithiasis should be individualized while considering any potential damage arising from stone-forming factors. This review introduces the most popular methods currently used to evaluate urolithiasis and the pharmacotherapy of urolithiasis based on patient-specific factors.

A Prospective, Double-Blind, Randomized, Placebo-Controlled, Crossover Study Using an Orally Administered Oxalate Decarboxylase (OxDC)

BACKGROUND

Hyperoxaluria is typically associated with excessive oxalate intake in the diet, decreased dietary calcium, hyperabsorption of oxalate, or increased endogenous production of oxalate. The disorder spectrum extends from recurrent kidney stones to ESKD. This clinical trial sought to evaluate the effectiveness of an acid stable oxalate decarboxylase (OxDC) to reduce urinary oxalate in healthy subjects on a high-oxalate diet.

METHODS

In this prospective, double-blind, randomized, placebo-controlled, crossover clinical trial, 33 healthy volunteers were randomized into two crossover sequences separated by a 2-day washout period. A controlled high-oxalate diet (750-800 mg oxalate, 500-550 mg calcium daily) was utilized, and six 24-hour urine collections were measured. Subjects were given approximately 1000 U (micromoles per minute per milligram) of OxDC or placebo with meals three times daily during the 4 days of treatment.

RESULTS

Urinary oxalate significantly decreased with OxDC treatment. The baseline corrected within-subject mean reduction in 24-hour urinary excretion (after OxDC dosing versus high-oxalate baseline preceding treatment) was 12.5 mg or 29% (P<0.001). OxDC treatment was effective (>5% reduction) in 31 of 33 subjects (94%). Compared with placebo, OxDC produced a 24% reduction (P<0.001) in 24-hour oxalate excretion. Other urinary parameters (creatinine, uric acid, citrate, magnesium, calcium) were not affected by OxDC. No serious adverse events and no product-related adverse events occurred.

CONCLUSIONS

An orally administered OxDC is capable of significantly reducing urinary oxalate levels in healthy volunteers on a high-oxalate diet without affecting creatinine clearance, urine creatinine, or other solutes related to supersaturation of calcium oxalate.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Evaluation of Nephure, and the Reduction of Dietary Oxalate, in Healthy Volunteers, NCT03661216.

Association Between Serum Magnesium and the Prevalence of Kidney Stones: a Cross-sectional Study

Kidney stones, a painful and costly disease, have become a public health problem worldwide. The aim of this study was to evaluate the association between serum magnesium levels and the prevalence of kidney stones in a large population context. This study was conducted in Xiangya Hospital, Central South University in Changsha, Hunan, China, between October 2013 and December 2015. A total of 6228 subjects aged ≥ 18 years old were included. Kidney stones were diagnosed by (1) direct visualisation of stone(s) on the abdominal ultrasound examination, and (2) presence of stone(s) with a diameter ≥ 4 mm. The chemiluminescence method was used to measure the serum magnesium concentration. The association between serum magnesium and the prevalence of kidney stones was evaluated using logistic and spline regression in a cross-sectional study. The prevalence of kidney stones was 6.1% (7.5% in men and 4.2% in women). Compared with the lowest quartile, the crude odds ratio for kidney stones was 0.62 (95% CI 0.46-0.85) for the highest quartile of serum magnesium, and there was an inverse dose-response relationship (P for trend = 0.038). Similar results were observed for men and women separately. The findings were not materially altered by adjustment for potential confounders. In conclusion, subjects with relatively lower levels of serum magnesium, even though within the normal range, were subject to a higher prevalence of kidney stones in a dose-response relationship manner, indicating that magnesium may play a certain role in the prevention or treatment of kidney stones.

The effectiveness and safety of extracorporeal shock wave lithotripsy for the management of kidney stones: A protocol of systematic review and meta-analysis

BACKGROUND

This study will assess the effectiveness and safety of extracorporeal shock wave lithotripsy (ESWL) for patients with kidney stones (KS).

METHODS

A comprehensive and systematic literature records search for studies will be conducted in MEDLINE, EMBASE, Cochrane Library, WANGFANG, VIP, Chinese Biomedical Literature Database, and China National Knowledge Infrastructure. All these databases will be searched from inception to the present without language limitation. Cochrane risk of bias tool will be used to assess the methodological quality for all included studies. Statistical analysis is performed using RevMan 5.3 software.

RESULTS

This study will provide synthesis of current evidence of ESWL for patients with KS through assessing primary outcomes of overall stone-free rate, and secondary outcomes of mean stone size (mm), pain intensity, urinary biochemical variables, mean hospital stay (day), quality of life, and adverse events.

CONCLUSION

This study will provide recommendations for the effectiveness and safety of ESWL for patients with KS, which may help to guide clinician.

PROSPERO REGISTRATION NUMBER

PROSPERO CRD42019157243.

Sex differences in redox homeostasis in renal disease

Sex differences in redox signaling in the kidney present new challenges and opportunities for understanding the physiology and pathophysiology of the kidney. This review will focus on reactive oxygen species, immune-related signaling pathways and endothelin-1 as potential mediators of sex-differences in redox homeostasis in the kidney. Additionally, this review will highlight male-female differences in redox signaling in several major cardiovascular and renal disorders namely acute kidney injury, diabetic nephropathy, kidney stone disease and salt-sensitive hypertension. Furthermore, we will discuss the contribution of redox signaling in the pathogenesis of postmenopausal hypertension and preeclampsia.

