[Electron spin resonance measurements on dried fruit. Carbohydrate composition and ESR signal structure of irradiated fruit]. / Elektronen-Spin-Resonanz-Messungen an Trockenfrüchten. Zusammenhang von Kohlenhydratzusammensetzung und ESR-Signal-Struktur der bestrahlten Früchte.

While in a previous work the ESR spectroscopic detection of irradiated dried fruits was reported, in this paper liquid chromatographic determination of the carbohydrate fraction of these fruits is introduced and connected with the ESR results. After irradiation of dried fruits three different types of ESR spectra are observed. In most cases the dried fruits can be attached to these various types by means of their sugar composition. It was also found that the ESR spectra observed for sucrose-rich fruits are very similar to that of pure sucrose. The structure of the ESR spectra can change with storage. Probably, radical rearrangement reactions in the samples are responsible for these changes.

Evaluation of a gas chromatographic method to identify irradiated chicken, pork, and beef by detection of volatile hydrocarbons.

A method suitable for routine application was used in an interlaboratory study to detect irradiation treatment of chicken carcass, pork, and beef. By using gas chromatographic analysis, 17 participating laboratories determined the quantity of 4 different radiation-induced volatile hydrocarbons (tetradecene, pentadecane, hexadecadiene, and heptadecene) in the fat fraction of coded specimens approximately 3 and 6 months after irradiation. The specimens of each type of meat were supplied by 2 different producers. The dose range tested (0.6-7.5 kGy) included levels commercially used to reduce the number of contaminating microorganisms (1-5 kGy). The method employed permitted a correct identification of irradiated or nonirradiated in 98.3% of the 864 specimens.

[ESR and HPLC studies of the detection of gamma irradiation of eggs]. / ESR- und HPLC-Untersuchungen zum Nachweis der gamma-Bestrahlung bei Eiern.

Two methods for the identification of irradiated eggs are presented. Electron spin resonance (ESR) detects radiation-specific radicals in the calcite matrix of eggshells. ESR gives unequivocal results for doses clearly below the technologically relevant dose. The stability of the radical in the calcite matrix was tested over a period of 6 weeks. Products that contain no or only low amounts of fat but a high percentage of protein can be identified by HPLC. Only in the chromatograms of irradiated samples is a peak of the amino acid ortho-tyrosine present. This HPLC method may be of great interest especially for the identification of irradiated pasteurized liquid egg white.

[Identification of irradiated pasteurized egg products: a combined method for use in routine control]. / Identifizierung bestrahlter pasteurisierter Eiprodukte: Ein kombiniertes Verfahren zum Einsatz in der Routinekontrolle.

Pasteurized egg products (whole egg, egg yolk and egg white) were tested for irradiation treatment in the German food control laboratories in Oldenburg/Niedersachsen and Kassel/Hessen as well as in the food irradiation laboratory of the German federal health office. Gas chromatographic/mass spectrometric measurements on the fat components of egg-products showed clearly whether the product had been irradiated or not. While in unirradiated samples no traces of special hydrocarbons (according to the fatty acid composition of egg) and no traces of the irradiation-specific compound 2-Dodecyl-cyclobutanone were found, irradiated control samples as well as products of two Belgian suppliers contained these substances. Additionally, regarding the rather high time consumption of gas chromatography, electron spin resonance (ESR)-measurements were carried out on the packaging material of egg products. Irradiated packaging material (cellulose) could be easily detected by the appearance of a signal pair in the ESR spectrum (cellulose radical). ESR measurements are very fast and easy to perform so that this method can be used for screening. Microbiological investigations showed remarkably reduced total numbers of microorganisms for some irradiated samples, but the microbiological status is influenced by other factors like storage-time and -temperature, so that microbiological tests can not be used successfully for screening on irradiation treatment.

Detection of irradiated food--methods and routine applications.

Irradiation of food for the purpose of extension of shelf life, control of microbial load, reduction of pathogenic microorganisms and disinfection is regarded by many consumers with suspicion. One reason is the lack of methods within food-controlling laboratories which can detect irradiation treatment and which are applied to control correct labelling. This review describes the potential of various methods to reveal irradiation treatment. Special emphasis is given to the three most successful methods, thermoluminescence, electron spin resonance spectroscopy and detection of volatiles. The possibilities and limitations of applying the methods in routine control are discussed.

An automated flow cytometric micronucleus assay for human lymphocytes.

A new flow cytometric method is presented for scoring micronuclei (MN) in human lymphocytes after in vitro gamma-irradiation. Fifty to fifty-five hours after PHA-stimulation, the frequency of micronuclei per nucleus and the fraction of cells in the second cell cycle were measured using flow cytometry. All data were automatically analysed using our DAS-software package. Eight individual linear-quadratic dose response curves derived from five donors revealed inter- and intra-individual variabilities of all curve parameters. Since also an age dependence was found for spontaneous MN-frequencies and for the linear curve parameter, a combined linear-quadratic age-dose-effect model was used to fit the data. The 90% prediction intervals show that a reliable individual dose estimation for donors aged between 23 and 54 years cannot be achieved for exposures below 1 Gy.

