Zur Kenntnis und Bewertung von Herniaria rotundifolia Visiani

In very polymorfic complex Herniaria glabra L. the taxon Herniaria rotundifolia Vis. is treated as a good morphological and chorological subspecies. Herniaria rotundifolia Vis. indicates endemic to Quarnero Islandes and Litorale Croaticum.     

Fragen der Regulation und Determination an umgeordneten Furchungsstadien und verschmolzenen Keimen von Triton

Ohne Zusammenfassung Mit Tafel VII und VIII und 13 Textabbildungen.     

Entwicklung eines hochempfindlichen Enzymimmuntests zum Nachweis von Ochratoxin A

Antibodies against ochratoxin A were produced in rabbits after immunization with an ochratoxin A-keyhole limpet hemocyanine conjugate. The immunogen was found to be very efficient, and high antibody titers were detected in the sera of all immunized rabbits. In a competitive enzyme immunoassay using ochratoxin A-horseradish peroxidase as the labelled antigen, low levels of ochratoxin A in buffer solution could be detected. The mean standard curve detection limit and 50% inhibition level of the optimized assay were at 15 pg/ml and 50 pg/ml, respectively. Relative cross-reactivity of ochratoxin B was found to be 2%. With these characteristics, this novel enzyme immunoassay should be useful for the routine detection of ochratoxin A in food and in biological samples at levels well below 1 ng/g.     

Modulation der zytotoxischen Aktivität von humanen natürlichen Killerzellen durch Ochratoxin A und C

The effect of ochratoxin A (OTA) and C (OTC) on the cytolytic activity of natural killer cells (NK cells) was studied using a fluorescence based bioassay with the cell line NK-92 as effector cell line and K-562 as target cell line. Different OTA and OTC preparations were included in the study. After exposure to very low toxin concentrations (1–10 ng/ml) a slight stimulation of NK cell activity was noted, whereas after addition of higher toxin concentrations (100–1000 ng/ml) NK cell function was suppressed. Preparations containing OTC showed a stronger effect than those containing OTA.     

Anwendung der automatisierten Festphasenextraktion bei der Bestimmung von Ochratoxin A

For some foodstuffs, determination of the mycotoxin ochratoxin A (OTA) requires time consuming clean up by means of solid phase extraction (SPE). Therefore a system for automated SPE was tested for cleaning up roasted coffee as a possible way of shortening preparation time. Validation of the method in accordance to the so called “Concept '98” led to a LOD of 0.2 μg/kg and a recovery rate of 92%. By using the described procedure with samples of roasted coffee the OTA contents varied between the LOD and 3.4 μg/kg. This method was also used to determine ochratoxin A in liquorice roots, ginger and valerian.

Presented at the 26^th Mykotoxin Workshop in Herrsching, Germany, May 17–19, 2004     

Ochratoxin A Analysen im Blut von Arbeitnehmern in der Abfallwirtschaft

Tasks such as manual sorting of domestic wastes for recyclable goods and the deposition of various materials may result in inhalation of mycotoxin-containing aerosols. Ochratoxin A (OTA) was analyzed in blood samples from workers employed at waste handling facilities in Southern Germany to assess the potential impact of this mycotoxin, and explore its use as a biomarker of exposure to bioaerosols. Results from this analysis are reported: OTA serum levels (median values) in subgroups of workers involved in waste deposition (n=76 ‘Deponierer’) or in waste sorting (n=60 ‘Wertstoffsortierer’) were 0.36 and 0.53 ng/ml, respectively. Both groups are natives of countries within the European Community (EU). In waste sorters who were born in other European (non-EU) countries (n=72) or elsewhere (n=12 from Asia, Africa), the OTA serum levels were 0.50 and 0.37 ng/ml, respectively. In controls (n=84 office clerks at the facilities; EU citizens) the median OTA value was 0.39 ng/ml. Comparing the different groups, and previously published data on median OTA levels in the general population (0.21 ng/ml) which result from dietary (background) exposure to OTA in Germany, our data point to an additional uptake of this mycotoxin by inhalation in workers with exposure to bioaerosols. The results support the view that apart from the pathogenic and allergological relevance of microbial emissions from garbage, secondary fungal metabolites, and thus toxicological aspects, deserve further attention.

Presented at the 25^th Mykotoxin Workshop in Giessen, Germany, May 19–21, 2003     

Nebenwirkungen Insektenpathogener Pilze Auf Mensch und Wirbeltiere: Aktuelle Fragen

Ohne Zusammenfassung Nach einem Vortrag beim Symposium ?Zur Prüfung insektenpathogener Viren und Pilze auf hygienische Unbedenklichkeit?, veranstaltet von der Kommission ?Insektenpathologie und mikrobiologische Sch?dlingsbek?mpfung? der O.I.L.B. am 2. und 3. M?rz 1967 in Zürich.     

Ochratoxin A: Contamination of grain

Ochratoxin A was quantitatively monitored in grain extracts by indirect solid-phase enzyme immunoassay with the use of an immobilized conjugate of the toxin with gelatin and polyclonal rabbit antibodies raised against the ochratoxin A-BSA conjugate. This monitoring found that 1.7 to 18.5% of the samples were contaminated with the toxin at a concentration of 25.9–291.7 μg/kg. An analysis of forage grain found ochratoxin A at concentrations of 440-3250 μg/kg.     

