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C Wiezorek

Publications and source records attributed to C Wiezorek.

10 recordsLinked to original sources
PubMed1994

[Chemiluminescence method for the detection of radiation-induced oxidation products in fat-containing foods].

Radiation-induced oxidation of fatty foods was detected by a chemiluminescence method. Hazelnuts, peanuts and poultry were used as foodstuff samples. Additional investigations were performed with a model system and sunflower oil. The irradiation of the samples was carried out in a x-ray-fluorescence-apparatus. Thereby it is to note that the G-value of the x-ray-radiation is much higher than the G-value of a cobalt-60-source normally used for irradiation of food. A dependence of the integral of the light curve on the irradiation doses could be proved. Investigations with model systems which contained different amounts of alpha-tocopherol showed a decreasing chemiluminescence signal at low irradiation doses in presence of alpha-tocopherol. At higher doses the chemiluminescence signal enlarges with increasing amounts of alpha-tocopherol because irradiation products of alpha-tocopherol overlay its antioxidative effect. Irradiated poultry samples differ significantly from unirradiated samples after a deep-freeze storage of 26 weeks. A quantification of the doses is not possible without knowledge of the storage time, because the integrals decrease differently after irradiation during storage. In any case the chemiluminescence method is useful as a "screening method" for the detection of irradiation of foodstuffs with the possibility of automation and high sensitivity.

Animals↗
PubMed1990

Applicability of LLD in neutron dosimetry.

The applicability of LLD in neutron dosimetry was tested and the optimum materials were determined. Investigations have been performed on lyoluminescence variations in sensitivity (X-rays and neutrons) for five different materials: the polyalcohols, mannitol and xylitol, the saccharides, trehalose and glucose and the amino acid, leucine. The decisive factor for the choice of a dosimetric material is its tissue equivalence. The results show striking differences in neutron and gamma sensitivities between the dosimetric materials. The different sensitivities for fast neutrons and gamma-rays can be used for simultaneous determination of neutron and gamma doses in mixed neutron photon radiation fields. The successful application of this dosimetric method can be shown by phantom- and in-vivo-measurements.

Glucose↗
PubMed1989

[Fluorescent formazans in flow cytometry. Studies of their oxygen sensitivity].

In order to supply the tetrazolium salt procedure to flow cytometry we have synthesized monotetrazolium salts which are converted into fluorescent formazans on reduction. In this preliminary study we investigated the "oxygen sensitivity" of four of our compounds and compared them to the commercially available nitrotetrazole blue (NBT). The amount of formazan produced by Ehrlich ascites tumour cells via the succinic dehydrogenase reaction during oxic and anoxic incubations was determined by elution technique. Under oxic conditions no NBT formazan but much cyano-di-chlorophenyl formazan (==CCPC) was generated. The yields of this formazan differed only slightly between oxic and anoxic incubations. Twice as much of the amount of the other three formazans cyano-ditolyl- (==CTC, Stellmach 1984), cyanodiphenyl- (==CPC), and cyano-dianisyl tetrazolium chloride (==CAC), were produced in nitrogen atmosphere as in oxygen. The amount of all formazans investigated increased both in oxic and in anoxic conditions if cyanide was present. All cyano-aryl formazans have the maximum of absorbance between 430 and 470 nm and fluoresce in the spectral range above 580 nm with CTC formazan being the brightest. The tetrazolium salts, i.e. in unreduced state, did not fluoresce in the visible part of the spectrum. The formazans could be applied to flow cytometry. After staining the nuclear DNA with the fluorochrome DAPI, we obtained detailed two-parametric distributions correlating the amount of formazan per cell with the DNA content. The results are a step to establish a method for automated identification of malignant cells.

Animals↗
PubMed1984

Cell cycle dependence of Hoechst 33342 dye cytotoxicity on sorted living cells.

The effect of staining cellular DNA with the bisbenzimidazole dye Hoechst 33342 on the colony forming efficiency of Chinese Hamster Ovary Cells in different cell cycle phases has been studied. Exposures of 90 and 120 min to 5 microM Hoechst 33342 provided a considerable loss of clonogenicity depending on the cycle phase at staining procedure. The G2+M cells reveal to be the most sensitive fraction followed by the G1 cells. The highest resistance was found on S-phase cells with a colony forming efficiency exceeding that of the G2+M fraction by a factor of two.

Animals↗
PubMed1984

Comparison of radiation-induced radical yields in short peptides and constituent amino acids by detection of trapped oxygen isotope 18O.

This report compares the radiosensitivity of small polypeptides and constituent isolated amino acids using a novel technical approach. The radiation-induced oxygen isotope 18O trapping was measured by means of nuclear reactions. Most of the peptides reveal a higher sensitivity than a mixture of their constituent amino acids. This observation can be rationalized with a simple model which implies intramolecular energy transfer.

Amino Acids↗
PubMed1984

Stereoselectivity of X-irradiated amino acid enantiomers in H218O aqueous solution.

Asymmetric radiation-induced decomposition of D,L-alanine and D,L-phenylalanine in isotope-enriched H218O aqueous solution has been investigated by use of a new method involving detection of 18O-marked products by nuclear reactions. X-irradiated D-enantiomers are revealed to be more sensitive for 18O trapping than their L-type counterparts.

Alanine↗
PubMed1983

A new fluid switching flow sorter.

Conventional cell sorters produce potentially hazardous microdroplets containing dyes and radiolabeled compounds commonly used to identify and trace subpopulations of cells. Many of these substances are potential toxins, mutagens, or carcinogens constituting a risk to personal associated with the sorting device. The separation of living cells for continued study of cell growth from an "in air" sample stream includes the risk of contamination with microorganisms altering the following cultures. To avoid those risks, we have constructed a new capsular flow cytometer sorter which consists of a small chamber completely encasing the sorting mechanism. Data acquisition, analysis, and processing are accomplished by using a microcomputer-based pulse height analyser.

Animals↗