Pathological Mineralization: The Potential of Mineralomics

Pathological mineralization has been reported countless times in the literature and is a well-known phenomenon in the medical field for its connections to a wide range of diseases, including cancer, cardiovascular, and neurodegenerative diseases. The minerals involved in calcification, however, have not been directly studied as extensively as the organic components of each of the pathologies. These have been studied in isolation and, for most of them, physicochemical properties are hitherto not fully known. In a parallel development, materials science methods such as electron microscopy, spectroscopy, thermal analysis, and others have been used in biology mainly for the study of hard tissues and biomaterials and have only recently been incorporated in the study of other biological systems. This review connects a range of soft tissue diseases, including breast cancer, age-related macular degeneration, aortic valve stenosis, kidney stone diseases, and Fahr’s syndrome, all of which have been associated with mineralization processes. Furthermore, it describes how physicochemical material characterization methods have been used to provide new information on such pathologies. Here, we focus on diseases that are associated with calcium-composed minerals to discuss how understanding the properties of these minerals can provide new insights on their origins, considering that different conditions and biological features are required for each type of mineral to be formed. We show that mineralomics, or the study of the properties and roles of minerals, can provide information which will help to improve prevention methods against pathological mineral build-up, which in the cases of most of the diseases mentioned in this review, will ultimately lead to new prevention or treatment methods for the diseases. Importantly, this review aims to highlight that chemical composition alone cannot fully support conclusions drawn on the nature of these minerals.

Loss of the androgen receptor suppresses intrarenal calcium oxalate crystals deposition via altering macrophage recruitment/M2 polarization with change of the miR-185-5p/CSF-1 signals

Crystals can trigger a wide range of kidney injuries that may link to the development of kidney stones. Infiltrating macrophages may influence hyperoxaluria-induced intrarenal calcium oxalate (CaOx) crystals deposition, yet their linkage to sex hormones remains unclear. Here we demonstrated that suppressing the androgen receptor (AR) expression in renal tubular epithelial cells increased the macrophage recruitment/M2 polarization that may result in enhancing the phagocytosis of intrarenal CaOx crystals. Mechanism dissection suggested that AR can suppress macrophage colony-stimulating factor 1 (CSF-1) expression via increasing miRNA-185-5p expression to suppress the M2 macrophage polarization-mediated intrarenal CaOx crystals phagocytosis. The preclinical study using glyoxylate-induced intrarenal CaOx crystals deposition mouse model revealed that renal tubule-specific AR knockout mice have less intrarenal CaOx crystals deposition with more recruited M2 macrophages in the kidney compared with the wild-type mice. Results from the in vivo rat model using hydroxy-L-proline-induced CaOx crystals deposition also demonstrated that targeting the AR with ASC-J9® suppressed the intrarenal CaOx crystals deposition via increasing the renal macrophage recruitment/M2 polarization. Together, results from multiple preclinical studies using multiple in vitro cell lines and in vivo mouse/rat models all demonstrated that targeting the AR with a small molecule ASC-J9® may function via altering macrophage recruitment/M2 polarization to decrease the intrarenal CaOx crystals deposition, a key phenotype seen in many kidney stone disease patients with hyperoxaluria.

The Demographic Diversity of Food Intake and Prevalence of Kidney Stone Diseases in the Indian Continent

Food intake plays a pivotal role in human growth, constituting 45% of the global economy and wellbeing in general. The consumption of a balanced diet is essential for overall good health, and a lack of equilibrium can lead to malnutrition, prenatal death, obesity, osteoporosis and bone fractures, coronary heart diseases (CHD), idiopathic hypercalciuria, diabetes, and many other conditions. CHD, osteoporosis, malnutrition, and obesity are extensively discussed in the literature, although there are fragmented findings in the realm of kidney stone diseases (KSD) and their correlation with food intake. KSD associated with hematuria and renal failure poses an increasing threat to healthcare infrastructures and the global economy, and its emergence in the Indian population is being linked to multi-factorial urological disorder resulting from several factors. In this realm, epidemiological, biochemical, and macroeconomic situations have been the focus of research, even though food intake is also of paramount importance. Hence, in this article, we review the corollary associations with the consumption of diverse foods and the role that these play in KSD in an Indian context.

Conventional Treatment of Hypoparathyroidism

Conventional therapy of hypoparathyroidism consists of oral calcium and either activated vitamin D or vitamin D supplements at varying doses. Although adjusting dosing of calcium and/or activated vitamin D or vitamin D itself, the serum calcium should be obtained weekly or monthly depending on the clinical situation. Calcium supplementation in hypoparathyroidism usually consists of calcium carbonate because it is 40% elemental calcium by weight. However, calcium citrate (21% elemental calcium) is indicated for patients with achlorhydria and proton pump inhibitor therapy. Many clinicians prefer to uptitrate the activated form of vitamin D to reduce the amount of calcium supplementation.

Drosophila melanogaster as a function-based high-throughput screening model for antinephrolithiasis agents in kidney stone patients

Kidney stone disease involves the aggregation of stone-forming salts consequent to solute supersaturation in urine. The development of novel therapeutic agents for this predominantly metabolic and biochemical disorder have been hampered by the lack of a practical pre-clinical model amenable to drug screening. Here, Drosophila melanogaster, an emerging model for kidney stone disease research, was adapted as a high-throughput functional drug screening platform independent of the multifactorial nature of mammalian nephrolithiasis. Through functional screening, the therapeutic potential of a novel compound commonly known as arbutin that specifically binds to oxalate, a key component of kidney calculi, was identified. Through isothermal titration calorimetry, high-performance liquid chromatography and atomic force microscopy, arbutin was determined to interact with calcium and oxalate in both free and bound states, disrupting crystal lattice structure, growth and crystallization. When used to treat patient urine samples, arbutin significantly abrogated calculus formation in vivo and outperformed potassium citrate in low pH urine conditions, owing to its oxalate-centric mode of action. The discovery of this novel antilithogenic compound via D. melanogaster, independent of a mammalian model, brings greater recognition to this platform, for which metabolic features are primary outcomes, underscoring the power of D. melanogaster as a high-throughput drug screening platform in similar disorders. This is the first description of the use of D. melanogaster as the model system for a high-throughput chemical library screen. This article has an associated First Person interview with the first authors of the paper.

