Hepatitis E virus in wild rabbits and European brown hares in Germany

Recently, a change of hepatitis E from being a typical travel-associated disease to an autochthonous zoonosis in Germany was observed. An increasing number of autochthonous infections with the hepatitis E Virus (HEV) have been recognized in developed countries. Venison from wild boar is already known to be a potential source of infection, if not prepared properly by the consumer. In Germany, certain wild animals are known to be a reservoir for HEV. However, current information is missing about European brown hares (Lepus europaeus) and wild rabbits (Oryctolagus cuniculus). Thus, a total of 833 hunting-harvested animals (European brown hares n = 669; wild rabbits n = 164) were tested for the occurrence of HEV RNA and HEV antibodies. For this, liver and blood specimens were taken after hunts in six German federal states. HEV antibodies were found by ELISA in 2.2% (624/14) of European brown hares, but no HEV RNA was detectable by nested real-time RT-PCR. In contrast, a seroprevalence of 37.3% (126/47) was observed for wild rabbits, and 17.1% (164/28) of the samples were HEV RNA positive. Genomic analysis revealed that these partial sequences clustered within the rabbit clade of HEV-3 genotype. In addition, one rabbit sequence segregated into subtype 3g of HEV-3. Highest seroprevalences for hares and rabbits were detected in the federal states of Bavaria and of Schleswig-Holstein, respectively. Comparing urban, rural and insular areas, the highest seroprevalence was shown for wild rabbits in rural areas and for European brown hares on the northern island Fehmarn. This study provides evidence that European brown hares and wild rabbits from Germany can be infected with HEV. The different prevalences indicate that wild rabbits are a potential reservoir for HEV in Germany, whereas European brown hares seem to be only of minor importance for the epidemiology of HEV.

Stability of bovine spongiform encephalopathy prions: absence of prion protein degradation by bovine gut microbiota

Bovine spongiform encephalopathy (BSE) is transmitted by the oral route. However, the impacts of anaerobic fermentation processes in cattle on the stability of BSE-associated prion protein (PrP(Sc)) are still unresolved. In this study, experiments were designed to assess the ability of complex ruminal and colonic contents of bovines to degrade BSE-derived PrP(Sc). No significant decrease in PrP(Sc) levels in BSE brain homogenates was detected by Western blotting after up to 66 h of co-incubation with intestinal fluids. These results indicate that BSE-associated PrP(Sc) survive gastrointestinal digestion processes in cattle and might be excreted via faeces.

Cellular prion protein in mammary gland and milk fractions of domestic ruminants

The present study shows that PrP(c) is expressed in the mammary gland and milk fractions of domestic ruminants in a species-specific manner. By applying immunohistochemistry, Western blot and ELISA, clear expression differences between bovine, ovine and caprine mammary gland, skimmed milk, acid whey and cream could be demonstrated, the highest relative PrP(c) levels being associated with the cream fraction. In the bovine gland PrP(c) was preferentially detectable at the basolateral surface of mammary gland epithelial cells, whereas in ovine and caprine samples the prion protein was more homogeneously distributed. Moreover, in ovine and caprine bovine mammary gland epithelial cells, apocrine secretory vesicles were strongly stained. Ovine and caprine milk proved to contain PrP(c) in all fractions with an additional truncated form at 12kDa in Western blot. This truncated isoform is the predominate one in caprine acid whey. These results support the hypothesis that the apocrine secretion mode of milk fat globules is a major way of PrP(c) transport into the milk.

