A mutant adenine phosphoribosyltransferase in 2,8-dihydroxyadenine urolithiasis.

In one case of 2,8-dihydroxyadenine urolithiasis, reduced adenine phosphoribosyltransferase activity was found. The patient's enzyme had normal affinity for adenine but reduced affinity for substrate phosphoribosyl-pyrophosphate. It was much more stable at 60 degrees C than control. It seems that erythrocyte adenine phosphoribosyltransferase obtained from the patient may be a variant enzyme.

Uric acid nephrolithiasis and acute renal failure secondary to streptozotocin nephrotoxicity.

Uric acid nephrolithiasis developed in a 75-year-old man who had received a large cumulative dose of streptozotocin for treatment of metastatic islet cell carcinoma of the pancreas. Oligoanuric renal failure mediated by massive intraureteral uric acid deposits occurred despite normal serum concentrations of uric acid. This case implicates the uricosuric effects of streptozotocin in the pathogenesis of uric acid nephropathy and suggests that renal uric acid excretion should be monitored routinely in patients receiving large cumulative doses of this drug.

The electret effect of kidney stones.

Surgically removed kidney stones were powdered and samples made from them were subjected to a d.c. field of 20-50 kV/cm whilst being heated at 1 degree C/min. The thermally stimulated polarization (TSP) spectrum obtained showed the dipolar nature of the material. Dipolar polarization in the stones was confirmed by other experiments.

Observations of the ultrastructure of infected kidney stones.

Struvite stones are formed as the result of urinary tract infection by urease-producing bacteria. Ultrastructural examination of calculi removed from a patient revealed bacteria incorporated throughout the stone matrix. Exopolysaccharide stained by ruthenium red was associated with most of the bacteria, but it represented only a small portion of the organic matrix in the stone. Localised deposits of calcium and phosphorus, components of carbonate-apatite, and magnesium, a struvite component, were detected in close proximity to the cells. Histochemical examinations revealed that several of the gram-negative bacteria within the stone matrix possessed high levels of urease activity. We propose that bacterial slime production, intimately involved in the initiation of stone matrix deposition, is less prominent in mature stones because of the increased incorporation of host-derived mucoproteins and mucopolysaccharides.

New technique for endourologic treatment of cystine nephrolithiasis.

Cystine renal calculi are fragmented using a unique combination of ultrasonic and electrohydraulic lithotripsy. This endourologic application of a mining principle can be used to fragment any hard urinary stones.

The unbreakable stone?

A case of a failed percutaneous ultrasonic lithotripsy is reported as an unusual occurrence.

Clinical experience with low dosage of propionohydroxamic acid (PHA) in infected renal stones.

The use of drugs inhibiting bacterial urease represents an interesting improvement in preventive treatment of renal infected stones. The low dose (120 mg/day) for one week followed by 60 mg/day of propionohydroxamic acid (PHA) has shown excellent anti-urease activity. The nearly normal absence of side effects also allows long-term administration.

Place of extracorporeal shock-wave lithotripsy (ESWL) in management of cystine calculi.

We treated 12 patients with sixteen renal and one ureteral cystine stones primarily with extracorporeal shock-wave lithotripsy (ESWL). Among the stones thirteen were greater than 25 mm. In four stones less than 25 mm, three stones completely disappeared and 1 was reduced to small fragments, following ESWL. In thirteen stones greater than 25 mm, twelve were treated by ESWL initially, and one by surgery. Of the 12 cases treated initially by ESWL, 4 became stone-free, 4 remained with small fragments, and 1 remained with large fragments. Two patients were operated on because of poor response to ESWL and 1 patient lost kidney function because of prolonged obstruction. Disintegration of cystine stones greater than 25 mm required an average of 8,522 shock-waves in 4.33 sessions. The problems associated with application of ESWL monotherapy to cystine stones are presented.

Biochemical risk factors in patients with renal staghorn stone disease.

Thirty-three patients operated on for renal staghorn calculous disease were studied retrospectively with respect to urine and stone composition, bacteriuria, and abnormalities of the urinary tract. Calcium phosphate was the most common stone constituent, present in 30 of 31 concrements. Twenty-one of these stones also contained magnesium ammonium phosphate, despite the fact that only 10 patients had presented evidence of urinary tract infection during the initial period of the disease. Twenty-four-hour urine composition was normal in only 3 patients. In 59 per cent an increased CaOx risk index was observed suggesting that CaOx risk factors might contribute to the development of staghorn concrements. A metabolic evaluation of staghorn stone formers appears to be of importance for design of the postoperative treatment.