Effect of Consumption of Cocoa-Derived Products on Uric Acid Crystallization in Urine of Healthy Volunteers

The purpose of this study was to determine the effects of consumption of different cocoa-derived products on uric acid crystallization in urine of 20 healthy volunteers. Participants were requested to select the specific diet that they wished to follow during the 12 h prior to collection of urine. The only restriction was that the diet could not include any product with cocoa, coffee, or caffeine. On the first day, each volunteer followed their selected diet, and an overnight 12 h urine sample was collected as the baseline urine. After seven days on an unrestricted diet, each volunteer repeated the same diet with 20 g of milk chocolate, chocolate powder, or dark chocolate during breakfast and another 20 g during dinner. Overnight 12 h urine samples were then collected. Urine volume, pH, oxalate, creatinine, uric acid, theobromine, and a uric acid crystallization test were determined for each sample. The results for all 20 patients show that uric acid crystallization was significantly lower following the consumption of chocolate powder or dark chocolate relative to baseline or following the consumption of milk chocolate. The results indicated that increased concentrations of urinary theobromine reduced the risk of uric acid crystallization.

Uric acid stones, clinical manifestations and therapeutic considerations

Uric acid stones account for 10%-15% of all urinary stones. Changes in dietary habits, environment or both can result in the increase of uric acid stones. The formation of uric acid stones is related to hyperuricosuria, low urinary volume and persistently low urinary pH. Diabetes and obesity also significantly increase the risk of stone formation. Dual-energy CT provides a convenient and reliable method for diagnosis. Stone composition analysis and 24-hour urine metabolic evaluations should be considered for further evaluation. Most small uric acid stones (diameter <2 cm) can be treated by pharmacotherapy or extracorporeal shock wave lithotripsy. However, ureteroscopy and other minimally invasive procedures should be reserved for larger stones (diameter ≥2 cm), or patients with concomitant urinary tract obstruction and/or infections. Additionally, adjustment of potential pathophysiologic defects by pharmacotherapy and dietary modification is strongly recommended for the prevention of uric stone recurrence.

Relationships between enteral nutrition facts and urinary stones in a cohort of pediatric patients in rehabilitation from severe acquired brain injury

BACKGROUND & AIMS

Urolithiasis affects pediatric patients with severe acquired brain injury, in whom the role of several clinical variables and of the presence and composition of enteral nutrition has not been investigated.

METHODS

Retrospective chart review on 371 pediatric patients with severe acquired brain injury. We used an essential electronic database to check the association between stones and enteral feeding. We then picked at random paper clinical records until we collected 20 and 20 complete records for patients with/without stones, not matched. With that information, we tested the association of stones with: nutrition facts of enteral formulae (sodium, potassium, calcium, magnesium, phosphorus, proteins, vitamin C); bladder dysfunction, urinary infections, catheterisms, tracheostomy, gallstones, way of feeding; blood and urine exams before stones diagnosis; age, type and severity of injury; prior physical activity, relevant drugs.

RESULTS

All patients with stones were fed enterally. At univariate statistics they were older, weighed more, received bigger volumes of hydration and nutrition; they had worse GCS, more UTIs and they alone received catheterisms; their nutrition mixes were richer in sodium. In multivariate logistic regression for stone development, UTIs (OR 11.4, 95% C.I. 1.6-83.4) and higher sodium nutrition content (OR 7.5, 95% C.I. 1.6-34.3) were risk factors; higher GCS (OR 0.66, 95% C.I. 0.43-0.99) and higher calcium nutrition content (OR 0.14, 95% C.I. 0.03-0.73) were protective factors.

CONCLUSIONS

Besides known risk factors for urolithiasis, including UTIs, catheterisms, worse neurological states, also enteral nutrition was a risk factor, particularly with higher sodium and lower calcium contents. Future studies should test the effect of different sodium/calcium nutrition contents on lithogenesis.

Kidney Stone Disease: An Update on Current Concepts

Kidney stone disease is a crystal concretion formed usually within the kidneys. It is an increasing urological disorder of human health, affecting about 12% of the world population. It has been associated with an increased risk of end-stage renal failure. The etiology of kidney stone is multifactorial. The most common type of kidney stone is calcium oxalate formed at Randall's plaque on the renal papillary surfaces. The mechanism of stone formation is a complex process which results from several physicochemical events including supersaturation, nucleation, growth, aggregation, and retention of urinary stone constituents within tubular cells. These steps are modulated by an imbalance between factors that promote or inhibit urinary crystallization. It is also noted that cellular injury promotes retention of particles on renal papillary surfaces. The exposure of renal epithelial cells to oxalate causes a signaling cascade which leads to apoptosis by p38 mitogen-activated protein kinase pathways. Currently, there is no satisfactory drug to cure and/or prevent kidney stone recurrences. Thus, further understanding of the pathophysiology of kidney stone formation is a research area to manage urolithiasis using new drugs. Therefore, this review has intended to provide a compiled up-to-date information on kidney stone etiology, pathogenesis, and prevention approaches.

Effects of statin treatment with atorvastatin on urolithiasis-associated urinary metabolic risk factors: an experimental study

PURPOSE

To investigate whether atorvastatin has favorable effects on urinary metabolic risk factors associated with urolithiasis.

METHODS

Sixteen male Sprague-Dawley rats were randomly divided into two groups, and baseline spot and 24-h urine samples were collected. Distilled water and atorvastatin were administered to rats during 4 weeks in the control and atorvastatin groups, respectively. At the end of the experimental procedure, spot and 24-h urine samples were collected again. Citrate, oxalate, cystine, uric acid, calcium and magnesium levels were determined in 24-h urine samples. Citrate/creatinine, oxalate/creatinine, uric acid/creatinine, calcium/creatinine and magnesium/creatinine ratios were also calculated in spot urine samples. Comparison of the baseline and post-experimental levels of these parameters was made in each group.