Infectivity of scrapie prion protein (PrPSc) following in vitro digestion with bovine gastrointestinal microbiota

The influence of a complex microflora residing in the gastrointestinal tract of cattle on the prion protein plays a crucial role with respect to early pathogenesis and the potential infectivity of faeces resulting in contamination of the environment. It is unknown whether infectious prion proteins, considered to be very stable, are inactivated by microbial processes in the gastrointestinal tract of animals during digestion. In our previous study it was shown that the scrapie-associated prion protein was degraded by ruminal and colonic microbiota of cattle, as indicated by a loss of anti-prion antibody 3F4 immunoreactivity in Western blot. Subsequently, in this study hamster bioassays with the pre-treated samples were performed. Although the PrP(Sc) signal was reduced up to immunochemically undetectable levels within 40 h of pre-treatment, significant residual prion infectivity was retained after degradation of infected hamster brain through the gastrointestinal microflora of cattle. The data presented here show that the loss of anti-prion antibody 3F4 immunoreactivity is obviously not correlated with a biological inactivation of PrP(Sc). These results highlight the deficiency of using Western blot in transmissible spongiform encephalopathies inactivation assessment studies and, additionally, point to the possibility of environmental contamination with faeces containing PrP(Sc) following an oral ingestion of prions.

[25 years Mycotoxin workshop]

Mycotoxin research has a long tradition in Germany and is documented by a series of annual meetings which started 25 years ago. This paper gives an historical review on these Mycotoxin-Workshops. The first mycotoxin workshop in 1979 at the Federal Centre for Meat Research in Kulmbach was initiated by the former Federal Ministry of Agriculture and mainly thought to bring together scientists from the Federal research facilities. Main topics at that early time of mycotoxin research were food and feed safety, the mycology of toxin producers, the analysis and toxicology of mycotoxins. In the following years the Mycotoxin Workshop was influenced not only by working groups from the Federal research facilities but also from universities, state laboratories, other organisations and research scientists from outside Germany and with different disciplines. The number of participants increased from 19 at the beginning to more than 150 up to now and in order to organise these annual meetings at varying locations, in 1997 the society for mycotoxin research was founded. Since that time the Society for Mycotoxin Research (www.mykotoxin.de) is responsible for the organisation of the Mycotoxin Workshops.In addition the Society for Mycotoxin Research organizes the Brigitte Gedek science award, endowed with ¢ 10,000, and the Münchner Mycotoxin fellowship program, both intented to promote scientific research in mycotoxinology.

[Meat and potential risks]

By the term "meat" the consumer understands muscle meat, that is skeletal muscle. The german regulations, the "Leitsätze für Fleisch und Fleischerzeugnisse" as well as the Codex Alimentarius define meat in a much broader sense to include all edible parts of slaughtered or shot warm-blooded animals (skeletal muscles, fat, heart, gut, liver etc). Therefore, a differentiated procedure is required when the risk of BSE transmission by meat has to be estimated. This must be based on knowledge of occurrence, amount, and persistence of BSE agents in the organs of animals. The risk evaluation has to include further factors: differences between animal species, age of the animal at the time of slaughter, the possibility of contamination during the slaughtering and cutting process, and--as far as meat products are concerned--the processing technology. To date there are no indications for the existence of transmissible spongiform encephalopathy in pigs, poultry and fish, even though BSE has been transmitted to pigs experimentally by intracranial administration. Muscle meat of these species can be considered safe. Muscle meat of experimentally infected cattle in the preclinical stage and even of animals with clinically manifest BSE has not shown infectivity in homologous and autologous bioassays performed so far. This finding justifies the assumption that the risk of BSE exposure by the consumption of beef can be classified as extremely low. Nevertheless, the absence of a proof of infectivity can at present not be equated with absence of BSE agents. This is because of the limits of sensitivity of the bioassays and because muscle meat does contain non-muscle tissue such as connective tissue collagen, nerve and lymph tissue and blood vessels.

