Dissolution of artificial (natural) stones in a standard model: first results

In studying the dissolution of stones in vitro, the advantage of artificial stones in comparison to natural stones is that one can get substance-specific standardized and reproducible results. Our investigations were performed with artificial stones composed of natural material (calcium apatite). These stones were of spherical form and consisted of layers built up around a core. They were comparable to natural stones in their physical properties. Litholysis was performed in a special apparatus with continuous exposure to Suby G solution under standard conditions. Natural stones of the same chemical composition served as a reference. Statistical measurements were performed. By hardening of the artificial stones, it was possible to reach a dissolution comparable to natural stones composed of calcium apatite depending on the Suby G concentration (artificial 2.5 resp. 4.75 mg/h; natural 2.18 resp. 4.2 mg/h). For the first time, an artificial stone model has been created with reproducible behaviour in response to chemolitholysis and with properties of dissolution comparable to those of natural stones of identical chemical composition.

Current aspects of epidemiology and nutrition in urinary stone disease

Current examples for the development of urinary stone disease are discussed by means of data from the literature and our own studies. Urinary stone disease has gained increasing significance due to changes in living conditions, i.e., industrialization and malnutrition. Changes in prevalence and incidence, the occurrence of stone types and stone location, and the manner of stone removal are explained. The importance of nutrition in the prevention of calcium oxalate stone disease is discussed in terms of fluid intake, calcium and oxalate metabolism, and dietary fat intake. The results of a study on a standardized mixed diet or an ovo-lactovegetarian diet show that well-balanced nutrition with consecutive high intake of fluids leads to a significant decrease in the risk for urinary stone formation (calculated as relative supersaturation with calcium oxalate by the computer program EQUIL).

N-acetyl-beta-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.

Measurement of urinary oxalic acid: a comparison of five methods

OBJECTIVE

Five methods for oxalate analysis in urine are compared with respect to reliability, accuracy, and practicability.

RESULTS

Suppressed and unsuppressed ionchromatography, as well as the enzymatic Sigma-Kit, achieve low coefficients of variation for the within-batch imprecision (1.1-8.0%) and between-day imprecision (1.6-7.2%). The results of these methods are comparable and the mean recovery rate ranges between 99.7% and 100.9%. The enzymatic Boehringer-Kit gives higher CV (3.1-9.5%) and the results are lower than those obtained by the methods mentioned above; the recovery rate is sufficient (92.4%).

CONCLUSION

The handling of the chromatographic methods is very easy, whereas the enzymatic methods require more manual work. In relation to sample throughput, charges for the enzymatic methods are about twice as high as for the chromatographic methods. In respect to reliability and accuracy, the chromotropic acid method cannot be recommended (recovery rate 68%).

Primary peritonitis in previously healthy children--clinical and bacteriological features

A prospective study of cases of primary peritonitis in children at the Korle-Bu Teaching Hospital, Accra, was undertaken to find diagnostic clinical and aetiological features of the disease. Seventeen children, 15 females and two males, diagnosed as primary peritonitis underwent laparotomy with peritoneal toiletting. Peritoneal exudate and high vaginal swabs (HVS) were taken under anaesthesia for bacteriological analysis. Patients were followed up for one month. Thirteen patients (70%) were aged between 6 to 10 years. Presentation was early (65% presented in less than 48hrs of onset of symptoms). The commonest presenting feature were fever (100%) and abdominal pain (100%) in the absence of headache (100%). All had classical signs of diffuse peritonitis. There was leucocytosis in 15 cases (88%). No bacterial growth was obtained in 50% of cases cultured. Pneumococcus was the commonest organism isolated (33.3%). Of the 7HVS taken, 4 did not yield any bacterial growth and 2 grew escherichia coli but no pneumococcus. There was no correlation between the bacteriological findings of the peritoneal exudate and the HVS. Post-operative complications were few, insignificant and there was no mortality recorded. Sixty five percent (11/17) of cases could be predicted from the clinical symptoms and signs. The results of this study do not support any aetiological theory of causation.