RESULTS

The majority of the parameters were similar before and after the experimental procedure in each group. In the atorvastatin group, uric acid and calcium levels were affected. Administration of atorvastatin was significantly decreased the levels of uric acid, whereas increased the levels of calcium (P = 0.025 and P = 0.017, respectively).

CONCLUSIONS

Our study revealed that atorvastatin has decreasing effect on UUa levels, whereas increasing effect on UCa levels. We think it cannot certainly be deduced that atorvastatin could be beneficial on overall urinary metabolic risk factors. Contrarily, atorvastatin may lead to an increased risk of calcium stones, but when considering its UUa decreasing effect, it may help in reducing the uric acid stone recurrence.

Antiurolithiatic effect of the taraxasterol on ethylene glycol induced kidney calculi in male rats

Taraxasterol is one of the important constituents of Taraxacum officinale L. (Compositae) with antioxidant potential. The present study was designed to evaluate and compare the antiurolithiatic effects of taraxasterol and potassium citrate in the ethylene glycol induced urolithiatic rat. Urolithiasis was induced by ammonium chloride and ethylene glycol in adult male rats. Taraxasterol (2, 4 and 8 mg/kg) and potassium citrate (2.5 g/kg) were treated for 33 days by gavage. Then, the animals were anesthetized and weighted and blood, urine, liver and kidney sampling were done. The kidney sections were prepared by hematoxylin & eosin staining. The liver and kidney coefficients, urine pH, calcium, magnesium, oxalate and citrate levels, serum albumin, calcium and magnesium levels, serum alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase activities, superoxide dismutase and glutathione peroxidase activities in serum, kidney and liver, number of calcium oxalate crystal deposits, score of crystal deposits, score of histopathological damages and score of inflammation in kidney sections were evaluated. The results showed that taraxasterol decreased liver and kidney coefficients (p < 0.001), serum calcium (p < 0.01) level, serum alanine aminotransferase (p < 0.001), aspartate aminotransferase (p < 0.001), lactate dehydrogenase (p < 0.05) activities, urine magnesium (p < 0.05) and oxalate (p < 0.001) levels, number of crystal deposits (p < 0.001), score of crystal deposits (p < 0.01), score of histopathological damages (p < 0.001) and score of inflammation (p < 0.01) in kidney sections, while increased urine pH (p < 0.01), calcium (p < 0.001) and citrate (p < 0.05), serum magnesium (p < 0.001) and albumin (p < 0.01) levels, superoxide dismutase and glutathione peroxidase in serum (p < 0.01), kidney (p < 0.05 and p < 0.001, respectively) and liver (p < 0.01 and p < 0.001, respectively) tissue homogenates in treated urolithiatic rats in comparison to the control urolithiatic rats. The effect of potassium citrate is the same as taraxasterol in treated urolithiatic rats. In conclusion, the effect of taraxasterol could be by improving liver function, changing serum and urine parameters, maintaining the antioxidant environment, reducing crystal deposition, excretion of small deposits from kidney and reducing the chance of them being retained in the urinary tract.

Non-alcoholic fatty liver disease and the development of nephrolithiasis: A cohort study

Background

Non-alcoholic fatty liver disease (NAFLD), a hepatic manifestation or precursor of metabolic syndrome, may increase nephrolithiasis, a renal manifestation of insulin resistance, but the prospective association between NAFLD and incident nephrolithiasis has not been evaluated. We examined the association of NAFLD with the development of nephrolithiasis in a large cohort of Korean men and women.

Methods

We performed a cohort study of 208,578 Korean adults who underwent a health checkup examination between January 2002 and December 2014 and were followed-up annually or biennially through December 2014. NAFLD was defined as the presence of fatty liver in the absence of excessive alcohol use or other identifiable causes. Fatty liver and nephrolithiasis were determined based on ultrasonographic findings. We used a parametric Cox model to estimate the adjusted hazard ratios (HRs) of nephrolithiasis according to the presence of NAFLD.

Results

During 1,054,887.6 person-year of follow-up, 16,442 participants developed nephrolithiasis. After adjusting for age, center, year of screening exam, smoking status, alcohol intake, physical activity, education level, body mass index, history of hypertension and diabetes, HOMA-IR, uric acid and C-reactive protein, male participants with NAFLD had a significantly increased risk of nephrolithiasis than those without NAFLD (adjusted HR 1.17, 95% CI 1.06–1.30). However, no association between NAFLD and nephrolithiasis was observed in women (adjusted HR 0.97, 95% CI 0.81–1.16).

Conclusions

In this large cohort study of young and middle-aged Koreans, NAFLD was significantly associated with an increased incidence of nephrolithiasis in men but not in women.

Incidence of and risk factors for nephrolithiasis in patients with gout and the general population, a cohort study

BACKGROUND

Nephrolithiasis (NL) is known to be associated with gout, although there are few comparative studies on risk and risk factors for NL in gout compared to population cohorts. In this cohort study we investigated: (1) overall incidence of NL in gout (cases) and general population controls; (2) risk and risk factors (common comorbidities and medications) for first-time NL in cases and controls separately.

METHODS

Cases (n = 29,968) and age-matched and sex-matched controls (n = 138,678) were identified from the regional healthcare database in western Sweden (VEGA). The analyzed risk factors (comorbidities and current medication use) for first-time NL, and socioeconomic factors were retrieved from VEGA and other national Swedish registers. For cases, follow up began on 1 January 2006 or on the first diagnosis of gout if this occurred later, and for controls on their index patient's first diagnosis of gout. Follow up ended on death, emigration or 31 December 2012. Incidence rates (IR) per 1000 person-years and hazard ratios (HR) were calculated. The incidence calculations were performed for cases (regardless of prior NL) and their controls. HRs with first occurrence of NL as outcome were calculated only in those without previous NL.