Survey of Romanian slaughtered pigs for the occurrence of mycotoxins ochratoxins A and B, and zearalenone

Blood serum, kidney, liver and muscle sample per animal were collected from slaughtered pigs (n = 52). The samples were analysed for ochratoxin A (OTA) and B (OTB) by HPLC methods. Zearalenone (ZEA) in serum was analysed by enzyme immunoassay. A total of 98% serum samples were OTA positive in the range of 0.05-13.4 ng/ml and 85% contained under 5 ng OTA/ml. The incidences of OTA in kidney and liver were very similar (79%, 75%) with mean levels of 0.54 ng/g and 0.16 ng/g, respectively. The lowest incidence (17%) and the lowest mean level contamination (0.15 ng/g) were in muscle samples. The mean distribution in tissues followed the pattern serum > kidney > liver > muscle (100%; 0.26%; 8.5%; 2.57%). No kidney, liver or muscle sample was found OTA positive above the maximum admitted limit in Romania (5 ng/g). No sample was found to be positive for OTB. A very similar OTA contamination (mean = 4.19 ng/ml, coefficient of variation = 34.4%) was observed in the serum samples (n = 10) collected from the same farm. A possible difference in regional distribution of OTA in Romania is suggested. Zearalenone was detected only in 17.3% of the serum samples with a maximum concentration of 0.96 ng/ml. This study shows the presence of OTA and ZEA in Romanian slaughtered pigs at levels comparable to those reported in other countries.

A simple HPLC method for the determination of the mycotoxins ochratoxin A and B in blood serum of swine

This paper presents a simple method for the determination of ochratoxins A (OTA) and B (OTB) in pig blood serum. The method includes serum acidification (pH < 1.6) and precipitation of protein with 15% trichloroacetic acid, liquid partitioning with dichloromethane and fluorescence detection. The estimated detection limits were 0.1 ng OTA/ml and 0.2 ng OTB/ml. The mean recoveries from artificially contaminated samples (n = 6 replicates/mycotoxin) spiked at 0.3, 1 and 3ng OTA and OTB/ml, respectively, were 86.8% (s.d. = 8.4) for OTA and 90.0% (s.d. = 9.8) for OTB. Forty-nine Romanian pig blood serum samples (94% of 52 analysed) were found to be naturally contaminated with OTA in the range 0.1-13.4 ng/ml. No sample was found positive for OTB. The method is technically simple, specific, cost effective, suitable for large sample throughput and requires small amount of sample and reagents. It fulfils the criteria for a routine method and could be a suitable toolfor surveying OTA in pig herds and in slaughtered pigs.

Preliminary results on Ochratoxin A concentrations in blood of patients with various kidney diseases in Germany

Ochratoxin A (OTA) is supposed to induce renal diseases in man and animals and a correlation between renal diseases and OTA concentration in blood is suspected. Therefore, we measured OTA concentrations in blood of subjects suffering from various renal diseases as e.g. interstitial nephritis or mesangial proliferating glomerular nephritis (GN) and compared them with the blood concentration of healthy individuals. We found OTA in 87% of all samples. There was no significant difference between OTA concentrations of healthy individuals and patients but some renal diseases (e.g. chronic glomerular nephritis) showed increased numbers of samples containing more than 1.5 nmol/l OTA in sera. In contrast, in samples from patients suffering from membranous or focal-sclerotic glomerular nephritis no concentrations above 1.5 nmol/l were found. Our preliminary results show that OTA is abundant in nearly all serum samples but some renal diseases show increased numbers of samples with high (>1.5 nmol/l) OTA concentrations.

[Relevance of mycotoxin contaminated feed for farm animals and carryover of mycotoxins to food of animal origin]

Contaminated feed is the main source for mycotoxin infestation of farm animals. The oral intake of fungal metabolites with feed results in a negative impact on all relevant parameters of animal production. Moreover, under experimental conditions mycotoxins and/or their metabolites can be traced in meat, edible tissues, milk and eggs. However due to the high concentrations of toxins involved, such findings are rare in the daily practice. In Germany today only aflatoxins (aflatoxin M1 in milk) and ochratoxin A (in blood, meat and edible tissues from swine) are of practical relevance from the view of food hygiene and food safety. Other mycotoxins at present discussed like toxins of Fusaria (trichothecenes, zearaleone, fumonisins) and ergot alkaloids are of no importance as possible contaminants in food from animal origin although they could have a negative impact on animal production.