Selective extraction of quercetrin in vegetable drugs and urine by off-line coupling of boronic acid affinity chromatography and high-performance liquid chromatography

Quercetrin, quercetin and chlorogenic acid were measured in urine or in drugs by combination of boronic acid affinity chromatography and HPLC. Simple reversed-phase HPLC with UV detection was used to determine quercetrin in five different Solidago virgaurea drugs. For determination of quercetrin in human urine immobilized boronic acid was applied for sample pretreatment. this procedure leads to a determination limit of 0.01 micrograms/ml with a recovery rate of 95.3%. The first results using this method for quercetrin pharmacokinetics are presented.

Glycosaminoglycans in urine and extracorporeal shock wave lithotripsy

In 50 calcium oxalate stone-forming patients, the total excretion of glycosaminoglycans (GAGs) and of four subgroups [chondroitin-4-sulfate (CS-A), chondroitin-6-sulfate (CS-C), dermatan sulfate (DS) and hyaluronic acid (HY)] were investigated before extracorporeal shock wave lithotripsy (ESWL) and during the subsequent 5 days. The standard value was determined by reference to a group of healthy test subjects. The excretion of GAGs was significantly higher in healthy test persons than in stone-forming patients. Twenty-four hours after ESWL administration, GAG excretion was enhanced significantly but returned to normal values over the course of 3 days. ESWL had no influence on the proportional composition of GAG subgroups CS-A, CS-C, DS and HY. The increase in GAG excretion after ESWL indicates a transient injury of renal tissue or of the mucus layer lining the urothelium. This lesion, however, can be regarded as temporary with later restitutio ad integrum.

Influence of a mixed and a vegetarian diet on urinary magnesium excretion and concentration

Urinary Mg is suggested to be an effective inhibitor of the formation and growth of calcium oxalate stones. In order to examine the influence of variations in dietary Mg on urinary Mg excretion, ten healthy male subjects were kept on two different standard diets for 5 d each. In the course of the test period, 24 h urine samples were collected. Diets 1 and 2 were calculated according to the dietary recommendations of the German Society of Nutrition (Deutsche Gesellschaft für Ernährung, 1986). Diet 1 was established as a model of a balanced mixed diet, whereas diet 2 represented an ovo-lacto-vegetarian meal plan. Diets 1 and 2 were isoenergetic with equal amounts of the main nutrients, estimated from food tables, and a constant fluid intake. In contrast to the content of Mg (336 mg) and dietary fibre (28 g) of diet 1, diet 2 was rich in Mg (553 mg) and dietary fibre (52 g). On the ingestion of diet 1, renal Mg excretion was 5.09 (SEM 0.35) mmol on the control day and increased slightly but not significantly to 5.40 (SEM 0.52) mmol on the corresponding day on diet 2. Urinary Mg excretion as a percentage of estimated dietary intake was about double on the balanced mixed diet (37%) than on the Mg-rich vegetarian diet (24%). As both diets contained equal amounts of most nutrients, these results indicate a lower excretion rate of Mg from the vegetarian diet than from the mixed diet.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

[3-D ultrasound--data acquisition and representation]

A three-dimensional (3D) workstation for data acquisition, processing, registration and presentation of 3D ultrasound information is described. The ultrasound images needed for further processing are generated by a standard diagnostic ultrasound system. The 3D transducers used here include frequencies of 3.5, 5 and 7.5 MHz. The presentation of reconstructed 3D data is performed by computer-assisted projection of volumetric data or by the presentation of user-selectable slices from the 3D object. Besides improved diagnosis of 3D structures, the system enables precise volume measurements.

The influence of dietary factors on the risk of urinary stone formation

The action of various beverages and foods on the composition of the urine in the circadian rhythm and in the 24-hour urine has been investigated under standardized conditions. Orange juice leads to a significant increase of urinary pH and citric acid excretion. Black tea leads to a raised excretion of oxalic acid by only 7.9%. In the short term, beer increases diuresis, but afterwards leads to a compensatory antidiuresis with increased risk of stone formation. Depending on their composition, mineral waters have very different effects on the urinary constituents. Milk as well as cocoa beverage significantly increase calcium excretion; moreover, cocoa causes an increase in the oxalic acid excretion. The leafy vegetable foods containing oxalate, e.g., spinach and rhubarb, lead to peaks of oxalate excretion of 300-400% in the circadian excretion curve. Cheese leads to a significant rise of calcium excretion with acidification of the urine and lowering of citrate excretion. Calcium excretion is increased by 30% by sodium chloride. Foods containing purine result in an increased uric acid excretion over several days. Depending on their phytic acid content, brans bind calcium, but lead to an increased oxalic acid excretion. Analysis of the urine indicates that average diet in Germany entails a high risk of urinary stone formation. As a result of the change to a balanced mixed or vegetarian diet, according to the requirements, significant alterations in urinary pH, calcium, magnesium, uric acid, citric acid, cystine, and glycosaminoglycan excretion are measured, resulting in a drastic reduction in the risk of urinary stone formation.

