Biomedical subjects
Publications and source records attributed to W Berg.
The pharmacokinetics and pathophysiology of oxalic acid in human organism are presented. In the formation of urinary calculi the level of urinary oxalic acid is important, but the knowledge of metabolism and various disturbances is the guide of a successful treatment and metaphylaxis. Therefore, the diagnostics is a prerequisite for successful dietetic and therapeutic measures as shown in absorptive hyperoxaluria.
By oral administration of 14C-labelled oxalic acid (2.2 microns Ci; 2 mg), the mean enteral oxalate absorption in 24-h urines (collecting intervals 3, 3, 6, 12 h) of 19 healthy control subjects was determined to be 8.3%. It was 14.6% (alpha less than 1%) in 20 patients with recurrent idiopathic calcium-oxalate lithiasis. The differences in absorption were most marked in the first two 3-h urines. Under the test conditions described, maximum excretion of 14C oxalate had already occurred after 3 h (55%-57%); after 6 h it was about 85%, and after 12 h 95% of the total activity in the 24-h urine. In 68% of the control subjects, the oxalate absorption values were below 10%; in 32% they were less than or equal to 15%. For the group of lithiasis patients, these findings suggest a metabolic disorder of gastrointestinal origin. In 40%, the oxalate absorption rates were clearly above 15%. The test method described is simple to carry out and can be recommended for the assessment of idiopathic calcium-oxalate lithiasis.
For five samples of our 5th international ring test for the quality control of methods of urinary calculus analysis we received 46 results from 19 countries obtained by means of ten different methods. The mean standard of quality (SQ) for all participants with quantitative methods is 2.11. Most laboratories employed X-ray diffraction (n = 21; SQ = 2.09) for quantitative calculus analysis. The mean deviation (delta x) per component from the ideal composition is fortunately low--about 0.10 molar parts for all participants, 0.06 molar parts for X-ray and infrared spectroscopy technique together. From the aspect of accuracy, the physical methods of analysis, X-ray diffraction and IR spectrophotometry, are clearly superior to all other analytical techniques.
Acidosis induced increase in renal calcium excretion and decrease in renal citrate excretion was produced by means of ammonium chloride load in 15 patients with recurrent oxalate lithiasis and in 15 control subjects. The expected increase in the calcium citrate relationship in urine is more marked and more lasting in stone patients. Stone formers obviously respond to an acidotic metabolic situation by a more clear relative decrease in citrate excretion, in addition to more intensive calcium excretion, which is known. A certain individual sensitivity of renal tubular mechanisms is discussed with regard to acid base changes.
For five test samples of the fourth International Ring Test to check the quality of methods for urinary calculus analysis, 45 findings obtained by 10 different methods were sent from 16 countries. The mean deviation of 0.11 molecular parts per component for all five samples is considerably low. The average standard SQ for all participants is 2.44. It falls off from X-ray diffraction via IR down to other quantitative methods. Advantages and disadvantages of X-ray diffraction and IR-spectroscopic analyses are discussed. Analysis of urinary calculi according to centralized, methodically uniform standards offers advantages in analytical quality.
The procedure described confirms that the Ni2+/S2O4(2-) tablet test is a suitable quick cystine screening test for large groups. In 16 (0.67%) of 2,395 one- to three-year-old crèche children significantly enhanced cystine levels of 0.60-0.96 mmol/l were found. The corresponding creatinine values (mmol/l) did not reveal any significant deviations from the normal values. In a preliminary group of 9 children, enhanced lysine levels support the suspicion of the existence of cystinuria without clinical symptoms. This also forms the basis for further necessary family histories as well as for prophylactic measures.
With extensive analytical and clinical examinations it is shown that the proof of carbonate in apatite may allow no additional reference of an infection with urea-splitting bacteria. With certain analytical methods the presence of carbonate is demonstrable in each urinary calculus apatite phase. Carbonate-bearing apatite indeed is accompanied frequently with struvite, but may be occur also without an infection. Therefore, in the future it should be renounced on the differentiation of apatite and carbonate apatite in routine analyses of urinary calculi.