Mycotoxin production and cytotoxicity of Fusarium strains isolated from Norwegian cereals

Thirty-four isolates of the eight most common Fusarium species isolated from Norwegian cereals; F. avenaceum, F. culmorum, F. equiseti, F. graminearum, F. poae, F. sporotrichioides, F. torulosum and F. tricinctum were studied for their cytotoxicity and ability to produce mycotoxins. The strains were cultivated on rice, and analysed for trichothecenes (all species), zearalenone (all species), fusarochromanone (F. equiseti), wortmannin (F. torulosum), moniliformin and enniatins (F. avenaceum, F. tricinctum and F. torulosum). The cytotoxicity of the extracts were examined with an (in vitro) MTT-cell culture assay. All F. graminearum and five of seven F. culmorum isolates belonged to chemotype IA, producing deoxynivalenol and 3-acetyl-deoxynivalenol, while the two other F. culmorum strains were nivalenol producers (chemotype II). The F. equiseti isolates and one of the F. poae isolates produced both type A and B trichothecenes, and relatively large quantities of fusarochromanone were detected in the F. equiseti cultures. All Fusarium species studied showed significant cytotoxicity, but with a large variation between species, and also within each species. F. sporotrichioides and F. equiseti showed the highest average cytotoxicity.

Clinical experience and results of a Sentinel Health Investigation related to indoor fungal exposure

This is a review of exposure conditions, clinical presentation, and morbidity of children and adults with indoor fungal exposure such as toxic Stachybotrys chartarum. Indoor exposure was characterized using different methods including microscopic, culture, cytotoxicity screening tests, and chemical analyses. Clinical case histories and physical and laboratory findings are presented of children (age < 18 years, n = 22; mean age 9 years; 60% females) and adults (age >18 years, n = 125; mean age 39 years, 67% females) who consulted an environmental health specialty clinic. In the pediatric patients' exposure history, widespread fungal contamination of water-damaged building materials with known toxic or allergic fungi was identified. Primarily disorders of the respiratory system, skin, mucous membranes, and central nervous system were reported. Some enumeration and functional laboratory abnormalities, mainly of the lymphatic blood cells, were observed, although no statistically significant differences were found. IgE or IgG fungi-specific antibodies, used as exposure markers, were positive in less than 25% of all tested cases. In an evaluation of a symptomatic girl 11 years of age (sentinel case investigation) living in an apartment with verified toxigenic fungi (i.e., S. chartarum), several health indicators showed improvement after exposure cessation.

Comparison of ELISA and HPLC for the determination of histamine in cheese

A competitive direct enzyme-linked immunosorbent assay (CD-ELISA) for histamine in cheese was compared with a reversed-phase liquid chromatography (RP-HPLC) method. Cheese was homogenized with phosphate-buffered saline (PBS), centrifuged, and filtered, and the supernatant was diluted with PBS for CD-ELISA. For RP-HPLC, biogenic amines (histamine, tyramine, putrescine, and cadaverine) were derivatized with 9-fluorenylmethylchloroformate, followed by reversed-phase chromatography and fluorescence detection. Detection limits and mean recoveries (10-1000 mg/kg) were 2 mg/kg and 93% for CD-ELISA and 1 mg/kg and 99% for RP-HPLC, respectively. Analysis of 50 commercial cheeses according to both methods showed good agreement for histamine (r = 0.979; concentration range = 2-1800 mg/kg). At a threshold level of 10 mg/kg, the ELISA gave no false-negative and three false-positive results. The results show that the ELISA is suitable for the determination of histamine in cheese.