RESULTS

In cases there were 678 NL events (IR: 6.16 events per 1000 person-years (95% CI: 5.70-6.64) and in controls 2125 NL events (IR 3.85 events per 1000 person-years (95% CI: 3.69-4.02), resulting in an age-sex-adjusted incidence rate ratio of 1.60 (95% CI:1.47-1.74). Point estimates for predictive factors were similar in cases and controls, except for a significant interaction for losartan which increased the risk of NL only in controls (HR = 1.49 (95% CI: 1.03-2.14). Loop diuretics significantly decreased the risk of NL by 30-34% in both cases and controls. Further significant predictors of NL in gout cases were male sex, diabetes and obesity and in controls male sex and kidney disease.

CONCLUSIONS

The risk (age and sex adjusted) of NL was increased by 60% in cases compared to controls. None of the commonly used medications increased the risk of NL in gout patients.

Antiurolithiatic Effect of Sirupeelai Samoola Kudineer: A Polyherbal Siddha Decoction on Ethylene Glycol-induced Renal Calculus in Experimental Rats

Background:

Sirupeelai Samoola Kudineer (SK), a polyherbal decoction containing four medicinal plants has been used in Siddha system of medicine, practiced in Southern parts of India for the management of urolithiasis.

Objective:

The present study is carried out to scientifically validate the traditional claim and to study the mechanism of action of the drug.

Materials and Methods:

In the present study, anti-urolithiatic effect of SK was evaluated in Sprague-Dawley rats using ethylene glycol through drinking water and intraperitoneal injection of sodium oxalate. Renal damage was confirmed by the increased production of thiobarbituric acid reactive substance (TBARS).

Results:

Co-treatment with SK to urolithiatic rats for 21 days significantly prevented the elevation of renal and urinary stone biomarkers in plasma and renal tissue thereby preventing renal damage and the formation of renal calculi. Administration of SK at all doses and cystone restored the antioxidant (glutathione) levels by preventing the elevation of TBARS in the kidney tissue, which was further confirmed by histological sections.

Conclusions:

SK treatment promotes diuresis which leads to flushing of the renal stones and maintains the alkaline environment in the urinary system which probably mediates the antilithiatic activity. SK provides structural and functional protection to the kidneys by enhancing its physiological function against stone formation and validates its clinical use.

SUMMARY

SK exhibited antilithiatic and diuretic potential in ethylene glycol and sodium oxalate induced urolithiasis in rats

Elevated urinary stone markers (Calcium, oxalate, uric acid, magnesium and phosphates) in plasma and renal tubular enzymes (LDH, GGT, ALP, AST ALT) in urolithiatic rats were reversed by SK treatment

SK administration significantly reduced the level of renal stress markers like Urea, Creatinine, LPO and elevated SOD, GPx, GSH levels aiding in nephroprotection

SK also provides structural and functional protection against ethylene glycol- induced renal calculus in rats as evidenced by histopathological studies.

Abbreviations used: SK: Sirupeelai Samoola Kudineer; TBARS: ThioBarbituric Acid Reactive Substances; SOD: SuperOxide Dismutase; GPx: Gluthathione peroxidase; GSH- Glutathione; LPO: Lipid peroxidation as measured as TBARS; AST: Aspartate AminoTransferase; ALT: Alanine Amino transferase; GGT: Gamma Glutamyl Transferase; LDH: Lactate Dehydrogenase.

Herbal remedies for urinary stones used in India and China: A review

ETHANOPHARMACOLOGICAL RELEVANCE

The process of formation or appearance of a urinary stone anywhere in the renal tract is known as urolithiasis. It is a longstanding health problem, known to exist since early age of civilization. Records about symptoms, signs and treatment strategies of urinary stones diseases are found in the several ancient texts of traditional medicines such as Ayurveda, Traditional Chinese Medicine (TCM), Siddha and Unani. In Ayurveda, urolithiasis has been considered as one of the eight most troublesome diseases. Ayurvedic management and cure of urinary stone involves herbal formulas, alkaline liquids and surgical procedures. Whereas, TCM recommends polyherbal drugs, acupuncture and mexibustion for treatment of the urinary stones. Among these therapies, herbal remedies are in practice till today for the treatment and cure urinary stone diseases.

MATERIALS AND METHODS

A comprehensive review of the scientific literature about pathophysiology of urinary stones and antiurolithiatic plants was undertaken using the following bibliographic databases: MEDLINE/PubMed, Scopus, Web of Knowledge and Google Scholar. The search was conducted from publications from all years until Dec., 2015 by combination of the search terms and Boolean operators; 'urinary stone' OR 'kidney stone' AND 'plant' OR 'medicine' OR 'antiurolithiatic plants'. Outputs were restricted to those completed studies only published in English. In this review, literatures about plants which are used as diuretic and/or in treatment urinary tract infections have not also been considered. The Plant List and Royal Botanical Garden, Kew databases were used to authenticate botanical names of plants. Books and monographs published in English were used to collect information about historical records of antiurolithiatic plants.

RESULTS

Recent pharmacological interventions accredited ancient antiurolithiatic claims to several plants and their formulations. The majority of antiurolithiatic plants were found to either dissolve the stones or inhibit the process of urinary stone formation. Plants such as Phyllanthus niruri L. and Elymus repens (L.) Gould, as well as herbal products including 'Wu-Ling-San' formula, 'Cystone' and 'Herbmed' have been proved their utility as promising antiurolithiatic medicines in the different phases of clinical trials. In addition, some of the isolated phytochemicals such as berberine, lupeol, khelin, visnagin, 7-hydroxy-2',4',5'-trimethoxyisoflavone and 7-hydroxy-4'-methoxyisoflavone were reported to have potent antiurolithiatic activity.

