A missense mutation in the hypoxanthine phosphoribosyltransferase gene in a pediatric patient with hyperuricemia

We have identified a mutation in the gene coding for the enzyme hypoxanthine phosphoribosyltransferase in a pediatric patient with hyperuricemia and nephrolithiasis. The mutation is a nucleotide substitution causing an amino acid substitution in the hypoxanthine phosphoribosyltransferase protein. In this patient, fibroblasts but not lymphocytes showed resistance to 6-thioguanine, and reduced enzyme activity was detected in lymphocytes. These results are consistent with the intermediary phenotype associated with partial hypoxanthine phosphoribosyltransferase enzyme deficiency. Altogether, six males in this family suffered from hyperuricemic symptoms, and small differences in phenotype were seen.

A review of new concepts in renal stone research

Clinical and basic research in the field of urolithiasis has developed rapidly in recent years. Progress in extracorporeal shock wave lithotripsy (ESWL) and percutaneous nephrolithotomy (PNL) has brought about a revolution in the surgical treatment of urolithiasis and research at the cellular and molecular level is now expanding. In spite of these advances, however, clinical treatment of urolithiasis remains far from satisfactory. Stone recurrence in many patients cannot be predicted and is beyond control of urologists mainly because the mechanisms of stone formation are still not fully understood. It is necessary to study the process of stone-formation more intensely at the cellular and molecular level, and to strengthen the links between basic and clinical research in the field. In this review, the processes involved in the formation of stones are compared with those involved in normal bio-mineralization and a model of urolithiasis is put forward based on modern systems science. Attention is concentrated on: (a) Directions of research based on physico-chemical theories of stone formation; (b) The role of renal tubular defects in urolithiasis; (c) The role of free radical reactions in stone formation; and (d) Macromolecular abnormalities and their correction.

Adenine phosphoribosyltransferase deficiency with renal deposition of 2,8-dihydroxyadenine leading to nephrolithiasis and chronic renal failure

Homozygous adenine phosphoribosyltransferase deficiency is a genetic defect that is associated with 2,8-dihydroxyadenine urolithiasis. Since the prevalence of the heterozygous state is found in 0.4% to 1.2% of the population, it is surprising that more cases of 2,8-dihydroxyadenine urolithiasis have not been reported. Herein we describe a patient with complete adenine phosphoribosyltransferase deficiency with 2,8-dihydroxyadenine urolithiasis leading to chronic renal failure. Gene sequencing revealed that the patient is a compound heterozygote. One of the mutations (a T insertion between bases 346 and 347) has been encountered before, but the second (a G-to-A substitution at base 1356) has not been previously reported. Possible explanations for the unexpected rarity of 2,8-dihydroxyadenine urolithiasis are discussed.

Urinary type IV collagenase: elevated levels are associated with bladder transitional cell carcinoma

Accumulating experimental evidence has linked the overproduction of extracellular matrix-degrading metalloproteinases with tumor cell invasion. In the present study one member of the metalloproteinase family, type IV collagenase (M(r) 72,000 gelatinase), is shown to be elevated in the urine of patients with transitional cell carcinoma of the bladder. The form of the enzyme in the urine was studied by three independent methods: enzyme-linked immunosorbent assay, Western immunoblotting; and gelatin zymography. Immunoblotting revealed that the enzyme was present as a series of fragments, each retaining the amino terminus of the mature proenzyme. A prominent M(r) 43,000 fragment was associated with the transitional cell carcinoma cases. Zymography demonstrated that multiple enzyme species with gelatinase activity were present in urine and that high-molecular-weight bands of substrate lysis corresponded to complexes between type IV collagenase and tissue inhibitor of metalloproteinases 2. The total amount of type IV collagenase antigen was significantly elevated in the urine of 37 transitional cell carcinoma patients (range, 0-1081 ng/ml; mean, 318.4 +/- 147.3) compared to 19 normal controls (P < or = 0.004) and 17 inflammatory disease controls (P < or = 0.011). Immunohistochemical staining of bladder tumor biopsies verified that the transitional cell carcinoma cells were producing the M(r) 72,000 enzyme. Thus, M(r) 72,000 type IV collagenase, which is present in the urine in many forms including fragments and complexes with inhibitors, may be a useful marker for bladder cancer diagnosis or prognosis.

