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M Gareis

Publications and source records attributed to M Gareis.

30 records · Page 2Linked to original sources
PubMed1988

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.

Animals↗
PubMed1988

[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.

Chromatography, High Pressure Liquid↗
PubMed1988

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).

Animals↗
PubMed1987

[Changes in the genital tract of female swine after feeding with practice-relevant amounts of zearalenone].

Zearalenone is one of the most frequent, naturally occurring mycotoxins in feedstuffs: 13.9% of 710 samples analyzed contained zearalenone in concentrations of 1.0 to 1,725 micrograms/kg. Trial feeding with female pigs demonstrated that a zearalenone concentration of 250 micrograms/kg feed produced distinct redness and swelling of the vulva, slight swelling of the mamma and numerous vesicular follicles and some cystic follicles on the ovaria. The symptoms on the external genital tract were not observed when the zearalenone concentration in the feedstuff, was 50 micrograms/kg but the section also established that vesicular follicles on the ovaria of these animals were more frequent than on the ovaria of the control animal.

Animal Feed↗
PubMed1986

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.

Animals↗
PubMed1985

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.

Animals↗
PubMed1985

[Fusarium toxins in feed. Detection and occurrence of trichothecenes].

Mycotoxicoses have been recognized worldwide to cause problems in animal production. Trichothecene mycotoxins, for the most part produced by Fusarium spp., have obtained particular importance. Between 1982 and 1984, 295 samples of feedstuffs (cereals and mixed feeds) have been analyzed on natural occurrence of type-A trichothecenes. The skin toxicity test with guinea pigs was used as a screening method. Analysis of trichothecenes by capillary gaschromatography with flame ionization detection was complicated by interfering substances from the complex matrix of the sample-material. Definite results were only obtained by the use of gaschromatography-mass spectrometry. In comparison to the electron impact ionization the chemical ionization technique showed to be advantageous. Forty-two of the 295 samples analyzed were found to be positive in the biological assay. Nine of these positive samples contained trichothecenes as determined by mass spectrometry: T-2 toxin in mixed feed (65 micrograms/kg); oats (80 and 86 micrograms/kg) and wheat (100 micrograms/kg); diacetoxyscirpenol in mixed feed (125 micrograms/kg) and wheat (50 micrograms/kg); neosolaniol in oats (310 and 350 micrograms/kg); HT-2 toxin in oats (700 micrograms/kg). Oats proved to be contaminated more frequently as compared to the other cereals and the analyzed mixed feeds.

Animal Feed↗
PubMed1984

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.

Aflatoxin B1↗
PubMedDate not supplied

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.

Androstadienes↗
PubMedDate not supplied

[Analytical methods for mycotoxins].

Biological, physico-chemical and immunochemical methods are available today for solving the multiple problems which turn up in the course of mycotoxin diagnosis and mycotoxin research. In this review, selected analysis techniques are presented and their limits and possibilities are discussed. The biological methods (chicken-embryo-test, skin irritation test, cell cultures) indicate only toxicities, mostly without further specification for mycotoxins. In contrast, modern physico-chemical analysis (DC, HPLC, CLC, MS) allows the detection of defined mycotoxins in the picogram range; these methods should be employed or official and judicial purposes. The recently developed immunochemical methods (RIA, EIA) are characterized by a simple sample preparation, a short test duration and a high sensitivity; they could be used as a screening method in the course of mycotoxicological control of food and feed.

Animal Feed↗