Cystine calculi: clinical management and in vitro observations.

Although cystine stones account for 1 to 3 per cent of renal calculi, many of these patients are difficult to manage because of recurrent urolithiasis. Seven cases of homozygous cystinuria are summarized. The evolution to the present treatment of percutaneous extraction and chemolysis appears to be the preferred form of treatment although extracorporeal shock wave lithotripsy (ESWL) may also be utilized. In addition, in vitro experiments were conducted to study the effectiveness of different chelating agents and buffers at different urinary pHs. The effect of cystinuric and noncystinuric urines was also evaluated.

Therapeutic options for the management of upper tract calculi.

The cry of "ESWL for all" was heard at the 84th Annual Meeting of the American Urological Association, and actually, this is not far from the truth. Those physicians who are not familiar with percutaneous techniques, or who do not have the necessary equipment available, may actually attempt ESWL for all calculi regardless of stone burden or location. Patients who are interested in avoiding manipulation may request ESWL, even if the results may not be as good as those obtained with concomitant manipulation or with percutaneous procedures. Nevertheless, indications still exist for percutaneous techniques, and these procedures will not become obsolete even as ESWL technology advances. Studies are being conducted to identify the ideal treatment for all varieties of stones in the genitourinary system. As ESWL and endoscopic technology continue to advance, the treatment of stone disease will continue to change.

Role of percutaneous procedures in the management of renal calculi.

Appropriate management of the variety of patients with stone disease demands access to all methods of stone removal. Percutaneous procedures are an integral aspect of the surgical management of stone patients, and the urologist must recognize when a patient's situation is best served by percutaneous surgery. Percutaneous stone removal procedures are preferred when: 1. The stone is large, i.e., greater than 2 to 3 cm. 2. The stone is staghorn in configuration, with percutaneous measures being used either as primary treatment or in combination with shock wave lithotripsy. 3. The stone is composed of cystine 4. When certain removal of the stone is important. 5. When there is obstructive uropathy. 6. When other modalities have failed. 7. In morbidly obese individuals and others whose body habitus precludes use of the shock wave machine. 8. In children, at least until the issue of long-term safety of extracorporeal lithotripsy is settled.

Identification of renal calculi by computerized infrared spectroscopy.

A method is described for the assessment of renal calculi by means of a computerized IR spectrometer. A preliminary reference library of IR spectra of 34 different renal calculi of known composition has been created. The reference library used in the operation of a computerized search program indicates the closest matches in the reference library data with the IR spectrum of an unknown sample. The computerized method of characterizing renal calculi has the advantage that it greatly reduces the likelihood of introducing errors because of operator bias in the subjective interpretation of spectral data.

Some features of paediatric urolithiasis in a group of Syrian children.

A group of 28 Syrian children (19 males and 9 females; age ranging from 2.5 to 12 years) were diagnosed clinically and radiologically to have upper urinary tract stones. The commonest presentations were renal colic, vomiting, haematuria, pyrexia and vague abdominal pain. Family history of renal stones was present in 21% of cases. Haematological picture and chemical analysis of blood were within the normal limits for their age and sex. Urine analysis, however, showed significantly marked increase in the 24-hour excretions of calcium and uric acid. Microscopic examination showed haematuria and pyuria in 72% of the children with urolithiasis. Chemical analysis of removed stones revealed that most of them were mixed stones of calcium oxalate and urate or/and phosphate. Pure stones of calcium oxalate or calcium phosphate were less common. Radiologically, about 95% of all stones were demonstrated by plain X-ray, while 5% only after IVP.

Experiments with extracorporeal shock wave nephrolithotripsy.

Two sets of experiments were carried out on 14 live rabbits having renal calculi from nephrolithiasis patients implanted in their kidneys. Shock waves were used to disintegrate the implanted concrements. It took 100 to 150 sound pulses to crush struvite stones to fragments less than 2 mm in size, with 400 to 800 pulses needed to destroy calcium oxalate stones. After multiple exposures to shock waves there were no indications of any gross damage to the soft tissues of the experimental animals. Mechanisms for destruction of kidney stones by shock waves were considered.

Composition and structure of renal and ureteral calculi in patients under covalitin therapy.

