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Biomedical subjects

A Hesse

Publications and source records attributed to A Hesse.

At least 19 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↗
PubMed1992

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.

Animals↗
PubMed1991

High-performance liquid chromatographic determination of urinary cysteine and cystine.

A method for quantitative determination of cystine and its monomer, cysteine, is presented using reversed phase HPLC with precolumn derivatization by ophthaldialdehyde (OPA). The new application exhibits a two step procedure for overcoming the minimal fluorescence of the OPA-derivatives of cysteine and cystine: after reduction of cystine to cysteine by dithiothreitol the sulfhydryl-group of cysteine is blocked with iodoacetic acid. Optimum reaction conditions of this derivatization procedure are described. Special precautions relating to the rather fast oxidation of cysteine are necessary. Collecting urine directly into sulphosalicylic acid prevents oxidation of cysteine up to 5 days. Initial results of urinary concentration of cysteine and cystine of healthy control persons and patients suffering from cystinuria are presented.

Chromatography, High Pressure Liquid↗
PubMed1991

Investigations of the efficacy of ascorbic acid therapy in cystinuria.

We investigated ascorbic acid therapy for cystinuria in a study of seven healthy control persons and seven cystinuric patients. The study lasted 9 days. During the first period, we collected 24-h urine specimens from all subjects on 3 consecutive days. Starting on day 4, all were given 5 g ascorbic acid/day for a period of 6 days. On the last 3 days, 24-h urine specimens were again collected. Quantitative amino acid determination was performed using an HPLC method described elsewhere. During ingestion of ascorbic acid, the mean excretion of cysteine by the control group increased from 134.1 to 159 mumol/day, whereas the excretion of cystine decreased from 107.1 to 82 mumol/day. The corresponding values for the cystinuric patients increased from 352.4 to 452.1 mumol/day for cysteine and decreased from 4,131.6 to 3,663.2 mumol/day for cystine. Thus, ascorbic acid seems to have only mild reducing properties in respect to cystine.

Ascorbic Acid↗
PubMed1991

Significance of glycosaminoglycans for the formation of calcium oxalate stones.

Glycosaminoglycans (GAG) are polysaccharide chains composed of repeating disaccharides of identical composition. Little is known about the mechanism of their excretion, but there is no doubt that urinary GAGs are degradation products of high molecular weight proteoglycans. Renal excretion takes place chiefly as glomerular filtration, and tubular reabsorption or secretion has not been demonstrated. Differences in the literature comparing GAG excretion in urolithiasis patients and healthy subjects are mainly attributable to methods of analysis and noncomparability of the investigation conditions. We found no differences between the two groups in several series. It is interesting to note that GAG excretion in men is significantly higher than in women, that a circadian rhythm of GAG concentration and excretion occurs in healthy subjects on a standardized diet, and that values are raised postprandially and at night. Seasonal course of GAG excretion curves is almost synchronous for men and women, irrespective of the absolute values, and GAG excretion in the spring and summer significantly exceeds that in winter months by up to 50%. All crystallization models cited demonstrate that GAG reduce the risk of calcium oxalate stone formation. Inhibitors of crystal growth and aggregation act by blocking the growth sites. Inhibition of calcium oxalate crystallization is also attributed to direct binding of calcium to GAG. In the presence of urate ions, and favorable pH, the ability of chondroitin sulfate C to bind calcium may be impaired by as much as 31%. These measurements support the concept that urate ions interact with GAG in urine.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium Oxalate↗
PubMed1991

[Three-dimensional ultrasonic diagnosis in gynecology and obstetrics].

Three-dimensional reconstruction of an organ requires a coordinated sequence of cross-sectional scans. In ultrasound this can be solved by rotating the scan plane horizontally or vertically. Two scan heads have been built, one to rotate the plane around a horizontal, the second around a vertical axis. There are two ways to reconstruct the scans taken by ultrasound into a three-dimensional image: --to contour the surface of the organ in each scan and to reconstruct these contours to a ring-shaped structure. This procedure needs a lot of time; moreover, contouring must be performed via cursor on the screen. --calculate a transparent image of the organ. To obtain the best spatial image by the "transparent method", the image must be moved on the screen. Both methods of reconstruction are shown and compared in this paper. First experiences show that they can be applied in tumour diagnostic and in the diagnosis of malformations in early pregnancy. Further clinical studies will have to prove this.

