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Biomedical subjects

A Classen

Publications and source records attributed to A Classen.

11 recordsLinked to original sources
PubMed1992

Dietary fibre: the effectiveness of a high bran intake in reducing renal calcium excretion.

Fifteen healthy women were given a standardized calcium-rich diet (1800 mg calcium/day) with or without 36 g bran for 5 days. A similar study was also carried out with rice, soy and wheat bran. Urine samples were also collected 24 h. With all brans renal calcium excretion decreased and renal oxalic acid excretion increased. However, influence of rice bran was statistically significant. After 5 days of consuming 36 g rice bran/day 14 of 15 subjects showed decreased calcium excretion, but increased oxalic acid excretion. Relative supersaturation with calcium oxalate, as a measure for the risk of calcium stone formation, increased after addition of all brans.

Adult↗
PubMed1990

Simultaneous determination of urinary phosphate and sulphate by ion-chromatography.

An ion-chromatographic system was used for the simultaneous determination of urinary phosphate and sulphate. This method was compared with conventional methods (colorimetric, turbidimetric) with regard to practicability and reliability. All methods showed good precision and accuracy. The comparative analysis of phosphate in 80 samples revealed that both methods lead to identical results. However, in case of sulphate a significant difference of about 8% was found between the two methods. Overestimation of the analyte concentration by the turbidimetric method might be responsible for this difference. From the point of view of economy, routine analysis of urinary phosphate and sulphate by ion-chromatography is acceptable only if automated systems are used.

Chromatography, Ion Exchange↗
PubMed1989

Experimental investigations on dissolution of incrustations on the surface of catheters.

On the basis of a standardized in vitro irrigation model, the incrustation behavior of catheters was investigated using collected urine with controlled contamination (Proteus, mirabilis). Irrigation treatment with a NaCl solution did not effectively reduce incrustation compared to the control experiment. On the other hand, incrustations were definitively prevented or existing crystal deposits were largely dissolved with a citrate solution of pH 4.0 (Suby G). Analytical investigations (infrared spectroscopy, scanning electron microscopy) of the deposits on the catheter revealed the presence of struvite (MgNH4PO4 x 6H2O), brushite (CaHPO4 x 2H2O) and carbonate apatite (Ca10[PO4] [CO3OH]6[OH]2).

Catheters, Indwelling↗
PubMed1988

2,8-Dihydroxyadeninuria: laboratory diagnosis and therapy control.

This report is concerned with the experience gained with two 2,8-dihydroxyadenine (2,8-DHA) stone patients. When adenine phosphoribosyltransferase (APRT) deficiency is suspected, the risk of stone formation can be detected at an early stage from the crystalline urinary sediment. Infrared spectroscopic analysis of the crystals or of a urinary stone, if present, will confirm the diagnosis. Determination of the APRT activity will facilitate quantification of the enzyme deficiency and elucidation of the hereditary history. 2,8-DHA excretion in the 24-hour urine and its circadian rhythm were determined at 3-hour intervals using a new method of high performance liquid chromatography determination. This method also provides a means of monitoring the effectiveness of allopurinol therapy.

Adenine↗
PubMed1987

Measurement of urinary oxalate: an enzymatic and an ion chromatographic method compared.

An ion chromatographic and an enzymatic method for determination of oxalic acid in urine were compared on the basis of reliability and practicability. Both methods displayed a within-run imprecision of under 5% and a total imprecision of under 10%. The mean recovery of 0.2 mmol/l sodium oxalate lay close to 100% for both methods. After 80 parallel determinations, both methods produced statistically identical results. In terms of cost per analysis, ion chromatography is the method currently preferred when large numbers of samples are involved. If only a few samples are to be analysed the enzymatic method--without any loss of reliability--can be employed.

Carboxy-Lyases↗
PubMed1986

Dependence of urine composition on the age and sex of healthy subjects.

The lithogenic and inhibitory substances in the 24-h urine of 150 healthy females and 150 healthy males were recorded. These two groups were further subdivided into 6 different age-groups, with 25 in each group. The 24-h excretion in these various age-groups displayed considerable differences in some cases, particularly in the case of the pH value, and the Ca, Mg, citrate and phosphate excretion of the women, and the Ca, Mg, uric acid, Na and K excretion of the men. All the parameters measured with respect to the males displayed higher levels of excretion than those of the females.

Adolescent↗
PubMed1985

An evaluation of test sticks used for the measurement of the specific gravity of urine from patients with stone disease.

A test stick for the measurement of the SG of the urine of stoneformers was examined. In 230 spontaneously voided urines and 45 25 h-urines the SG was measured by the test stick and compared with urinometer measurements. The two methods showed a good correlation (r = 0.86). Due to the principle of reaction of the SG-teststick a direct relationship of the SG-values to the sodium concentration and to the ionic strength of urine was found. There is no correlation between the relative supersaturation of CaOx and the SG-determination (urinometer, test stick). The handling of the SG-test stick is simple and can be easily performed by the patient.

Calcium↗