[Experience with the use of a blood culture system for demonstration of clinically relevant bacteria in veterinary medicine diagnosis]

268 diagnostic samples from dogs, cats, horses and cattle were examined in a commercially available blood culture system. Samples of blood, liquor, ascites, thorax punctate, synovia and urine were examined with a blood culture system (Oxoid) over a period of two years in cooperation with the veterinary clinical institutes of internal medicine and surgery, Ludwig-Maximilians-University, Munich and different veterinarians. It was shown that this blood culture system, which has been initially developed for the requirements of human bacteriology, can be used for isolation of clinical important microorganisms in veterinary medicine. In 29% of examined samples isolation of bacteria was possible. Even bacteria, which are not often cultivated and bacteria, which could not be identified biochemically, could be isolated. Because of experience in human bacteriology and in conclusion of our results, the use of blood culture systems can be recommended for veterinary diagnosis, in particular when sepsis is suspected.

[Determination of Escherichia coli Shiga-like toxins by means of the MTT bioassay]

Tissue culture cells' metabolism and viability are measured by the mitochondrial reduction rate of a yellow tetrazolium salt (MTT) to blue formazan crystals in the MTT-bioassay. Thus the MTT-bioassay is a standardizable and reproducible bioassay for measuring cytotoxicity or cytostimulation. It is shown that the MTT-bioassay is also very suitable for determining bacterial cytotoxins using Escherichia coli's Shiga-like toxins as example. 177 strains of E. coli, isolated from carcasses and organs of cattle, are classified biochemically and tested for cytotoxin production by means of the MTT-bioassay. One of these strains is recognized as producer of Shiga-like toxin 2. 4 Enterohemolysin-producing strains of E. coli are cultivated from a feces sample of a diarrhoeic nubian ibex and identified as Shiga-like toxin 1 producers by help of the MTT-bioassay.

[Efficiency of microbank systems for the conservation of microorganisms relevant to veterinary medicine and others which are not easy to cultivate]

In this paper the conservation of different bacteria, yeasts and molds from diagnostic material was examined with a commercial deep freeze system. 137 bacteria isolated from the stomachs of dogs, cats and pigs and from duodenal juice of cats and 7 isolates of yeasts and fungi from diagnostic material were conserved with the deep freeze system MICROBANK-TM (Mast Diagnostica). Furthermore 62 Helicobacter pylori-isolates and 1 Helicobacter felis-isolate were conserved with this system. After a storage period of 24 hours up to 20 months the isolates were recultured. 96% of the conserved microorganisms could be grown. It was not possible to cultivate 1 fungus-isolate (Fusarium sp.). 2 Helicobacter pylori-isolates, spiral bacteria from the stomach of a pig and a Clostridium tyrobutyricum-isolate were only recultured after 24 hours, 1 isolate Moraxella sp. after 2 months and another 4 anaerobe isolates after 5 months. The system MICROBANK-TM proved to be suitable for conservation and was also efficient for the conservation of microorganisms, which could not easily be cultivated.

Cytotoxicity of mycotoxins evaluated by the MTT-cell culture assay

The application of a modified colorimetric bioassay for the evaluation of the biological effects of mycotoxins is reported. Using three different monolayer cell lines (swine kidney, Madin Darby canine kidney, HeLa) the influence of nine different mycotoxins on the cellular methylthiazoltetrazolium (MTT)-cleavage activity was evaluated. The yellow tetrazolium salt MTT is converted by mitochondrial dehydrogenases of metabolically active cells to an insoluble purple formazan product, which was then solubilized with dimethylsulfoxide. The optical density of this homogeneous solution was suitable for a precise spectrophotometric measurement by a plate reader at a wavelength of 510 nm. Nine mycotoxins were simultaneously tested in all three cell lines, from which the swine kidney cell line proved to be the most sensitive. The effects of additional 35 mycotoxins were therefore tested using swine kidney monolayers as target cells. A total of 28 toxins of the 44 mycotoxins tested proved to be cytotoxic in the MTT-bioassay. Most of them belong to the group of trichothecene mycotoxins. Concentrations ranged between 0.01 micrograms and 100 micrograms/ml of cell culture medium. The MTT cleavage assay was found to be a quick (24 hours) and easy to perform system for the evaluation of the biological activity of many different mycotoxins and may also provide a useful tool for the testing of a large variety of sample materials.