Scanning electron microscopy of 2,8-dihydroxyadenine crystals and stones

The lack of purine salvage enzyme, adenine phosphoribosyltransferase (APRT), leads to 2,8-dihydroxyadenine stone formation and/or crystalluria because it is insoluble in urine. Urolithiasis composed of 2,8-dihydroxyadenine is not only formed in a complete defect of APRT, but also in a partial deficiency of this enzyme. The defect is inherited as an autosomal recessive trait, the homozygous state is associated with high urinary levels of 2,8-dihydroxyadenine and with crystalluria, calculus formation, and potential nephrotoxicity. Determination of the APRT activity will facilitate quantification of the enzyme deficiency and elucidation of the hereditary history. 2,8-dihydroxyadenine excretion in the 24-hour urine and its circadian rhythm were determined using a new method of high performance liquid chromatography determination. By means of a standard case presentation, we illustrate the analysis of urinary sediments and calculi as well as the scanning electron microscopic images of this kind of stone.

Urinary saturation and nephrocalcinosis in preterm infants: effect of parenteral nutrition

Urinary lithogenic and inhibitory factors were studied in 27 preterm infants; 16 had total parenteral nutrition (TPN) and 11 had breastmilk with an additional glucose-sodium chloride infusion. Urines were collected for 24 hours on day 2 (period A), day 3 (B), and once between days 4 and 10 (C). Urinary calcium oxalate saturation was calculated by the computer program EQUIL 2. Renal ultrasonography was performed every second week until discharge. The calcium/creatinine ratio increased in infants on TPN (A 0.91; C 1.68 mol/mol) and was significantly higher at period C than that in infants on breastmilk/infusion (A 0.52; C 0.36). The oxalate/creatinine ratio was persistently higher with TPN (203 mmol/mol) than with breastmilk/infusion (98; 137). The citrate/creatinine remained constant with TPN (0.44 mol/mol), whereas it increased significantly with breastmilk/infusion (0.26; 0.49). Calcium/citrate rose considerably with TPN, but decreased with breastmilk/infusion to a significantly lower level than with TPN. The urinary calcium oxalate saturation increased with TPN (2.4; 4.5) and decreased with breastmilk/infusion (2.1; 1.5) to a significantly lower value than with TPN. Nephrocalcinosis developed in two infants on TPN. Mean daily calcium intake was similar in both groups, whereas protein, sodium, and phosphorus intake were significantly higher on TPN. It is concluded that the increase in urinary calcium oxalate saturation observed with TPN is due to the combined effect of an increased urinary calcium excretion and higher urinary oxalate/creatinine and calcium/citrate ratios. The changes observed are likely to be caused by TPN itself, which differs in several respects from breastmilk feeding.

[The infection risk for dogs raised helminth-free in conventional conditions in an urban area]

The present investigations were carried out to clarify whether or not and to what extent helminth-free raised dogs acquire patent and impatent helminth infections when exposed to an urban area contaminated with dog faeces. Groups of each 3 bitches at an age of 3, 6 or 9 months were taken out to an urban area (with average dog density of 1.5 per ha) for 3 hours daily on 5 days per week for a period of 3 month. During the whole trial the bitches and puppies born during this period were maintained under conditions which excluded other infections than those acquired during exposure in the urban area. The examination of the animals had the following results: All 9 bitches remained coproscopically negative until the end of the trial. In these bitches neither intestinal stages nor somatic helminth larvae were found. Seven out of 45 puppies from these bitches shed Toxocara canis eggs with the faeces. Shedding of eggs began 21 to 28 days after birth. Eggs excretion in most cases was low (< 33 eggs per gram). In 12 puppies from 5 litters intestinal stages of T. canis were found with a maximum of 4 specimens per animal. In 9 puppies only male or female T. canis were found.

