Alteration of endogenous formaldehyde level following mercury accumulation in different pig tissues.

The effect of mercury accumulation on the formaldehyde cycle of different pig tissues resulted by a single dose of mercury (0.4 mg mercury in Hg(II)-chloride form, 500 kBq Hg-203/animal) has been studied. Daily mercury excretion was tracked, and having reached the steady-state mercury level of the body (10th day), samples were taken from the liver, kidney and muscle (musculus longissimus dorsi). After reaction with dimedone the endogenous formaldehyde levels in the samples were measured by high performance liquid chromatography. Our results show that the endogenous formaldehyde level decreased by more than 50% in the liver and the kidney, where the average mercury accumulation was the highest (1017 Bq/100 g and 625 Bq/100 g, respectively). In contrast, the muscle tissues, with a low mercury level (139 Bq/100 g), responded to the stress effect by about a 30% increase in their endogenous formaldehyde level.

Determination of sulphur and total sulphur dioxide in wines by an ICP-AES method.

Sulphur contents of the original sample and the sample free from sulphur dioxide were determined by ICP-AES following nitric acid digestion under high pressure (using PAAR HPA equipment), and the total sulphur content was calculated from the difference between the results obtained. With the aim of preparing a sample free from sulphur dioxide, bound sulphur dioxide was released by sodium hydroxide, then after acidifying by phosphoric acid, boiling was carried out. Relative standard deviations of the results obtained for total sulphur, the sulphur without S(IV) and total sulphur dioxide were lower than 2.5, 3.5 and 5% respectively. Various amounts of sulphur (in the form of Na(2)SO(4)), added to wine samples, were successfully recovered between 95.5 and 104.9%. Based on comparative analyses performed by a widely accepted classic method, the indirect method developed was found to be adequate for the determination of total sulphur dioxide. The procedure is suitable for serial tests.

Determination of milk-oxidised ketone bodies as an acetone derivative by electron capture gas chromatography.

Following the deproteination of the milk sample by means of zinc hexacyanoferrate, acetoacetic acid was decarboxylated by heating; the acetone originally present was then determined together with the acetone formed. The essence of the determination was that acetone reacted with bromine in the presence of sulphuric acid, following which, the bromoacetone formed was extracted into toluene, separated by gas chromatography and measured using an electron capture detector. The calibration curve was found to be linear up to a concentration of 2 mmol l(-1) acetone. The detection limit calculated from the threefold noise level and the slope of the calibration curve was 9x10(-7) mol l(-1). The reliability of the method meets the practical requirements. Its application may be recommended above all for the establishment of subclinical ketosis.

A gas chromatographic method for the determination of nitrite ions in natural waters.

Following the treatment of the sample with zinc hydroxide, nitrite reacts with potassium iodide in the presence of acetone and sulphuric acid. The released iodine and the propanone derivative resulting from the acetone are extracted in n-hexane. The extract is subjected to gas chromatographic separation and detection using an electron capture detector. The calibration curve was found to be linear up to a concentration of 2.5 mg 1(-1) NO(-)(2). The detection limit calculated from the threefold noise level and the slope of the calibration curve is 0.008 mg 1(-1). The relative standard deviation (including that of the blank) was less than 8%. The reliability of the method is adequate for practical uses. Amongst the advantages is that the method does not require the use of exceedingly toxic reagents. On the other hand, the method is applicable for samples that even after being subjected to clarification procedures still do not become fully transparent.

[Selenium supplementation with bread]. / Szelénpótlás kenyérrel.

Bread produced with selenium-enriched yeast was given to ten volunteers. The daily dose contained approximately 100 micrograms of selenium. The subjects' mean baseline whole blood selenium concentration (52.2 +/- 16.7 micrograms/l) was indicative of a suboptimal selenium status. After two weeks of supplementation, the subjects' mean whole blood selenium level increased significantly (to 66.1 +/- 11.9 micrograms/l). Supplementation of selenium-enriched bread seems to be an easily implementable and promptly acting method of selenium status improvement.

Selenium in the blood of patients with colorectal cancer and neoplastic polyp.

Samples of whole blood were obtained from 51 patients with newly diagnosed colorectal cancer as well as from 76 patients with neoplastic colorectal polyp, and from 30 healthy blood bank donors. Selenium was determined by the fluorimetric method. Significantly decreased selenium concentrations of blood samples from patients with colorectal cancer and villous adenoma were found. There was not any correlation between the blood selenium levels of patients with adenomatous polyp and the severity of dysplasia in removed polyps. The lowest mean selenium level in patients with villous adenoma indicates that selenium deficiency may be an important factor in the development of colorectal cancer arising from villous adenomas.

Dependence of selenium content of cow's milk on health condition of udders.

It was found that milk samples from cows with mastitis have markedly higher selenium concentrations and higher standard deviations than those of healthy cows. A good correlation was found between the severity of the disease and increase of selenium concentration.