[Effect of the fungicide matador (tebuconazole/triadimenol) on mycotoxin production by Fusarium culmorum]

Applications of the fungicide Matador to winter wheat (Slejpner) inoculated at earing with Fusarium culmorum resulted in a considerable decrease in the incidence of Fusarium headblight. In the study presented here, subsequent mycotoxin analyses by selected ion monitoring gas chromatography-mass spectrometry revealed higher levels of nivalenol (NIV) in samples singly treated with Matador at 1 L/ha. Amounts as high as 2432 micrograms NIV/kg and 860 micrograms NIV/kg, representing a 16- or six-fold increase as compared to controls, were found in wheat treated with the fungicide 3 h before or 24 h after inoculation of the grain with F. culmorum, respectively. In parallel, higher cytotoxic activities of these samples were obtained when testing crude sample extracts in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-cell culture bioassay using swine kidney monolayers as target cells. It is concluded that treatment of grain with the fungicide Matador could result in a marked stimulation of the production of NIV by F. culmorum. As the incidence of Fusarium headblight did not correlate with the amount of mycotoxins found, the need for mycotoxin analyses combined with bioassays such as the MTT-cell culture assay is recommended for a meaningful assessment of the quality of grain treated in such a manner.

In vitro transformation of the Fusarium mycotoxins deoxynivalenol and zearalenone by the normal gut microflora of pigs

The biotransformation of the Fusarium mycotoxins deoxynivalenol and zearalenone by the normal bacterial gut flora of pigs was examined in this in vitro study. For that purpose, suspensions of intestinal contents (duodenum, jejunum, caecum, colon, rectum) of porcine origin were incubated anaerobically with deoxynivalenol (DON) or zearalenone (ZEA). DON and ZEA were degraded by the flora of the caudal segments (caecum, colon, rectum) of the gut--particularly the colon content--whereas the microorganisms of the cranial segments (duodenum, jejunum) exhibited no transforming activity. DON was showed to be deepoxidated, ZEA was hydrolyzed to alpha-zearalenol and an unknown metabolite. The transformation of DON was correlated with a loss of cytotoxicity, which could be demonstrated in the MTT(3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium++ + bromide)-cell-culture assay using swine kidney cells as target cells. The results of the study presented here correspond with the data found in in vivo studies. On the basis of these findings one could conclude that this in vitro method seems to be well suited to the study of the transformation of mycotoxins by the microflora of the gut. The in vitro study is cheaper than a feeding trial, and the preliminary information on the metabolism of mycotoxins obtained in such studies is helpful in designing feeding trials more clearly. Besides the simple and fast handling, reproducibility and the protection of the animals studied are further advantages of this in vitro method. In connection with the MTT-cell-culture assay, additional information about the cytotoxic potential of the bacterial transformation products can be obtained.

Use of liposomes, viral capsids, and nanoparticles as DNA carriers

We tested a variety of liposomes for parameters such as DNA binding capacity and DNase I protection of incorporated and attached DNA to elucidate their use as vehicles for DNA transfer into cells and animals. The results were compared to other potential DNA vehicles, empty viral capsids, and nanoparticles. Maximal binding capacity was achieved for positively charged nanoparticles, DNase I protection was observed for most preparations with neosome preparations being least efficient. The uptake of radiolabeled DNA by cells in culture was determined for cationic and nonionic surfactant vesicles, viral capsids, and nanoparticles. Cellular DNA uptake was best for dioleoyl-derived positively charged liposomes (N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride; DOTMA) and the DNA could be shown to be physiologically active. The recombination rate for DNA fragments transfected in polyoma capsids in live mice was higher than for liposome mediated transfection. Homologous recombination could be observed for both DOTMA and polyoma-mediated DNA transfer.