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A semiquantitative method is presented for the determination of cysteine in urine, based on the formation of a red cysteine/nitroprusside salt. The method is suitable as a rapid test for checking the progress of ascorbic acid therapy of cystinuria and cystine urolithiasis. It guarantees acceptable reproducibility of values and can be easily carried out in any clinical chemical laboratory. With the K2CO3/nitroprusside test described and an additional colorimetric determination of cystine (CN-/nitroprusside), a separate semiquantitative differentiation of cysteine and cystine in fresh (!) urine is possible.
In this paper a method of semiquantitative cysteine determination is presented, which is based on the formation of a red cysteine-Na-nitroprusside salt. The method is a suitable rapid test for checking the process of ascorbic acid therapy in cystinuria and cystine urolithiasis patients. It guarantees acceptable reproducibility of values and can be easily carried out in every clinicochemical laboratory. With the K2CO3/nitroprusside test described and an additional cystine rapid test (Ni2+/S2O4(2-) tablet reagency) a separate semiquantitative differentiation of cysteine and cystine in fresh (!) urine is possible.
Acidosis induced increase in renal calcium excretion was produced by means of ammonium chloride load in 12 control persons and in 76 patients with recurrent oxalate lithiasis. This increase is more marked in stone patients - even in those with normocalciuria - than in control persons. The calcium excretion is especially increased in patients with renal hypercalciuria. This might result from the primary nature of the renal defect. The acid load did not prove useful in the diagnosis of hyperparathyroidism.
In 43 healthy reference persons and 54 patients with relapsing calcium oxalate nephrolithiasis the absorption of oxalic acid was measured by means of 14C-oxalic acid. In patients with oxalate calculi the absorption of oxalic acid is totally increased and also in such ones with Whewellite-calculi. It is decreased in carriers of Weddelite calculi. The increase of the absorption of oxalic acid in patients with mixed calculi is not significant.
In two test series additional oxalic acid excretion in urine was induced in healthy test persons by administering a spinach diet. This additional excretion could be markedly reduced by magnesium administration. Calcium and citrate excretions are largely unaffected by magnesium administration. Magnesium excretions, however, are clearly increased. The calcium oxalate crystallization rates in the 5-or 7-hour urines reveal a behavior parallel to that of the oxalic acid excretion profile. In the control urines, the crystal picture is characterized by numerous medium-sized whewellite crystals. In contrast, in the test series weddellite crystals are reduced in size and frequency after magnesium administration. New aspects of magnesium effects must be discussed; above all the possible absorption changes resulting from gastrointestinal diseases.
17 cystine stone patients were treated with high doses of ascorbic acid (5 g p. d.). During the observation period, a total of only two natural passages of cystine stones could be observed. For five patients the therapeutic strategy was altered because the recurrence rate did not change and the cystine concentration in the urine was enhanced. One mixed calcium-oxalate/cystine stone had to be resected. In this case as well as on the occasion of further medical check-ups of other patients, an increased risk of calcium-oxalate stone formation was signalled by an enhanced oxalic-acid concentration in the 24-hour urine. Changes in blood serum and impairment in hepatic and renal functions were not observed. With three patients, the therapy had to be interrupted because of gastritis symptoms. The use of high-dose ascorbic acid therapy is recommended and is continued. In special cases, an additive of low do ses of alpha-mercaptopropionyl-glycine is recommended.
The present study describes a modified method of the semiquantitative determination of cystine in the urine which is based on the decomposition of cystine by dithionite ions and formation of a mixed nickel/cystein/sulfide-complex. The method is suitable as rapid and search test, it guarantees an acceptable reproducibility as well as the exactness of the values and is simply to be performed in every clinical-chemical laboratory. The criteria of analytic applicability are confirmed in comparisons of methods. It must be urged to treat fresh urines.
Of 5 analysis tests of the 3rd International Ring Experiment for the control of the quality of methods of the analysis of urinary calculi 38 findings compiled according to 9 different techniques came in from 12 countries. The average deviation per component concerning all 5 analysis tests is considerably low with 0.10 mol proportions. The average quality measure SQ concerning all participants is approximately 2.00; it deteriorates from the X-ray diffraction method over the IR-technique to the other quantitative methods used. Advantages and disadvantages of the X-ray diffraction and IR-spectroscopic analysis are discussed. A methodically homogeneous and centralized performed analysis of urinary calculi shows advantages in the quality of the analyses.
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