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Biomedical subjects

G Kohlbecker

Publications and source records attributed to G Kohlbecker.

9 recordsLinked to original sources
PubMed1989

[Quantitative measurement of sulcus fluid with new self-coloring paper indicator strips: a comparison with Periotron].

Quantitative measurements of gingival crevicular fluid are used to examine gingival inflammation. In order to simplify such measurements we evaluated for the first time testing papers with chemically bound pH indicators. The height of the fluid can be seen instantly as a color change. Calibration curves showed a rise in linear proportional increments in the magnitude of 1 mm per 0.1 microliters. To evaluate this method, we made a comparative study using 26 patients and Periotron ratings. Both methods can be regarded as congruent. Using the color-indicator paper is a methodological advantage, as measurements can be taken without the need of further devices, chemical substances or procedures.

Color↗
PubMed1989

[Toxic impurities in chlorhexidine digluconate].

Three preparations of chlorhexidine-digluconate were analysed for contamination with a newly developed high-pressure liquid chromatographic method. Of special interest was p-chloroaniline, a toxic as well as a carcinogenic compound. We found concentrations from 1.7 to 8.5 mmol p-chloroaniline per mol chlorhexidine-digluconate, i.e. five-fold differences in the different products. Besides p-chloroaniline many other contaminating substances were found, amongst others p-chlorophenyl-isocyanate and p-chlorophenyl-carbodiimide. The least contamination was found in a branded article, and the highest degree of contamination in a "no-name"-product. During a storage period of half a year in dark glass bottles in a solution of 0.2% under various light and temperature values the p-chloroaniline concentrations increased linearly with the period of storage, with the exception of storage in the dark at 5 degrees C. A constant temperature of 35 degrees C in the dark caused a greater increase than storing at 20-25 degrees C in the dark or the light or in direct sunlight. Therefore under similar conditions it is mostly warmth which causes an increase in toxic compounds.

Chlorhexidine↗
PubMed1981

Direct spectrophotometric determination of serum and urinary oxalate with oxalate oxidase.

A new enzymatic method for direct photometric determination of oxalate in serum and urine is described, using oxalate oxidase. The resulting H2O2 is measured with a coupled enzyme system of catalase and aldehyde dehydrogenase. Percentage recovery of added oxalate was 99 +/- 4 in serum, and 98 +/- 4 in urine (n - 10). Oxalate serum levels varied from 16.9 to 44.8 mumol/l. Oxalate values can be determined within 20 minutes, without time consuming pretreatment of samples. The detection limit is 5 mumol/l.

Aldehyde Dehydrogenase↗
PubMed1980

Oxalate urolithiasis: significance of serum and urinary oxalate.

With a new enzymatic test using oxalate oxidase, serum and urinary oxalate can easily and quickly be determined. Serum oxalate in females was significantly higher than in males (39.5 mumol/l, 30.8 mumol/l). Increased serum levels were found only in male patients. Urinary excretion did not reveal sex-dependent differences in healthy persons. The normal range of oxalate excretion in 104 adult healthy persons was 83-365 mumol/day (95% quartile). In 130 stone formers (nonrecurrent and recurrent group) urinary oxalate excretion was found to be in the normal range. Evaluation of urinary oxalate concentration in morning samples showed increased levels in both groups of male stone formers. Oxalate concentration was unaltered in female patients.

Adult↗
PubMed1980

Dietary influence on serum and urinary oxalate in healthy subjects and oxalate stone formers.

With a new enzymatic method, the dietary influence of oxalate, glycine, protein, and ascorbic acid on serum and urinary oxalate has been examined. Healthy and oxalate stone-forming subjects were compared. Two doses of sodium oxalate (130 and 400 mg daily) were administered. The high dose induced significant hyperoxaluria. No changes of serum oxalate were seen. Neither glycine (4.5 g daily) nor protein (50 g daily, 50% animal protein) had any effect on serum or urinary oxalate. Urinary oxalate excretion did not increase upon ingestion of large amounts of ascorbic acid (1--6 g daily), but serum oxalate levels were significantly elevated. The value of severe dietary restrictions concerning the compounds examined here seems to be questionable, as a significant increase of urinary oxalate excretion is lacking.

Ascorbic Acid↗
PubMed1979

Determination of oxalate in urine using oxalate oxidase: comparison with oxalate decarboxylase.

The oxalate content of urine is determined by means of oxalate oxidase and simple pH measurement. The enzyme specifically decarboxylates oxalate, producing two moles CO2 per mole oxalate. The CO2 diffuses into an alkaline buffer solution (Hallson, P. C. & Rose, G. A. (1974), Clin. Chim. Acta 55, 29--39) in the closed reaction vessel, and reduces the pH value, which is measured with an electrode. Only 125 microliter native urine is required to measure oxalate concentrations in the range of 80 mumol/l to 1.6 mmol/l (corresponding to 7 to 144 mg anhydrous oxalic acid per liter). The limit of detection is 10 nmol oxalate, and the accuracy is 101% with a coefficient of variation of 6%. The method described is insensitive to various interfering factors, such as reducing and oxidizing substances, cloudy or colored samples. It is therefore also suitable for oxalate determination in food technology and plant breeding.

Carboxy-Lyases↗