[Electron spin resonance spectroscopy as probes for spices. Detection of treatment with ionizing radiation]. / Elektronen-Spin-Resonanz-Spektroskopie an Gewürzproben. Nachweis einer Behandlung mit ionisierenden Strahlen.

Detection of irradiated spices by electron spin resonance (ESR) measurements was not successful in the past because a central line of unknown origin was detected in the ESR-spectra of both irradiated and unirradiated samples. Identification of irradiated samples by measuring the increase of intensity of this signal after irradiation is limited because the signal intensity decreases over a period of some weeks of storage and reaches the range of unirradiated samples. By changing the measurement conditions (low microwave power) we could detect two additional lines on both sides of the main signal. This line pair appears only in the spectra of irradiated spices. A similar line pair was found in the spectra of irradiated nutshells and possibly derives from cellulose radicals in the sample. For some spices, especially paprika, the identification of irradiated samples by detecting these additional lines was possible even after relatively long periods of storage.

Multiparametric flow cytometric analysis of radiation-induced micronuclei in mammalian cell cultures.

A new flow cytometric method is presented that quantifies the frequency of radiation-induced micronuclei in mammalian cell cultures with high precision. After preparing a suspension of main nuclei and micronuclei stained with ethidium bromide and Hoechst 33258, both types of particles are measured simultaneously in a flow cytometer using forward light scatter and three fluorescence emission intensities excited by UV, 488 nm, and by energy transfer from Hoechst 33258 to ethidium bromide. Nonspecific debris overlapping the micronucleus distribution especially in the low fluorescence intensity region was discriminated from micronuclei by calculating ratios of the different fluorescences. The frequencies of radiation-induced micronuclei measured with this new technique agreed well with results obtained by conventional microscopy. The lower limit of the DNA content of micronuclei identified by this technique was found to be about 0.5%-0.75% of the DNA content of G1-phase nuclei. Dose effect curves and the time-dependent induction of micronuclei were measured for two different mouse cell lines.

Increased serum amylase in patients after radiotherapy as a probable bioindicator for radiation exposure.

The radiation-induced increase of serum amylase is investigated in 41 patients following either whole body irradiation or irradiation of the head- and neck-region. The radiation treatment caused a dose-independent serum amylase increase up to 80 times of the preirradiation measured in controls. This increase can only be induced if the salivary glands are within the radiation field. An isoenzyme analysis differentiated between salivary and pancreatic amylase. It was shown that also in case of whole body irradiation pancreatic proteins either contribute only to a small extent to the increase or show no recognizable change. Although great variations in radiation response remain, the increase of serum amylase produced by salivary glands is highly significant and serves as a bioindicator for radiation exposures.

Assessment of electrophoretic mobility changes of human erythrocytes by free flow electrophoresis after in vitro and in vivo irradiation.

Single cell measurements of electrophoretic mobility showed a linear dose-response of human erythrocytes after exposure to ionizing radiation. To establish a biological indicator- or dosimeter-system for application to dose-estimations after accidental exposures, we tried to measure dose dependent EPM-changes by the free flow electrophoresis technique, a rapid and efficient method which supplies the capacity needed for application. The in vitro irradiated erythrocytes of most donors showed an oscillating dose-response but erythrocytes from several other individuals in a contradictory manner whereby the EPM of erythrocytes from radiotherapy patients increased linearly with the amount of administered dose. However, the wide interindividual EPM-range of unirradiated erythrocytes inhibits the application of this technique in biological dosimetry.

Changes in oligosaccharides of human blood cells measured by tritium- and FITC-labeled lectins after in vitro- and in vivo-irradiation--lectin binding as a 'biological dosemeter'?

The lectin-binding system has been described previously as a biological dosimeter, by revealing induced changes in oligosaccharides of the cell membrane. The measurements were performed by binding [3H]concanavalin A to blood cells. Our results on human blood cells irradiated in vitro with doses in the range 0.5-5 Gy indicate great difficulties in using radioactive labeled Con-A for an accurate quantitative analysis of radiation effects on cell membranes. It appears nearly impossible to differentiate between only a few damaged cells and the remaining undamaged cells. Using fluorescein-labeled Con-A and wheat germ agglutinin, single-cell measurements of fluorescence intensity by flow cytometry revealed enhanced lectin-binding to platelets, lymphocytes and monocytes in the dose range 0.5-5 Gy after in vitro irradiation. But even by this method it was impossible to discriminate irradiations in either partial or whole-body irradiated patients. There were no significant or reproducible changes in the binding capacities of the blood-cell membranes of these patients. Therefore, the suitability of lectin binding as a 'biological indicator' for irradiation could not be confirmed.