Chemolysis of struvite stones by acidification of artificial urine--an in vitro study

Effects of two commercial diets and two supplements on urinary pH in dogs

BACKGROUND

Urinary pH manipulation by therapeutic foods or supplements is part of the treatment for urolithiasis. The effectiveness of these diets and supplements should be studied to determine which of these strategies is most effective.

HYPOTHESIS/OBJECTIVES

To assess the effect of the oral supplementation of potassium citrate, an ammonium chloride solution (Urical) and two dry therapeutic foods-Hill's® Prescription Diet® u/d® Canine (u/d diet) and Royal Canin® Urinary S/O dog (S/O diet)-on a dog's urinary pH at different time points over 8 h.

ANIMALS

Seven healthy adult male research beagle dogs.

METHODS

A prospective interventional study lasting 31 days. The dogs either received a supplement (potassium citrate or rical) with a dry adult maintenance diet (control diet) or the therapeutic diet (u/d diet or S/O diet). Each treatment had a duration of 2-5 days, with 2- to 4-day washout periods in between. Urinary pH measurements were performed every 2 h between 07h00 and 15h00, with the food being given at 07h00 and 15h00, right after urine collection. The pH measurements obtained in each of the four treatments were compared to control (same dogs fed the control diet exclusively).

RESULTS

When compared to the control diet at the same time points, biologically relevant changes in urinary pH (defined as ≥0.5) were: increase with potassium citrate at 7h00 and 13h00; increase with u/d diet at 9h00, 13h00, and 15h00; decrease with S/O diet at 9h00 and 11h00; Urical did not have a detectable effect on urinary pH.

CONCLUSIONS AND CLINICAL IMPORTANCE

The present study confirms that therapeutic foods S/O and u/d, and potassium citrate supplement affected acid-base balance in healthy adult male beagle dogs, with the tested diets being more effective than the administered doses of the tested supplements at influencing urinary pH.

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.

Urinary Calculi of Small Ruminants

Urolithiasis is a multifactorial disease of male ruminants causing significant economic loss and compromise of animal welfare. Known risk factors include anatomic factors, urine pH, water intake, dietary composition, and genetic factors. Clinical cases of obstructive urolithiasis may be treated using a variety of medical and surgical interventions, including tube cystostomy, perineal urethrostomy, urinary bladder marsupialization, and modifications of these procedures designed to optimize patient outcome.

Combined Application of Aminoglycosides and Ascorbic Acid in the Elimination of Proteus mirabilis Rods Responsible for Causing Catheter-Associated Urinary Tract Infections (CAUTIs)-A Molecular Approach

Proteus mirabilis is a common cause of catheter-associated urinary tract infections (CAUTIs). In this study, we verified the effectiveness of amikacin or gentamicin and ascorbic acid (AA) co-therapy in eliminating uropathogenic cells, as well as searched for the molecular basis of AA activity by applying chromatographic and fluorescent techniques. Under simulated physiological conditions, a combined activity of the antibiotic and AA supported the growth (threefold) of the P. mirabilis C12 strain, but reduced catheter colonization (≤30%) in comparison to the drug monotherapy. Slight modifications in the phospholipid and fatty acid profiles, as well as limited (≤62%) 2',7'-dichlorofluorescein fluorescence, corresponding to the hydroxyl radical level, allowed for the exclusion of the hypothesis that the anti-biofilm effect of AA was related to membrane perturbations of the C12 strain. However, the reduced (≤20%) fluorescence intensity of propidium iodide, as a result of a decrease in membrane permeability, may be evidence of P. mirabilis cell defense against AA activity. Quantitative analyses of ascorbic acid over time with a simultaneous measurement of the pH values proved that AA can be an effective urine acidifier, provided that it is devoid of the presence of urease-positive cells. Therefore, it could be useful in a prevention of recurrent CAUTIs, rather than in their treatment.

Composition and spatial distribution of elements and isotopes of a giant human bladder stone and environmental implications