[Two cases of 2.8-dihydroxyadenine stone with a partial deficiency of adenine phosphoribosyltransferase]

We report two cases of 2.8-dihydroxyadenine stones due to partial deficiency of adenine phosphoribosyltransferase. The first patient is a 41-year-old female. Radiologic examination revealed left radiolucent renal stones and contracted kidney. Left nephrectomy was performed. Infrared spectrometric analysis of the stones revealed 2.8-dihydroxyadenine calculi. The adenine phosphoribosyltransferase activity in lymphocyte (T cell) was 19.5% of the control level. After the operation, the patient was given 300 mg/day of alloprinol. There have been no signs of recurrence. The second patient was a 52-year-old male. Radiologic examination revealed radiolucent stones of the right kidney and the urine bladder. Percutaneous nephrolithotomy and cystolithotripsy were performed. Infrared spectrometric analysis of the stones revealed 2.8-dihydroxyadenine calculi. The adenine phosphoribosyltransferase activity in the lymphocytes (T cell) was 21% of the control level. After the operation the patient was given 200 mg/day of alloprinol and put on a low purine diet. There have been no signs of recurrence.

Immunohistochemical detection of renal carbonic anhydrase of patients with recurrent urolithiasis

In renal exploratory excisions the isoenzyme C of the carbonic anhydrase was detected in 51 operative treated patients with recurrent urolithiasis and in 6 patients with ren mobilis or stenosis of the ureteral pelvic junction by using the immunohistochemical PAP-method. In the distal tubules and collecting ducts there is an alternating occurrence of cells with small and those with strong reactivity. This correlates with the distribution of mean or principal (P-, small reaction) and intercalated (I-, strong reaction) cells. The number of carbonic anhydrase rich cells and the degree of their cytoplasmic reaction to this enzyme seem to correlate with the ability of the urine to acidify. The patients were divided into four groups according to the mean urine pH estimated for a period of two weeks. The third group with predominantly acid urine (pH less than 5.8) showed a significantly increased number of carbonic anhydrase rich cells (mean = 63% +/- 6, n = 18) as compared to the first group (controls) without urolithiasis and normal urine (pH 5.8-6.8, mean = 46% +/- 8, n = 6) or the second group with urolithiasis and normal urine (pH 5.8-6.8, mean = 46% +/- 8, n = 28). The fourth group with predominant alkaline urine (pH greater than 6.8) showed a significantly decreased number of intercalated cells (mean = 42% +/- 16, n = 5) in comparison to the third group. Indeed, the difference with the control group is not significant but the cytoplasmic reaction of I-cells decreases distinctly in comparison to all other groups.

[Localization and extent of tissue damage caused by extracorporeal lithotripsy (ESWL)]

Extracorporeal shock wave lithotripsy (ESWL) causes proteinuria. In our study we investigated the protein fractions and the electrolyte composition of the urine in patients who had been treated with ESWL. The aim was to obtain information on the degree and the localisation of the glomerular, tubular or vascular destruction caused by ESWL in humans. A total of 34 patients with stones had been treated with ESWL. As parameters we used: urine output, creatinine clearance, total protein, albumin, immunoglobulin G, N-acetyl-beta-D-glucosaminidase (beta-NAG), alpha-1-microglobulin, the fractional excretion of Na+ and apolipoprotein-A-1. After ESWL treatment proteinuria and albuminuria are found. Our parameters show no deterioration of the glomerula or the tubulus. The increase in apolipoprotein-A-1, a postglomerular parameter, however, is interpreted as a manifestation of vascular destruction after ESWL; this is normally temporary, leaving no permanent damage.