Breast Neoplasms↗
PubMed1991

[Improvements in 3-D ultrasonic imaging].

The problem of gaining a coordinated sequence of section cuts by ultrasound is solved by rotating the plane section around a vertical and a horizontal axle. There are two possibilities in presenting the 3D image of the examined organ: ring structure image or transparent image. Precondition in the ring structure image is time consuming and defective since it has to be done by hand using a cursor. These pitfalls can be avoided when using a method without contouring by showing the 3D image transparently. Each section cut has to be calculated transparently. Both methods are presented in this paper and compared as to their applicability in medicine. The problem of the transparent 3D presentation lies in the fact that it cannot be well presented on printed paper, as is done her. The moving picture on the computer screen gives an optimal 3D image. This new method seem to be useful in tumor diagnostic and diagnostic of malformations in early pregnancies.

Computer Graphics↗
PubMed1990

Metabolism of aspirin after therapeutic and toxic doses.

1 The urinary recovery of metabolites of aspirin (ASA) was studied in 45 volunteers who took a therapeutic dose (600 mg) of ASA by mouth and in 37 patients who took ASA in overdose. 2 The main metabolite recovered from the volunteers was the glycine conjugate, salicyluric acid (SUA), which accounted for 75.01 +/- 1.19% of total urinary metabolites, whereas salicylic acid (SA) accounted for 8.82 +/- 0.56%. Recovery of SUA was negatively correlated with that of SA (r = -0.8625, P less than 0.001). 3. In 24 patients with admission plasma salicylate concentrations of 240-360 mg l-1, SUA accounted for 46.66 +/- 3.22% and SA for 31.88 +/- 4.02%. 4. In 13 patients with admission plasma salicylate concentrations of 715-870 mg l-1, SUA accounted for 21.57 +/- 3.65% and SA for 64.72 +/- 4.82%. 5. Reduced excretion of salicylate as SUA was also accompanied by increased elimination as gentisic acid and salicylic acid phenolic glucuronide indicating that the unsaturated processes that lead to the formation of these metabolites contribute significantly (22-23%) to the inactivation of large doses of salicylate. 6. While the Michalis-Menten kinetics of ASA have been well demonstrated at lower doses, our findings illustrate the progressive saturation of SUA formation under conditions of increasing ASA load to toxic amounts and raise issues about the in-vivo glycine pool when ASA is taken in overdose.

Adolescent↗
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↗
PubMed1989

Analysis of urinary stones by computerized infrared spectroscopy.

The computerized assessment of infrared spectra of urinary stones with existing programmes such as SEARCH (Lehmann, C. A. et al. (1988) Clin. Chim. Acta 173, 107-116), TWIN or CIRCOM (Hesse, A. et al. (1988) Fresenius Z. Anal. Chem. 330, 372-373) has proved to be unreliable when used for routine urinary stone analysis. A more refined method has to be used in place of simple comparison algorithms. STONES is a new programme for computerized analysis of urinary stones developed with the intention of simulating the former non-computerized analysis procedure. STONES is a rule-based system, which interprets the infrared spectra qualitatively by its rules. A quantitative result is obtained by means of library search. Combining these two methods 93% of the tests were correct with regard to clinical relevance.

Evaluation Studies as Topic↗
PubMed1987

Experimental determination of the kinetics of calcium-binding with chondroitin sulphate and the effects of uric acid on this process.

The calcium-binding kinetics of chondroitin sulphate C (CS) have been determined using equilibrium analysis including 45Ca. There is a linear relationship between the extent of the Ca binding and the concentration of CS present. 1 mumol CS disaccharide unit binds 0.757 mumol Ca. Scatchard plots of the data have revealed a single constant of dissociation (KD = 0.1429). In the presence of urate ions, and dependent on the pH value, the ability of CS to bind Ca may be impaired by as much as 31%. These measurements have supported the theory that urate ions interact with the GAGs in urine.

Calcium↗