D. Heimbach

Chemolysis of Struvite Stones by Acidification of Artificial Urine - An in vitro Study

OBJECTIVEnThe aim of the study was to look for strategies that improve the clinical outcome of struvite stones. An in vitro experimental set up with artificial stones made of struvite (BON(N)-STONES) was chosen to perform standardized and reproducible analyses on various artificial urines with pH-values that may be reached by acidification with oral methionine treatment.nnnMATERIALS AND METHODSnArtificial ball-shaped stones made of struvite (BON(N)-STONES) with a diameter of 0.8 cm were used. The investigations on chemolysis were performed using a dissolution device which simulates the physiological conditions in the upper urinary tract with computer-assisted on line measurement of data. For chemolysis of struvite BON(N)-STONES artificial urines according to Griffith at four different pH-values (pH 5.75, pH 6.0, pH 6.25, pH 6.5) were used. Furthermore natural and struvite BON(N)-STONES were treated with Suby G-solution (pH = 4.0).nnnRESULTSnComparing natural and artificial struvite stones after treatment with Suby G there was no significant difference regarding their dissolution rate. The dissolution rate of struvite stones in artificial urine rose with a decreasing pH-value. The diminution of the pH-value from 6.5 to 5.75 lead to an increase of the dissolution rate of more than 35%. This increase in the dissolution rate decreased with falling pH-value.nnnCONCLUSIONSnThe acidification of urine accelerated the dissolution rate of struvite stones in vitro. Considering in vivo conditions the intake of 1,500-3,000 mg L-methionine may lead to a sufficient acidification for a good dissolution of struvite stones.Objective: The aim of the study was to look for strategies that improve the clinical outcome of struvite stones. An in vitro experimental set up with artificial stones made of struvite (BON(N)-STONES) was chosen to perform standardized and reproducible analyses on various artificial urines with pH-values that may be reached by acidification with oral methionine treatment. Materials and Methods: Artificial ball-shaped stones made of struvite (BON(N)-STONES) with a diameter of 0.8 cm were used. The investigations on chemolysis were performed using a dissolution device which simulates the physiological conditions in the upper urinary tract with computer-assisted on line measurement of data. For chemolysis of struvite BON(N)STONES artificial urines according to Griffith at four different pH-values (pH 5.75, pH 6.0, pH 6.25, pH 6.5) were used. Furthermore natural and struvite BON(N)-STONES were treated with Suby G®-solution (pH = 4.0). Results: Comparing natural and artificial struvite stones after treatment with Suby G® there was no significant difference regarding their dissolution rate. The dissolution rate of struvite stones in artificial urine rose with a decreasing pH-value. The diminution of the pH-value from 6.5 to 5.75 lead to an increase of the dissolution rate of more than 35%. This increase in the dissolution rate decreased with falling pH-value. Conclusions: The acidification of urine accelerated the dissolution rate of struvite stones in vitro. Considering in vivo conditions the intake of 1500-3000 mg L-methionine may lead to a sufficient acidification for a good dissolution of struvite stones.

When Is the Indication of Percutaneous Chemolysis Justified

Persistent residual stone fragments after extracorporeal shockwave lithotripsy (ESWL), percutaneous nephrolitholapaxy (PNL) as well as pyelo- and nephrolithotomy represent a great problem in the treatment of stones. The choice of therapy for patients with insufficient renal drainage, poor renal function, and a high anesthetic risk also remains quite difficult. Between 1991 and 1993, 5 patients underwent percutaneous antegrading chemolysis with Suby G solution. Two patients, presenting struvite and apatite stones, were free of stones afterwards. In 1 patient, where stone size could be observed. In 2 other brushite component, a large decrease in stone size could be observed. In 2 other cases, with stones mainly consisting of whewellite and weddelite, chemolysis proved ineffective. Evaluating our own clinical experience and relevant medical literature, the present study goes on to prove that the indication of percutaneous chemolysis in risk patients as described above is dependent on stone analysis, and must be regarded as an effective adjuvant treatment.