Increased serum alkaline phosphatase activity: a possible indicator of renal damage

Increased levels of serum alkaline phosphatase (ALP) (E.C.3.1.3.1.) were observed in 25 patients with various urological conditions involving the kidneys: malignancy, complicated nephrolithiasis, and surgical and percutaneous manipulations. Other possible sources for increased ALP level, mainly hepatic and osseous, were excluded by history, laboratory tests, and liver and bone imaging. Studies of isoenzymes of ALP did not show a distinctive pattern. ALP levels returned to the normal range by treating the underlying lesions involving the kidney: nephrectomy, complete removal of stones, or removal of nephrostomy. The increase in serum ALP activity may be derived from the injury to the brush border membrane of the renal tubular cells. Renal function impairment and contrast media induced nephrotoxicity may also be responsible for the increased serum ALP. Serum ALP may be a marker for involvement of the kidneys in pathological processes and an indicator of complete treatment. This clinical observation is worthy of further study.

Identification of a splice mutation at the adenine phosphoribosyltransferase locus in a German family

We examined the molecular basis of adenine phosphoribosyltransferase (APRT) deficiency in homozygous-deficient, identical twin brothers who were born to non-consanguineous German parents. DNA was isolated from blood, and the APRT gene was amplified by PCR, subcloned into M13, and sequenced completely. A single T insertion between bases 1831-1832 or 1832-1833 was identified. This alters the consensus sequence at the exon 4 - intron 4 spice donor site and leads to aberrant splicing. The same mutation has been described previously in two affected brothers from Belgium, and the Indianapolis group has also identified it in two other, unrelated Caucasian patients. Thus, this mutation may be a common cause of APRT deficiency in the Caucasian population.

The excretion of carbonic anhydrase isozymes CA I and CA II in the urine of apparently healthy subjects and in patients with kidney disease

Carbonic anhydrase isozymes CA I and CA II were assayed by a radio-immunosorbent technique in the plasma and urine of apparently healthy subjects and of patients with renal disease. The concentrations (mean +/- SD, n = 8) of CA I and CA II in the plasma of healthy subjects were 2.3 +/- 2.3 and 0.8 +/- 0.5 mg/l, respectively. The urinary excretion values were 3.8 +/- 2.0 and 3.5 +/- 1.9 micrograms/24 h, and the apparent renal clearances were 21 +/- 17 and 52 +/- 44 microliters/min, respectively, values that are similar to those of other low molecular weight proteins. CA I and CA II have mol. wt of 28,850 and 29,300, respectively, they are globular in shape and have a Stoke-Einstein radius of 25 A. They could, therefore, be expected to be filtered at the glomeruli and thereafter reabsorbed by the proximal tubules. CA II is also present in the cytoplasm of renal proximal and distal tubular cells. A study of the pattern of urinary excretion of CA I and CA II could permit detection of damage to renal tubular cells in two ways--either from defective reabsorption of filtered CA I and CA II by the proximal tubular cells, or from leakage of CA II from the proximal or distal tubules into the urine. Some patients with hypercalcuria and renal tubular acidosis showed increased excretion of these enzyme proteins and of beta 2-microglobulin (BMG) into the urine, but the prevalence was rather low (27%). Further studies of patients with more severely damaged kidneys are required.

[NAG (N-acetyl-beta-D-glucosaminidase)--a sensitive marker for disorders of kidney function]

In a clinical study we tested the use of the lysosomal enzyme NAG as a parameter of kidney function. Following prospective randomization, we examined NAG excretion during cisplatin treatment with/without nephroprotection, after intravenous urography with ionic/non-ionic contrast media, during lower/upper urinary tract infections and before/after extracorporeal shockwave lithotripsy for intrarenal calculi (first-generation equipment used). Measurements were performed in 3-h urine specimens and in urine collected over 24 h, using a simple method of analysis. A correlation between NAG leakage and functional disorder of the renal tubular cells seemed likely on the basis of additional clinical and experimental data. Increases, in some cases dramatic, in NAG excretion were observed after the administration of cisplatin and ionic contrast media, in acute pyelonephritis, and after extracorporeal shockwave lithotripsy. However, the increase in NAG excretion was less impressive during cisplatin therapy when nephroprotective amino acids were infused, and in the urography group when non-ionic contrast media were used. Infections of the lower urinary tract did not increase NAG excretion. The results indicate that NAG is a sensitive marker of occult renal dysfunction, which can be checked by non-invasive techniques and can be used in a clinic setting to detect functional disorders of the kidney.