CONCLUSION

In ancient medicinal texts, antiurolithiatic potential has been ascribed to several plants and their formulations. Present scientific studies provide scientific evidences for few of these claims however, they are insufficient to establish many of these plants and herbal formulations as therapeutic remedies for the treatment and management of urinary stones. Conversely, findings of pre-clinical and clinical studies about some plants and herbal formulations are promising, which underlines the utility of herbal remedies as alternative medicines for the treatment and management of urinary stones in the future.

Urolithiasis analysis in a multiethnic population at a tertiary hospital in Nairobi, Kenya

Background

Urolithiasis is a global problem whose incidence is reported to be on the rise across the world. Previously, urolithiasis was reported as being rare among the indigenous African population but recent data suggest otherwise. This study reviewed the demographic and clinical characteristics of patients with urolithiasis seen at the Aga Khan University hospital Nairobi (AKUHN) as well as the chemical composition of the stones and the modalities of therapy used.

Methods

This was a retrospective study which utilized patients’ clinical and laboratory records from 2013 to 2014. Sixty-seven symptomatic patients with confirmed urolithiasis formed the study. This study aimed to describe the clinical characteristics of patients, modalities of treatment as well as the chemical composition of renal stones from patients diagnosed and managed for urolithiasis during a duration spanning 17 months. Wet chemistry was utilized for analyzing the chemical composition of the urinary calculi. Data on age, sex, symptoms, radiological investigations done, location of the calculi, chemical composition of calculi and therapeutic procedures instituted were extracted and analyzed.

Results

Ages ranged from 3 to 87 years with a median of 42; males were the majority (79%) and the commonest presenting symptoms were flank pain (91%) and dysuria (19%). The majority of the stones were located in the ureters (46%) and at the pelvi-ureteric junction (25%). A statistically significant difference in frequency of lodgment at the pelvi-ureteric site between males and females was noted. However, the number of female patients in this study was small and studies with larger numbers of female participants are required to confirm this observation. All stones contained calcium and oxalate, often as the only constituents (72%). In the remainder of the stones, other constituents such bicarbonate, ammonium, phosphorous, magnesium, uric acid and cystine occurred in varying combinations with calcium oxalate. Laser lithotripsy was the most performed therapeutic procedure (77.6%).

Conclusions

Males formed the majority of patient with urolithiasis. Overall, most of the calculi were located in the ureters except in women where the pelviureteric location was commoner. Stones containing calcium oxalate only were predominant across the age groups and in both sexes. Lithotripsy was the commonest mode of management.

Inhibitory effect of an aqueous extract of Radix Paeoniae Alba on calcium oxalate nephrolithiasis in a rat model

Objective: To examine the effect of an aqueous extract of Radix Paeoniae Alba (RPA) on the formation of calcium oxalate (CaOx) stones and the potential mechanism underlying the effect.

Materials and methods: An in vitro assay was used to determine whether the RPA extract prevents the formation of CaOx or promotes CaOx dissolution. We also investigated the efficacy of the extract in vivo as a preventive and therapeutic agent for experimentally induced CaOx nephrolithiasis in rats. Various biochemical, molecular, and histological parameters were assessed in kidney tissue and urine at the end of the in vivo experiment.

Results: Significant dissolution of formed crystals (8.99 ± 1.43) and inhibition of crystal formation (2.55 ± 0.21) were observed in vitro after treatment with 64 mg/mL of the RPA extract compared with a control treatment (55.10 ± 4.98 and 54.57 ± 5.84, respectively) (p < .05). In preventive protocols, the RPA extract significantly reduced urinary and renal oxalate levels and increased urinary calcium and citrate levels compared to the control. In addition, the RPA preventive protocol significantly decreased osteopontin expression, renal crystallization, and pathological changes compared to the control. These changes were not observed in rats on the therapeutic protocol.

Conclusions: RPA is a useful agent that prevents the formation of CaOx kidney stones.

Epidemiology of stone disease across the world

Nephrolithiasis is a highly prevalent disease worldwide with rates ranging from 7 to 13% in North America, 5-9% in Europe, and 1-5% in Asia. Due to high rates of new and recurrent stones, management of stones is expensive and the disease has a high level of acute and chronic morbidity. The goal of this study is to review the epidemiology of stone disease in order to improve patient care. A review of the literature was conducted through a search on Pubmed^®, Medline^®, and Google Scholar^®. This review was presented and peer-reviewed at the 3rd International Consultation on Stone Disease during the 2014 Société Internationale d'Urologie Congress in Glasgow. It represents an update of the 2008 consensus document based on expert opinion of the most relevant studies. There has been a rising incidence in stone disease throughout the world with a narrowing of the gender gap. Increased stone prevalence has been attributed to population growth and increases in obesity and diabetes. General dietary recommendations of increased fluid, decreased salt, and moderate intake of protein have not changed. However, specific recommended values have either changed or are more frequently reported. Geography and environment influenced the likelihood of stone disease and more information is needed regarding stone disease in a large portion of the world including Asia and Africa. Randomized controlled studies are lacking but are necessary to improve recommendations regarding diet and fluid intake. Understanding the impact of associated conditions that are rapidly increasing will improve the prevention of stone disease.