Beeinflussung der Zytokinsekretion von Maus-Thymom-Zellen (EL-4) durch Ochratoxin A

The murine thymoma cell line EL-4 was used as an in vitro T-cell model to assess the immunomodulating effect of pure Ochratoxin A (OTA) and an Aspergillus ochraceus raw toxin preparation. Cytokine production (IL-2, IL-4, IL-5, IL-6) and cell viability of PMA-stimulated EL-4 cells were investigated in the presence of OTA. The cytotoxic effect of the raw toxin could be observed at lower concentrations than pure OTA. The IC50 values were 3 µg/ml and 11 µg/ml, respectively. Increasing concentrations of both OTA preparations caused an inhibition of cytokine production, but the inhibition effect of the raw toxin was stronger than of pure OTA. This is supposed to be the effect of further up to now not characterized substances in the raw toxin. Differences in the susceptibility of the mechanisms of production and regulation of each cytokine are indicated by the different concentrations for inhibition effects. Both toxin preparations showed also stimulating effects on some cytokines (IL-2 and IL-6) while others (IL-4 and IL-5) were depressed at these OTA concentrations. This indicates the immunomodulating properties of the toxin.     

Ochratoxin A: study of grain contamination

Ochratoxin A was quantitatively monitored in grain extracts by indirect solid-phase enzyme immunoassay with the use of an immobilized conjugate of the toxin with gelatin and polyclonal rabbit antibodies raised against the ochratoxin A-BSA conjugate. This monitoring found that 1.7 to 18.5% of the samples were contaminated with the toxin at a concentration of 25.9-291.7 micrograms/kg. An analysis of forage grain found ochratoxin A at concentrations of 440-3250 micrograms/kg.     

Ochratoxin A: an important western Canadian storage mycotoxin

Ochratoxin A (OA) is a mycotoxin produced by certain species of storage fungi of the Penicillium and Aspergillus genera. Toxin production by these fungi is influenced by species and even strain of fungi, time and temperature of incubation, moisture content of substrate, and type of substrate. OA has been shown to occur in various grains, cereals and other plant products, animal feeds, meats, and human tissues in countries throughout the world. Of interest is the discovery of OA in a high percentage of blood from humans in Germany. OA is acutely toxic to many different animals and in addition to being a nephrotoxin, it is a hepatotoxin, a teratogen, a very potent carcinogen, possibly a mutagen, and an immunosuppressive agent. OA is rapidly absorbed throughout the entire gastrointestinal tract and distributes itself in the body as a two-compartment open model and has a particular high affinity for serum albumin. OA is hydrolyzed by the intestinal microflora into nontoxic compounds (7-carboxy-5-chloro-8-hydroxy-3,4-dihydro-3R-methylisocoumarin (O alpha) and phenylalanine). It is excreted as either OA, hydroxylated OA, or O alpha in both the urine and feces. OA appears to exert its toxic effect by promoting an increased level of lipid peroxidation, by inhibition of an amino acylation reaction, and possibly by conversion into metabolites that are capable of binding DNA. These in turn cause other secondary effects associated with OA. It would appear that this compound presents a true potential hazard for humans as its occurrence is wide spread and it is highly carcinogenic.     

Ochratoxin A adsorption phenotype: An inheritable yeast trait

This study aimed to evaluate the inheritance of the trait ochratoxin A adsorption in two wine strains of Saccharomyces cerevisiae and their 46 descendants. Each strain was inoculated in triplicate in test tubes containing 10 ml of must obtained from the Calabrian Zibibbo white grape variety, artificially contaminated with ochratoxin A to reach a total content of 4.10 ng/ml. The microvinification trials were performed at 25°C. After 30 days, ochratoxin A values ranged from 0.74 to 3.18 ng/ml, from 0.01 to 2.69 ng/ml, and from 0.60 to 2.95 ng/ml respectively in wines, in lees after washing, and in the saline solution used to wash the lees. The analysis of OTA in wines was performed to find the residual toxin content after yeast activity, thus obtaining technological evidence of yeast influence on wine detoxification. The analysis of OTA in lees after washing was performed to distinguish the OTA linked to cells. The analysis of OTA in the saline solution used to wash the lees was performed to distinguish the OTA adsorbed on yeast cell walls and removed by washing, thus focusing on the adsorption activity of wine yeast through electrostatic and ionic interactions between parietal mannoproteins and OTA. Ploidy of the two parental strains was controlled by flow cytometry. Results demonstrated that the ochratoxin A adsorption is genetically controlled and is a polygenic inheritable trait of wine yeasts. The majority of the descendants are characterized by a great and significant diversity compared to their parents. Both the parental strains had genome sizes consistent with their being diploid, so validating the observed results. These findings constitute an initial step to demonstrate the mechanisms of inheritance and establish breeding strategies to improve the ochratoxin A adsorption trait in wine yeasts. This will allow a decrease in the ochratoxin A content of contaminated musts during winemaking, by using genetically improved wine yeasts.