Cardiac amyloidosis: a review and report of a new transthyretin (prealbumin) variant

Cardiac amyloidosis is caused by amyloid deposits derived from different human plasma proteins. It can lead to cardiac conduction disturbances, restrictive cardiomyopathy, and low output heart failure. The heart is variably involved during the development of systemic amyloidosis and seems to be more frequently affected in immunoglobulin (primary) than in reactive (secondary) amyloidosis. Amyloid is common in the elderly. Isolated atrial amyloid, for which a major subunit is the atrial natriuretic peptide, seems to be three times more frequent than senile cardiac amyloid, which is derived from normal prealbumin (transthyretin). Like polyneuropathy, cardiac amyloidosis is a prominent clinical feature of hereditary amyloidosis, namely of the autosomal dominant transthyretin (TTR) type. All 28 cases of TTR amyloidoses reported so far were heterozygotes for a single nucleotide change in the gene for TTR that resulted in amino acid substitutions in the mature protein. A new TTR genetic variant is reported in a German family where the index patient presented at the age of 63 with anginal pain and arrhythmia. Electrocardiography was suggestive of a pseudoinfarction pattern, and echocardiography and cardiac catheterisation showed signs of hypertrophic nonobstructive cardiomyopathy with increased ventricular filling pressures and a prominent "a" wave. Amyloid of the TTR type was identified by immunohistochemistry in the endomyocardial biopsy specimen. Hybrid isoelectric focusing established heterozygosity by showing normal TTR protein and an electrically neutral TTR variant differing from all known TTR variants so far. The patient died in an accident before investigations were complete. Electrophoretic analysis of the plasma from his first degree relatives (son, daughter, brother, and mother) identified the asymptomatic 22 year old son as an apparently heterozygous carrier of the mutant TTR protein. Comparative tryptic peptide mapping and sequencing showed that isoleucine at position 68 of the amino acid sequence was replaced by leucine.

[The effect of different food forms on the urine composition and the risk of calcium oxalate stone formation]

The aim of this 17-day study was to examine the influence of four different diets on urine composition and the risk of calcium oxalate stone formation in 10 healthy male subjects. In the course of phase 0, the subjects were on their individual diet for 2 days. In the following phases I, II, and III the subjects received three different standard diets for a duration of 5 days each. Whereas DIET 1 (normal mixed diet) corresponded to the dietary habits of men aged 19 to 35 years, DIET 2 (balanced mixed diet) and DIET 3 (ovo-lacto-vegetarian diet) were calculated according to the dietary recommendations of the German Society of Nutrition (DGE) for the same age-group. The risk of calcium oxalate stone formation, calculated by the computer program EQUIL of FINLAYSON, was highest on the self-selected diet and on DIET 1, but declined significantly on the intake of DIET 2 by 50% on average compared to DIET 1 and by 61% compared to phase 0. On DIET 3 no further significant decline in the risk of calcium oxalate stone formation was observed. Therefore, it can be concluded that the change of usual dietary habits into a balanced mixed diet significantly reduces the risk of calcium oxalate stone formation. With a vegetarian diet a comparable decline in urine supersaturation of calcium oxalate can be achieved with respect to a mixed diet according to requirements. Since urinary oxalic acid excretion increased significantly, a vegetarian diet is not recommend for calcium oxalate stone patients with absorptive hyperoxaluria.

In vitro investigations into the formation and dissolution of infection-induced catheter encrustations

Encrustations are the most frequent complications occurring with indwelling catheters and urine drainage systems. The conditions for bacterial infections, using synthetic urine and controlled contamination by Proteus vulgaris, were standardised by using an in vitro model. Crystal deposits on catheters were analysed by infra-red spectroscopy and scanning electron microscopy. The main components of deposits in all investigations were struvite (MgNH4PO4.6H2O) 60-70% and carbonate apatite (Ca10(PO4,CO3)6 (OH,CO3)2) 30-40%. Investigations as to the quality and quantity of encrustations confirmed the analysis. Irrigation treatment was carried out with physiological saline solution and citric acid solution (Suby G) to study and quantify the dissolution of crystal deposits. Regular irrigation with citric solution resulted in a 70% dissolution of encrustations and ensured free flow as ascertained by measuring flow rates.