Nanoparticle Tracking Analysis for the Enumeration and Characterization of Mineralo-Organic Nanoparticles in Feline Urine

Urinary stone disease, particularly calcium oxalate, is common in both humans and cats. Calcifying nanoparticles (CNP) are spherical nanocrystallite material, and are composed of proteins (fetuin, albumin) and inorganic minerals. CNP are suggested to play a role in a wide array of pathologic mineralization syndromes including urolithiasis. We documented the development of a clinically relevant protocol to assess urinary CNP in 9 healthy cats consuming the same diet in a controlled environment using Nanoparticle Tracking Analysis (NTA^®). NTA^® is a novel method that allows for characterization of the CNP in an efficient, accurate method that can differentiate these particles from other urinary submicron particulates. The predominant nanoscale particles in feline urine are characteristic of CNP in terms of their size, their ability to spontaneously form under suitable conditions, and the presence of an outer layer that is rich in calcium and capable of binding to hydroxyapatite binders such as alendronate and osteopontin. The expansion of this particle population can be suppressed by the addition of citrate to urine samples. Further, compounds targeting exosomal surfaces do not label these particulates. As CNP have been associated with a number of significant urologic maladies, the method described herein may prove to be a useful adjunct in evaluating lithogenesis risk in mammals.

Hypoparathyroidism and pseudohypoparathyroidism: etiology, laboratory features and complications

OBJECTIVES

To identify a clinical profile and laboratory findings of a cohort of hypoparathyroidism patients and determine the prevalence and predictors for renal abnormalities.

MATERIALS AND METHODS

Data from medical records of five different visits were obtained, focusing on therapeutic doses of calcium and vitamin D, on laboratory tests and renal ultrasonography (USG).

RESULTS

Fifty-five patients were identified, 42 females and 13 males; mean age of 44.5 and average time of the disease of 11.2 years. The most frequent etiology was post-surgical. Levels of serum calcium and creatinine increased between the first and last visits (p < 0.001 and p < 0.05, respectively); and serum levels of phosphate decreased during the same period (p < 0.001). Out of the 55 patients, 40 had USG, and 10 (25%) presented with kidney calcifications. There was no significant difference in the amount of calcium and vitamin D doses among patients with kidney calcifications and others. No correlation between serum and urinary levels of calcium and the presence of calcification was found. Urinary calcium excretion in 24h was significantly higher in patients with kidney calcification (3.3 mg/kg/d) than in those without calcification (1.8 mg/kg/d) (p < 0.05).

CONCLUSIONS

The reduction of hypocalcemia and hyperphosphatemia suggest an effectiveness of the treatment, and the increase in serum creatinine demonstrates an impairment of renal function during follow-up. Kidney calcifications were prevalent in this cohort, and higher urinary calcium excretion, even if still within the normal range, was associated with development of calcification. These findings suggest that lower rates of urinary calcium excretion should be aimed for in the management of hypoparathyroidism.

Differentiation of ureteral stones and phleboliths using Hounsfield units on computerized tomography: a new method without observer bias

To differentiate ureteral stones and phleboliths by measuring density [as Hounsfield unit (HU)] and volume (as mm³) of the opacities in the bony pelvis on unenhanced computerized tomography (U-CT). A total of 52 patients, who underwent semirigid ureteroscopy and laser lithotripsy for distal ureteral stone and had isochoronous phleboliths in U-CT, were included. Images were reviewed for density and volume of the opacities. Data were compared, and a cut-off value was defined with receiver operating characteristics curve analysis to differentiate the nature of the opacity. Using the cut-off values of 171 mm³ for volume (sensitivity 75 %, specificity 100 %) and 643 HU for density (sensitivity 75 %, specificity 93 %), differentiation between stone and phlebolith was achieved. Differentiation of pelvic opacities needs meticulous observation with certain signs on U-CT. On the other hand, our study offers a new method, with certain cut-off values, such as 643 HU and 171 mm³, which can be used to precisely predict the actual nature of opacities of interest.

A Double-Blind, Placebo Controlled, Randomized Phase 1 Cross-Over Study with ALLN-177, an Orally Administered Oxalate Degrading Enzyme

BACKGROUND

Hyperoxaluria may result from increased endogenous production or overabsorption of dietary oxalate in the gastrointestinal tract leading to nephrolithiasis and, in some, to oxalate nephropathy and chronic kidney disease. ALLN-177 is an oral formulation of a recombinant, oxalate specific, microbial enzyme oxalate decarboxylase intended to treat secondary hyperoxaluria by degrading dietary oxalate in the gastrointestinal tract, thereby reducing its absorption and subsequent excretion in the urine.

METHODS

This double-blind, placebo controlled, randomized, cross-over, phase 1 study of ALLN-177 evaluated the tolerability of ALLN-177 and its effect on urinary oxalate excretion in 30 healthy volunteers with hyperoxaluria induced by ingestion of a high oxalate, low calcium (HOLC) diet. The primary end point was the difference in the mean 24-hour urinary oxalate excretion during the ALLN-177 treatment period compared with the placebo treatment period.

RESULTS

The daily urinary oxalate excretion increased in the study population from 27.2 ± 9.5 mg/day during screening to 80.8 ± 24.1 mg/day (mean ± SD) on the HOLC diet before introducing ALLN-177 or placebo therapy for 7 days. Compared to placebo, ALLN-177 treatment reduced urinary oxalate by 11.6 ± 2.7 mg/day, p = 0.0002 (least squares mean ± SD).

CONCLUSIONS

In healthy volunteers, with diet-induced hyperoxaluria treatment with ALLN-177, when compared to placebo, significantly reduced urinary oxalate excretion by degrading dietary oxalate in the gastrointestinal tract and thereby reducing its absorption. ALLN-177 may represent a new approach for managing secondary hyperoxaluria and its complications.