[2,8-dihydroxyadenine urinary calculus: the significance of exact physical calculus analysis]

A 21-year-old female patient was treated with Uralyt-U for 3 months for a radiolucent kidney stone. During this therapy the stone increased significantly in volume. After treatment by ESWL, the stone was analyzed by a chemical method and by X-ray diffraction. Calcium phosphate and urate were detected by the chemical method and 2,8-dihydroxyadenine by X-ray diffraction. This case report emphasizes the importance of precise stone analysis for medical treatment is emphasized.

[The proteolysis-ion theory of the pathogenesis of nephrolithiasis]

A study was made of urinary proteolysis. This parameter turned to be decreased in patients with nephrolithiasis versus normal subjects. The authors developed an original proteoclastic-ion theory of nephrolithiasis pathogenesis, based on the two main risk factors triggering the disease: low levels of urinary proteolysis leading to the formation of a calculous matrix; the urine pH values optimal for the sedimentation of lithiasic salts. The combination of both risk factors was responsible for the development of calculous crisis and the formation of microlith. The decreased index of urinary proteolysis calculated with the formula offered could be regarded as a risk indication to the microlith formation. A possible elimination of the both risk factors was demonstrated. The technique of microlithiasis metaphylaxis was developed with regard to the major and minor risk factors and the possibility of their elimination. The values of urinary proteolysis were the criteria for a successful therapeutic response. With regard to the number of risk factors the risk of primary nephrolithiasis or lithiasis relapses could be predicted.

2,8-dihydroxyadenine urolithiasis: report of a case first diagnosed after renal transplant

We report a case of homozygous adenine phosphoribosyl transferase (APRT) deficiency associated with 2,8-dihydroxyadenine stones recurrent in a patient with a renal transplant. The disease was diagnosed 23 years after the initial episode of renal colic. At that time the disease was unknown. Our patient is only the second case of this disorder reported from the United States. Correct diagnosis is important because long-term maintenance with allopurinol and a low purine diet can effectively prevent stone formation and renal failure.

2,8-Dihydroxyadenine lithiasis

2,8-Dihydroxyadenine (2,8-DHA) lithiasis is a form of kidney stone previously mistaken for uric acid because of identical reactivity in non-specific tests used routinely in stone analysis. Unlike uric acid, the stones crush easily and do not react with uricase. The biochemical basis for the defect is a deficiency of the enzyme adenine phosphoribosyltransferase (APRT). A complete deficiency has been reported in 29 patients from 11 countries. The number of stone formers reported in Japan (10 homozygotes, 16 heterozygotes) Austria (3), and Switzerland (2) suggests more efficient diagnosis in those countries. The defective enzyme in heterozygotes in Japan is a kinetic mutant demonstrable in intact not lysed cells. 20% of APRT-deficient subjects have been asymptomatic. An equal number have presented in acute renal failure, three of whom are now on dialysis. Formation of the nephrotoxic 2,8-DHA can be prevented by allopurinol. This underlines the importance of early diagnosis, since such severe renal damage should be avoidable.

[Clinico-biochemical and morphological changes in obstructive calculous pyelonephritis in children]

The article presents results of a comparative study of clinico-biochemical and morphological alterations in 38 patients with obstructive calculous pyelonephritis before and after operation. The data obtained show considerably elevated activity of LDG and other enzymes, content of cholesterin, total phospholipids followed by histomorphological alterations in the kidney.

Deficient urinary fibrinolysis in renal stone disease

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