Stages in development of mink cell focus-inducing (MCF) virus-accelerated leukemia in AKR mice.

Flow cytometric techniques involving correlated dual parameter analysis of fluorescence and light scatter and transplantation bioassays were used to describe a series of cellular changes in thymus of young (1-4 mo old) AKR mice during development of mink cell focus-inducing (MCF) virus-accelerated leukemia. Three stages of leukemogenesis were defined before appearance of frankly leukemic mice. Stage 1, apparent 28-40 d after injection of MCF 69L1 virus, represented steady-state infection of thymocytes by MCF virus without apparent change in light scatter properties of the cells or in expression of alloantigens Thy-1, Lyt-1, Lyt-2, L3T4a, B2A2, or H-2K on the major thymocyte subpopulations. Expression of MCF virus was highest in the population of small cortical thymocytes. Stage II was observed at highest frequency 50-60 d postinjection and represented the emergence of a clonal population of cells with transformed properties which could be resolved from normal thymocytes by light scatter and expression of B2A2, H-2K, and gp70 antigens. Stage III was observed at highest frequency at 70 d postinjection, when considerable enlargement of thymus had occurred, and appeared to represent the outgrowth of fully transformed cells that replaced the normal thymocyte subpopulations. The alloantigen phenotype of blast cells from frankly leukemic mice did not differ qualitatively from that of stage II or stage III cells but displayed considerable heterogeneity with respect to quantitative expression of alloantigens and gp70. At least two populations of leukemic blasts could be resolved in the majority of primary thymomas analyzed. It is unclear whether these populations represent the outgrowth of independent clones of transformed cells or if they are related in some way. Our data are consistent with MCF virus-induced transformation of cells in the lineage to small peanut agglutinin-positive, cortisone-sensitive thymocytes, a subpopulation that predominates in the thymus and which is thought to be destined for cell death in situ.

[Thin-layer chromatography and high-pressure liquid chromatography in mycotoxin analysis]. / Dünnschichtchromatographie und Hochdruckflüssigkeitschromatographie in der Mykotoxinanalytik.

In a discussion of mycotoxin analysis it is concluded that TLC and HPLC methods mutually support each other by guring the opportunity of corroborating values by a second technique. The DC method is preferred when the samples to be analysed are of variable origin while HPLC is the method of choice when samples are uniform or at least similar.

Detection of estrogen-like compounds by thin-layer chromatography.

There are different national food regulations concerning the use of hormoneactive substances in the breeding of domestic animals that serve as human food. This situation requires specific and sensitive methods for the detection of any residues in food. The hormones used in practice can be determined with improved sensitivity by coupling to the diazonium compound Fast Dark Blue R Salt. After thin-layer chromatography on high-performance thin-layer chromatographic plates with two different solvent mixtures, zeranol, estradiol, estriol and estrone are analysed as azo dyestuffs. The detection limit of these hormones is below 10 ng.

[Cadmium uptake by mushrooms (author's transl)]. / Uber die Cadmiumanreicherung in Champignons.

Mushrooms of the subgenus Rubescentes (for example Agaricus bisporus and Agaricus campestris) accumulate for less cadmium than most species of the subgenus Flavescentes (for example Agaricus arvensis and Agaricus silvicola). Hence it appears there is no danger for human health, from too much cadmium, when eating the often gathered Agaricus campestris. The caps of the mushrooms enrich cadmium to twice the amount present in the stems. The authors analysed 32 samples of wild mushrooms of the subgenus Rubescentes and 39 samples of wild mushrooms of the subgenus Flavescentes. They furthermore cultivated mushrooms (Agaricus bisporus) on substrates with different amounts of added cadmium.