Use of primer pools for specific gene amplification

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Cleavage of zearalenone-glycoside, a "masked" mycotoxin, during digestion in swine

Comparative analyses of cereal samples pretreated with or without beta-glucosidase indicate the presence of zearalenone-glycoside. To examine the stability of zearalenone-glycoside during digestion, mixed feed was artificially contaminated with synthesized zearalenone-4-beta-D-glucopyranoside (395 micrograms/kg) and fed to a pig over a period of 14 days. The metabolites detected in feces and urine samples were zearalenone and alpha-zearalenol. These results demonstrate that zearalenone-4-beta-D-glucopyranoside is decomposed during digestion and the aglucone, zearalenone, is released. Since zearalenone-glycoside is not detected during routine analysis, but hydrolysed during digestion, it seems likely that such "masked mycotoxins" are involved in cases of mycotoxicoses.

Isolation of a mycotoxin (gliotoxin) from a bovine udder infected with Aspergillus fumigatus

A bovine udder infected with Aspergillus fumigatus was analysed by physico-chemical methods (thin layer chromatography, high performance liquid chromatography and direct exposure probe-mass spectrometry) for the presence of mycotoxins. Gliotoxin, a fungal metabolite with cytotoxic and immunosuppressive properties was isolated for the first time from naturally infected tissue. The gliotoxin concentration analysed (9.2 mg kg-1 udder) was approximately 100 times higher than the concentration known to produce morphological changes of cells. Gliotoxin may play an important role in the establishment and development of an infection with A fumigatus.

Metabolism of T-2 toxin in vascularly autoperfused jejunal loops of rats

The intestinal metabolism of T-2 toxin, a major trichothecene mycotoxin, was investigated in rats using the method of the vascularly autoperfused jejunal loop in situ. Tritium-labeled T-2 toxin was injected into the tied-off intestinal segments at a dose of 5 or 500 nmol, respectively. T-2 toxin and its metabolites in the blood draining from the jejunal loops, in the intestinal lumen, and in the intestinal tissue were determined by HPLC and GLC-MS. There was an extensive metabolic degradation of T-2 toxin, the metabolite pattern being similar for the two dosage levels. During the experimental period of 50 min only some 2% of the total dose appeared in the effluent plasma as unchanged T-2 toxin. Likewise at the end of the experiments unchanged T-2 toxin in the intestinal lumen and tissue was present in minute amounts only (less than 1% of the dose). HT-2 toxin was the main metabolite. About 25% of the total radioactivity administered appeared in the effluent plasma as HT-2 toxin, 18% in the lumen and 10% in the tissue. 3'-OH-HT-2 toxin accounted for 4-7% (effluent plasma), 5% (lumen), and 2% (tissue) of the total dose. Furthermore small amounts (less than 2% of the dose) of 3'-OH-T-2 toxin, T-2 tetraol, and 4-deacetylneosolaniol were found. No glucuronide or sulfate conjugates could be detected. In the jejunal segments which had been exposed to the 5-nmol dose only minimal morphological alterations were observed. On the other hand, in jejunal segments exposed to the high dose marked tissue damage was present. Nevertheless the gut tissue retained its ability to metabolize T-2 toxin. From the present results it is concluded that T-2 toxin is subject to a marked presystemic first pass effect after oral ingestion in vivo.

[Determination of ochratoxin A in human milk]

A method for the determination of ochratoxin A in milk is described. The milk is homogenized in a buffer solution at pH 1.6 to release ochratoxin A from its bond to proteins. Ochratoxin A is extracted with chloroform and the extract cleaned up using a base clean-up step. Analysis is performed by high-pressure liquid chromatography, using a reversed-phase column and fluorescence detection. The detection limit of the method is 0.1 ng/ml and the average recovery rate, tested in the range between 0.5 and 10.0 ng/ml, was found to be 83.1%. Chemical ionization mass spectrometry (direct exposure probe) and an enzyme immunoassay were used as confirmatory tests. Using this method, trace amounts of ochratoxin A were found in 4 of 36 randomly collected human milk samples.