Chemolitholysis and Lithotripsy of Infectious Urinary Stones – An in vitro Study

Objectives: This study was performed to look for an improvement of therapeutic strategies with regard to the treatment of infectious urinary stones using artificial stones made of struvite and apatite (‘Bon(n) stones’) which are comparable to their natural counterparts. Materials and Methods: Using an experimental arrangement simulating the physiological conditions in the upper urinary tract, the efficacy of artificial urine (pH 5.7), Suby G solution (pH 3.6), mixtures of artificial urine with Suby G (pH 3.9 and pH 4.1) in dissolving artificial struvite and apatite stones (Bon(n) stones) was investigated. The dissolution of natural infectious urinary stones was also measured. Additionally, investigations on shock-wave lithotripsy (SWL) combined with initial chemolytic treatment of the stones were performed. Results: The efficacy of Suby G solution in dissolving artificial stones was demonstrated. Direct comparison of chemolysis of natural and artificial stones showed no statistical difference between infectious urinary stones and Bon(n) stones of the same material. The investigations on SWL showed a significant improvement on stone comminution, especially of artificial apatite stones after initial chemolytic treatment with Suby G. Conclusion: New basics to improve dissolution of infectious urinary stones have been developed by performing standardized in vitro investigations. Local chemolysis with Suby G is an effective tool in the treatment of infectious stone disease. SWL can be improved by varying the physical properties of infectious stones through initial treatment with Suby G solution.

N-acetyl-β-D-Glucosaminidase Excretion in Calcium Oxalate Stone Patients and its Relation to the Risk of Stone Formation

A tubular renal damage induced by crystals in the renal tubuli can be the triggering primary but also secondary cause of stone formation. In 72 calcium oxalate stone patients (45 men, 27 women) N-acetyl-beta-D-glucosaminidase [NAG] excretion in 24h-urine was investigated. 48 healthy test persons (27 men, 21 women) served as a control group and helped to establish reference values. In order to find out a possible relation between NAG reference values and the risks of urolithiasis, lithogenous and inhibitory substances were determined in both groups. In the following, relative calcium oxalate supersaturation, representing a risk of urinary stone formation, was analyzed and compared to NAG excretion values. The threshold value of pathologic NAG excretion was determined in the group of healthy test subjects (mean value +/- 2 standard deviation) and was fixed at 4.2 U/d (women 3.06 U/d, men 4.24 U/d). In our investigations on NAG excretion significantly (p < 0.05) increased values were found in stone patients (4.43 U/d +/- 4.27) as compared to healthy test persons (2.13 U/d +/- 1.02). In the case of increased NAG excretion in stone patients there was a positive correlation between NAG excretion and increased phosphate, sulphate, uric acid, oxalate, and creatinine excretion. Only in female patients there was a relation between relative calcium oxalate supersaturation and NAG excretion values. As a result, NAG determination is considered to be an appropriate means of tracing a certain risk group within calcium oxalate stone patients.

Production of Artificial Urinary Stones from Natural Materials and their Physical Properties

Considered from a clinical point of view, all artificial stones known so far are inappropriate for experimental investigations, because they do not correspond to natural urinary stones in shape, physical properties and chemical composition. A special technique has now been developed for the production of biometric artificial stone models. Standard artificial carbonate apatite stones were produced by a coating technique where several layers of a suspension consisting of pure substance were applied around a core. Density and crushing strength of these ball-shaped artificial stones corresponded to natural apatite stones. Experimental chemolitholysis investigations showed comparable results in respect to the dissolution of artificial apatite stones and of natural stones of the same chemical composition. The disintegration behaviour was studied in ESWL tests which revealed a correlation between generator voltage and number of shock waves necessary for complete disintegration. For the first time, an artificial urinary stone has now been produced which is comparable to a natural stone of the same chemical composition not only in shape but also in its physical properties and lysis behaviour. These stones are suitable for use in systemic scientific investigations on disintegration and chemolitholysis.