In Silico Modeling of Liver Metabolism in a Human Disease Reveals a Key Enzyme for Histidine and Histamine Homeostasis

Primary hyperoxaluria type I (PH1) is an autosomal-recessive inborn error of liver metabolism caused by alanine:glyoxylate aminotransferase (AGT) deficiency. In silico modeling of liver metabolism in PH1 recapitulated accumulation of known biomarkers as well as alteration of histidine and histamine levels, which we confirmed in vitro, in vivo, and in PH1 patients. AGT-deficient mice showed decreased vascular permeability, a readout of in vivo histamine activity. Histamine reduction is most likely caused by increased catabolism of the histamine precursor histidine, triggered by rerouting of alanine flux from AGT to the glutamic-pyruvate transaminase (GPT, also known as the alanine-transaminase ALT). Alanine administration reduces histamine levels in wild-type mice, while overexpression of GPT in PH1 mice increases plasma histidine, normalizes histamine levels, restores vascular permeability, and decreases urinary oxalate levels. Our work demonstrates that genome-scale metabolic models are clinically relevant and can link genotype to phenotype in metabolic disorders.

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In silico model of liver metabolism reveals global metabolic alterations in PH1

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Changes in amino acid metabolism in PH1 result in a reduction of histidine and histamine

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GPT overexpression normalizes histamine levels and reduces oxalate in PH1 mice

Polyacrylic acid attenuates ethylene glycol induced hyperoxaluric damage and prevents crystal aggregation in vitro and in vivo

The study explores calcium oxalate crystal inhibiting characteristic of polyacrylic acid (pAA), an anionic polymer in in vitro and in vivo. Animals were divided into 5 groups where group 1 served as control, group 2 were made hyperoxaluric by supplementing with Ethylene glycol (EG) 0.75% (v/v) for 30 days. Group 3, 4 & 5 were also given with EG and treated simultaneously with 2.5, 5 & 10 mg of pAA/kg of body weight, respectively. Urine, serum and tissue analyses along with histological studies were performed at the end of the 30 days study. In vitro crystallization was significantly inhibited by pAA and further it was supported by particle size analyses, XRD and FT-IR studies. Toxicological analyses showed that pAA was safe to use in animals at concentrations below 100 mg/kg BW. In vivo anti-urolithic study showed significant improvement in urinary lithogenic factors (calcium, oxalate, phosphate, citrate & magnesium) and renal function parameters (creatinine, urea and protein). Tissue analyses on anti-oxidant enzyme activity and lipid peroxides showed maintenance of tissue antioxidant status in the pAA supplemented rats and histological studies demonstrated the nephroprotection offered by pAA and were concurrent to the biochemical analyses. Supplementation of pAA not only reduces the crystal aggregation but also regulates the expression and localization of crystal inhibiting proteins and gene expression of inflammatory cytokines in experimental animals. In summary, pAA is a potent anti-urolithic agent in rats and we can propose that 10 mg/kg body weight is the effective dosage of pAA and this concentration can be used for further studies.

Targeted delivery to bone and mineral deposits using bisphosphonate ligands

The high concentration of mineral present in bone and pathological calcifications is unique compared with all other tissues and thus provides opportunity for targeted delivery of pharmaceutical drugs, including radiosensitizers and imaging probes. Targeted delivery enables accumulation of a high local dose of a therapeutic or imaging contrast agent to diseased bone or pathological calcifications. Bisphosphonates (BPs) are the most widely utilized bone-targeting ligand due to exhibiting high binding affinity to hydroxyapatite mineral. BPs can be conjugated to an agent that would otherwise have little or no affinity for the sites of interest. This article summarizes the current state of knowledge and practice for the use of BPs as ligands for targeted delivery to bone and mineral deposits. The clinical history of BPs is briefly summarized to emphasize the success of these molecules as therapeutics for metabolic bone diseases. Mechanisms of binding and the relative binding affinity of various BPs to bone mineral are introduced, including common methods for measuring binding affinity in vitro and in vivo. Current research is highlighted for the use of BP ligands for targeted delivery of BP conjugates in various applications, including (1) therapeutic drug delivery for metabolic bone diseases, bone cancer, other bone diseases, and engineered drug delivery platforms; (2) imaging probes for scintigraphy, fluorescence, positron emission tomography, magnetic resonance imaging, and computed tomography; and (3) radiotherapy. Last, and perhaps most importantly, key structure-function relationships are considered for the design of drugs with BP ligands, including the tether length between the BP and drug, the size of the drug, the number of BP ligands per drug, cleavable tethers between the BP and drug, and conjugation schemes.

Monocyte Mitochondrial Function in Calcium Oxalate Stone Formers

OBJECTIVE

To investigate whether mitochondrial function is altered in circulating immune cells from calcium oxalate (CaOx) stone formers compared to healthy subjects.

MATERIALS AND METHODS

Adult healthy subjects (n = 18) and CaOx stone formers (n = 12) were included in a pilot study. Data collection included demographic and clinical values from electronic medical records. Bioenergetic function was assessed in monocytes, lymphocytes, and platelets isolated from blood samples using the Seahorse XF96 Analyzer. Plasma interleukin-6 (IL-6) was measured using enzyme-linked immunosorbent assay.

RESULTS

All participants were age matched (44.5 ± 3.0 years for healthy subjects vs 42.3 ± 4.8 years for CaOx stone formers, P = .6905). CaOx stone formers did not have urinary tract infection, ureteral stones, or obstructing renal stones. Monocyte mitochondrial function was decreased in CaOx stone formers compared to healthy subjects. Specifically, mitochondrial maximal respiration (P = .0011) and reserve capacity (P < .0001) were significantly lower. In contrast, lymphocyte and platelet mitochondrial function was similar between the 2 groups. The bioenergetic health index, an integrated value of mitochondrial function, was significantly lower in monocytes from CaOx stone formers compared to healthy subjects (P = .0041). Lastly, plasma IL-6 levels were significantly increased (P = .0324).

CONCLUSION

The present pilot study shows that CaOx stone formers have decreased monocyte mitochondrial function. Plasma IL-6 was also increased in this cohort. These data suggest that impaired monocyte mitochondrial function and inflammation may be linked to CaOx kidney stone formation. Further studies are needed to confirm these findings in a larger cohort of patients.