Enzyme immunoassay for the macrocyclic trichothecene roridin A: production, properties, and use of rabbit antibodies

Antisera against roridin A were prepared by using a roridin A-hemisuccinate derivative coupled to human serum albumin as the immunogen. Antibodies could be detected in the sera of the immunized rabbits as early as 4 weeks after the initial exposure. After one booster injection at week 14, high antibody titers were measured over a period of 21 weeks. The specificity and sensitivity of the antibodies were tested by using roridin A-hemisuccinate coupled to horseradish peroxidase as an enzyme-linked toxin in a competitive assay with a double-antibody solid phase. The assay was most specific for the tested macrocyclic trichothecenes, and the relative cross-reactivities with roridin A, roridin J, verrucarin A, satratoxin H, and satratoxin G were 1, 0.41, 0.15, 0.15, and 0.07, respectively. When 16 nonmacrocyclic trichothecenes were tested, only diacetylverrucarol (0.0015) and verrucarol (0.0005) showed minor cross-reactivity. The sensitivity of the enzyme immunoassay for the detection of roridin A was in the range of 5 to 50 ng/ml (0.16 to 1.6 ng per assay).

Identification of glucuronide metabolites of T-2 toxin and diacetoxyscirpenol in the bile of isolated perfused rat liver

Isolated rat livers were perfused with either 2 mg T-2 toxin or diacetoxyscirpenol (DAS) in a recirculating perfusion system. To identify glucuronide conjugates, equal amounts of bile samples were incubated with and without (control) a beta-glucuronidase preparation and analyzed by capillary gas liquid chromatography-chemical ionization mass spectrometry. Enzyme treatment of bile obtained from liver perfused with T-2 toxin resulted in the detection of a total of 954 micrograms HT-2 toxin (control 6 micrograms), demonstrating that excretion into the bile was mainly as glucuronide conjugates. Minor metabolites of T-2 toxin in bile were identified as 3'-hydroxy HT-2 toxin (TC-3), 3'-hydroxy-7-hydroxy HT-2 toxin (TC-6), and the glucuronide form of T-2 triol (trace amount). The glucuronide conjugates of monoacetoxyscirpenol (340 micrograms) and scirpenetriol (10 micrograms) were found in bile obtained from liver perfused with DAS, while nonconjugated metabolites were not detected. It is assumed that considerable amounts of T-2 toxin and DAS were metabolized biphasically. In phase I both trichothecenes were deacetylated, in phase II the metabolites were conjugated giving rise to the glucuronic acid adducts.

Kinetic profiles of diacetoxyscirpenol and two of its metabolites in blood serum of pigs

Orally administered diacetoxyscirpenol (2 mg/kg of body weight) was rapidly absorbed into the blood serum of pigs; within 1 h, the highest amounts of diacetoxyscirpenol (9.6 to 21.9 ng/ml) were detected. Two metabolites of diacetoxyscirpenol were identified by gas chromatography-mass spectroscopy as monoacetoxyscirpenol and scirpenetriol. The three trichothecenes were present in the blood serum of pigs for only 24 h, indicating a rapid metabolism of these compounds.

Stimulation of aflatoxin B1 and T-2 toxin production by sorbic acid

Aspergillus flavus grown on yeast extract-sucrose medium produced higher amounts of aflatoxin B1 in the presence of 0.025% sorbic acid than without this chemical with a maximum at 17 days of incubation. Addition of 0.05 to 0.0125% sorbic acid stimulated T-2 toxin production of Fusarium acuminatum cultures grown on maize meal. The highest amounts of the mycotoxin were detected in 14-day-old cultures containing 0.025% sorbic acid. It is assumed that certain amounts of sorbic acid near the minimal inhibitory concentration reduce the activity of the tricarboxylic acid cycle; this may lead to an accumulation of acetyl coenzyme A, which is an essential intermediate in the biosynthesis of aflatoxin B1 and T-2 toxin.