Improving cystine stone therapy: an in vitro study of dissolution

OBJECTIVESnTo perform an in vitro study analyzing the possibilities in therapeutic strategies for an effective treatment of cystine stones.nnnMETHODSnArtificial stones made of cystine [Bon(n)-Stones] with a ball-shaped size of 0.9 cm in diameter were used. Chemolysis of artificial cystine stones with different solvents (artificial urine, physiologic sodium chloride solution, acetylcysteine, tris-(hydroxymethylene)-aminomethane [THAM], and combinations of these) was investigated. An experimental arrangement with computer-assisted online measurement of data simulating the physiologic conditions in the upper urinary tract at varying pH values was used.nnnRESULTSnAll solutions showed a statistical improvement in the solubility of cystine stones compared with artificial urine and physiologic sodium chloride solution. The combination of THAM (pH 10) and 2% acetylcysteine was most effective (1 3.91 +/- 1.73 mg/hr) and demonstrated a 41 -fold higher ability to dissolve cystine calculi compared with artificial urine.nnnCONCLUSIONSnOur data indicate that local chemolysis with special solutions is an effective treatment modality in cystine stone therapy.

Isolated Echinococcal Cyst of the Kidney: Case report and review of the literature

We report an isolated echinococcal cyst of the kidney as a rare extrahepatic manifestation of the parasitic infestation. The pathogenesis, problems of diagnosis and treatment of renal hydatid disease are reviewed and discussed.

Influence of Alkaline Solutions on Chemolitholysis and Lithotripsy of Uric Acid Stones

Objectives: This study was performed to look for an improvement of therapeutic strategies with regard to the treatment of uric acid stones using artificial stones made of uric acid (BON(N)–STONES) which are comparable to their natural counterparts.Materials and Methods: Using an experimental arrangement simulating the physiological conditions in the upper urinary tract the efficacy of different alkaline solutions and artificial urine in dissolving artificial uric acid stones (BON(N)–STONES) was investigated. The dissolution of natural uric acid stones was measured and investigations on shock wave lithotripsy (SWL) combined with initial chemolytic treatment of the stones were performed.Results: The efficacy of alkaline solutions, especially THAM at a pH of 10, in dissolving artificial uric acid stones was demonstrated. The investigations on SWL showed a significant improvement on stone comminution of artificial uric acid stones after initial chemolytic treatment with THAM.Conclusions: New basics to improve dissolution of uric acid stones have been developed by performing standardized in vitro investigations. The suggestion was confirmed that stone fragility and thus SWL can be improved by varying the physical properties of uric acid stones through initial treatment with THAM solution.

PERCUTANEOUS CHEMOLYSIS : AN IMPORTANT TOOL IN THE TREATMENT OF UROLITHIASIS

Persistent residual calculi after therapy, i.e. extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolitholapaxy (PNL), as well as pyelo-and nephrolithotomy are big problems in the treatment of urolithiasis. Furthermore, the therapy of stones is problematic in patients with inadequate drainage, impaired kidney function, or with high risks against anaesthetics. Between 1991 and 1997 percutaneous antegrade chemolysis was carried out in eleven patients. In nine of them complete dissolution of stones was achieved. In two further cases, in which calcium oxalate was the main component of the stoens, chemolysis was unsuccessful. Through our was the main component of the stones, chemolysis was unsuccessful. Through our own cases and under consideration of the literature, we will show that percutaneous chemolysis in these cases is useful and effective in the treatment of urolithiasis.

Maximal displacement of the ureter by a liposarcoma

We describe a patient with displacement of both ureters to the right side caused by a liposarcoma. The left ureter was displaced beyond the right ureter. The risk of intraoperative trauma to the ureter could be minimized by preoperative placement of ureteral stents.