The composition and spatial distribution of minerals, trace elements, as well as carbon and nitrogen isotopes from the outer crust to inner nucleus of a 20-year old giant human bladder stone comprising thirteen layers were intensively investigated. Calcium oxalate monohydrate (COM) was found to concentrate in the inner and middle layers, struvite was concentrated in middle and outer layers, and fluorapatite occurred in almost all layers. The spatial distribution of minerals has the potential to provide preliminary knowledge regarding the long-term urine composition, or even the physiological condition of the patient. The stable carbon isotope ratio (δ¹³C) and stable nitrogen isotope ratio (δ¹⁵N) were measured in each layer and significant correlation was found between δ¹³C with calcium oxalate monohydrate content and between δ¹⁵N and struvite content. Nearly constant values of -23.2‰ and 7.1‰ for δ¹³C and δ¹⁵N, respectively, were found in the organic components of the stone. Both isotope ratios indicate a long-term fixed diet consisting mainly of C3 plants, such as rice and wheat, for the 20-year time period of the stone formation. In addition, eighteen elements (Ca, P, Mg, K, Na, Al, Fe, Zn, Pb, Cu, Sr, Ba, Ti, V, Cr, Ni, Mn and Co) were measured in all the layers. The trace elements Al, Fe, Cu, Zn, Pb, Sr, Ba and Ti showed a similar spatial distribution pattern from the outer crust to the inner core. Although there were complex correlations between elements and minerals, Factor Analysis suggests that the occurrence of these elements in stones may be mainly the result of environmental exposure to metals during the formation of the stone, indicating that urinary stones may serve as potential long-term biomonitors. In particular, Ni and Cr showed a distinct distribution pattern in the stone, which may relate to human metabolic activities.

Limited Dissolved Phosphorus Runoff Losses from Layered Double Hydroxide and Struvite Fertilizers in a Rainfall Simulation Study

The enrichment of P in surface waters has been linked to P runoff from agricultural fields amended with fertilizers. Novel slow-release mineral fertilizers, such as struvite and P-exchanged layered double hydroxides (LDHs), have received increasing attention for P recycling from waste streams, and these fertilizers may potentially reduce the risk of runoff losses. Here, a rainfall simulation experiment was performed to evaluate P runoff associated with the application of recycled slow-release fertilizers relative to that of a soluble fertilizer. Monoammonium phosphate (MAP), struvite, and LDH granular fertilizers were broadcasted at equal total P doses on soil packed in trays (5% slope) and covered with perennial ryegrass ( L.). Four rainfall simulation events of 30 min were performed at 1, 5, 15, and 30 d after the fertilizer application. Runoff water from the trays was collected, filtered, and analyzed for dissolved P. For the MAP treatment, P runoff losses were high in the first two rain events and leveled off in later rain events. In total, 42% of the applied P in the MAP treatment was lost due to runoff. In the slow-release fertilizer treatments, P runoff losses were limited to 1.9 (struvite) and 2.4% (LDH) of the applied doses and were more similar over the different rain events. The use of these novel P fertilizer forms could be beneficial in areas with a high risk of surface water eutrophication and a history of intensive fertilization.

Effect of L-Methionine on the Risk of Phosphate Stone Formation

OBJECTIVE

To determine the physiological effects following administration of the sulfur-containing amino acid L-methionine on urinary risk factors for calcium oxalate and phosphate stone formation under controlled, standardized conditions.

SUBJECTS AND METHODS

Twelve healthy subjects were studied while consuming a standardized diet for 6 days. Day 5 was considered as control day. On day 6 (test day), participants received 1500 mg L-methionine at 9 AM. On the control and test days, 24-hour fractional urine collections were obtained.

RESULTS

After single-dose administration of L-methionine, 24-hour fractional urinary pH decreased to values between 5.98 and 6.32. Urinary sulfate excretion, a direct marker for the metabolism of L-methionine, and ammonium excretion, which reflects the increase in net acid production, increased significantly after L-methionine administration. Urinary calcium excretion did not differ between control and test day (5.55 vs 5.45 mmol/24 hours; P = .754). The relative supersaturation of brushite and struvite decreased significantly by 25% (P = .010) and 34% (P = .049), respectively, whereas the risk of calcium oxalate stone formation was not affected by application of L-methionine (P = .477).

CONCLUSION

The present findings show that L-methionine effectively decreases urinary pH and the risk of struvite and calcium phosphate stone formation in healthy subjects. Hypercalciuria is not expected to occur at physiological doses of L-methionine.

New potential solutions for the chemolysis of urinary phosphate calculi determined by an in vitro study

To find a more efficient solution for chemolysis of urinary calculi, several organic acids were chosen to form solutions by consulting the composition of a classic solution, Suby G. The solutions together with Renacidin, another classic solution, were designed to react with the 4 phosphate components of urinary stone. The processes were real-time measured and analysed by a focused beam reflectance measurement, and the efficiency factors were investigated and discussed in detail. The results show that several organic acids, e.g. hydroxyacetic acid, lactic acid and α-ketoglutaric acid, are more efficient than citric acid in dissolving urinary phosphate calculus. The new solutions containing the organic acids are promising for improving chemolysis treatment.

