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Your search keyword '"Harwig J"' showing total 22 results
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22 results on '"Harwig J"'

2. Brine Shrimp (Artemia salinaL.) Larvae as a Screening System for Fungal Toxins

Author

Harwig, J. and Scott, P. M.

Abstract

Concentrations resulting in 50% mortality, determined with brine shrimp (Artemia salinaL.) larvae exposed to known mycotoxins for 16 hr, were (μg/ml): aflatoxin G1, 1.3; diacetoxyscirpenol, 0.47; gliotoxin, 3.5; ochratoxin A, 10.1; and sterigmatocystin, 0.54. 4-Acetamido-4-hydroxy-2-butenoic acid γ-lactone gave no mortality at 10 μg/ml. Used as a screening system involving discs saturated with solutions of known mycotoxins, the larvae were relatively sensitive to aflatoxin B1, diacetoxyscirpenol, gliotoxin, kojic acid, ochratoxin A, rubratoxin B, sterigmatocystin, stemphone, and T-2 toxin. Quantities of 0.2 to 2 μg/disc caused detectable mortality. The larvae were only moderately sensitive to citrinin, patulin, penicillic acid, and zearalenone which were detectable at 10 to 20 μg/disc. They were relatively insensitive to griseofulvin, luteoskyrin, oxalic acid, and β-nitropropionic acid. The disc screening method indicated that 27 out of 70 fungal isolates from foods and feeds grown in liquid or solid media produced chloroform-extractable toxic material. Examination of toxic extracts by thin-layer chromatography for 17 known mycotoxins showed that the toxicity of eight isolates could be attributed to aflatoxin B1and B2, kojic acid, zearalenone, T-2 toxin, or ochratoxin A. Nine out of 32 of these fungal isolates grown in four liquid media yielded toxic culture filtrates from at least one medium. Chemical tests for kojic, oxalic, and β-nitropropionic acids showed the presence of one or two of these compounds in filtrates of seven of these nine isolates.

Published
1971
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3. A link between Reye's syndrome and aflatoxins?

Author

Harwig, J., Przybylski, W., and Moodie, C. A.

Subjects
Brain Diseases, Canada, Adolescent, Reye Syndrome, Infant, Thailand, Aflatoxins, Child, Preschool, Animals, Humans, Macaca, Autopsy, Child, Research Article
Published
1975

15. Fibrinogen uptake by thrombi: effect of thrombus age.

Author

Coleman RE, Harwig SS, Harwig JF, Siegel BA, and Welch MJ

Subjects
Animals, Dogs, Iodine Radioisotopes, Time Factors, Fibrinogen metabolism, Thrombophlebitis metabolism
Abstract

The uptake of radiolabeled fibrinogen in canine thrombi was determined at varying times after thrombus induction by electric current. The greatest thrombus/blood ratio was achieved when fibrinogen was administered 4 hr after thrombus induction but definite thrombus fibrinogen uptake was still observed when the tracer was administered up to 72 hr after thrombus induction. There was continued fibrinogen accumulation despite a decrease in weight of older thrombi suggesting that net thrombus propagation is not necessary for labeled fibrinogen uptake. Our results suggest that the fibrinogen uptake test may be useful for the diagnosis of deep vein thrombosis for several days after the onset of thrombosis.

Published
1975

16. Highly iodinated fibrinogen: a new thrombus-localizing agent.

Author

Harwig JF, Coleman RE, Harwig SS, Sherman LA, Siegel BA, and Welch MJ

Subjects
Animals, Dogs, Electrolysis, Hydrogen-Ion Concentration, Isotope Labeling, Methods, Molecular Weight, Fibrinogen isolation & purification, Fibrinogen metabolism, Iodine Radioisotopes, Radionuclide Imaging, Thrombosis diagnosis
Abstract

We have examined radioiodinated fibrinogen prepared at high levels of iodination as an agent for improved in vivo thrombus detection. Fibrinogen containing 25, 50, and 100 atoms of iodine per molecule is prepared by an electrolytic procedure and is compared with conventional radiolabeled fibrinogen (less than 0.5 iodine atom per molecule) prepared by the iodine monochloride method. The level of iodination has little effect on the isotopic clottability of the product, but its degree of aggregation and its rate of blood clearance in experimental animals is strongly dependent on iodination level. Isotopic thrombus: blood ratios obtained in recently induced thrombi with the 25 atom per molecule preparation average about 50:1, twice as high as the ratios obtained with conventionally labeled fibrinogen.

Published
1975

17. A link between Reye's syndrome and aflatoxins?

Author

Harwig J, Przybylski W, and Moodie CA

Subjects
Adolescent, Animals, Autopsy, Canada, Child, Child, Preschool, Humans, Infant, Macaca, Reye Syndrome pathology, Thailand, Aflatoxins poisoning, Brain Diseases chemically induced, Reye Syndrome chemically induced
Published
1975

18. Formation of diketopiperazines by Penicillium italicum isolated from oranges.

Author

Scott PM, Kennedy BP, Harwig J, and Chen YK

Subjects
Chemical Phenomena, Chemistry, Chromatography, Thin Layer, Hesperidin biosynthesis, Mass Spectrometry, Penicillium isolation & purification, Plant Diseases, Plants microbiology, Species Specificity, Spectrophotometry, Infrared, Spectrophotometry, Ultraviolet, Citrus, Penicillium metabolism, Piperazines biosynthesis
Abstract

Prolyl-2-(1',1'-dimethylallyl)tryptophyldiketopiperazine and 12,13-dehydroprolyl-2-(1',1'-dimethylallyl)tryptophyldiketopiperazine, known metabolites of Aspergillus ustus, were produced in low yield by Penicillium italicum in liquid culture and on unsterilized orange peel.

Published
1974
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19. Mycotoxins of possible importance in diseases of Canadian farm animals.

Author

Harwig J and Munro IC

Subjects
Aflatoxins toxicity, Animals, Canada, Cattle, Cattle Diseases chemically induced, Chickens, Citrinin toxicity, Female, Fetal Death veterinary, Kidney Diseases veterinary, Male, Ochratoxins toxicity, Patulin toxicity, Penicillic Acid toxicity, Poultry Diseases chemically induced, Pregnancy, Sheep, Sheep Diseases chemically induced, Swine, Swine Diseases chemically induced, Trichothecenes toxicity, Vulvovaginitis veterinary, Zearalenone toxicity, Animals, Domestic, Mycotoxins toxicity
Published
1975

21. Toxicity and excretion of ochratoxin A in rats intubated with pure ochratoxin A or fed cultures of Penicillium viridicatum.

Author

Van Walbeek W, Moodie CA, Scott PM, Harwig J, and Grice HC

Subjects
Animals, Chromatography, Thin Layer, Culture Media, Diet, Edible Grain, Feces analysis, Intubation, Kidney metabolism, Kidney pathology, Liver metabolism, Liver pathology, Male, Ochratoxins metabolism, Ochratoxins toxicity, Ochratoxins urine, Rats, Rats, Inbred Strains, Coumarins toxicity, Mycotoxins toxicity, Penicillium pathogenicity
Published
1971

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