We examined the composition and texture of 53 urinary calculi from patients receiving Covalitin therapy. The texture of the infection stones and of concrements containing mainly apatite showed no changes as compared to concrements from control groups receiving no such therapy. Calcium oxalate stones more often showed a whewellite texture (Type 2) and a less frequent occurrence of weddellite (Type 4) as compared to the control groups. Surface or marginal changes indicating a possible litholysis could not be shown.

Induced precipitation of calcium-oxalate crystals and its prevention in laboratory animals.

Induced precipitation of Ca-oxalate crystals and the possibility of its prevention were studied in dogs. In the first phase of the experiments precipitation of Ca-oxalate crystals in canine renal tubules was induced by intraperitoneal administration of Na-glyoxylate. Preventive medication (lipoic acid, vitamin B1, Milurit), applied in the second phase, resulted in a significant depression of induced precipitation. The successful experiments serve as a basis for clinical research aimed at a preventive medication of recurrent Ca-oxalate stone formation.

Ammonium urate urinary stone: its surface structure and incidence in Japan.

We report on a middle-aged woman with a stone in the right kidney, derived from ammonium urate. Its surface structure was examined by scanning electron microscopy. Ammonium urate is a very rare component of urinary stones in industrialized countries, and they are thought to have an incidence of lower than 0.1% in Japan. The aetiology of ammonium urate-derived stones was investigated from an endemo-epidemiological viewpoint.

[Correlation of the cause and composition of renal calculi. Value of morphologic and infrared analysis]. / Corrélations entre la cause et la composition des calculs rénaux Intérêt d'une analyse morphologique et infrarouge.

The morphological and infrared spectrophotometric analysis of the urinary stones of 300 patients have been reported in this article. Calculi are classified into six morphological types with their corresponding mineralogical natures. The type I (whewellite or C1) is pure in 18 p. cent of lithiasis, more often present in the center than on the surface, with hyperoxaluria in 81 p. cent. Calculi linked to piridoxilate intake (3 p. cent) have this composition. The type II (weddellite or C2) rarely pure, often associated with calcium phosphate are present in 47 p. cent of lithiasis, more often on the surface than in the center, and linked to hypercalciuria in 70 p. cent. The oxalates (C1 plus C2) are the most frequent components of calculi (75 p. cent). The type IIIa and IIIb (anhydrous and dehydrated uric acid) are pure in 8 p. cent, mixed in 6 p. cent; due to hyperuraturia in 55 p. cent, due to urinary acid pH in 60 p. cent. The type IVa (carbapatite) is pure in 5 p. cent, mixed in 26 p. cent, linked to hypercalciuria in 40 p. cent. The types IVb and IVc (struvite plus carbapatite) are present in 12 p. cent, due to urinary infection (90 p. cent), linked to proteus (70 p. cent). The type V (cystine) is rare, linked to hypercystinuria. The type VIa (1 p. cent) is made of proteins. The type VIb (2 p. cent) is composed of medications (triamterene, glafenine, antrafenine).

[Risk factors for the formation of urinary calcium-containing stones in diabetics].

Levels of 24-hour urinary calcium, magnesium, oxalate, citrate, uric acid, phosphorus and creatinine as well as urinary volume were determined in 85 patients and 81 normal subjects. Among the patients, 43 were diabetics without stone, 5 diabetics with stone and 37 with idiopathic calcium stone formation in the urinary tract. It is shown that the main risk factors involved in urinary calcium-containing stone formation are the levels of calcium, oxalate, uric acid and citrate and the volume of 24-hour urine. With the data obtained, the authors calculated the ion-activity products index of calcium oxalate and the relative probability of stone formation in the three groups of patients and the control group of normal subjects. The index in normal subjects, diabetics without stone, diabetics with stone and patients with idiopathic urinary calcium stone was 3.07 +/- 0.16, 2.90 +/- 0.25, 3.90 +/- 0.58 and 5.11 +/- 0.38 respectively. The upper limit of the relative probability in normal subjects was 0.54. Most of the patients with idiopathic urinary calcium stone (32/37) and all the 5 diabetics with stone had higher probability value than this, while most of the normal subjects (73/81) and of the diabetics without stone (39/43) had value lower than this. The results indicate that though the diabetics have higher level of urinary calcium and higher value of the product of calcium x oxalate x uric acid, they have also inhibitive factors for stone formation, such as increased level of urinary citrate. As a result, urinary stone formation will not be a frequent occurrence.