A case of staghorn stones in a kidney with an ileal ureter treated by percutaneous nephrolithotomy

BACKGROUND

A 59-year-old man was admitted to hospital for investigation of a 1-year history of intermittent hematuria. He had undergone ileal ureteral replacement for left renal stones 36 years earlier.

INVESTIGATIONS

Renal ultrasonography, physical examination, abdominal plain radiography, intravenous urography, CT urography, measurement of serum levels of creatinine, urea and electrolytes, renal scintigraphy, urinalysis and urine culture.

DIAGNOSIS

Staghorn calculi in the left kidney, with a high-lying anastomosis between the renal pelvis and the proximal ileal segment.

MANAGEMENT

The patient underwent percutaneous nephrolithotomy via a middle-calyx access for the large staghorn stones. After surgery, no residual calculi were found and the patient was discharged with an uneventful postoperative course. At 1 month, renal scintigraphy showed normal bilateral kidney function. The patient received potassium citrate supplementation and was followed up with 6-monthly imaging studies. At the last report, he had been stone-free for 7 months.

Nutritional biochemistry of spaceflight

As we approach the end of the first 50 years of human space travel, much has been learned about adaptation to microgravity and the risks associated with extended-duration space exploration. As the frequency and duration of flights grew, nutrition issues became more critical and the questions to be answered became more complex: What are the nutrient requirements for space travelers? Can nutrients be used as tools to mitigate the negative effects of space travel on humans? How does nutrition interrelate with other physiological systems (such as muscle, bone, and cardiovascular system) and their adaptation to microgravity? Much research has been done over the decades in both actual spaceflight and ground-based analogs. We review here much of what is known, and highlight areas of ongoing research and concerns for future exploration of the Moon, Mars, and beyond.

[Evidence-based pharmacological metaphylaxis of stone disease]

Approximately one-fourth of urolithiasis patients are at high risk for recurrent stone formation or severe metabolic disturbances. These patients need specific metaphylaxis for effective stone prevention, adjusted to their individual metabolic risk. Recent recommendations for the pharmacological treatment of stone diseases are summarized in this article. For the different treatment options, evidence from the literature was assessed. In addition, a follow-up concept for pharmacologically treated high-risk stone formers is discussed.

Pathophysiology and Management of Infectious Staghorn Calculi

The American Urological Association Nephrolithiasis Guidelines Panel recently conducted a critical meta-analysis of the existing literature to determine the optimal management for staghorn calculi. This article briefly discusses the pathophysiology of staghorn calculi and, based on the panel's recommendations, examines the alternative medical treatments (eg, chemolysis) and surgical treatments (eg, shock wave lithotripsy, open surgery, ureteroscopy, and percutaneous nephrolithotomy) available for staghorn patients. Considering the various modalities for staghorn disease, percutaneous nephrolithotomy should be the first-line treatment for most patients based on its superior efficacy and low morbidity.

Amino acid supplementation alters bone metabolism during simulated weightlessness

High-protein and acidogenic diets induce hypercalciuria. Foods or supplements with excess sulfur-containing amino acids increase endogenous sulfuric acid production and therefore have the potential to increase calcium excretion and alter bone metabolism. In this study, effects of an amino acid/carbohydrate supplement on bone resorption were examined during bed rest. Thirteen subjects were divided at random into two groups: a control group (Con, n = 6) and an amino acid-supplemented group (AA, n = 7) who consumed an extra 49.5 g essential amino acids and 90 g carbohydrate per day for 28 days. Urine was collected for n-telopeptide (NTX), deoxypyridinoline (DPD), calcium, and pH determinations. Bone mineral content was determined and potential renal acid load was calculated. Bone-specific alkaline phosphatase was measured in serum samples collected on day 1 (immediately before bed rest) and on day 28. Potential renal acid load was higher in the AA group than in the Con group during bed rest ( P < 0.05). For all subjects, during bed rest urinary NTX and DPD concentrations were greater than pre-bed rest levels ( P < 0.05). Urinary NTX and DPD tended to be higher in the AA group ( P = 0.073 and P = 0.056, respectively). During bed rest, urinary calcium was greater than baseline levels ( P < 0.05) in the AA group but not the Con group. Total bone mineral content was lower after bed rest than before bed rest in the AA group but not the Con group ( P < 0.05). During bed rest, urinary pH decreased ( P < 0.05), and it was lower in the AA group than the Con group. These data suggest that bone resorption increased, without changes in bone formation, in the AA group.